Evaluation of acute cardiorespiratory and hemodynamic changes in perioperative intravenous antimicrobial applications in cats / [Avaliação das alterações cardiorespiratórias e hemodinâmicas agudas em aplicações pré-operatórias de antimicrobianos, pela via intravenosa, em gatos]

The metabolic peculiarities of felines favor an intoxication. Fifty healthy female cats were divided into five groups: PG (placebo group), G2 (cefazolin), G3 (ceftriaxone), G4 (enrofloxacin) and G5 (ampicillin) were used. The parameters evaluated were: total expired carbon dioxide (ETCO2), oxygen saturation in hemoglobin (SpO2), heart rate (HR), respiratory rate (RR), body temperature (BT), systolic, mean and diastolic blood pressure (SBP, mBP and DBP) by invasive method, at T0, 5 (T5), 10 (T10), 15 (T15), 20 (T20), 25 (T25) and 30 (T30) minutes after administration of the treatments. HR presented reduction in G2 compared to PG at all times, except T20, and in G4, T25 and T30 were lower than the T0 values (P<0.05). BT showed increase in the G3 at T0 and T5 and all groups showed reduction in the values of BT relative to T0 (P<0.05). ETCO2 increased in G2 and G5 at all times compared to PG (P<0.05) and there were no differences among the times within each group. It was concluded that ceftriaxone is safer for the prophylactic antimicrobial use in cats, however the other antimicrobials are also indicated, because all the parameters, in all groups, basically did not change over the study and when this occurs it remains in reference interval.(AU)

As peculiaridades metabólicas dos felinos favorecem quadro de intoxicação. Foram utilizadas 50 gatas saudáveis, que foram divididas em cinco grupos: GP (grupo placebo), G2 (grupo cefazolina), G3 (grupo ceftriaxona), G4 (grupo enrofloxacina) e G5 (grupo ampicilina). Os seguintes parâmetros foram avaliados: dióxido de carbono expirado (ETCO2), saturação de oxigênio na hemoglobina (SpO2), frequência cardíaca (FC), frequência respiratória (FR), temperatura corporal (T°C), pressão arterial sistólica,média e diastólica (PAS, PAM e PAD), pelo método invasivo, em 0 (T0), 5 (T5), 10 (T10), 15 (T15), 20 (T20), 25 (T25) e 30 (T30) minutos após a administração dos tratamentos. A FC apresentou redução no G2 em relação ao GP em todos os momentos, exceto no T20, e, no G4, o T25 e o T30 foram inferiores aos valores do T0 (P<0,05). A T°C apresentou aumento no G3 no T0 e no T5, e todos os grupos apresentaram redução nos valores da T°C em relação ao T0 (P<0,05). O ETCO2 apresentou aumento no G2 e no G5, em todos os momentos, em relação ao GP (P<0,05). Concluiu-se que a ceftriaxona é mais segura para uso profilático em gatos, entretanto os outros antibióticos também são recomendados, pois todos os parâmetros praticamente não se modificaram e, quando alterados, mantiveram-se dentro dos padrões de referência.(AU)

Football society players over the age of 55: how stressful can a match be?

This study aimed atassessingthe physical activitylevel, heart rate and the salivary cortisol level of football society players.The sample consisted of 19 male mastersfootballplayerswith an average age of 56.7±3.9 years. The long form of the International Physical Activity Questionnaire (IPAQ)andPolar®heart rate monitors were usedas instruments, in additionto Salivette® tubes to measure salivary cortisol. Data analysis was performed by using the repeated measuresAnalysis of Variance (ANOVA) with Bonferroni post hoctest,and Spearman's Rank Correlation Coefficient. The results showed that the salivary cortisol concentration indicated an index of 1.97 ng/ml at the beginning of the match;40 minutes after that thesevalues increased to 8.00 ng/ml,and 60 minutesafter the match had started they reached 8.40 ng/ml. Considering the post-match moment, a moderate and positive correlation between the salivary cortisol concentration and heart rate (averageand maximum) wasseen. In conclusion,the physical effort expended during football Society practice needs to be monitored due to the high heart rate and high increase in the salivary cortisol concentrationofthis age group.

Effect of pre-administered flurbiprofen axetil on the EC50 of propofol during anesthesia in unstimulated patients: a randomized clinical trial / Efeito da pré‐ administração de flurbiprofeno axetil na CE50 do propofol durante anestesia em pacientes não estimulados: estudo clínico randomizado

Abstract Background and objectives Preoperative use of flurbiprofen axetil (FA) is extensively adopted to modulate the effects of analgesia. However, the relationship between FA and sedation agents remains unclear. In this study, we aimed to investigate the effects of different doses of FA on the median Effective Concentration (EC50) of propofol. Methods Ninety-six patients (ASA I or II, aged 18-65 years) were randomly assigned into one of four groups in a 1:1:1:1 ratio. Group A (control group) received 10 mL of Intralipid, and groups B, C and D received 0.5 mg.kg−1, 0.75 mg.kg−1 and 1 mg.kg−1 of FA, respectively, 10 minutes before induction. The depth of anesthesia was measured by the Bispectral Index (BIS). The "up-and-down" method was used to calculate the EC50 of propofol. During the equilibration period, if BIS ≤ 50 (or BIS > 50), the next patient would receive a 0.5 µg.mL−1-lower (or -higher) propofol Target-Controlled Infusion (TCI) concentration. The hemodynamic data were recorded at baseline, 10 minutes after FA administration, after induction, after intubation and 15 minutes after intubation. Results The EC50 of propofol was lower in Group C (2.32 µg.mL−1, 95% Confidence Interval [95% CI] 1.85-2.75) and D (2.39 µg.mL−1, 95% CI 1.91-2.67) than in Group A (2.96 µg.mL−1, 95% CI 2.55-3.33) (p = 0.023, p = 0.048, respectively). There were no significant differences in the EC50 between Group B (2.53 µg.mL−1, 95% CI 2.33-2.71) and Group A (p > 0.05). There were no significant differences in Heart Rate (HR) among groups A, B and C. The HR was significantly lower in Group D than in Group A after intubation (66 ± 6 vs. 80 ± 10 bpm, p < 0.01) and 15 minutes after intubation (61 ± 4 vs. 70 ± 8 bpm, p < 0.01). There were no significant differences among the four groups in Mean Arterial Pressure (MAP) at any time point. The MAP of the four groups was significantly lower after induction, after intubation, and 15 minutes after intubation than at baseline (p < 0.05). Conclusion High-dose FA (0.75 mg.kg−1 or 1 mg.kg−1) reduces the EC50 of propofol, and 1 mg.kg−1 FA reduces the HR for adequate anesthesia in unstimulated patients. Although this result should be investigated in cases of surgical stimulation, we suggest that FA pre-administration may reduce the propofol requirement when the depth of anesthesia is measured by BIS.

