Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 848
Filter
2.
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
3.
Biociencias ; 16(1): [87-104], 20210601.
Article in Spanish | LILACS, COLNAL | ID: biblio-1291182

ABSTRACT

Múltiples investigaciones evidencian una máxima incidencia del infarto agudo de miocardio en la mañana. El objetivo de este artículo es revisar la organización del sistema circadiano, su importancia en la fisiología del sistema cardiovascular y su relación con el desarrollo del infarto agudo de miocardio. Se realizó una búsqueda bibliográfica en diferentes bases de datos para identificar artículos publicados durante los últimos 20 años, centrados en la variación circadiana del infarto agudo de miocardio y en la cronoterapia cardiovascular. Se preseleccionaron 115 artículos, de los cuales se escogieron 60. Se concluyó que la mayor incidencia matutina del infarto agudo de miocardio se explica por la acción conjunta de factores endógenos (aumento matutino de cortisol, catecolaminas, presión arterial, frecuencia cardiaca, resistencias vasculares) y exógenos (alteración en el ciclo sueño-vigilia, bipedestación, e inicio de la actividad) que predispone a ruptura de la placa ateromatosa y aparición de episodios trombóticos durante la mañana.


Multiple investigations show a maximum incidence of acute myocardial infarction in the morning. The objective of this article is to review the organization of the circadian system, its importance in the physiology of the cardiovascular system and its relationship with the development of acute myocardial infarction. A bibliographic search was carried out in different databases to identify articles published during the last 20 years, focused on the circadian variation of acute myocardial infarction and on cardiovascular chronotherapy. 115 articles were preselected, of which 60 were chosen. It was concluded that the higher morning incidence of acute myocardial infarction is explained by the joint action of endogenous factors (morning increase in cortisol, catecholamines, blood pressure, heart rate, vascular resistance) and exogenous (alteration in the sleep-wake cycle, standing, and onset of activity) that predisposes to rupture of the atheromatous plaque and the appearance of thrombotic episodes during the morning.


Subject(s)
Humans , Infarction , Myocardial Contraction
4.
Acta Physiologica Sinica ; (6): 275-285, 2021.
Article in Chinese | WPRIM | ID: wpr-878256

ABSTRACT

This study aimed to explore the positive inotropic effect of phosphodiesterase type 9 (PDE9) inhibitor PF-04449613 in ratsand its cellular and molecular mechanisms. The heart pressure-volume loop (P-V loop) analysis was used to detect the effects of PF-04449613 on rat left ventricular pressure-volume relationship, aortic pressures and peripheral vessel resistance in healthy rats. The Langendorff perfusion of isolated rat heart was used to explore the effects of PF-04449613 on heart contractility. The cardiomyocyte sarcoplasmic reticulum (SR) Ca


Subject(s)
Animals , Calcium/metabolism , Myocardial Contraction , Myocytes, Cardiac/metabolism , Phosphodiesterase Inhibitors , Phosphoric Diester Hydrolases , Rats , Ryanodine Receptor Calcium Release Channel , Sarcoplasmic Reticulum
5.
Arq. bras. cardiol ; 115(1): 17-28, jul. 2020. tab, graf
Article in Portuguese | LILACS, SES-SP | ID: biblio-1131262

ABSTRACT

Resumo Fundamento A obesidade tem sido associada com ativação crônica do sistema renina-angiotensina-aldosterona e importantes alterações no desempenho cardíaco. Objetivo Avaliar a influência do bloqueio de receptores de angiotensina-II do tipo 1 (AT1) sobre a morfologia e desempenho cardíaco de ratos obesos por dieta Métodos Ratos Wistar (n=48) foram submetidos a dieta controle (2,9 kcal/g) ou hiperlipídica (3,6 kcal/g) durante 20 semanas. Após a 16ª semana, foram distribuídos em quatro grupos: Controle (CO), Obeso (OB), Controle Losartan (CL) e Obeso Losartan (OL). CL e OL receberam losartan (30 mg/kg/dia) na água durante quatro semanas. Posteriormente, foram analisadas composição corporal, pressão arterial sistólica (PAS) e ecocardiograma. A função de músculos papilares foi avaliada em situação basal com concentração de cálcio ([Ca2+]o) de 2,50 mM e após manobras inotrópicas: potencial pós-pausa (PPP), elevação da [Ca2+]o e durante estimulação beta-adrenérgica com isoproterenol. A análise dos resultados foi feita por meio de Two-Way ANOVA e teste de comparações apropriado. O nível de significância considerado foi de 5%. Resultados Embora a alteração da PAS não tenha se mantido ao final do experimento, a obesidade se associou com hipertrofia cardíaca e maior velocidade de encurtamento da parede posterior do ventrículo esquerdo.No estudo de músculos papilares em condição basal, CL mostrou menor velocidade máxima de variação negativa da tensão desenvolvida (-dT/dt) do que CO. O PPP de 60s promoveu menor -dT/dt e pico de tensão desenvolvida (TD) em OB e CL, comparados ao CO, e maior variação relativa de TD e velocidade máxima de variação positiva (+dT/dt) no OL em relação a CL e OB. Sob 1,5, 2,0 e 2,5mM de [Ca2+]o, o grupo OL exibiu maior -dT/dt do que CL. Conclusão Losartan melhora a função miocárdica de ratos com obesidade induzida por dieta. (Arq Bras Cardiol. 2020; 115(1):17-28)


