Sanguinetti M C, West T C
J Pharmacol Exp Ther. 1981 Dec;219(3):715-22.
Ventricular and atrial tissues isolated from guinea-pig hearts were depolarized by exposure to 22 mM K+ to study the effects of papaverine on the Ca++-mediated slow inward current (Isi). Papaverine at 5 x 10(-6) to 5 x 10(-5) M caused a concentration-dependent decrease in the threshold current required to excite the field-stimulated tissues and an enhancement of action potential amplitude, action potential duration and maximum rate of depolarization of the Ca++-dependent action potentials. In ventricular preparations, 5 x 10(-5) and 10(-4) M papaverine invariably induced rhythmic spontaneous activity that was abolished by verapamil. It is proposed that the membranal electrical effects of papaverine in the K+-depolarized myocardium are caused by an enhancement of Isi and a decrease in K+ conductance. However, at the highest concentration studied (10(-4) M), papaverine inhibited Isi in atrial tissue, demonstrating that papaverine exerts another action on Isi opposite to that observed at lower concentrations.
从豚鼠心脏分离出的心室和心房组织，通过暴露于22 mM K+使其去极化，以研究罂粟碱对Ca++介导的慢内向电流（Isi）的影响。5×10(-6)至5×10(-5) M的罂粟碱导致刺激场组织所需的阈值电流呈浓度依赖性降低，并增强了动作电位幅度、动作电位持续时间以及Ca++依赖性动作电位的最大去极化速率。在心室标本中，5×10(-5)和10(-4) M的罂粟碱总是诱发有节律的自发活动，而维拉帕米可消除这种活动。有人提出，罂粟碱在K+去极化心肌中的膜电效应是由Isi增强和K+电导降低引起的。然而，在所研究的最高浓度（10(-4) M）下，罂粟碱抑制心房组织中的Isi，表明罂粟碱对Isi产生了与较低浓度下观察到的相反的另一种作用。