Resumo Justificativa e objetivos A administração pré‐operatória de Flurbiprofeno Axetil (FA) é amplamente usada para a modulação da analgesia. No entanto, a relação entre FA e fármacos sedativos permanece obscura. Neste estudo, nosso objetivo foi investigar os efeitos de diferentes doses de FA na Concentração Efetiva mediana (CE50) do propofol. Métodos Noventa e seis pacientes (ASA I ou II, com idades de 18-65 anos) foram alocados aleatoriamente em quatro grupos na proporção de 1:1:1:1. Dez minutos antes da indução, o Grupo A (grupo controle) recebeu 10 mL de Intralipid, enquanto os grupos B, C e D receberam FA na dose de 0,5 mg.kg‐1; 0,75 mg.kg‐1 e 1 mg.kg‐1, respectivamente. A profundidade da anestesia foi medida pelo Índice Bispectral (BIS). O método up‐and‐down foi usado para calcular a CE50 do propofol. Durante o período de equilíbrio, se o valor do BIS fosse ≤ 50 ou BIS > 50, o próximo paciente tinha a infusão de propofol ajustada para uma concentração alvo‐controlada 0,5 µg.mL‐1 inferior ou superior, respectivamente. Os dados hemodinâmicos foram registrados no início do estudo, 10 minutos após a administração de FA, após a indução, após a intubação e 15 minutos após a intubação. Resultados A CE50 do propofol foi menor no Grupo C (2,32 µg.mL‐1, Intervalo de Confiança de 95% [95% IC] 1,85-2,75) e D (2,39 µg.mL‐1, 95% IC 1,91-2,67) do que no Grupo A (2,96 µg.mL‐1; 95% IC 2,55-3,33) (p = 0,023, p = 0,048, respectivamente). Não houve diferenças significantes na CE50 entre o Grupo B (2,53 µg.mL‐1, 95% IC 2,33-2,71) e o Grupo A (p > 0,05). Não houve diferenças significantes na Frequência Cardíaca (FC) entre os grupos A, B e C. A FC foi significantemente menor no grupo D do que no grupo A após a intubação (66 ± 6 vs. 80 ± 10 bpm, p < 0,01) e 15 minutos após a intubação (61 ± 4 vs. 70 ± 8 bpm, p < 0,01). Não houve diferenças significantes entre os quatro grupos na Pressão Arterial Média (PAM) em qualquer momento. A PAM dos quatro grupos foi significantemente menor após a indução, após a intubação e 15 minutos após a intubação do que na linha de base (p < 0,05). Conclusão FA em altas doses (0,75 mg.kg‐1 ou 1 mg.kg‐1) reduz a CE50 do propofol, e 1 mg.kg‐1 de FA reduz a FC durante níveis adequados de anestesia em pacientes não estimulados. Embora esse resultado deva ser investigado na presença de estimulação cirúrgica, sugerimos que a pré‐administração de FA pode reduzir a necessidade de propofol durante anestesia cuja profundidade seja monitorada pelo BIS.

Propofol-ketamine versus dexmedetomidine-ketamine for sedation during upper gastrointestinal endoscopy in pediatric patients: a randomized clinical trial / Propofol­cetamina versus dexmedetomidina­cetamina para sedação durante endoscopia digestiva alta em pacientes pediátricos: estudo clínico randomizado

Abstract Background and objectives Day-case pediatric sedation is challenging. Dexmedetomidine is a sedative analgesic that does not induce respiratory depression. We compared dexmedetomidine to propofol when it was added to ketamine for sedation during pediatric endoscopy, regarding recovery time and hemodynamic changes. Methods We enrolled 120 patients (2−7 years in age) and randomly assigned them into two groups. Each patient received intravenous (IV) ketamine at a dose of 1 mg.kg-1 in addition to either propofol (1 mg.kg-1) or dexmedetomidine (0.5 µg.kg-1). The recovery time was compared. Hemodynamics, oxygen saturation, need for additional doses, postoperative complications and endoscopist satisfaction were monitored. Results There was no significant difference in hemodynamics between the groups. The Propofol-Ketamine (P-K) group showed significantly shorter recovery times than the Dexmedetomidine-Ketamine (D-K) group (21.25 and 29.75 minutes, respectively, p < 0.001). The P-K group showed more oxygen desaturation. Eleven and 6 patients experienced SpO2 < 92% in groups P-K and D-K, respectively. A significant difference was noted regarding the need for additional doses; 10% of patients in the D-K group needed one extra dose, and 5% needed two extra doses, compared to 25% and 20% in the P-K group, respectively (p = 0.001). The P-K group showed less post-procedure nausea and vomiting. No statistically significant difference between both groups regarding endoscopist satisfaction. Conclusions The P-K combination was associated with a shorter recovery time in pediatric upper gastrointestinal endoscopy, while the D-K combination showed less need for additional doses. Registration number Clinical trials.gov (NCT02863861).

Resumo Justificativa e objetivos A sedação ambulatorial pediátrica é um desafio. A dexmedetomidina é um analgésico sedativo que não induz à depressão respiratória. Comparamos a dexmedetomidina ao propofol quando associados à cetamina para sedação durante endoscopia pediátrica, quanto ao tempo de recuperação e às alterações hemodinâmicas. Métodos Foram recrutados 120 pacientes (2−7 anos de idade) que foram aleatoriamente alocados em dois grupos. Cada paciente recebeu cetamina IV na dose de 1 mg.kg‐1, além de propofol (1 mg.kg‐1) ou dexmedetomidina (0,5 µg.kg‐1). Comparamos o tempo de recuperação. A hemodinâmica, saturação de oxigênio, necessidade de doses adicionais, complicações pós‐operatórias e satisfação do endoscopista foram monitoradas. Resultados Não houve diferença significante entre os grupos no que diz respeito à hemodinâmica. O grupo Propofol‐Cetamina (P‐C) apresentou tempos de recuperação significantemente mais curtos do que o grupo Dexmedetomidina‐Cetamina (D‐C) (21,25 e 29,75 minutos respectivamente, p < 0,001). Observou‐se frequência maior de dessaturação de oxigênio no grupo P‐C. Onze e 6 pacientes apresentaram SpO2 < 92% nos grupos P‐C e D‐C, respectivamente. Uma diferença significante foi observada em relação à necessidade de doses adicionais; 10% dos pacientes no grupo D‐C precisaram de uma dose extra e 5% precisaram de duas doses extras, em comparação com 25% e 20% no grupo P‐C, respectivamente (p = 0,001). O grupo P‐C apresentou menos náuseas e vômitos após o procedimento. Não houve diferença estatisticamente significante entre os dois grupos em relação à satisfação do endoscopista. Conclusões A combinação P‐C foi associada a tempo mais curto de recuperação na endoscopia digestiva alta pediátrica, enquanto a combinação D‐C mostrou menor necessidade de doses adicionais. Número de registro Clinical trials.gov (NCT02863861).

