Intracerebroventricular endothelin receptor-A blockade in rats decreases phase-ii ventricular tachyarrhythmias during acute myocardial infarction.

摘要

Endothelin alters central sympathetic responses, but the resultanteffects on arrhythmogenesis are unknown. We examinedventricular tachyarrhythmias after endothelin receptor-A blockadein the brain of Wistar rats with acute myocardial infarction. Forthis aim, BQ-123 (n=6) or phosphate-buffered saline (n=6) wereinjected intracerebroventricularly. After 10 min, the left coronaryartery was ligated, followed by implantation of telemetrytransmitters. Electrocardiography and voluntary activity(as a surrogate of acute left ventricular failure) were continuouslymonitored for 24 h. Infarct-size was similar in the two groups.There were fewer episodes of ventricular tachyarrhythmias ofshorter average duration in treated rats, leading to markedlyshorter total duration (12.3±8.9 s), when compared to controls(546.2±130.3 s). Voluntary activity increased in treated ratsduring the last hours of recording, but bradyarrhythmic episodeswere comparable between the two groups. Endothelin receptor-Ablockade in the brain of rats decreases the incidence ofventricular tachyarrhythmias post-ligation, without affectingbradyarrhythmic episodes. These findings call for further researchon the pathophysiologic role of endothelin during acutemyocardial infarction.