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1.
Arq. bras. cardiol ; 118(2): 463-475, 2022. tab, graf
Article in English, Portuguese | LILACS | ID: biblio-1364328

ABSTRACT

Resumo Fundamento O remodelamento cardíaco patológico se caracteriza por disfunção diastólica e sistólica, levando à insuficiência cardíaca. Neste contexto, o cenário disfuncional do trânsito de cálcio miocárdico (Ca2+) tem sido pouco estudado. Um modelo experimental de estenose aórtica tem sido extensamente utilizado para aprimorar os conhecimentos sobre os principais mecanismos do remodelamento patológico cardíaco. Objetivo Entender o processo disfuncional dos principais componentes responsáveis pelo equilíbrio do cálcio miocárdico e sua influência sobre a função cardíaca na insuficiência cardíaca induzida pela estenose aórtica. Métodos Ratos Wistar de 21 dias de idade foram distribuídos em dois grupos: controle (placebo; n=28) e estenose aórtica (EaO; n=18). A função cardíaca foi analisada com o ecocardiograma, músculo papilar isolado e cardiomiócitos isolados. No ensaio do músculo papilar, SERCA2a e a atividade do canal de Ca2+ do tipo L foram avaliados. O ensaio de cardiomiócitos isolados avaliou o trânsito de cálcio. A expressão proteica da proteínas do trânsito de cálcio foi analisada com o western blot. Os resultados foram estatisticamente significativos quando p <0,05. Resultados Os músculos papilares e cardiomiócitos dos corações no grupo EaO demonstraram falhas mecânicas. Os ratos com EaO apresentaram menor tempo de pico do Ca2+, menor sensibilidade das miofibrilas do Ca2+, prejuízos nos processos de entrada e recaptura de cálcio pelo retículo sarcoplasmático, bem como disfunção no canal de cálcio do tipo L (CCTL). Além disso, os animais com EaO apresentaram maior expressão de SERCA2a, CCTL e trocador de Na+/Ca2+. Conclusão Insuficiência cardíaca sistólica e diastólica devido à estenose aórtica supravalvular acarretou comprometimento da entrada de Ca2+ celular e inibição da recaptura de cálcio pelo retículo sarcoplasmático devido à disfunção no CCTL e SERCA2a, assim como mudanças no trânsito de cálcio e na expressão das principais proteínas responsáveis pela homeostase de Ca2+ celular.


Abstract Background Maladaptive cardiac remodelling is characterized by diastolic and systolic dysfunction, culminating in heart failure. In this context, the dysfunctional scenario of cardiac calcium (Ca2+) handling has been poorly studied. An experimental model of aortic stenosis has been extensively used to improve knowledge about the key mechanisms of cardiac pathologic remodelling. Objective To understand the dysfunctional process of the major components responsible for Ca2+ balance and its influence on cardiac function in heart failure induced by aortic stenosis. Methods Male 21-day-old Wistar rats were distributed into two groups: control (sham; n= 28) and aortic stenosis (AoS; n= 18). Cardiac function was analysed by echocardiogram, isolated papillary muscle, and isolated cardiomyocytes. In the papillary muscle assay, SERCA2a and L-type Ca2+ channel activity was evaluated. The isolated cardiomyocyte assay evaluated Ca2+ handling. Ca2+ handling protein expression was analysed by western blot. Statistical significance was set at p <0.05. Results Papillary muscles and cardiomyocytes from AoS hearts displayed mechanical malfunction. AoS rats presented a slower time to the Ca2+ peak, reduced Ca2+ myofilament sensitivity, impaired sarcoplasmic reticulum Ca2+ influx and reuptake ability, and SERCA2a and L-type calcium channel (LTCC) dysfunction. Moreover, AoS animals presented increased expression of SERCA2a, LTCCs, and the Na+/Ca2+ exchanger. Conclusion Systolic and diastolic heart failure due to supravalvular aortic stenosis was paralleled by impairment of cellular Ca2+ influx and inhibition of sarcoplasmic reticulum Ca2+ reuptake due to LTCC and SERCA2a dysfunction, as well as changes in Ca2+ handling and expression of the major proteins responsible for cellular Ca2+ homeostasis.


Subject(s)
Animals , Male , Rats , Aortic Valve Stenosis/pathology , Heart Failure/pathology , Papillary Muscles , Calcium/metabolism , Rats, Wistar , Myocytes, Cardiac/pathology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Myocardial Contraction/physiology
2.
Braz. J. Pharm. Sci. (Online) ; 55: e17742, 2019. graf
Article in English | LILACS | ID: biblio-1039072

ABSTRACT

The essential oil of the leaves of Eugenia sulcata, in the Myrtaceae family, has a demonstrated antihypertensive effect, but its effects on heart muscle and its toxicity have not yet been elucidated. Little chemical or biological data are available for E. sulcata, whether emphasizing the beneficial effects or the pharmacological security of this species. This study aims to evaluate myocardial contractility and to analyze angiotensin converting enzyme (ACE) and myosin ATPase activities associated with use of this essential oil. In addition, we evaluated the immunotoxicity of E. sulcata essential oil. Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were treated daily for 30 days (10 mg/kg of oil) to evaluate the isometric force of the papillary muscle, ACE measured by fluorimetry, and myosin ATPase activities by inorganic phosphate. Lymphocyte cultures were used to evaluate cytotoxicity, DNA damage, and mutagenicity of the essential oil. The results demonstrate that the treatment did not change the cardiac contraction force and did not alter the functioning of the sarcoplasmic reticulum, extrusion of the membrane calcium, or modify the membrane calcium channels or ß-adrenergic receptor activity. Tetanic contractions were potentiated in the SHR animals. Myosin ATPase activity was also increased in the SHR animals. Cardiac ACE activity was reduced in both animal strains, and the serum ACE was reduced only in the SHR animals. The essential oil did not cause cytotoxicity or mutagenicity and presented low DNA damage. Our results demonstrated that the essential oil does not change myocardial contractility and does not present relevant immunotoxicity


Subject(s)
Animals , Male , Rats , Plant Oils/adverse effects , Myrtaceae/adverse effects , Eugenia/adverse effects , Myocardial Contraction/physiology , Angiotensin-Converting Enzyme Inhibitors/immunology , Myocardial Contraction
3.
Arq. bras. cardiol ; 111(2): 172-179, Aug. 2018. tab, graf
Article in English | LILACS | ID: biblio-950219

ABSTRACT

Abstract Background: Regulation of intracellular calcium (Ca2+) in cardiomyocytes is altered by hypertension; and aerobic exercise brings benefits to hypertensive individuals. Objective: To verify the effects of aerobic exercise training on contractility and intracellular calcium (Ca2+) transients of cardiomyocytes and on the expression of microRNA 214 (miR-214) in the left ventricle of spontaneously hypertensive rats (SHR). Methods: SHR and normotensive Wistar rats of 16 weeks were divided into 4 groups -sedentary hypertensive (SH); trained hypertensive (TH); sedentary normotensive (SN); and trained normotensive (TN). Animals of the TH and TN groups were subjected to treadmill running program, 5 days/week, 1 hour/day at 60-70% of maximum running velocity for 8 weeks. We adopted a p ≤ 0.05 as significance level for all comparisons. Results: Exercise training reduced systolic arterial pressure in hypertensive rats. In normotensive rats, exercise training reduced the time to 50% cell relaxation and the time to peak contraction and increased the time to 50% decay of the intracellular Ca2+ transients. In SHR, exercise increased the amplitude and reduced the time to 50% decay of Ca2+ transients. Exercise training increased the expression of miR-214 in hypertensive rats only. Conclusion: The aerobic training applied in this study increased the availability of intracellular Ca2+ and accelerated the sequestration of these ions in left ventricular myocytes of hypertensive rats, despite increased expression of miR-214 and maintenance of cell contractility.


