Angiotensin-(1-7) at 0.22 nmol/L reduced the incidence and duration of reperfusion arrhythmias in isolated rat hearts (n=11), an effect blocked by A-779 and indomethacin.
Does angiotensin-(1-7) reduce reperfusion arrhythmias in isolated rat hearts?
Angiotensin-(1-7) demonstrates cardioprotective, antiarrhythmogenic effects during ischemia/reperfusion in isolated rat hearts, mediated by specific receptors and prostaglandin release.
In this study we evaluate the effects of angiotensin-(1-7) on reperfusion arrhythmias in isolated rat hearts. Rat hearts were perfused according to Langendorff technique and maintained in heated (37+/-1 degrees C) and continuously gassed (95% O(2)/5% CO(2)) Krebs-Ringer solution at constant pressure (65 mm Hg). The electrical activity was recorded with an ECG (bipolar). Local ischemia was induced by coronary ligation for 15 minutes. After ischemia, hearts were reperfused for 30 minutes. Cardiac arrhythmias were defined as the presence of ventricular tachycardia and/or ventricular fibrillation after the ligation of the coronary artery was released. Angiotensin II (0.20 nmol/L, n=10) produced a significant enhancement of reperfusion arrhythmias. On the other hand, Ang-(1-7) presented in the perfusion solution (0.22 nmol/L, n=11) reduced incidence and duration of arrhythmias. The antiarrhythmogenic effects of Ang-(1-7) was blocked by the selective Ang-(1-7) antagonist A-779 (2 nmol/L, n=9) and by indomethacin pretreatment (5 mg/kg IP, n=8) but not by the bradykinin B(2) antagonist HOE 140 (100 nmol/L, n=10) or by L-NAME pretreatment (30 mg/kg IP, n=8). These results suggest that the antiarrhythmogenic effect of low concentrations of Ang-(1-7) is mediated by a specific receptor and that release of endogenous prostaglandins.by Ang-(1-7) contributes to the alleviation of reversible and/or irreversible ischemia-reperfusion injury.
Ferreira et al. (Sat,) conducted a other in Myocardial ischemia/reperfusion arrhythmias (n=56). Angiotensin-(1-7) vs. Angiotensin II and various antagonists was evaluated on Incidence and duration of reperfusion arrhythmias (ventricular tachycardia and/or ventricular fibrillation). Angiotensin-(1-7) at 0.22 nmol/L reduced the incidence and duration of reperfusion arrhythmias in isolated rat hearts (n=11), an effect blocked by A-779 and indomethacin.