Abstract Background Obesity has been associated with chronic activation of the renin-angiotensin-aldosterone system and with significant changes in cardiac performance. Objective To assess the impact of a blockade of angiotensin-II receptor type 1 (AT1receptor) on morphology and on myocardial functional performance in rats with high-fat diet- induced obesity. Methods Wistar rats (n=48) were submitted to control (2.9 kcal/g) or high-fat (3.6 kcal/g) diet for 20 weeks. After the 16thweek they were divided into four groups: Control (CO), Obese (OB), Control Losartan (CL) and Obese Losartan (OL). CL and OL received losartan (30 mg/kg/day) in drinking water for four weeks. Subsequently, body composition, systolic blood pressure (SBP) and echocardiographic variables were analyzed. Papillary muscle function was assessed at baseline with 2.50 mM calcium concentration ([Ca2+]o) and after inotropic maneuvers: post-pause potentiation (PPP), [Ca2+]oelevation, and during beta-adrenergic stimulation with isoproterenol. Analysis of the results was performed by the Two-Way ANOVA and by the appropriate comparison test. The level of significance was set at 5%. Results Although SBP change had been not maintained at the end of the experiment, obesity was associated with cardiac hypertrophy and with increased left ventricle posterior wall shortening velocity. In the study of papillary muscles in basal condition, CL showed lower developed tension maximum negative variation velocity (-dT/dt) than CO. The 60s PPP promoted lower -dT/dt and maximum developed tension (DT) in OB and CL compared with CO, and higher relative DT variation and maximum positive variation velocity (+dT/dt) in OL compared with CL and OB. Under 1.5, 2.0, and 2.5mM [Ca2+]o, the OL group showed higher -dT/dt than CL. Conclusion Losartan improves myocardial function in high-fat diet-induced obesity. (Arq Bras Cardiol. 2020;115(1):17-28)


Subject(s)
Animals , Rats , Diet, High-Fat/adverse effects , Obesity/drug therapy , Papillary Muscles , Rats, Wistar , Physical Functional Performance , Myocardial Contraction
6.
Braz. j. med. biol. res ; 53(3): e8761, 2020. tab, graf
Article in English | LILACS | ID: biblio-1089339

ABSTRACT

Nitric oxide (NO) inhibition by high-dose NG-nitro-L-arginine methyl ester (L-NAME) is associated with several detrimental effects on the cardiovascular system. However, low-dose L-NAME increases NO synthesis, which in turn induces physiological cardiovascular benefits, probably by activating a protective negative feedback mechanism. Aerobic exercise, likewise, improves several cardiovascular functions in healthy hearts, but its effects are not known when chronically associated with low-dose L-NAME. Thus, we tested whether the association between low-dose L-NAME administration and chronic aerobic exercise promotes beneficial effects to the cardiovascular system, evaluating the cardiac remodeling process. Male Wistar rats were randomly assigned to control (C), L-NAME (L), chronic aerobic exercise (Ex), and chronic aerobic exercise associated to L-NAME (ExL). Aerobic training was performed with progressive intensity for 12 weeks; L-NAME (1.5 mg·kg-1·day-1) was administered by orogastric gavage. Low-dose L-NAME alone did not change systolic blood pressure (SBP), but ExL significantly increased SBP at week 8 with normalization after 12 weeks. Furthermore, ExL promoted the elevation of left ventricle (LV) end-diastolic pressure without the presence of cardiac hypertrophy and fibrosis. Time to 50% shortening and relaxation were reduced in ExL, suggesting a cardiomyocyte contractile improvement. In addition, the time to 50% Ca2+ peak was increased without alterations in Ca2+ amplitude and time to 50% Ca2+ decay. In conclusion, the association of chronic aerobic exercise and low-dose L-NAME prevented cardiac pathological remodeling and induced cardiomyocyte contractile function improvement; however, it did not alter myocyte affinity and sensitivity to intracellular Ca2+ handling.