Resumo Fundamento: A regulação intracelular de cálcio (Ca2+) em cardiomiócitos é alterada pela hipertensão, e o exercício físico aeróbico traz benefícios para hipertensos. Objetivo: Verificar os efeitos do treinamento físico aeróbico sobre a contratilidade e a concentração intracelular de Ca2+ transitória em miócitos e a expressão do microRNA 214 no ventrículo esquerdo (VE) de ratos espontaneamente hipertensos (SHR). Métodos: SHR e ratos Wistar normotensos com 16 semanas de idade foram divididos em 4 grupos de 13 animais cada: hipertenso sedentário (HS); hipertenso treinado (HT); normotenso sedentário (NS); normotenso treinado (NT). Os animais dos grupos HT e NT foram submetidos a um programa de treinamento progressivo de corrida em esteira, 5 dias/semana, 1 hora/dia, em intensidade de 60-70% da velocidade máxima de corrida, durante 8 semanas. Adotou-se p ≤ 0,05 como nível de significância em todas as comparações. Resultados: O treinamento físico reduziu a pressão arterial sistólica nos animais hipertensos. Nos animais normotensos, o treinamento físico reduziu o tempo para 50% de relaxamento celular e o tempo para o pico de contração celular, mas aumentou o tempo para 50% de decaimento da concentração intracelular de Ca2+ transitória. Nos animais SHR, o treinamento físico aumentou a amplitude e reduziu o tempo para 50% de decaimento da concentração intracelular de Ca2+ transitória, sem alterar a contratilidade celular. O treinamento físico aumentou a expressão do miR-214 apenas nos animais hipertensos. Conclusão: O treinamento aeróbico utilizado aumenta a disponibilidade e acelera o sequestro de Ca2+ intracelular em miócitos do VE de ratos hipertensos, apesar do aumento da expressão de miR-214 e da manutenção da contratilidade celular.


Subject(s)
Animals , Rats , Physical Conditioning, Animal/physiology , Blood Pressure/physiology , Calcium/metabolism , Myocytes, Cardiac/metabolism , Hypertension/metabolism , Myocardial Contraction/physiology , Rats, Inbred SHR , Calcium Signaling , Myocytes, Cardiac/physiology , MicroRNAs/metabolism , Hypertension/physiopathology
4.
Arq. bras. cardiol ; 110(4): 383-387, Apr. 2018. tab
Article in English | LILACS | ID: biblio-1038530

ABSTRACT

Abstract The study of myocardial contractility, based on the new anatomical concepts that govern cardiac mechanics, represents a promising strategy of analysis of myocardial adaptations related to physical training in the context of post-infarction. We investigated the influence of aerobic training on physical capacity and on the evaluation parameters of left ventricular contraction mechanics in patients with myocardial infarction. Thirty-one patients (55.1 ± 8.9 years) who had myocardial infarction in the anterior wall were prospectively investigated in three groups: interval training group (ITG) (n = 10), moderate training group (MTG) n = 10) and control group (CG) (n = 10). Before and after 12 weeks of clinical follow-up, patients underwent cardiopulmonary exercise testing and cardiac magnetic resonance imaging. The trained groups performed supervised aerobic training on treadmill, in two different intensities. A statistically significant increase in peak oxygen uptake (VO2) was observed in the ITG (19.2 ± 5.1 at 21.9 ± 5.6 ml/kg/min, p < 0.01) and in the MTG 18.8 ± 3.7 to 21.6 ± 4.5 ml/kg/min, p < 0.01). The GC did not present a statistically significant change in peak VO2. A statistically significant increase in radial strain (STRAD) was observed in the CG: basal STRAD (57.4 ± 16.6 to 84.1 ± 30.9%, p < 0.05), medial STRAD (57.8 ± 27, 9 to 74.3 ± 36.1%, p < 0.05) and apical STRAD (38.2 ± 26.0 to 52.4 ± 29.8%, p < 0.01). The trained groups did not present a statistically significant change of the radial strain. The present study points to a potential clinical application of the parameters of ventricular contraction mechanics analysis, especially radial strain, to discriminate post-infarction myocardial adaptations between patients submitted or not to aerobic training programs.


Resumo O estudo da contratilidade miocárdica, baseado nos novos conceitos anatômicos que regem a mecânica cardíaca, representa uma estratégia promissora de análise das adaptações do miocárdio relacionadas ao treinamento físico no contexto do pós-infarto. Nós investigamos a influência do treinamento aeróbico na capacidade física e nos parâmetros de avaliação da mecânica de contração do ventrículo esquerdo em pacientes com infarto do miocárdio. Foram prospectivamente investigados 30 pacientes, 55,1 ± 8,9 anos, acometidos por infarto do miocárdio de parede anterior, aleatorizados em três grupos: grupo treinamento intervalado (GTI) (n = 10), grupo treinamento moderado (GTM) (n=10) e grupo controle (GC) (n = 10). Antes e após as 12 semanas de seguimento clínico, os pacientes realizaram teste cardiopulmonar de exercício e ressonância magnética cardíaca. Os grupos treinados realizaram treinamento aeróbico supervisionado, em esteira ergométrica, aplicando-se duas intensidades distintas. Observou-se aumento estatisticamente significante do consumo de oxigênio (VO2) pico no GTI (19,2 ± 5,1 para 21,9 ± 5,6 ml/kg/min, p < 0,01) e no GTM (18,8 ± 3,7 para 21,6 ± 4,5 ml/kg/min, p < 0,01). O GC não apresentou mudança estatisticamente significante no VO2 pico. Houve aumento estatisticamente significante do strain radial (STRAD) somente no GC: STRAD basal (57,4 ± 16,6 para 84,1 ± 30,9%, p < 0,05), STRAD medial (57,8 ± 27,9 para 74,3 ± 36,1%, p < 0,05) e STRAD apical (38,2 ± 26,0 para 52,4 ± 29,8%, p < 0,01). Os grupos treinados não apresentaram mudança estatisticamente significante do strain radial. Os achados do presente estudo apontam para uma potencial aplicação clínica dos parâmetros de análise da mecânica de contração ventricular, notadamente do strain radial, em discriminar adaptações do miocárdio pós-infarto entre pacientes submetidos ou não a programas de treinamento aeróbico.


