Experamental study of ethacizine on the electrophysiologic aspects of cultured cardiomyocyte from neonatal rats / 中国药理学通报

ABSTRACT

AIM: To study the relation between the antiarrthymic effect and the inhibition of slow-reaction-cardiomyocyte of ethacizine (EC). METHODS: The beating rate and action potentials of cultured slow-response-cardiomyocyte from neonatal rats was recorded. RESULTS: EC 0.1-5.0 μmol· L-1 produced a concentration-dependent suppressing effect on spontaneous beating rate of cultured cardiac cells with IC50 of 0.17 μmol· L-1 and the maximal inhibitory rate was 52%. The steady state of inhibition to beating rate was achieved after adding EC for 15-30 min. The effective inhibition of beating rate by EC lasted for over 1 h. As EC 2.5 μmol·L-1 depressed beating rate to the steady state, effects of CaCl2 2 mmol·L-1 and Iso 1 μmol·L-1 on beating rate were partially reduced, and the effect of aconitine 0.2 mg·L-1 was abolished. EC 0.3-2.5 μmol·L-1 pruduced the concentration-dependent depression on APA, Vmax, OS, SP4 and MDP, and prolongation of SCL of the slow response action potentials. APD90 was also lengthened at the concentration of EC 0.9-2.5 μmol·L-1. CONCLUSIONS: The effective depression of EC on abnormal automaticity and conductance of the slow-response-cardiomyocyte in heart ischemic zone may be an important mechanism for its effective termination on some arrhythimas. EC may depress Ca2+, especially Na+ currents on slow-response-cardiomyocyte.