Subject(s)
Animals , Male , Physical Conditioning, Animal/physiology , Calcium/analysis , Nitric Oxide Synthase/drug effects , NG-Nitroarginine Methyl Ester/pharmacology , Enzyme Inhibitors/pharmacology , Myocardial Contraction/drug effects , Body Weight/physiology , Rats, Wistar , Ventricular Pressure/drug effects , Nitric Oxide Synthase/metabolism , NG-Nitroarginine Methyl Ester/administration & dosage , Models, Animal , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/physiology , Enzyme Inhibitors/administration & dosage , Adiposity , Hemodynamics , Motor Activity/physiology , Myocardium/pathology
9.
Medisan ; 23(2)mar.-abr. 2019. ilus
Article in Spanish | LILACS | ID: biblio-1002636

ABSTRACT

Los digitálicos son fármacos con capacidad de aumentar la contractilidad miocárdica (inotrópico positivo), que han desempeñado un rol primordial en el tratamiento de pacientes con insuficiencia cardiaca; su uso inapropiado puede traer complicaciones serias a estos pacientes, incluso, hasta la muerte. La más importante de estas complicaciones es la intoxicación digitálica, originada por la sobredosis de dichos fármacos, a causa de la combinación del efecto inhibitorio en la conducción nodal y la estimulación sobre las fibras individuales auriculares y ventriculares. Debido al uso frecuente de estos medicamentos en todos los niveles de atención de salud y lo difícil que resulta diagnosticar dicha complicación por la complejidad de su cuadro clínico y de su expresión electrocardiográfica, se realizó una revisión bibliográfica exhaustiva sobre el tema para brindar amplia información, que permita una atención adecuada a los pacientes con este diagnóstico


Digitalis are drugs with the capacity of increasing myocardial contractility (inotropic positive agents) which have carried out an important role in the treatment of heart failure; their inappropriate use can bring severe complications to the patient, even, to death. The most important in these complications is the digitalis toxicity, originated by the overdose of these drugs, caused by the combination of the inhibitory effect in the nodal conduction and stimulation on the individual atrial and ventricular fibers. Due to the frequent use of these medications at all levels of medical care and to the difficulty in diagnosing this complication caused by the complexity of their clinical pattern and of their electrocardiographic expression, an exhaustive literature review was carried out on the topic to give a wide information that allows an appropriate care to the patients with this diagnosis


Subject(s)
Humans , Male , Female , Digitalis Glycosides/poisoning , Digitalis Glycosides/pharmacology , Drug-Related Side Effects and Adverse Reactions , Myocardial Contraction/drug effects , Poisoning , Drug Overdose/metabolism
10.
Medisan ; 23(1)ene.-feb. 2019. graf
Article in Spanish | LILACS | ID: biblio-990178

ABSTRACT

Se realizó una investigación descriptiva, longitudinal y prospectiva de 41 pacientes con antecedentes de infarto agudo del miocardio, que formaron parte de un programa de rehabilitación cardiovascular en el Servicio de Terapia Física y Rehabilitación del Hospital General Docente Dr Juan Bruno Zayas Alfonso de Santiago de Cuba, desde mayo de 2017 hasta igual mes de 2018, con vistas a evaluar el efecto del entrenamiento físico sobre la función cardiovascular de estos. Se examinó la función cardiovascular a través del ecocardiograma y el electrocardiograma, antes y después de aplicado el programa, y al final del estudio se obtuvo una modificación positiva de las variables eco- y electrocardiográficas, con un mayor grado de recuperación de la contractilidad segmentaria. Pudo concluirse que el programa tuvo un papel importante en la restauración de la función cardíaca y, con ello, se mejoró la capacidad física y psicológica de los pacientes, de manera que fue beneficioso para estos y para la sociedad.