Oximetría, Frecuencia Cardíaca, Apnea y Actividad de los Músculos Masticatorios en Sujetos con BS / Oximetry, Heart Rate, Apnea and Mastication Muscle Activity in Subjects with Sleep Bruxism

RESUMEN: El objectivo de este estudio fue describir los valores promedio de oximetría, frecuencia cardíaca y eventos de apnea durante la noche y la actividad de los músculos maseteros y temporales en un grupo de adultos jóvenes con BS. Estudio observacional descriptivo de serie de casos que consideró una muestra 20 jóvenes entre 21 y 25 años diagnosticados con BS mediante polisomnografía. Se describieron las condiciones de actividad de los músculos maseteros y temporales mediante electromiografía y los valores e los signos vitales mediante polisomnografía. El análisis estadístico fue de tipo descriptivo, se aplicaron medidas de tendencia central, frecuencias absolutas y relativas. El promedio de la actividad muscular durante la masticación de los maseteros fue (D: 86) (I: 520). El promedio de la actividad muscular durante la masticación de los temporales fue (D: 340) (I: 510). El promedio en los episodios de hipopnea fue de (28,9). El promedio de oximetría fue (NMOR: 93,5) (MOR: 93,8). El promedio de la tasa cardiaca fue (NMOR: 65,4) (MOR: 66,8) latidos/minuto. El promedio de eventos de bruxismo fue (NREM: 135,4) (REM: 120,2).y el índice (eventos BS/hora) (40,60). Las características de las musculares masticatorias y los signos vitales durante el sueño de los sujetos con BS pueden ayudar al entendimiento y a la toma de decisiones en el tratamiento.

ABSTRACT: The objective of the study was to describe the average oximetry, heart rate, and apnea events values during sleep, and the activity of masseter and temporal muscles in a group of young adults with SB (Sleep Bruxism). This serial case and observational descriptive study comprised of a sample of 20 young people between 21 and 25 years of age, who were diagnosed with SB through a polysomnography test. Electromyography recordings served to describe the activity conditions of masseter and temporal muscles, while polysomnography was used to obtain measurement values and vital signs. A descriptive statistical analysis accounting for measures of central tendency, absolute and relative frequencies was performed. During mastication, the average masseter and temporal muscle activity values registered at (D: 86) (I: 520), and (D: 340) (I: 510) respectively. While, the average value for hypopnea episodes was (28.9), and (NREM: 93.5) (REM: 93.8) for oximetry. The average heart rate exhibited a value of (NREM: 65.4) (REM: 66.8) beats / minute, while the values for bruxism events registered at (NREM: 135.4) (REM: 120.2) with an index value of (SB events / hour) (40.60). Muscles of mastication characteristics, and vital signs during sleep for subjects with SB can aid in understanding and decision making in treatment.

Passive Cigarette Smoking Impact on Blood Pressure Response to Epinephrine and Felypressin in 1K1C Hypertensive Rats Treated or not with Atenolol / Impacto do Tabagismo Passivo na Resposta Pressórica à Epinefrina e Felipressina em Ratos Hipertensos 1K1C Tratados ou não com Atenolol

Abstract Background: Cigarette smoking is usually associated with hypertension and may modify vasoconstrictor response. Objective: The present study aimed to analyze and compare the interaction of passive cigarette smoking and hypertension on epinephrine and felypressin blood pressure effects after intravascular injection. Method: 45-day male Wistar rats had the main left renal artery partially constricted and the right kidney removed (1K1C model). Rats were placed in the chamber for exposition to passive cigarette smoking (10 cigarettes) during 10 min (6 days a week). Hypertensive rats received atenolol (90 mg/kg/day) by gavage for two weeks. Hypotensive and hypertensive response, response duration and heart rate were recorded from direct blood pressure values. The significance level was 5%. Results: Passive cigarette smoking increased maximal hypertensive response to epinephrine in normotensive and 1K1C-atenolol treated rats and to felypressin only in 1K1C-atenolol treated rats; it also reduced epinephrine hypotensive response. Epinephrine increased heart rate in normotensive and hypertensive passive smokers or non-smoker rats. Comparing the two vasoconstrictors, epinephrine showed greater hypertensive response in normotensive smokers, 1K1C-atenolol treated smokers and non-smokers. However, in normotensive-nonsmoker rats, felypressin showed a greater and longer hypertensive effect. Conclusions: Our results suggest that passive cigarette smoking may reduce epinephrine vasodilation and increase hypertensive response when compared to felypressin. Therefore, felypressin may be safe for hypertensive patients to avoid tachycardia and atenolol interaction, but for normotensive and non-smoker patients, epinephrine may be safer than felypressin.

Resumo Fundamento: O tabagismo geralmente está associado à hipertensão e pode modificar a resposta vasoconstritora. Objetivo: O presente estudo teve como objetivo analisar e comparar a interação do tabagismo passivo e hipertensão sobre os efeitos da epinefrina e felipressina na pressão arterial após injeção intravascular. Métodos: Ratos Wistar machos de 45 dias tiveram a artéria renal principal esquerda parcialmente obstruída e o rim direito removido (modelo 1K1C). Os ratos foram colocados na câmara para exposição ao tabagismo passivo (10 cigarros) durante 10 minutos (6 dias por semana). Ratos hipertensos receberam atenolol (90 mg/kg/dia) por gavagem durante duas semanas. A resposta hipotensora e hipertensiva, a duração da resposta e a frequência cardíaca foram registradas a partir da medida dos valores diretos da pressão arterial. O nível de significância foi de 5%. Resultados: O tabagismo passivo aumentou a resposta hipertensiva máxima à epinefrina em ratos normotensos e ratos 1K1C tratados com atenolol e à felipressina apenas em ratos 1K1C tratados com atenolol; também reduziu a resposta hipotensiva à epinefrina. A epinefrina aumentou a frequência cardíaca em ratos fumantes passivos ou não-fumantes, normotensos e hipertensos. Comparando os dois vasoconstritores, a epinefrina apresentou maior resposta hipertensiva em fumantes normotensos, ratos 1K1C fumantes e não fumantes tratados com atenolol. No entanto, em ratos normotensos e não fumantes, a felipressina apresentou um efeito hipertensivo maior e mais prolongado. Conclusões: Nossos resultados sugerem que o tabagismo passivo pode reduzir a vasodilatação da epinefrina e aumentar a resposta hipertensiva quando comparado à felipressina. Portanto, a felipressina pode ser segura para pacientes hipertensos, com o objetivo de evitar a interação entre taquicardia e atenolol, mas para pacientes normotensos e não-fumantes, a epinefrina pode ser mais segura que a felipressina.