Subject(s)
Humans , Middle Aged , Exercise/physiology , Ventricular Function, Left/physiology , Exercise Therapy/methods , Myocardial Contraction/physiology , Myocardial Infarction/physiopathology , Myocardial Infarction/rehabilitation , Oxygen Consumption/physiology , Time Factors , Blood Pressure/physiology , Pilot Projects , Prospective Studies , Reproducibility of Results , Treatment Outcome , Statistics, Nonparametric , Exercise Test/methods , Heart Rate/physiology , Heart Ventricles/physiopathology
5.
Arq. bras. cardiol ; 110(3): 256-262, Mar. 2018. tab, graf
Article in English | LILACS | ID: biblio-888032

ABSTRACT

Abstract Background: The lack of cardiac β1-adrenergic receptors (β1-AR) negatively affects the regulation of both cardiac inotropy and lusitropy, leading, in the long term, to heart failure (HF). Moderate-intensity aerobic exercise (MCAE) is recommended as an adjunctive therapy for patients with HF. Objective: We tested the effects of MCAE on the contractile properties of left ventricular (LV) myocytes from β1 adrenergic receptor knockout (β1ARKO) mice. Methods: Four- to five-month-old male wild type (WT) and β1ARKO mice were divided into groups: WT control (WTc) and trained (WTt); and β1ARKO control (β1ARKOc) and trained (β1ARKOt). Animals from trained groups were submitted to a MCAE regimen (60 min/day; 60% of maximal speed, 5 days/week) on a treadmill, for 8 weeks. P ≤ 0.05 was considered significant in all comparisons. Results: The β1ARKO and exercised mice exhibited a higher (p < 0.05) running capacity than WT and sedentary ones, respectively. The β1ARKO mice showed higher body (BW), heart (HW) and left ventricle (LVW) weights, as well as the HW/BW and LVW/BW than WT mice. However, the MCAE did not affect these parameters. Left ventricular myocytes from β1ARKO mice showed increased (p < 0.05) amplitude and velocities of contraction and relaxation than those from WT. In addition, MCAE increased (p < 0.05) amplitude and velocities of contraction and relaxation in β1ARKO mice. Conclusion: MCAE improves myocyte contractility in the left ventricle of β1ARKO mice. This is evidence to support the therapeutic value of this type of exercise training in the treatment of heart diseases involving β1-AR desensitization or reduction.


Resumo Fundamento: A falta de receptores β1-adrenérgicos (β1-AR) cardíacos afeta negativamente a regulação de inotropismo e lusitropismo cardíacos, levando, no longo prazo, a insuficiência cardíaca (IC). Recomenda-se exercício aeróbico contínuo de intensidade moderada (EACM) como adjuvante no tratamento de pacientes com IC. Objetivo: Testar os efeitos do EACM nas propriedades contráteis de miócitos do ventrículo esquerdo (VE) de camundongos com nocaute para o receptor β1-adrenérgico (β1ARKO). Método: Camundongos machos com 4 a 5 meses de idade, wild-type (WT) e β1ARKO foram divididos em grupos: WT controle (WTc) e treinado (WTt); e β1ARKO controle (β1ARKOc) e treinado (β1ARKOt). Os grupos treinados foram submetidos a regime de EACM (60 min/dia; 60% da velocidade máxima, 5 dias/semana) em esteira rolante, por 8 semanas. Adotou-se P ≤ 0,05 como nível de significância em todas as comparações. Resultados: Os animais β1ARKO (β1ARKOc + β1ARKOt) correram uma distância maior do que os animais WT (WTc + WTt) (p < 0,05). Os camundongos β1ARKO apresentaram maiores pesos corporal (PC), do coração (PCo) e do ventrículo esquerdo (PVE), assim como PCo/PC e PVE/PC do que os camundongos WT. Entretanto, o EACM não afetou tais parâmetros. Os miócitos do VE de camundongos β1ARKO apresentaram maiores (p < 0,05) amplitude e velocidades de contração e relaxamento do que os dos camundongos WT. Além disso, o EACM aumentou (p < 0,05) a amplitude e as velocidades de contração e relaxamento nos camundongos β1ARKO. Conclusão: O EACM melhora a contratilidade do miócito do VE de camundongos β1ARKO. Tal achado confirma o valor terapêutico desse tipo de treinamento físico para o tratamento de doenças cardíacas envolvendo dessensibilização ou redução de β1-AR.


Subject(s)
Animals , Male , Rats , Physical Conditioning, Animal/physiology , Physical Conditioning, Animal/methods , Ventricular Function, Left/physiology , Receptors, Adrenergic, beta-1/physiology , Myocytes, Cardiac/physiology , Myocardial Contraction/physiology , Time Factors , Reproducibility of Results , Mice, Knockout , Exercise Test/methods , Exercise Therapy/methods , Heart Failure/physiopathology
6.
Rev. bras. cir. cardiovasc ; 32(4): 276-282, July-Aug. 2017. tab
Article in English | LILACS | ID: biblio-897928

ABSTRACT

Objective: The objective of our study was to determine the feasibility of early extubation and to identify the risk factors for delayed extubation in pediatric patients operated for ventricular septal defect closure. Methods: A prospective, observational study was carried out at our Institute. This study involved consecutive 135 patients undergoing ventricular septal defect closure. Patients were extubated if feasible within six hours after surgery. Based on duration of extubation, patients were divided two groups: Group 1= extubation time ≤ 6 hours, Group 2= extubation time >6 hours. Results: A total of 99 patients were in Group 1 and 36 patients in Group 2. Duration of ventilation was 4.4±0.9 hours in Group 1 and 25.9±24.9 hours in Group 2 (P<0.001). Univariate analysis showed that young age, low weight, low partial pressure of oxygen, trisomy 21, multiple ventricular septal defect, high vasoactive inotropic score, transient heart block and low cardiac output syndrome were associated with delayed extubation. However, regression analysis revealed that only trisomy 21 (OR: 0.248; 95%CI: 0.176-0.701; P=0.001), low cardiac output syndrome (OR: 0.291; 95%CI: 0.267-0.979; P=0.001), multiple ventricular septal defect (OR: 0.243; 95%CI: 0.147-0.606; P=0.002) and vasoactive inotropic score (OR: 0.174 95%CI: 0.002-0.062; P=0.039) are strongest predictors for delayed extubation. Conclusion: Trisomy 21, low cardiac output syndrome, multiple ventricular septal defect and high vasoactive inotropic score are significant risk factors for delay in extubation. Age, weight, pulmonary artery hypertension, size of ventricular septal defect, aortic cross-clamp and cardiopulmonary bypass time did not affect early extubation.


Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Perioperative Care/standards , Airway Extubation/standards , Heart Septal Defects, Ventricular/surgery , Time Factors , Cardiac Output, Low/complications , Feasibility Studies , Prospective Studies , Risk Factors , Down Syndrome/complications , Heart Septal Defects, Ventricular/complications , Heart Septal Defects, Ventricular/rehabilitation , Myocardial Contraction/physiology
7.
Arq. bras. cardiol ; 108(5): 443-451, May 2017. tab, graf
Article in English | LILACS | ID: biblio-838732

ABSTRACT

Abstract Background: Cardiovascular diseases are the leading cause of mortality and long-term disability worldwide. Various studies have suggested a protective effect of lactation in reducing the risk of cardiovascular diseases. Objective: This study was designed to assess the effects of pregnancy and lactation on the vulnerability of the myocardium to an ischemic insult. Methods: Eighteen female rats were randomly divided into three groups: ischemia-reperfusion (IR), in which the hearts of virgin rats underwent IR (n = 6); lactating, in which the rats nursed their pups for 3 weeks and the maternal hearts were then submitted to IR (n = 6); and non-lactating, in which the pups were separated after birth and the maternal hearts were submitted to IR (n = 6). Outcome measures included heart rate (HR), left ventricular developed pressure (LVDP), rate pressure product (RPP), ratio of the infarct size to the area at risk (IS/AAR %), and ventricular arrhythmias - premature ventricular contraction (PVC) and ventricular tachycardia (VT). Results: The IS/AAR was markedly decreased in the lactating group when compared with the non-lactating group (13.2 ± 2.5 versus 39.7 ± 3.5, p < 0.001) and the IR group (13.2 ± 2.5 versus 34.0 ± 4.7, p < 0.05). The evaluation of IR-induced ventricular arrhythmias indicated that the number of compound PVCs during ischemia, and the number and duration of VTs during ischemia and in the first 5 minutes of reperfusion in the non-lactating group were significantly (p < 0.05) higher than those in the lactating and IR groups. Conclusion: Lactation induced early-onset cardioprotective effects, while rats that were not allowed to nurse their pups were more susceptible to myocardial IR injury.


Resumo Fundamento: As doenças cardiovasculares são a principal causa de mortalidade e invalidez a longo prazo a nível mundial. Diversos estudos têm sugerido um efeito protetor da lactação na redução do risco para doenças cardiovasculares. Objetivo: Este estudo foi desenvolvido para avaliar os efeitos da gestação e da lactação sobre a vulnerabilidade do miocárdio ao insulto isquêmico. Métodos: Dezoito ratas foram divididas aleatoriamente em três grupos: isquemia-reperfusão (IR), no qual os corações de ratas virgens foram submetidos à IR (n = 6); lactantes, no qual as ratas amamentaram seus filhotes por 3 semanas e os corações maternos foram, em seguida, submetidos à IR (n = 6); e não lactantes, no qual os filhotes foram separados após o nascimento e os corações maternos foram submetidos à IR (n = 6). As medidas de desfecho incluíram frequência cardíaca (FC), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), razão do tamanho do infarto sobre a área sob risco (TI/ASR %) e arritmias ventriculares - contração ventricular prematura (CVP) e taquicardia ventricular (TV). Resultados: O TI/ASR foi substancialmente menor no grupo de lactantes quando comparado ao grupo de não lactantes (13,2 ± 2,5 versus 39,7 ± 3,5, p < 0,001) e ao grupo IR (13,2 ± 2,5 versus 34,0 ± 4,7, p < 0,05). A avaliação das arritmias ventriculares induzidas pela IR indicou que o número de CVPs compostas na isquemia, e o número e a duração das TVs na isquemia e nos primeiros 5 minutos de reperfusão no grupo de não lactantes foram significativamente (p < 0,05) mais elevados do que os encontrados nos grupos IR e de lactantes. Conclusão: A lactação induziu o aparecimento precoce de efeitos cardioprotetores, enquanto ratas que não foram permitidas a amamentar seus filhotes se mostraram mais suscetíveis à lesão miocárdica por IR.


Subject(s)
Animals , Female , Pregnancy , Lactation , Myocardial Reperfusion Injury/prevention & control , Myocardial Ischemia/rehabilitation , Myocardial Infarction/prevention & control , Arrhythmias, Cardiac/prevention & control , Random Allocation , Rats, Sprague-Dawley , Ventricular Pressure/physiology , Models, Animal , Heart Rate/physiology , Myocardial Contraction/physiology
8.
Arq. bras. cardiol ; 108(5): 417-426, May 2017. tab, graf
Article in English | LILACS | ID: biblio-838738

ABSTRACT

Abstract Background: Normal coronary flow velocity reserve (CFVR) (≥ 2) obtained in the left anterior descending coronary artery (LAD) from transthoracic echocardiography is associated with a good prognosis, but there is no study correlating CFVR with submaximal target heart rate (HR). Objective: To evaluate the prognostic value of CFVR obtained in the LAD of patients with preserved (>50%) left ventricular ejection fraction (LVEF) who completed a dobutamine stress echocardiography (DSE), considering target HR. Methods: Prospective study of patients with preserved LVEF and CFVR obtained in the LAD who completed DSE. In Group I (GI = 31), normal CFVR was obtained before achieving target HR, and, in Group II (GII = 28), after that. Group III (G III=24) reached target HR, but CFVR was abnormal. Death, acute coronary insufficiency, coronary intervention, coronary angiography without further intervention, and hospitalization were considered events. Results: In 28 ± 4 months, there were 18 (21.6%) events: 6% (2/31) in GI, 18% (5/28) in GII, and 46% (11/24) in GIII. There were 4 (4.8%) deaths, 6 (7.2%) coronary interventions and 8 (9.6%) coronary angiographies without further intervention. In event-free survival by regression analysis, GIII had more events than GI (p < 0.001) and GII (p < 0.045), with no difference between GI and GII (p = 0.160). After adjustment, the only difference was between GIII and GI (p = 0.012). Conclusion: In patients with preserved LVEF and who completed their DSE, normal CFVR obtained before achieving target HR was associated with better prognosis.


Resumo Fundamento: A reserva de velocidade de fluxo coronariano (RVFC) adequada (≥ 2) obtida na artéria descendente anterior (ADA) através do ecocardiograma transtorácico associa-se a bom prognóstico, mas não há estudo correlacionando-a com a frequência cardíaca (FC) alvo (submáxima). Objetivo: Avaliar o valor prognóstico da RVFC obtida na ADA de pacientes com fração de ejeção do ventrículo esquerdo (FEVE) preservada (>50%) e ecocardiograma sob estresse com dobutamina (EED) concluído, considerando a FC alvo submáxima. Métodos: studo prospectivo de pacientes com FEVE preservada e RVFC obtida na ADA durante EED concluído. No Grupo I (GI=31), a RVFC adequada foi obtida antes de se atingir a FC alvo, e no Grupo II (G II=28), após. O Grupo III (G III=24) atingiu a FC alvo, mas a RVFC foi inadequada. Foram considerados eventos: óbito, insuficiência coronariana aguda, intervenção coronariana, coronariografia sem intervenção subsequente e internamento hospitalar. Resultados: Em 28 ± 4 meses, ocorreram 18 (21,6%) eventos, sendo 6% (2/31) no GI, 18% (5/28) no GII e 46% (11/24) no GIII. Foram 4 (4,8%) óbitos, 6 (7,2%) intervenções coronarianas e 8 (9,6%) coronariografias sem intervenção subsequente. Na sobrevida livre de eventos pela análise de regressão, GIII apresentou mais eventos do que GI (p < 0,001) ou GII (p < 0,045), não havendo diferença entre GI e GII (p = 0,160). Após o ajustamento, foi mantida a diferença apenas entre GIII e GI (p = 0,012). Conclusão: Em pacientes com FEVE preservada e EED concluído, a RVFC adequada obtida antes da FC alvo associou-se ao melhor prognóstico.


