Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes.

Aim To elucidate the possible mechanisms underlying antiarrhythmia of the non-selecthe Na (superscript +)/H(superscript +)exchanger inhibitor-amiloride. 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 (10~100μmol•L^(-1)) , the L-type and T-type calcium currents were depressed. Amiloride resulted in a concentration-dependent inhibition of peak I(subscript 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 1-lmyocytes were incubated witn 100µmol•L^(-1) amiloride I(subscript Kr) was slightly depressed and I(subscript Ks) did not change. Amiloride (1~100µmol•L^(-1)) depressed I(subscript K1) in a concentration-dependent manner. Couclusion Amiloride depressed potassium and calcium currents, which may give support to its uses in some diseases of the cardiovascular system.