Feasibility of non-intubated anesthesia and regional block for thoracoscopic surgery under spontaneous respiration: a prospective cohort study

Data about the feasibility and safety of thoracoscopic surgery under non-intubated anesthesia and regional block are limited. In this prospective study, 57 consecutive patients scheduled for thoracoscopic surgery were enrolled. Patients were sedated with dexmedetomidine and anesthetized with propofol and remifentanil. Ropivacaine was used for intercostal nerve and paravertebral block. Lidocaine was used for vagal block. The primary outcomes were mean arterial pressure (MAP), heart rate (HR), oxygen saturation, and end-tidal carbon dioxide partial pressure (ETCO2) at T0 (pre-anesthesia), T1 (immediately after laryngeal mask/nasopharyngeal airway placement), T2 (immediately after skin incision), T3 (10 min after opening the chest), T4 (end of surgery), and T5 (immediately after laryngeal mask/nasopharyngeal airway removal). One patient required conversion to intubation, 15 developed intraoperative hypotension, and two had hypoxemia. MAP at T0 and T5 was higher than at T1-T4; MAP at T3 was lower (P<0.05 vs other time points). HR at T0 and T5 was higher (P<0.05 vs other time points). ETCO2 at T2 and T3 was higher (P<0.05 vs other time points). Arterial pH, PCO2, and lactic acid at T1 differed from values at T0 and T2 (P<0.05). The Quality of Recovery-15 (QoR-15) score at 24 h was lower (P<0.05). One patient experienced dysphoria during recovery. Thoracoscopic surgery with regional block under direct thoracoscopic vision is a feasible and safe alternative to conventional surgery under general anesthesia, intubation, and one-lung ventilation.

Acute effect of ambient fine particulate matter on heart rate variability: an updated systematic review and meta-analysis of panel studies

BACKGROUND@#Decreased heart rate variability (HRV) is a predictor of autonomic system dysfunction, and is considered as a potential mechanism of increased risk of cardiovascular disease (CVD) induced by exposure to particulate matter less than 2.5 μm in diameter (PM@*METHODS@#An updated systematic review and meta-analysis of panel studies till November 1, 2019 was conducted to evaluate the acute effect of exposure to ambient PM@*RESULTS@#A total of 33 panel studies were included in our meta-analysis, with 16 studies conducted in North America, 12 studies in Asia, and 5 studies in Europe. The pooled results showed a 10 μg/m@*CONCLUSION@#Short-term exposure to PM

The effects of remifentanil used during cesarean section on oxidative stress markers in correlation with maternal hemodynamics and neonatal outcome: a randomized controlled trial / Os efeitos do remifentanil sobre os marcadores do estresse oxidativo durante a cesariana, em correlação com a hemodinâmica materna e o desfecho neonatal: um estudo randômico controlado

Abstract Background and objective: Remifentanil is used to attenuate maternal hemodynamic response to intubation and surgical stress during Induction-Delivery period of cesarean section. The goal was to compare the effects of two remifentanil dosing regimens on oxidative stress level, in correlation with its hemodynamic and neonatal effects. Methods: Fifty-one patients, 17 per group, enrolled for elective cesarean section were randomly divided by computer-generated codes into three parallel groups: (A) patients received a 1 µg.kg-1 remifentanil bolus immediately before induction, followed by 0.15 µg.kg-1.min-1 infusion, that was stopped after skin incision; (B) patients received a 1 µg.kg-1 remifentanil bolus immediately before induction; (C) (control), patients did not receive remifentanil until delivery. Maternal venous blood samples were taken at basal time, at extraction and 30 minutes after the end of operation for spectrophotometrical determination of malondialdehyde and advanced oxidation protein products concentration. The same was conducted for umbilical venous sample. Results: Systolic blood pressure and heart rate remained significantly lower in group A compared to B and C during entire Induction-Delivery period (p < 0.001, p = 0.02 after intubation; p = 0.006, p = 0.03 after skin incision; p = 0.029, p = 0.04 after extraction; respectively). Malondialdehyde concentration was lower at time of extraction in maternal blood in group A compared to B and C (p = 0.026). All neonatal Apgar scores were ≥ 8 and umbilical acid-base values within normal range. Conclusions: The remifentanil dosing regimen applied in group A significantly attenuated lipid peroxidation and maternal hemodynamic response during entire I-D period, without compromising neonatal outcome.

Resumo Justificativa e objetivo: O remifentanil é usado para atenuar a resposta hemodinâmica materna à intubação e ao estresse cirúrgico durante o intervalo indução-parto cesariana. O objetivo foi comparar os efeitos de dois regimes posológicos de remifentanil sobre o nível de estresse oxidativo, em correlação com seus efeitos na hemodinâmica materna e no neonato. Métodos: Mediante códigos gerados por computador, 51 pacientes (17 por grupo) programadas para cesariana eletiva foram randomicamente divididas em três grupos paralelos (A, B e C). No Grupo A, as pacientes receberam remifentanil em bolus de 1 µg.kg-1 imediatamente antes da indução, seguido por infusão de 0,15 µg.kg-1.min-1 que foi interrompida após a incisão da pele; no Grupo B, as pacientes receberam remifentanil em bolus de 1 µg.kg-1 imediatamente antes da indução; no Grupo C (controle), as pacientes não receberam remifentanil até o parto. Amostras de sangue venoso materno foram colhidas no momento basal, na extração do feto e 30 minutos após o término da operação para determinar espectrofotometricamente as concentrações do malondialdeído e dos produtos proteicos de oxidação avançada. O mesmo foi feito para a coleta das amostras de sangue venoso umbilical. Resultados: A pressão arterial sistólica e a frequência cardíaca permaneceram significativamente menores no Grupo A, comparado aos grupos B e C, durante todo o intervalo indução-parto (p < 0,001, p = 0,02 após a intubação; p = 0,006, p = 0,03 após a incisão da pele; p = 0,029, p = 0,04 após a extração do feto, respectivamente). No momento da extração do feto, a concentração do malondialdeído foi menor no sangue materno do Grupo A, comparado aos grupos B e C (p = 0,026). Todos os escores de Apgar neonatais foram ≥ 8 e os valores da avaliação ácido-base do cordão umbilical estavam dentro da faixa normal. Conclusões: O regime posológico de remifentanil aplicado ao Grupo A atenuou de modo significativo a peroxidação lipídica e a resposta hemodinâmica materna durante todo o intervalo indução-parto, sem comprometer o desfecho neonatal.