Subject(s)
Humans , Male , Female , Middle Aged , Aged , Coronary Artery Disease/diagnostic imaging , Echocardiography, Stress , Fractional Flow Reserve, Myocardial/physiology , Heart Rate/physiology , Prognosis , Stroke Volume/physiology , Coronary Artery Disease/mortality , Survival Analysis , Prospective Studies , Follow-Up Studies , Myocardial Ischemia/mortality , Myocardial Ischemia/diagnostic imaging , Echocardiography, Doppler, Pulsed/instrumentation , Echocardiography, Doppler, Pulsed/methods , Myocardial Contraction/physiology
9.
Arq. bras. cardiol ; 108(2): 129-134, Feb. 2017. tab, graf
Article in English | LILACS | ID: biblio-838688

ABSTRACT

Abstract Background: Three-dimensional (3D) echocardiography coupled with speckle-tracking echocardiographic (STE) capability is a novel methodology which has been demontrated to be useful for the assessment of left atrial (LA) volumes and functional properties. There is increased scientific interest on myocardial deformation analysis in adult patients with corrected tetralogy of Fallot (cTOF). Objectives: To compare LA volumes, volume-based functional properties and strain parameters between cTOF patients and age- and gender-matched healthy controls. Methods: The study population consisted of 19 consecutive adult patients with cTOF in sinus rhythm nursing at the University of Szeged, Hungary (mean age: 37.9 ± 11.3 years, 8 men, who had repair at the age of 4.1 ± 2.5 years). They all had undergone standard transthoracic two-dimensional Doppler echocardiographic study extended with 3DSTE. Their results were compared to 23 age- and gender-matched healthy controls (mean age: 39.2 ± 10.6 years, 14 men). Results: Increased LA volumes and reduced LA emptying fractions respecting cardiac cycle could be demonstrated in cTOF patients compared to controls. LA stroke volumes featuring all LA functions showed no differences between the 2 groups examined. LA global and mean segmental uni- and multidirectional peak strains featuring LA reservoir function were found to be diminished in adult patients with cTOF as compared to controls. Similarly to peak strains reduced global and mean segmental LA strains at atrial contraction characterizing atrial booster pump function could be demonstrated in cTOF patients as compared to controls. Conclusions: Significant deterioration of all LA functions could be demonstrated in adult patients with cTOF late after repair.


Resumo Fundamento: Ecocardiografia tridimensional (3D) acoplada à técnica de speckle-tracking (3DSTE) é uma nova metodologia útil para a avaliação de volumes e propriedades funcionais do átrio esquerdo (AE). Há crescente interesse científico na análise da deformação miocárdica em adultos com tetralogia de Fallot corrigida (cTOF). Objetivos: Comparar os volumes de AE, propriedades funcionais baseadas no volume e parâmetros de strain entre pacientes com cTOF e controles saudáveis pareados por idade e sexo. Métodos: A população do estudo consistiu em 19 adultos com cTOF consecutivos, em ritmo sinusal, acompanhados na Universidade Szeged, Hungria (idade média: 37,9 ± 11,3 anos; 8 homens; com correção cirúrgica aos 4,1 ± 2,5 anos de idade). Todos foram submetidos a ecocardiografia transtorácica bidimensional com Doppler padrão e 3DSTE. Os resultados foram comparados aos de 23 controles saudáveis pareados por idade e sexo (idade média: 39,2 ± 10,6 anos; 14 homens). Resultados: Aumento dos volumes de AE e redução das frações de esvaziamento de AE em relação ao ciclo cardíaco foram demonstrados em pacientes com cTOF em comparação aos dos controles. Os volumes de ejeção de AE caracterizando todas as funções do AE não diferiram entre os dois grupos. Strains de AE global e segmentar médio uni- e multidimensional, caracterizando função de reservatório de AE, estavam diminuídos em adultos com cTOF em comparação aos de controles. À semelhança dos strains de pico, reduzidos strains de AE global e segmentar médio na contração atrial, caracterizando função de bomba atrial, foram demonstrados em pacientes com cTOF em comparação aos de controles. Conclusões: Demonstrou-se significativa deterioração das funções de AE em adultos com cTOF em fase tardia após correção.


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Tetralogy of Fallot/surgery , Tetralogy of Fallot/pathology , Echocardiography, Three-Dimensional/methods , Myocardium/pathology , Organ Size , Reference Values , Stroke Volume , Tetralogy of Fallot/physiopathology , Tetralogy of Fallot/diagnostic imaging , Echocardiography, Doppler/methods , Case-Control Studies , Risk Factors , Atrial Function , Heart/physiopathology , Heart Atria/pathology , Heart Atria/diagnostic imaging , Myocardial Contraction/physiology
10.
Braz. j. med. biol. res ; 50(5): e5742, 2017. tab, graf
Article in English | LILACS | ID: biblio-839290

ABSTRACT

Cardiac remodeling is defined as changes in shape and function of the heart in response to aggression (pressure overload). The sarcoplasmic reticulum calcium ATPase cardiac isoform 2a (SERCA2a) is a known factor that influences function. A wide spectrum of studies report a decrease in SERCA2a in heart failure, but none evaluate it's the role in early isolated diastolic dysfunction in supravalvular aortic stenosis (AoS). Our hypothesis was that SERCA2a participates in such dysfunction. Thirty-day-old male Wistar rats (60-80 g) were divided into AoS and Sham groups, which were submitted to surgery with or without aorta clipping, respectively. After 6 weeks, the animals were submitted to echocardiogram and functional analysis by isolated papillary muscle (IPM) in basal condition, hypoxia, and SERCA2a blockage with cyclopiazonic acid at calcium concentrations of 0.5, 1.5, and 2.5 mM. Western-blot analyses were used for SERCA2a and phospholamban detection. Data analysis was carried out with Student's t-test and ANOVA. AoS enhanced left atrium and E and A wave ratio, with preserved ejection fraction. Basal condition in IPM showed similar increases in developed tension (DT) and resting tension (RT) in AoS, and hypoxia was similar between groups. After cyclopiazonic acid blockage, final DT was equally decreased and RT was similar between groups, but the speed of relaxation was decreased in the AoS group. Western-blot was uniform in all evaluations. The hypothesis was confirmed, since functional parameters regarding SERCA2a were changed in the AoS group.


