| Abstract: | Isolated rat hearts were subjected to global ischemia (15 min) and reperfusion (20 min). Transmembrane potentials were recorded on the epicardial surface and contractile force was measured. Ischemia reduced the resting potential, the action potential (AP) amplitude and the AP duration (APD) in control animals. Pretreatment with synthetic antioxidant ionol (BHT, 50 mg/kg, per os) didn't influence the time course of changes in the resting potential and AP amplitude during ischemia, but significantly increased APD. In the pretreated group, 5 min after the aorta clamping, the APD at 50% and 90% levels of repolarization was 36% (p less than 0.05) and 13% (p less than 0.1) higher in comparison to the preischemic level and 10 min after clamping by 27% (p less than 0.1) and 29% (p less than 0.05), respectively. By the end of ischemia in the pretreated group, APD re-decreased almost to basal level, but in control group, it remained decreased. During reperfusion BHT improved the recovery of bioelectrical activity and the contractile function. The BHT 10-fold reduced the malignant arrhythmias duration and 2.5-fold the incidence of ventricular tachycardia and fibrillation during reperfusion. These results indicate that the induced by BHT increase in APD can contribute to the mechanism of BHT antiarrhythmic action. |