Bradycardic and Antiarrhythmic Effects of the D-Limonene in Rats / Efeitos Bradicárdicos e Antiarrítmicos do D-Limoneno em Ratos

Abstract Background: D-limonene (DL) is a monoterpene and is the major component in the essential oil of citrus fruit. It presents antihyperglycemic and vasodilatation activities. Objectives: This study evaluated the cardiovascular effects and potential antiarrhythmic of DL in rats. Methods: Hemodynamic and electrocardiographic (ECG) parameters were measured in male Wistar rats, which under anesthesia had been cannulated in the abdominal aorta and lower vena cava and had electrodes subcutaneously implanted. In the in vitro approach, the heart was removed and perfused using the Langendorff technique. The significance level adopted was 5% (p < 0.05). Results: DL, in doses of 10, 20, and 40 mg/kg (i.v), produced intense and persistent bradycardia associated with hypotension. Bradycardia with prolonged QTc was observed in the ECG in vivo recording. In the in vivo model of arrhythmia induced by Bay K8644, DL (10 mg/kg) decreased the arrhythmia score from 15.33 ± 3.52 to 4.0 ± 2.64 u.a (p < 0.05, n = 4). In isolated perfused hearts, DL (10-3 M) promoted significant reductions in heart rate (from 228.6 ± 8.5 ms to 196.0 ± 9.3 bpm; p < 0.05) and left ventricular development pressure (from 25.2 ± 3.4 to 5.9 ± 1.8 mmHg; n = 5, p < 0.05). Conclusions: DL produces bradycardia and antiarrhythmic activity in rat heart.

Resumo Fundamento: O D-limoneno (DL) é um monoterpeno e o principal componente do óleo essencial de frutas cítricas. Ele apresenta atividades anti-hiperglicêmicas e vasodilatadoras. Objetivos: Este estudo avaliou os efeitos cardiovasculares e antiarrítmicos potenciais do DL em ratos. Métodos: Os parâmetros hemodinâmicos e eletrocardiográficos (ECG) foram mensurados em ratos Wistar machos que, sob anestesia, tiveram a aorta abdominal e a veia cava inferior canuladas e receberam eletrodos implantados subcutaneamente. Na abordagem in vitro, o coração foi removido e perfundido utilizando a técnica de Langendorff. O nível de significância adotado foi de 5% (p < 0,05). Resultados: DL, nas doses de 10, 20 e 40 mg/kg (i.v), produziu bradicardia intensa e persistente associada à hipotensão. A bradicardia com QTc prolongado foi observada no registro in vivo do ECG. No modelo in vivo de arritmia induzida por Bay K8644, DL (10 mg / kg) houve diminuição do escore da arritmia de 15,33 ± 3,52 para 4,0 ± 2,64 u.a (p < 0,05, n = 4). Em corações perfundidos isolados, o DL (10-3 M) promoveu reduções significativas na frequência cardíaca (de 228,6 ± 8,5 ms para 196,0 ± 9,3 bpm; p < 0,05) e na pressão desenvolvida do ventrículo esquerdo (de 25,2 ± 3,4 para 5,9 ± 1,8 mmHg; n = 5, p < 0,05). Conclusões: O DL produz bradicardia e atividade antiarrítmica no coração de ratos.

Evaluación diagnóstica y manejo terapéutico farmacológico en pacientes con fibrilación auricular / Diagnostic evaluation and pharmacological therapeutic management in patients with atrial fibrillation

La fibrilación auricular (FA) es la arritmia sostenida más frecuente que puede presentarse en una amplia variedad de condiciones clínicas. A pesar de los progresos en el tratamiento de los pacientes con FA, esta arritmia sigue siendo una de las más importantes causas de accidente cerebrovascular, insuficiencia cardiaca, muerte súbita y morbilidad cardiovascular en todo el mundo. El objetivo del tratamiento con fármacos antiarrítmicos es mejorar los síntomas relacionados con la FA, y buscar un equilibrio entre la carga sintomática, la posibilidad de reacciones farmacológicas adversas y las preferencias del paciente. El control de la frecuencia cardiaca a corto y largo plazo se puede lograr con bloqueadores beta, digoxina, bloqueadores de los canales del calcio o tratamiento combinado. Si bien otros fármacos antiarrítmicos de clase III también tienen un efecto limitador de la frecuencia, solo deben emplearse para el control del ritmo cardiaco. Restaurar y mantener el ritmo sinusal también es una parte integral del tratamiento de la FA. Los fármacos antiarrítmicos de clase III duplican la tasa de pacientes en ritmo sinusal. El tratamiento para el control del ritmo está indicado para mejorar los síntomas de los pacientes con FA que siguen sintomáticos a pesar del tratamiento adecuado para el control de la frecuencia cardiaca. La combinación de antiarrítmicos que prolongan el intervalo QT no se debe emplear para el control del ritmo cardiaco en la FA(AU)

Atrial fibrillation (AF) is the most frequent sustained arrhythmia that can occur in a wide variety of clinical conditions. Despite progress in the treatment of patients with AF, this arrhythmia remains one of the most important causes of stroke, heart failure, sudden death and cardiovascular morbidity worldwide. The aim of treatment with antiarrhythmic drugs is to improve the symptoms related to AF, and to look for a balance between the symptomatic load, the possibility of adverse pharmacological reactions and the patient preferences. The short and long term heart rate control can be achieved with beta blockers, digoxin, calcium channel blockers or combination therapy. Although other class III antiarrhythmic drugs also have a frequency-limiting effect, they should only be used for the control of heart rhythm. Restoring and maintaining sinus rhythm is also an integral part of the treatment of AF. Class III antiarrhythmic drugs double the rate of patients who maintain their sinus rhythm. Treatment for rhythm control is indicated to improve the symptoms of patients with AF who remain symptomatic despite adequate treatment for heart rate control. The combination of antiarrhythmics that prolong the QT interval should not be used to control heart rhythm in AF(AU)

Anesthetic quality and cardiovascular and respiratory effects of continuous intravenous infusion of tiletamine-zolazepam in bitches / Qualidade anestésica e efeitos cardiovascular e respiratória da infusão intravenosa contínua de tiletamina-zolazepam em cadelas

