Abstract: AimTo elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na⁺/H⁺ exchanger inhibitoramiloride. MethodsSingle 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^-1amiloride，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.