Reoxygenation dysrhythmias in the isolated guinea-pig heart: sensitivity to prazosin, atenolol and practolol.

Isolated guinea-pig hearts were perfused aerobically for 60 min, then made anoxic for 30 min and finally reoxygenated for 30 min. The effects of prazosin, atenolol and practolol on contractility, coronary pressure, ECG and LDH release were examined. Prazosin and atenolol were able to reduce significantly the incidence of ventricular fibrillation and LDH release. The same two drugs increased the recovery of normal electrical activity after 30 min of reoxygenation. Practolol, on the other hand, was ineffective in reducing the incidence of ventricular arrhythmias and LDH release.