Subject(s)
Animals , Male , Aortic Stenosis, Supravalvular/complications , Hypertrophy, Left Ventricular/physiopathology , Sarcoplasmic Reticulum Calcium-Transporting ATPases/physiology , Ventricular Dysfunction, Left/physiopathology , Aortic Stenosis, Supravalvular/metabolism , Calcium-Binding Proteins/analysis , Collagen/analysis , Diastole/physiology , Disease Models, Animal , Echocardiography , Heart Ventricles/pathology , Heart Ventricles/physiopathology , Hypertrophy, Left Ventricular/etiology , Hypertrophy, Left Ventricular/metabolism , Hypoxia/metabolism , Hypoxia/physiopathology , Indoles , Myocardial Contraction/physiology , Rats, Wistar , Sarcoplasmic Reticulum Calcium-Transporting ATPases/analysis , Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism , Time Factors , Ventricular Dysfunction, Left/etiology , Ventricular Dysfunction, Left/metabolism , Ventricular Remodeling/physiology
11.
Arq. bras. cardiol ; 107(6): 542-549, Dec. 2016. tab, graf
Article in English | LILACS | ID: biblio-838656

ABSTRACT

Abstract Background: Hyperthyroidism is currently recognized to affect the cardiovascular system, leading to a series of molecular and functional changes. However, little is known about the functional influence of hyperthyroidism in the regulation of cytoplasmic calcium and on the sodium/calcium exchanger (NCX) in the cardiac muscle. Objectives: To evaluate the functional changes in papillary muscles isolated from animals with induced hyperthyroidism. Methods: We divided 36 Wistar rats into a group of controls and another of animals with hyperthyroidism induced by intraperitoneal T3 injection. We measured in the animals' papillary muscles the maximum contraction force, speed of contraction (+df/dt) and relaxation (-df/dt), contraction and relaxation time, contraction force at different concentrations of extracellular sodium, post-rest potentiation (PRP), and contraction force induced by caffeine. Results: In hyperthyroid animals, we observed decreased PRP at all rest times (p < 0.05), increased +df/dt and -df/dt (p < 0.001), low positive inotropic response to decreased concentration of extracellular sodium (p < 0.001), reduction of the maximum force in caffeine-induced contraction (p < 0.003), and decreased total contraction time (p < 0.001). The maximal contraction force did not differ significantly between groups (p = 0.973). Conclusion: We hypothesize that the changes observed are likely due to a decrease in calcium content in the sarcoplasmic reticulum, caused by calcium leakage, decreased expression of NCX, and increased expression of a-MHC and SERCA2.


Resumo Fundamento: Sabe-se atualmente que o hipertireoidismo afeta o sistema cardiovascular, ocasionando uma série de alterações funcionais e moleculares. No entanto, pouco se sabe sobre a influência funcional do hipertireoidismo na regulação do cálcio citoplasmático e no trocador de sódio/cálcio (NCX) no músculo cardíaco. Objetivos: Avaliar as alterações funcionais de músculos papilares isolados de animais com hipertireoidismo induzido. Métodos: Ao todo, 36 ratos Wistar foram distribuídos em um grupo controle e outro grupo com hipertireoidismo induzido por injeção intraperitoneal de T3. Nos músculos papilares isolados dos animais foram medidos a força máxima de contração, a velocidade de contração (+df/dt) e relaxamento (-df/dt), o tempo de contração e relaxamento, a força de contração em diferentes concentrações de sódio extracelular, o potenciação pós-pausa (PPP) e a força de contração induzida por cafeína. Resultados: Em animais com hipertireoidismo, observamos uma diminuição da PPP em todos os períodos de repouso (p < 0,05), aumento do +df/dt e -df/dt (p < 0,001), baixa resposta inotrópica positiva à concentração reduzida de sódio extracelular (p < 0,001), diminuição da força máxima de contração induzida por cafeína (p < 0,003) e diminuição do tempo total de contração (p < 0,001). A força máxima de contração não diferiu significativamente entre os grupos (p = 0,973). Conclusões: Nossa hipótese é de que as alterações observadas são provavelmente resultantes de uma diminuição do conteúdo de cálcio do retículo sarcoplasmático causada por vazamento de cálcio, redução da expressão do NCX e aumento da expressão de a-MHC e SERCA2.


Subject(s)
Animals , Male , Papillary Muscles/physiopathology , Heart/physiopathology , Hyperthyroidism/physiopathology , Organ Size , Reference Values , Time Factors , Transducers , Random Allocation , Calcium/analysis , Calcium/metabolism , Rats, Wistar , Sodium-Calcium Exchanger/metabolism , Muscle Strength/physiology , Myocardial Contraction/physiology
12.
Rev. méd. Chile ; 144(6): 767-771, jun. 2016. ilus, tab
Article in Spanish | LILACS | ID: lil-793987

ABSTRACT

The contractile state of the heart is the result of myocardial contractility, the intrinsic mechanism that regulates the force and the shortening of the ventricle and determines the ventricular ejection volume. However, the ejection volume is also modulated by ventricular preload (diastolic ventricular volume) and afterload (resistance to ejection). Accordingly, a decrease in contractility may be masked by changes in preload or afterload, maintaining a normal ejection volume and delaying the diagnosis of myocardial damage. Thus, it is necessary to develop a non-invasive method to measure contractility in the clinical practice. We review in this article the basic principles of cardiac contraction, the concept of contractility and its measurement with the ventricular pressure-volume loop, an experimental method that also measures most of the hemodynamic variables of the cardiac cycle including preload, afterload, ventricular work, ventricular lusitropy and arterial elastance. This method has been recently validated in cardiac patients and allows to evaluate the evolution of contractility in heart failure in a non invasive way. Although some modifications are still necessary, it will probably have an extensive use in practical cardiology in the near future.


Subject(s)
Humans , Animals , Stroke Volume/physiology , Ventricular Function/physiology , Myocardial Contraction/physiology , Hemodynamics/physiology
13.
Arq. bras. cardiol ; 106(2): 92-96, Feb. 2016. tab
Article in Portuguese | SES-SP, LILACS, SES-SP, SESSP-IDPCPROD, SES-SP | ID: lil-775097

ABSTRACT

Abstract Background: Prolonged aerobic exercise, such as running a marathon, produces supraphysiological stress that can affect the athlete's homeostasis. Some degree of transient myocardial dysfunction ("cardiac fatigue") can be observed for several days after the race. Objective: To verify if there are changes in the cardiopulmonary capacity, and cardiac inotropy and lusitropy in amateur marathoners after running a marathon. Methods: The sample comprised 6 male amateur runners. All of them underwent cardiopulmonary exercise testing (CPET) one week before the São Paulo Marathon, and 3 to 4 days after that race. They underwent echocardiography 24 hours prior to and immediately after the marathon. All subjects were instructed not to exercise, to maintain their regular diet, ingest the same usual amount of liquids, and rest at least 8 hours a day in the period preceding the CPET. Results: The athletes completed the marathon in 221.5 (207; 250) minutes. In the post-marathon CPET, there was a significant reduction in peak oxygen consumption and peak oxygen pulse compared to the results obtained before the race (50.75 and 46.35 mL.kg-1 .min-1; 19.4 and 18.1 mL.btm, respectively). The echocardiography showed a significant reduction in the s' wave (inotropic marker), but no significant change in the E/e' ratio (lusitropic marker). Conclusions: In amateur runners, the marathon seems to promote changes in the cardiopulmonary capacity identified within 4 days after the race, with a reduction in the cardiac contractility. Such changes suggest that some degree of "cardiac fatigue" can occur.


