Aim To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na +/H + exchanger inhibitoramiloride. Methods Single
ventricular cells were isolated using a double-enzyme method. Effects of
amiloride on voltage-dependent
potassium and calcium
currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques. Results Exposure to amiloride (10-100 μmol·L -1), the L-type and T-type calcium currents were
depressed. Amiloride resulted in a concentration-dependent inhibition of peak I Ca,L, But amiloride did not change the shape of their I-V curves. It only decreased the amplitudes of the currents of the two types. When
myocytes were incubated with 100 μmol·L -1 amiloride,I Kr was slightly depressed and I Ksdid not change. Amiloride (1-100 μmol·L -1) depressed I K1 in a concentration-dependent manner. Conclusion Amiloride depressed potassium and calcium currents,which may give support to its uses in some diseases of the cardiovascular system.