The objective of this study was to evaluate the quality and recovery from anesthesia promoted by the tiletamine-zolazepam (TZ) combination administered intravenously (IV) continuously in bitches pre-medicated with acepromazine. Eight cross-bred, clinically healthy bitches weighing 13.7 ±1.9kg on average were used in this study. After a food fast of 12 h and a water fast of four hours, the animals were treated with acepromazine (0.1mg/kg, intramuscular) and, after 15 minutes, anesthesia was induced with a combination of tiletamine-zolazepam (2mg/kg, IV) immediately followed by continuous IV infusion thereof at a dose of 2mg/kg/h for 60 min. The following parameters were measured in all animals immediately before administration of acepromazine (M15), immediately before anesthetic induction (M0), and at 5, 10, 20, 30, 40, 50, and 60 min after initiation of continuous infusion (M5, M10, M20, M30, M40, M50, and M60): electrocardiography (ECG), heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), body temperature (BT), and arterial hemogasometry, with the last performed only at experimental times M15, M0, M30, and M60. A subcutaneous electrical stimulator was used to evaluate the degree of analgesia. Myorelaxation and quality of anesthetic recovery were also assessed, classifying these parameters as excellent, good, and poor. Anesthetic recovery time was recorded in minutes. HR increased significantly at time M10 in relation to that at M-15, and at times M5, M10, M40, and M50 in relation to that at M0. MAP decreased significantly at M20 and M30 compared with the baseline. BT decreased significantly at M50 compared with that at M0, but no hypothermia was observed. RR showed significant reduction at M5, M10, and M20 in relation to that at M-15, and at M5 and M10 in relation to that at M0, and bradypnoea was observed during the first 20 min after anesthetic induction. Significant decreases in the PR interval at times M10, M40, and M50 were observed in relation to that at M15. Amplitude of the R wave showed significant decrease at M20 compared with that at M-15. In the other ECG parameters, no significant difference was observed between the times evaluated. Hemogasometric parameters and analgesia did not show significant alterations. Myorelaxation and quality of anesthetic recovery were considered excellent. Recovery time was 15.1±7.7 min for positioning of sternal decubitus and 45.5±23.1 minutes for return of ambulation. Continuous IV administration of TZ combination does not produce satisfactory analgesia and does not cause severe cardiorespiratory and hemogasometric effects in bitches pre-medicated with acepromazine.(AU)

Objetivou-se avaliar a qualidade e a recuperação da anestesia promovida pela associação tiletamina-zolazepam, administrada por via intravenosa (IV) contínua, em cadelas pré-medicadas com acepromazina. Foram utilizadas oito cadelas, sem raças definidas, clinicamente sadias, pesando em média 13,7±1,9kg. Após jejum alimentar de 12 horas e hídrico de quatro horas, os animais foram medicados com acepromazina (0,1mg/kg, via intramuscular) e, após 15 minutos, a anestesia foi induzida com a associação tiletamina-zolazepam (2mg/kg, IV) seguida imediatamente pela infusão IV contínua da mesma, na dose de 2mg/kg/h, durante 60 minutos. Os parâmetros que foram mensurados em todos os animais, imediatamente antes da administração da acepromazina (M-15), imediatamente antes da indução anestésica (M0) e, aos 5, 10, 20, 30, 40, 50 e 60 minutos após o início da infusão contínua (M5, M10, M20, M30, M40, M50 e M60) foram os seguintes: eletrocardiografia (ECG), frequência cardíaca (FC), pressão arterial média (PAM), frequência respiratória (f), temperatura corpórea (TC) e hemogasometria arterial, esta sendo realizada apenas nos momentos M-15, M0, M30 e M60. Para avaliação do grau de analgesia foi empregado um estimulador elétrico subcutâneo. Também se avaliou o miorrelaxamento e a qualidade da recuperação anestésica, classificando estes parâmetros em: excelente, bom e ruim. O tempo de recuperação anestésica foi registrado em minutos. A FC aumentou significativamente no momento M10 em relação ao M-15, e nos momentos M5, M10, M40 e M50 em relação ao M0. A PAM diminuiu significativamente em M20 e M30 em comparação ao valor basal. A TC diminuiu significativamente em M50 em comparação ao M0, mas não foi observada hipotermia. A f apresentou uma redução significativa nos momentos M5, M10 e M20 em relação ao M-15, e em M5 e M10 em relação ao M0, sendo observado bradipneia durante os primeiros 20 minutos após a indução anestésica. Foram observadas diminuições significativas do intervalo PR nos momentos M10, M40 e M50, em relação ao M-15. A amplitude da onda R apresentou diminuição significativa em M20 em comparação ao M-15. Nos demais parâmetros da ECG não houve diferença significativa entre os momentos avaliados. Os parâmetros hemogasométricos e a analgesia não apresentaram alterações significativas. O miorrelaxamento e a qualidade da recuperação anestésica foram considerados excelentes. O período de recuperação foi de 15,1±7,7 minutos para posicionamento do decúbito esternal e 45,5±23,1 minutos para retorno da deambulação. A administração intravenosa contínua de tiletamina-zolazepam não produz analgesia satisfatória e não causa efeitos cardiorrespiratórios e hemogasométricos severos, em cadelas pré-tratadas com acepromazina.(AU)

Protective efficacy of combined use of parecoxib and dexmedetomidine on postoperative hyperalgesia and early cognitive dysfunction after laparoscopic cholecystectomy for elderly patients

Abstract Purpose: To investigate efficacy of combined use of parecoxib and dexmedetomidine on postoperative pain and early cognitive dysfunction after laparoscopic cholecystectomy for elderly patients. Methods: The present prospective randomized controlled study included a total of 80 patients who underwent laparoscopic cholecystectomy surgery during January 2016 to November 2017 in our hospital. All patients were randomly divided into 4 groups, the parecoxib group, the dexmedetomidine group, the parecoxib and dexmedetomidine combined group, and the control group. Demographic data and clinical data were collected. Indexes of heart rate (HR), mean arterial pressure (MAP), levels of jugular venous oxygen saturation (SjvO2) and jugular venous oxygen pressure (PjvO2) were recorded at different time points before and during the surgery. The mini-mental state examination (MMSE) score, Ramsay score and Visual Analogue Score (VAS) were measured. Results: Levels of both SjvO2 and PjvO2 were significantly higher in parecoxib group, dexmedetomidine group and the combined group than the control group. Meanwhile, levels of both SjvO2 and PjvO2 in the combined group were the highest. VAS scores were significantly lower in the combined group than all other groups, and total patient controlled intravenous analgesia (PCIA) pressing times within 48 h after surgery were the lowest in the combined group. Both Ramsay and MMSE scores were the highest in the combined group compared with other groups, while were the lowest in the control group. Conclusion: The combined use of parecoxib and dexmedetomidine could reduce the postoperative pain and improve the postoperative sedation and cognitive conditions of patients after laparoscopic cholecystectomy.