Resumo Fundamento: O exercício aeróbico prolongado, como correr uma maratona, produz um estresse suprafisiológico que pode ter impacto na homeostase do atleta. Algum grau de disfunção miocárdica transitória ("fadiga cardíaca") pode ser observado ao longo de vários dias após a prova. Objetivos: Verificar se ocorrem alterações na capacidade cardiopulmonar, no inotropismo e no lusitropismo cardíaco de maratonistas amadores após a realização de uma maratona. Métodos: A amostra foi composta por 6 corredores amadores masculinos. Todos realizaram teste cardiopulmonar de exercício (TCPE) uma semana antes da Maratona de São Paulo e 3 a 4 dias após a mesma. Realizaram ecocardiograma 24 horas antes e imediatamente após a prova. Todos foram orientados a não se exercitar, manter dieta regular, ingerir a mesma quantidade habitual de líquidos e descansar pelo menos 8 horas ao dia no período anterior ao TCPE. Resultados: Os atletas completaram a maratona em 221,5 (207; 250) minutos. No TCPE pós-maratona, ocorreu redução significativa no consumo de oxigênio e no pulso de oxigênio de pico em relação àqueles obtidos antes da prova (50,75 e 46,35 ml.kg-1.min-1; 19,4 e 18,1 ml.btm, respectivamente). Ao ecocardiograma, encontramos redução significativa na onda s' (marcador do inotropismo). A relação E/e' não apresentou alteração significativa após a maratona (marcador do lusitropismo). Conclusões: Em atletas amadores, a maratona parece promover alterações na capacidade cardiopulmonar identificadas pelo menos em até 4 dias após a prova, com redução na contratilidade e, portanto, no inotropismo cardíaco. Tais modificações sugerem que algum grau de "fadiga cardíaca" possa ocorrer.


Subject(s)
Humans , Male , Adult , Middle Aged , Heart/physiology , Muscle Fatigue/physiology , Oxygen Consumption/physiology , Running/physiology , Echocardiography , Exercise Test , Myocardial Contraction/physiology , Reference Values , Statistics, Nonparametric , Time Factors , Ventricular Function
14.
In. Kalil Filho, Roberto; Fuster, Valetim; Albuquerque, Cícero Piva de. Medicina cardiovascular reduzindo o impacto das doenças / Cardiovascular medicine reducing the impact of diseases. São Paulo, Atheneu, 2016. p.73-88.
Monography in Portuguese | LILACS | ID: biblio-971529
15.
Braz. j. med. biol. res ; 49(1): e4794, 2016. graf
Article in English | LILACS | ID: biblio-951643

ABSTRACT

Cardiac remodeling involves changes in heart shape, size, structure, and function after injury to the myocardium. The proinflammatory adaptor protein myeloid differentiation protein 88 (MyD88) contributes to cardiac remodeling. To investigate whether excessive MyD88 levels initiate spontaneous cardiac remodeling at the whole-organism level, we generated a transgenic MyD88 mouse model with a cardiac-specific promoter. MyD88 mice (male, 20-30 g, n=∼80) were born at the expected Mendelian ratio and demonstrated similar morphology of the heart and cardiomyocytes with that of wild-type controls. Although heart weight was unaffected, cardiac contractility of MyD88 hearts was mildly reduced, as shown by echocardiographic examination, compared with wild-type controls. Moreover, the cardiac dysfunction phenotype was associated with elevation of ANF and BNP expression. Collectively, our data provide novel evidence of the critical role of balanced MyD88 signaling in maintaining physiological function in the adult heart.


Subject(s)
Animals , Male , Rabbits , Ventricular Remodeling/physiology , Myeloid Differentiation Factor 88/metabolism , Heart Diseases/physiopathology , Organ Size , Mice, Transgenic , Echocardiography , Blotting, Western , Atrial Natriuretic Factor/metabolism , Natriuretic Peptide, Brain/metabolism , Myeloid Differentiation Factor 88/genetics , Organ Dysfunction Scores , Heart Diseases/metabolism , Heart Failure/physiopathology , Heart Failure/pathology , Myocardial Contraction/physiology , Myocardium/pathology
16.
Article in English | WPRIM | ID: wpr-110209

ABSTRACT

OBJECTIVE: To assess magnetic resonance imaging (MRI) features of coronary microembolization in a swine model induced by small-sized microemboli, which may cause microinfarcts invisible to the naked eye. MATERIALS AND METHODS: Eleven pigs underwent intracoronary injection of small-sized microspheres (42 microm) and catheter coronary angiography was obtained before and after microembolization. Cardiac MRI and measurement of cardiac troponin T (cTnT) were performed at baseline, 6 hours, and 1 week after microembolization. Postmortem evaluation was performed after completion of the imaging studies. RESULTS: Coronary angiography pre- and post-microembolization revealed normal epicardial coronary arteries. Systolic wall thickening of the microembolized regions decreased significantly from 42.6 +/- 2.0% at baseline to 20.3 +/- 2.3% at 6 hours and 31.5 +/- 2.1% at 1 week after coronary microembolization (p < 0.001 for both). First-pass perfusion defect was visualized at 6 hours but the extent was largely decreased at 1 week. Delayed contrast enhancement MRI (DE-MRI) demonstrated hyperenhancement within the target area at 6 hours but not at 1 week. The microinfarcts on gross specimen stained with nitrobluetetrazolium chloride were invisible to the naked eye and only detectable microscopically. Increased cTnT was observed at 6 hours and 1 week after microembolization. CONCLUSION: Coronary microembolization induced by a certain load of small-sized microemboli may result in microinfarcts invisible to the naked eye with normal epicardial coronary arteries. MRI features of myocardial impairment secondary to such microembolization include the decline in left ventricular function and myocardial perfusion at cine and first-pass perfusion imaging, and transient hyperenhancement at DE-MRI.