A descriptive, longitudinal and prospective investigation of 41 patients with a history of acute myocardial infarction who were part of a program of cardiovascular rehabilitation in the Service of Physical Therapy and Rehabilitation from Dr Juan Bruno Zayas Alfonso Teaching General Hospital in Santiago de Cuba was carried out from May, 2017 to the same month in 2018, with the aim of evaluating the effect of the physical training on their cardiovascular function. The cardiovascular function was examined through the echocardiogram and the electrocardiogram, before and after the program was applied, and at the end of the study a positive modification of the echocardiographical and electrocardiographical variables was obtained with a higher degree of recovery of the segmental contractility. It could be concluded that the program had an important role in the restoration of the heart function and, with it, the physical and psychological capacity of the patients improved, so that it was beneficial for them and for the society.


Subject(s)
Humans , Male , Female , Myocardial Ischemia/diagnosis , Electrocardiography , Exercise Therapy , Myocardial Infarction/therapy , Exercise , Prospective Studies , Longitudinal Studies , Myocardial Contraction
12.
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
13.
Article in Chinese | WPRIM | ID: wpr-776549

ABSTRACT

OBJECTIVE@#To investigate the effects of interval training on calcium transient and contractile function in ischemic ventricular myocytes of rats with myocardial infarction and their synchronization.@*METHODS@#Twenty-four male sprague-dawley rats in three years old, were randomly divided into three groups (n=8): sham-operated group(S), sedentary MI group(MI) and MI with interval training group (ME). The MI model was established by ligation of the left anterior descending coronary artery. The rats in ME group started training 1 week after MI operation. The S model was established by threading only without ligation. ME model took one week adaptive training, 10 m/min and 30 min/d, then took subsequently 8-week aerobic interval training: 10 min×10 m/min, then reran the rats with 2 intensities 15 m/min×6 min and 25 m/min×4 min, 1 h/d, 5 d/week. After training 24 hours, the cardiomyocytes of all groups were isolated by using the Langendorff fusion system. The contractile function and calcium transient of single ventricular myocyte in myocardial infarction adult rats were detected by IonOptix. Calcium transients were measured as [Ca] amplitude, departure velocity, ratio, TTB50%, TTP and TTP50%, return velocity and ratio amplitude. PTA, SL, ±dl/dtmax and SL shortening% were tested to evaluate contractility.@*RESULTS@#Compared with S, the levels of [Ca] amplitude, departure velocity, ratio amplitude and return velocity, SL shortening%, PTA and ±dl/dtmax of MI were decreased(P<0.01), the levels of TTP, TTP50% and TTB50% of MI were increased(P<0.01); Compared with MI, the levels of departure velocity, ratio amplitude, return velocity and [Ca] amplitude of ME were increased(P<0.01), the levels of TTB50%, TTP and TTP50% of ME were decreased(P<0.01, P<0.05). The levels of SL shortening%, PTA and ±dl/dtmax of ME were increased(P<0.01, P<0.05).@*CONCLUSION@#Interval training can improve calcium transient and contractile function of single ventricular myocyte in myocardial infarction adult rats.


Subject(s)
Animals , Calcium , Physiology , Male , Myocardial Contraction , Myocardial Infarction , Pathology , Myocytes, Cardiac , Physiology , Physical Conditioning, Animal , Random Allocation , Rats , Rats, Sprague-Dawley
14.
Article in English | WPRIM | ID: wpr-761797

ABSTRACT

Aurora kinases inhibitors, including ZM447439 (ZM), which suppress cell division, have attracted a great deal of attention as potential novel anti-cancer drugs. Several recent studies have confirmed the anti-cancer effects of ZM in various cancer cell lines. However, there have been no studies regarding the cardiac safety of this agent. We performed several cytotoxicity, invasion and migration assays to examine the anti-cancer effects of ZM. To evaluate the potential effects of ZM on cardiac repolarisation, whole-cell patch-clamp experiments were performed with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and cells with heterogeneous cardiac ion channel expression. We also conducted a contractility assay with rat ventricular myocytes to determine the effects of ZM on myocardial contraction and/or relaxation. In tests to determine in vitro efficacy, ZM inhibited the proliferation of A549, H1299 (lung cancer), MCF-7 (breast cancer) and HepG2 (hepatoma) cell lines with IC₅₀ in the submicromolar range, and attenuated the invasive and metastatic capacity of A549 cells. In cardiac toxicity testing, ZM did not significantly affect I(Na), I(Ks) or I(K1), but decreased I(hERG) in a dose-dependent manner (IC₅₀: 6.53 µM). In action potential (AP) assay using hiPSC-CMs, ZM did not induce any changes in AP parameters up to 3 µM, but it at 10 µM induced prolongation of AP duration. In summary, ZM showed potent broad-spectrum anti-tumor activity, but relatively low levels of cardiac side effects compared to the effective doses to tumor. Therefore, ZM has a potential to be a candidate as an anti-cancer with low cardiac toxicity.


