EFFECTS OF NICORANDIL ON SPONTANEOUS BEATING AND ACTION-POTENTIALS OF CULTURED MYOCARDIAL-CELLS OF NEONATAL RATS

AIM: To study the anti-arrhythmic mechanism of nicorandil (Nic), METHODS: The myocardial cells of neonatal rats were cultured and effects of Nic on spontaneous beating and action potential of cultured myocardial cells were observed. RESULTS: Nic 32 mu mol L(-1) and 160 mu mol L(-1) decreased the spontaneous beating rates of cultured myocardial cells of neonatal rats. Nic 64 mu mol L(-1) prevented the beating rats induced hy CaCl2 1 mmol L(-1) and isoproterenol 2 mu mol L(-1). Nic 32 and 160 mu mol L(-1) reduced the amplitude, maximal rate of rise, and shortened APD(50) and APD(90) repolarization. Nic prolonged the spontaneous sinus cycle length. CONCLUSION: The antiarrhythmic mechanism of Nic is related to its direct effects on the myocardial cells.