Wang Y X, Liu J W, Tan Y H, Sheng B H
Zhongguo Yao Li Xue Bao. 1989 Nov;10(6):516-9.
Cycloprotobuxine-A (CPB-A) 0.1-100 mumoles/L produced positive inotropic effects in left and right atria in a concentration-dependent manner. CPB-A 30 mumoles/L enhanced post-rest contraction, augmented the response of left atrium to increase in stimulating frequency, and increased the developing tension evoked by paired pulse stimulation. By taking simultaneous recordings of action potentials and contractile force of papillary muscles, it was found that CPB-A 30 mumoles/L increased the contractile force and prolonged the action potential duration at 50% of depolarization. It is concluded that the positive inotropic effect of CPB-A on myocardium may be associated with an increase in transsarcolemmal influx of calcium as well as an augmentation of the amount of calcium released from intracellular stores.
环原黄杨星A（CPB-A）0.1 - 100微摩尔/升以浓度依赖的方式对左右心房产生正性肌力作用。30微摩尔/升的CPB-A增强了舒张后收缩，增强了左心房对刺激频率增加的反应，并增加了成对脉冲刺激诱发的舒张期张力。通过同时记录乳头肌的动作电位和收缩力，发现30微摩尔/升的CPB-A增加了收缩力，并延长了去极化50%时的动作电位持续时间。结论是，CPB-A对心肌的正性肌力作用可能与跨肌膜钙内流增加以及细胞内钙库释放的钙量增加有关。
