环维黄杨星D对豚鼠离体心肌的正性变力作用

本文研究了环维黄杨星D(CVB—D) 对豚鼠离体心肌的变力作用.在0.3～100μmol/L范围内,CVB—D对左、右心房肌均呈现剂量依赖性正性变力作用.CVB—D 30μmol/L增强左心房肌静息后收缩正性阶梯和成对刺激效应.乳头状肌动作电位和收缩力同步记录的结果表明,CVB—D 30μmol/L加强心肌收缩力,延长APD_(50)和APD_(90),但对V_(max)、APA和RP影响不大.因此,CVB—D的正性变力作用可能是由于促进心肌细胞外Ca~(2+)跨膜内流和增加细胞内Ca~(2+)释放所致.

Positive inotropic effects of cyclovirobuxine D on isolated guinea pig myocardium

Cyclovirobuxine D(CVB-D)0.3~ 100μmol/L produced concentration-dependent positive inotropic action in left and right atria.CVB-D 30μmol/L enhanced post-rest contraction,augmented the response of left atria to increase in stimulation frequency and increased the developed tension evoked by paired stimulation.Taking recordings of action potential and contractile force of papillary muscle synchronously,it was found that CVB-D 30μmol/L brought about in-creases incontractile force and prolongation of APD50 and APD90 without significant effects on Vmax,APA and RP.It is concluded that the positive inotropic effects on myocardium might be associated with an increase in transsarcolemmal influx of calcium as well as an augmentation of the amount of calcium released from intracellular stores.