Subject(s)
Action Potentials , Animals , Antineoplastic Agents , Aurora Kinases , Cardiotoxicity , Cell Division , Cell Line , Humans , In Vitro Techniques , Ion Channels , Muscle Cells , Myocardial Contraction , Myocytes, Cardiac , Phosphotransferases , Rats , Relaxation
15.
Arq. bras. cardiol ; 111(3): 400-409, Sept. 2018. tab, graf
Article in English | LILACS | ID: biblio-973754

ABSTRACT

Abstract Background: Caloric restriction is known to impair the cardiac function and morphology in hypertrophied hearts of spontaneously hypertensive rats (SHR); however, the influence of fasting/refeeding (RF) is unknown. Objective: To investigate the fasting/refeeding approach on myocardial remodeling and function. In addition, the current study was designed to bring information regarding the mechanisms underlying the participation of Ca2+ handling and b-adrenergic system. Methods: Sixty-day-old male SHR rats were submitted to food ad libitum (C), 50% food restriction (R50) or RF cycles for 90 days. Cardiac remodeling was assessed by ultrastructure analysis and isolated papillary muscle function. The level of significance considered was 5% (a = 0.05). Results: The RF rats presented lower cardiac atrophy than R50 in relation to C rats. The C rats increased weight gain, R50 maintained their initial body weight and RF rats increased and decreased weight during RF. The RF did not cause functional impairment because the isotonic and isometric parameters showed similar behavior to those of C. The isotonic and isometric cardiac parameters were significantly elevated in RF rats compared to R50 rats. In addition, the R50 rats had cardiac damage in relation to C for isotonic and isometric variables. While the R50 rats showed focal changes in many muscle fibers, the RF rats displayed mild alterations, such as loss or disorganization of myofibrils. Conclusion: Fasting/refeeding promotes cardiac beneficial effects and attenuates myocardial injury caused by caloric restriction in SHR rats, contributing to reduce the cardiovascular risk profile and morphological injuries. Furthermore, RF promotes mild improvement in Ca2+ handling and b-adrenergic system.


Resumo Fundamento: A restrição calórica compromete a função e a morfologia cardíacas em corações hipertrofiados de ratos espontaneamente hipertensos (SHR). No entanto, a influência de ciclo de jejum/Realimentação é desconhecida. Objetivo: Investigar o efeito de ciclos de jejum/realimentação sobre a remodelação e função miocárdica. Além disso, o presente estudo foi desenhado para avaliar os mecanismos subjacentes à participação do trânsito de cálcio (Ca+2) e sistema beta-adrenérgico. Métodos: Neste estudo, SHR machos de 60 dias de idade foram submetidos a alimento ad libitum (grupo C), 50% de restrição alimentar (grupo R50) ou ciclos de RF (grupo RF) por 90 dias. A remodelação cardíaca foi avaliada por meio da análise ultraestrutural e função do músculo papilar isolado. Adotou-se o nível de significância de 5% (a = 0,05). Resultados: Os ratos do grupo RF apresentaram menor atrofia cardíaca do que os do grupo R50 em relação aos do grupo C. Os ratos do grupo C aumentaram peso corporal, os ratos do grupo R50 mantiveram seu peso corporal inicial e os ratos do grupo RF aumentaram e reduziram seu peso durante o ciclo RF. O ciclo RF não causou comprometimento funcional, pois os parâmetros isotônicos e isométricos apresentaram comportamento similar aos dos ratos do grupo C. Os parâmetros cardíacos isotônicos e isométricos mostraram-se significativamente elevados nos ratos do grupo RF em comparação aos dos ratos do grupo R50. Além disso, os ratos do grupo R50 apresentaram dano cardíaco em comparação aos ratos do grupo C quanto às variáveis isotônicas e isométricas. Os ratos do grupo R50 apresentaram alterações focais em muitas fibras musculares, enquanto os ratos do grupo RF apresentaram leves alterações, como perda ou desorganização de miofibrilas. Conclusão: Ciclos de Jejum/Realimentação promovem efeitos benéficos cardíacos e atenuam o dano miocárdico causado por restrição calórica em SHR, contribuindo para reduzir o risco cardiovascular e os danos morfológicos. Além disso, o ciclo de jejum/realimentação promove leve melhora do trânsito do Ca2+ e do sistema beta-adrenérgico.