Conducción anestésica de un paciente con bloqueo de rama izquierda agudo / Anesthetic approach of a patient with acute left-branch block

Introducción: El bloqueo de rama izquierda del haz de His dependiente de la frecuencia cardíaca no es una entidad común en la práctica clínica del anestesiólogo, sino que se presenta como consecuencia de enfermedades cardiacas o no que ocurren por lentitud de la frecuencia ventricular sobre todo, con enfermedad de las arterias coronarias planteadas solo como diagnóstico después de haberlas descartado. Objetivo: Describir el manejo clínico-anestésico de una paciente que presentó bloqueo de rama izquierda del haz de His para cirugía torácica electiva por tumor de mediastino. Desarrollo: Se presenta un caso clínico de una paciente con bloqueo de rama izquierda dependiente de la frecuencia cardiaca que se anunció para cirugía del tórax, sin historia previa de coronariopatía. La cirugía trascurrió sin complicaciones y con buenos resultados. Conclusiones: el bloque de rama izquierda dependiente de la frecuencia cardiaca es una entidad rara y un diagnóstico excluyente de otras entidades cardiovasculares o no como la isquemia miocárdica. Un adecuado manejo intraoperatorio del paciente proporciona excelentes resultados sin traducción clínica ni complicaciones(AU)

Introduction: Rate-dependent left bundle branch block is not a rare entity for the clinical practice in anesthesiology, but appears as a consequence of heart diseases or not always due to slowness in atrial frequency above all, with coronary artery diseases diagnosed only after their being ruled out. Objective: To describe the clinical-anesthetic management of a patient who presented left bundle branch block for elective thoracic surgery due to mediastinal tumor. Findings: We present a clinical case of a female patient with rate-dependent left bundle branch block who was announced for thoracic surgery, without a previous history of coronary artery disease. The surgery proceeded without complications and with positive outcome. Conclusions: Rate-dependent left-branch block is a rare entity and a diagnosis ruling out other cardiovascular entities or not, such as myocardial ischemia. An adequate intraoperative management of the patient provides excellent outcome without clinical translation or complications(AU)

Protective effect of dexmedetomidine against myocardial ischemia-reperfusion injury in rabbits

Abstract Purpose: To investigate the influence of dexmedetomidine on myocardial ischemia-reperfusion injury (IRI) in rabbits. Methods: Twenty-four New Zealand white rabbits were randomly divided into two equal-sized groups: IRI group (group IR) and dexmedetomidine group (group D). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), left ventricular diastolic pressure (LVDP), +dp/dtmax, -dp/dtmax, and t-dp/dtmax were recorded and calculated at the following time points: before (T0) and after (T1) dexmedetomidine infusion, after 30-min ischemia (T2), and after 120-min reperfusion (T3). The levels of plasma endothelin 1 (ET-1), thromboxane A2 (TXA2), and platelet activating factor (PAF); area of myocardial infarction (MI); and no-reflow area were evaluated. Results: SBP, DBP, LVSP, LVEDP, LVDP, and +dp/dtmax at T3 were higher in group D than in group IR (P<0.05). The average no-reflow area in group IR was significantly smaller than that in group D (14±3% vs. 38±5%, P=0.0116). The ET-1, TXA2, and PAF levels at T2 and T3 were higher than those at T0 in both groups (P<0.05). Conclusion: Dexmedetomidine could reduce the magnitude of ischemic myocardial no-reflow area and protect the myocardium with ischemia-reperfusion injury.

Efecto agudo del consumo de yerba mate (Ilex paraguariensis) sobre el ritmo cardíaco en pacientes derivados para estudio Holter / Acute effect of yerba mate (Ilex paraguariensis) consumption on heart rhythm in patients referred for Holter study

Resumen Introducción: El consumo de yerba mate (YM) (Ilex paraguariensis) es común en Sudamérica y se extiende a todo el mundo. Contiene muchas sustancias bioactivas que pueden ser beneficiosas. También existe la opinión de que puede tener efectos nocivos sobre el ritmo cardíaco, pero no encontramos investigaciones al respecto. Objetivo: Nuestro objetivo fue evaluar el efecto agudo de YM sobre el ritmo, en pacientes enviados para realizar un Holter. Método: Realizamos un estudio clínico seudoexperimental, de tipo antes y después. Tomamos 50 pacientes consumidores habituales de YM y se les realizó un Holter tomando YM y otro luego de 24 sin consumir. También se controló el uso de otros productos que pudieran interferir. Resultados: El 52% fueron mujeres y la edad, de 55 ± 15 años. El 78% tenía al menos un factor de riesgo vascular, el 44% cardiopatía estructural y el 90% tomaba medicación cardiovascular. La frecuencia cardíaca (FC) con y sin YM fue similar. Solo la FC mínima horaria fue menor tomando YM (61 ± 10 vs. 63 ± 9, p = 0.021). No hubo diferencia significativa en la incidencia de arritmias sostenidas, no sostenidas ni en la extrasistolia ventricular. El total de extrasístoles supraventriculares fue mayor sin YM (952 ± 3,538 vs. 1,294 ± 5,201, p = 0.014) y la cantidad máxima horaria también (86 ± 302 vs. 107 ± 360, p = 0.032). No hubo diferencia en la variabilidad de la FC. Conclusiones: En pacientes cardiológicos tomadores de YM, su consumo de la forma habitual no se asoció con cambios importantes de la FC ni con un aumento en la incidencia de arritmias. Hubo menos actividad ectópica supraventricular.

Abstract Introduction: The consumption of yerba mate (YM) (Ilex paraguariensis) is common in South America and is now used all over the world. It contains many bioactive substances that can be beneficial. There is also the opinion that it may have harmful effects on heart rhythm, but no studies have been found on this. Objective: The aim of this study was to evaluate the acute effect of YM on heart rhythm in patients referred for a Holter study. Method: A before and after pseudo-experimental clinical study was conducted by performing a Holter on 50 habitual users of YM, and another one after 24 without YM consumption. The use of other products that could interfere was also controlled. Results: The mean age of the subjects was 55 ± 15 years, and 52% were women. At least one vascular risk factor was found in 78%, with 44% structural heart disease, and 90% taking cardio- vascular medication. The heart rate (HR) with and without YM was similar. Only the minimum hourly HR was lower when taking YM (61 ± 10 vs. 63 ± 9, P = .021). There was no significant diffe- rence in the incidence of sustained or non-sustained arrhythmias, or in ventricular extrasystoles. The total number of supra-ventricular premature beats was higher without YM (952 ± 3,538 vs. 1,294 ± 5,201, P = .014) and also the maximum hourly (86 ± 302 vs. 107 ± 360, P = .032). There was no difference in HR variability. Conclusions: In cardiology patients, usual users of YM, habitual consumption was not associated with significant changes in HR or an increase in the incidence of arrhythmias. There was less ectopic supraventricular activity.

