Effects of glibenclamide and tolbutamide on ischemia- and ouabain-induced arrhythmias and membrane potentials of ventricular myocardium from rat and guinea pig

Glibenclamide (Gli) 0.3, 1, 3 mg.kg-1 and tolbutamide (Tol) 3, 10, 30 mg.kg-1 iv 10 min before ischemia or ouabain infusion prevented ventricular fibrillation induced by ischemia in rat and arrhythmias induced by ouabain in guinea pig. Gli 10 mumol.L-1 and Tol 1 mmol.L-1 increased APD and ERP in rat ventricular muscle. Gli 0.1, 1, 10 mumol.L-1 and Tol 0.01, 0.1, 1 mmol.L-1 prevented and reversed the shortening of APD and ERP induced by hypoxia in guinea pig ventricular muscle. These effects of Gli and Tol were dose-dependent. The results confirmed that Gli and Tol were effective on arrhythmias induced by ischemia and ouabain by blocking ATP-sensitive potassium channel.