Subject(s)
Animals , Male , Papillary Muscles/metabolism , Calcium/metabolism , Fasting/physiology , Animal Nutritional Physiological Phenomena/physiology , Cardiomyopathies/prevention & control , Papillary Muscles/pathology , Rats, Inbred SHR , Time Factors , Body Weight/physiology , Calcium/analysis , Ventricular Remodeling/physiology , Caloric Restriction/adverse effects , Isoproterenol/analysis , Isoproterenol/metabolism , Myocardial Contraction , Cardiomyopathies/pathology
16.
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
17.
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
18.
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
19.
ABC., imagem cardiovasc ; 31(1): f:57-l:66, jan.-mar. 2018. ilus, tab
Article in Portuguese | LILACS | ID: biblio-878762

ABSTRACT

Introdução: O macaco-capuchinho é uma espécie de primata não humano que demonstra grande potencial para estudos pré-clínicos devido às semelhanças anatômicas e fisiológicas com os seres humanos. Objetivo: Estudar os índices de deformação miocárdica em macacos-capuchinhos anestesiados utilizando speckle tracking. Métodos: Foram utilizados dezesseis animais do Parque Zoobotânico, em Teresina, Piauí, Brasil, com restrição química, utilizando uma combinação de cetamina e midazolam. Os estudos ecocardiográficos foram obtidos nos modos B, M e Doppler, medindo-se strain e strain rate através de speckle tracking. Resultados: As variáveis que apresentaram coeficientes de correlação estatisticamente significativos em relação ao peso foram a parede livre do ventrículo esquerdo em diástole (PLVEd), diâmetro interno do ventrículo esquerdo em diástole (DIVEd), diâmetro interno do ventrículo esquerdo em sístole (DIVEs), onda E, A'VD, movimento do anel mitral (MAM) e excursão sistólica do plano do anel tricúspide (TAPSE). A frequência cardíaca (FC) mostrou correlação positiva com a onda E e a onda A e correlação negativa com o tempo de relaxamento isovolumétrico (TRIV). A fração de encurtamento (FS) apresentou correlação positiva com a razão entre as ondas E e A (r = 0,61). TAPSE mostrou correlações positivas com E'VD e A'VD. Os valores obtidos para o strain circunferencial (-18,17 ± 4,68%), radial (47,13 ± 5,24%) e longitudinal (-26,46 ± 5,155%) para os macacos-capuchinhos estavam dentro dos intervalos normais para machos e fêmeas. Conclusão: O presente estudo fornece os primeiros valores de referência para medidas ecocardiográficas em modos B, M e Doppler para macacos-capuchinhos anestesiados com cetamina e midazolam. Os valores de strain e strain rate obtidos utilizando a técnica de speckle tracking mostraram-se semelhantes aos obtidos em seres humanos, sugerindo que esta ferramenta pode ser explorada em estudos pré-clínicos utilizando o modelo do macaco-capuchinho


Introduction: The capuchin monkey is a type of nonhuman primate that has shown great potential for preclinical studies because of its anatomical and physiological similarities to humans. Objective: To study the indices of myocardial deformation in anesthetized capuchin monkeys using speckle tracking. Methods: Sixteen animals from the Zoobotanical Park, Teresina, Piauí, Brazil, were used and chemically restrained using a combination of ketamine and midazolam. Echocardiography recordings were obtained in B, M and Doppler modes, and strain and strain rate were measured using speckle tracking. Results: The variables that showed statistically significant correlation coefficients in relation to weight were LVFWd, LVIDd, LVIDs, E wave, A'RV, MAM and TAPSE. HR showed a positive correlation with the E wave and A wave and a negative correlation with IVRT. FS presented a positive correlation with the E/A wave relationship (r = 0.61). TAPSE showed positive correlations with E'RV and A'RV. The values obtained for circumferential (-18.17 ± 4.68%), radial (47.13 ± 5.24%) and longitudinal (- 26.46 ± 5.15%) strain for the capuchin monkeys were within the normal ranges for males and females. Conclusion: The present study provides the first reference values for echocardiographic measurements in B, M and Doppler modes for capuchin monkeys anesthetized with ketamine and midazolam. The strain and strain rate values obtained using speckle tracking showed similarities with those obtained in humans, suggesting that this tool has the potential to be exploited in preclinical studies using the capuchin monkey model


