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

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.

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

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 ?mol?L -1 produced a concentration dependent suppressing effect on spontaneous beating rate of cultured cardiac cells with IC 50 of 0 17 ?mol?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 ?mol?L -1 depressed beating rate to the steady state ,effects of CaCl 2 2 mmol?L -1 and Iso 1 ?mol?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 ?mol?L -1 pruduced the concentration dependent depression on APA,V max ,OS,SP 4 and MDP,and prolongation of SCL of the slow response action potentials.APD 90 was also lengthened at the concentration of EC 0 9～2 5 ?mol?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 Ca 2+ ,especially Na + currents on slow response cardiomyocyte.