A study on reducing the absorption of lidocaine from the airway in cats

Abstract Purpose: To determine if the combination of lidocaine with epinephrine or gamma globulin would decrease the rate or reduce the amount of local absorption of lidocaine through the airway. Methods: Twenty adult male cats were randomly and evenly distributed into four groups: 1) Group LG: lidocaine administered with gamma globulin; 2) Group LS: lidocaine administered with physiological saline); 3) Group LE: lidocaine administered with epinephrine; 4) Group C: control group. Invasive blood pressure, heart rate, and concentration of lidocaine were recorded before and after administration. Results: The peak of plasma concentrations appeared difference (Group LG: 1.39 ± 0.23 mg/L; Group LS: 1.47 ± 0.29 mg/L and Group LE: 0.99 ± 0.08 mg/L). Compared to Group C, there were significant differences in the average heart rate of Groups LG, LS, and LE (P < 0.05). The average systolic blood pressures were significantly different when each group was compared to Group C (P < 0.05). The biological half-life, AUC0-120, peak time, and half-life of absorption among the three groups have not presented statistically significant differences (P > 0.05). Conclusion: Administering lidocaine in combination with gamma globulin through airway causes significant decrease the rate and reduce the amount of local absorption of lidocaine in cats.

Effects of low-dose recombinant human brain natriuretic peptide on anterior myocardial infarction complicated by cardiogenic shock

Abstract INTRODUCTION: The mortality due to cardiogenic shock complicating acute myocardial infarction (AMI) is high even in patients with early revascularization. Infusion of low dose recombinant human brain natriuretic peptide (rhBNP) at the time of AMI is well tolerated and could improve cardiac function. OBJECTIVE: The objective of this study was to evaluate the hemodynamic effects of rhBNP in AMI patients revascularized by emergency percutaneous coronary intervention (PCI) who developed cardiogenic shock. METHODS: A total of 48 patients with acute ST segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock and whose hemodynamic status was improved following emergency PCI were enrolled. Patients were randomly assigned to rhBNP (n=25) and control (n=23) groups. In addition to standard therapy, study group individuals received rhBNP by continuous infusion at 0.005 µg kg−1 min−1 for 72 hours. RESULTS: Baseline characteristics, medications, and peak of cardiac troponin I (cTnI) were similar between both groups. rhBNP treatment resulted in consistently improved pulmonary capillary wedge pressure (PCWP) compared to the control group. Respectively, 7 and 9 patients died in experimental and control groups. No drug-related serious adverse events occurred in either group. CONCLUSION: When added to standard care in stable patients with cardiogenic shock complicating anterior STEMI, low dose rhBNP improves PCWP and is well tolerated.

Efecto inotrópico y cronotrópico del propranolol sobre aurículas extraídas de ratas con insulina-resistencia inducida por fructosa / Inotropic and chronotropic effects of propranolol in isolated atrium of rats with fructose-induced insulin-resistance

La insulina-resistencia (IR) es una deficiencia metabólica asociada princi palmente con diabetes tipo 2 y comúnmente relacionada a la etiopatogenia de enfermedades cardiovasculares, siendo el factor determinante del síndrome metabólico. La investigación pretende conocer los efectos cronotrópico e inotrópico del propranolol sobre aurículas de ratas IR. Para ello, 16 ejemplares Sprague-Dawley, fueron divididos en Grupo control, alimentado ad libitum con alimento para perros Perrarina® y Grupo experimental, alimentado con Perrarina®-manteca vegetal, y suministro de agua con fructosa (20%)-sacarosa (20%) durante ocho meses. Al finalizar este periodo, se verificó la insulina-resistencia y las aurículas extraídas se mantuvieron en solución Krebs (37ºC, pH 7,4; 95% O2 - 5% CO2), en baño de órganos aislados marca Letica®, conectado a un polígrafo Grass®, registrándose la frecuencia de los latidos y evaluando las diferencias a través de la prueba t de Student (grado de significancia p<0,05). Se establecieron curvas dosis-respuesta acumulativas con isoproterenol y previa incubación de 15 minutos con propranolol (1x10 -6 M), registrándose un efecto cronotrópico negativo en el grupo control mas no así en las ratas IR, estableciéndose diferencias significativas entre el porcentaje de incremento de los latidos/seg en ambos grupos (Control 58,81±4,08; IR 68,84±4,16; p<0,001). La máxima fuerza de contracción auricular alcanzada por el grupo IR con propranolol (278,47±11,22), generó diferencias significativas (p<0,001), en comparación con el grupo control (42,60±3,13), evidenciándose que el propranolol no generó bloqueo sobre los receptores beta-adrenérgicos auriculares de las ratas insulina-resistentes.

Insulin resistance (IR) is a metabolic deficiency associated with type 2 diabe tes and commonly related to the pathogenesis of cardiovascular diseases, being the determining factor of the metabolic syndrome. This research aims to understand the chronotropic and inotropic effects of Propranolol in isolated atrium of rats with fructose-induced insulin-resistance. For this reason, 16 male Sprague-Dawley rats were assigned to two groups and given ad libitum access to one of the following diets: Perrarina® dog chow or Perrarina® dog chow supplemen ted with vegetable shortening and with fructose (20%) and sucrose (20%) added to the water supply. Both groups were maintained on their respective dietary regimens for eight months. At the end of this period insulin resistance was verified by routine blood test. The rat hearts were rapidly removed, and the atria were dissected and kept in Krebs solutions (37ºC, pH 7.4; 95% O2 - 5% CO2) in an isolated organ bath Letica®, connected to a polygraph Grass®, registering atria frequency. The Student ́s t-test was used to evaluate statistical differences between the two groups (p<0.05). Cumulative dose-response curves with isoproterenol were established in basal condition, and after fifteen minutes of pre-incubation with propranolol (1x10 -6 M). A significant positive chronotropic effect was observed in IR rats (8.84±4.16 vs 58.81±4.08 beats/sec of control; p<0.001). The maximum force of atrial contraction after pre-incubation with propranolol was significantly higher in the IR group (278.47±11.22 atrial contraction percentage; p<0.001). These findings suggest that a blunted response of atrial β-adrenoceptor to propranolol exists in rats with fructose-induced insulin-resistance.