Subject(s)
Animals , Anesthetics, Intravenous/therapeutic use , Echocardiography/methods , Models, Animal , Myocardial Contraction , Diagnostic Imaging , Echocardiography, Doppler/methods , Heart Defects, Congenital/genetics , Heart Rate , Heart Ventricles , Hematologic Tests/methods , Ketamine/therapeutic use , Midazolam/therapeutic use , Guidelines as Topic/methods , Data Interpretation, Statistical
20.
Rev. colomb. cardiol ; 24(6): 550-558, nov.-dic. 2017. tab, graf
Article in Spanish | LILACS, COLNAL | ID: biblio-900582

ABSTRACT

Resumen Objetivos: evaluar la utilidad del strain sistólico pico longitudinal bidimensional para detectar enfermedad coronaria significativa en pacientes con diagnóstico de infarto agudo del miocardio sin elevación del ST y su capacidad para identificar la arteria responsable del evento agudo. Métodos: estudio observacional descriptivo y transversal realizado entre marzo y noviembre de 2015 en pacientes con diagnóstico clínico de infarto agudo del miocardio sin elevación del ST, a quienes se les evaluó el strain sistólico pico longitudinal bidimensional del ventrículo izquierdo, previo a la angiografía coronaria. Resultados: se evaluó el strain longitudinal en 28 pacientes que cumplieron con los criterios de selección. Por análisis de curvas ROC, se identificó un punto de corte para el strain global ≥ -18,8% con sensibilidad del 85% y especificidad del 75% para reconocer presencia de enfermedad coronaria angiográficamente significativa. Un punto de corte ≥ -17,8% de strain global, identificó lesiones significativas con especificidad del 100%. Para el análisis segmentario se estableció un punto de corte de ≥ 3 segmentos con strain ≥ -14%, encontrando una sensibilidad de 90% y una especificidad 87,5% para diagnóstico de enfermedad coronaria significativa. Conclusiones: la técnica ecocardiográfica evaluada, aplicada a pacientes con diagnóstico clínico de infarto del miocardio sin elevación del ST, mostró su utilidad para identificar enfermedad coronaria significativa, pero no permitió hallar el vaso culpable del evento agudo.


Abstract Objectives: To evaluate the usefulness of two-dimensional longitudinal peak systolic strain to detect significant coronary disease in patients with a diagnosis of acute myocardial infarction without ST elevation, and its ability to identify the artery responsible for the coronary event. Methods: A descriptive, observational, and cross-sectional study was conducted between March and November 2015 on patients with a clinical diagnosis of acute myocardial infarction without ST elevation, and on whom the two-dimensional longitudinal peak systolic strain of the left ventricle was evaluated prior to coronary angiography. Results: The longitudinal strain was evaluated in 28 patients who fulfilled selection criteria. For the ROC curve analysis, a cut-off point of ≥ -18.8% for the overall strain was identified, with a sensitivity of 85% and a specificity of 75% to recognise the presence of angiographically significant coronary disease. A cut-off point of ≥ -17.8% of overall strain identified significant lesions, with a specificity of 100%. For the segmental analysis, a cut-off point of ≥ 3 segments with a strain ≥ -14% was established, finding a sensitivity of 90% and a specificity of 87.5% for the diagnosis of significant coronary disease. Conclusions: The evaluated echocardiographic technique, when applied to patients with a clinical diagnosis of myocardial infarction without ST elevation, was shown to be useful in identifying significant coronary disease, but was unable to find the vessel responsible for the acute event.


Subject(s)
Humans , Cardiac Imaging Techniques , Acute Coronary Syndrome , Coronary Vessels , Echocardiography , Myocardial Contraction
SELECTION OF CITATIONS
SEARCH DETAIL