Subject(s)
Animals , Coronary Angiography/methods , Coronary Vessels/pathology , Disease Models, Animal , Embolism/pathology , Female , Heart/diagnostic imaging , Image Processing, Computer-Assisted , Magnetic Resonance Imaging/methods , Microspheres , Myocardial Contraction/physiology , Myocardial Infarction/pathology , Myocardium/pathology , Nitroblue Tetrazolium , Staining and Labeling , Swine , Troponin T/blood , Ventricular Function, Left
17.
Arq. bras. cardiol ; 105(6): 588-596, Dec. 2015. tab, graf
Article in Portuguese | LILACS | ID: lil-769543

ABSTRACT

Abstract Background: Diet-induced obesity is frequently used to demonstrate cardiac dysfunction. However, some rats, like humans, are susceptible to developing an obesity phenotype, whereas others are resistant to that. Objective: To evaluate the association between obesity resistance and cardiac function, and the impact of obesity resistance on calcium handling. Methods: Thirty-day-old male Wistar rats were distributed into two groups, each with 54 animals: control (C; standard diet) and obese (four palatable high-fat diets) for 15 weeks. After the experimental protocol, rats consuming the high-fat diets were classified according to the adiposity index and subdivided into obesity-prone (OP) and obesity-resistant (OR). Nutritional profile, comorbidities, and cardiac remodeling were evaluated. Cardiac function was assessed by papillary muscle evaluation at baseline and after inotropic maneuvers. Results: The high-fat diets promoted increase in body fat and adiposity index in OP rats compared with C and OR rats. Glucose, lipid, and blood pressure profiles remained unchanged in OR rats. In addition, the total heart weight and the weight of the left and right ventricles in OR rats were lower than those in OP rats, but similar to those in C rats. Baseline cardiac muscle data were similar in all rats, but myocardial responsiveness to a post-rest contraction stimulus was compromised in OP and OR rats compared with C rats. Conclusion: Obesity resistance promoted specific changes in the contraction phase without changes in the relaxation phase. This mild abnormality may be related to intracellular Ca2+ handling.


Resumo Fundamento: A obesidade induzida por dieta é frequentemente utilizada para demonstração de disfunção cardíaca. No entanto, alguns ratos, como humanos, são suscetíveis ao desenvolvimento de um fenótipo de obesidade, enquanto outros são resistentes. Objetivo: Avaliar a relação entre resistência à obesidade e função cardíaca e o impacto da resistência à obesidade no trânsito de cálcio. Métodos: Ratos Wistar machos com trinta dias de idade foram distribuídos em dois grupos com 54 animais cada: controle (C; dieta padrão) e obesos (quatro dietas palatáveis hiperlipídicas) por 15 semanas. Após o protocolo experimental, os ratos alimentados por dietas hiperlipídicas foram classificados de acordo com o índice de adiposidade e subdivididos em propensos à obesidade (PO) e resistentes à obesidade (RO). Foram avaliados o perfil nutricional, comorbidades e remodelação cardíaca. A função cardíaca foi avaliada pelo estudo do músculo papilar isolado em condições basais e após manobras inotrópicas. Resultados: As dietas hiperlipídicas promoveram aumento na gordura corporal e no índice de adiposidade em ratos PO comparados com ratos C e RO. Os perfis de glicose, lipídios e pressão arterial permaneceram inalterados em ratos RO. Além disso, os ratos RO apresentaram peso total do coração e dos ventrículos direito e esquerdo mais baixos do que ratos PO, mas semelhantes aos ratos C. Os músculos cardíacos de todos os ratos apresentaram dados semelhantes na condição basal, mas a resposta miocárdica a um estímulo de contração pós-pausa estava comprometida em ratos PO e RO em comparação aos ratos C. Conclusão: A resistência à obesidade promoveu alterações específicas na fase de contração, sem alterar a fase de relaxamento. Esta anormalidade leve pode estar relacionada com o trânsito intracelular de Ca+2.


Subject(s)
Animals , Male , Calcium/metabolism , Diet, High-Fat , Myocardial Contraction/physiology , Obesity/metabolism , Adiposity/physiology , Body Weight , Blood Glucose/analysis , Blood Pressure/physiology , Disease Models, Animal , Glucose Tolerance Test , Insulin Resistance , Organ Size , Obesity/physiopathology , Papillary Muscles/physiopathology , Rats, Wistar , Reference Values
18.
Braz. j. med. biol. res ; 48(9): 813-821, Sept. 2015. tab, ilus
Article in English | LILACS | ID: lil-756408

ABSTRACT

Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the Langendorff technique and by isometric contractions of isolated left ventricular papillary muscles. SERCA2a, phospholamban (PLB), and phosphorylated PLB expression were investigated by Western blot. Exercise increased force development of isolated papillary muscles (Ex=1.0±0.1 g/mg vs Ct=0.63±0.2 g/mg, P<0.05). Post-rest contraction was greater in the exercised animals (Ex=4.1±0.4% vs Ct=1.7±0.2%, P<0.05). Papillary muscles of exercised animals developed greater force under increasing isoproterenol concentrations (P<0.05). In the isolated heart, exercise increased left ventricular isovolumetric systolic pressure (LVISP; Δ +39 mmHg; P<0.05) from baseline conditions. Hearts from the exercised rats presented a greater response to increasing diastolic pressure. Positive inotropic intervention to calcium and isoproterenol resulted in greater LVISP in exercised animals (P<0.05). The results demonstrated that a single resistance exercise session improved myocardial contractility in SHRs.


Subject(s)
Animals , Male , Rats , Blood Pressure/physiology , Heart Rate/physiology , Myocardial Contraction/physiology , Physical Conditioning, Animal/physiology , Rats, Inbred SHR
19.
Acta cir. bras ; 30(7): 484-490, 07/2015. graf
Article in English | LILACS | ID: lil-754985

ABSTRACT

PURPOSE: To study racemic bupivacaine, non-racemic bupivacaine and ropivacaine on myocardial contractility. METHODS: Isolated Wistar papillary muscles were submitted to 50 and 100 mM racemic bupivacaine (B50 and B100), non-racemic bupivacaine (NR50 and NR100) and ropivacaine (R50 and R100) intoxication. Isometric contraction data were obtained in basal condition (0.2 Hz), after increasing the frequency of stimulation to 1.0 Hz and after 5, 10 and 15 min of local anesthetic intoxication. Data were analyzed as relative changes of variation. RESULTS: Developed tension was higher with R100 than B100 at D1 (4.3 ± 41.1 vs -57.9 ± 48.1). Resting tension was altered with B50 (-10.6 ± 23.8 vs -4.7 ± 5.0) and R50 (-14.0 ± 20.5 vs -0.5 ± 7.1) between D1 and D3. Maximum rate of tension development was lower with B100 (-56.6 ± 38.0) than R50 (-6.3 ± 37.9) and R100 (-1.9 ± 37.2) in D1. B50, B100 and NR100 modified the maximum rate of tension decline from D1 through D2. Time to peak tension was changed with NR50 between D1 and D2. CONCLUSIONS: Racemic bupivacaine depressed myocardial contractile force more than non-racemic bupivacaine and ropivacaine. Non-racemic and racemic bupivacaine caused myocardial relaxation impairment more than ropivacaine. .


Subject(s)
Animals , Male , Amides/pharmacology , Anesthetics, Local/pharmacology , Bupivacaine/pharmacology , Myocardial Contraction/drug effects , Bupivacaine/chemistry , Depression, Chemical , Muscle Tonus/drug effects , Muscle Tonus/physiology , Myocardial Contraction/physiology , Papillary Muscles/drug effects , Papillary Muscles/physiology , Rats, Wistar , Reference Values , Stereoisomerism , Time Factors
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