Inhibition of Ca2+ inward current in rabbit sinoatrial node by bunazosin, an alpha-adrenoceptor antagonist.
Inhibition of Ca2+ inward current in rabbit sinoatrial node by bunazosin, an alpha-adrenoceptor antagonist.
复制标题
α-肾上腺素受体拮抗剂布那佐辛对兔窦房结 Ca2 内向电流的抑制作用。
DOI：
10.1016/0014-2999(87)90787-4
复制
发表时间：
1987
影响因子：
5
通讯作者：
H. Mashiba
中科院分区：
文献类型：
--
作者：
H. Kotake;M. Saitoh;K. Ogino;Y. Kurata;A. Ohtahara;J. Hasegawa;H. Mashiba
采用双微电极电压钳法，研究了新型α-肾上腺素能受体拮抗剂布那唑嗪对兔离体自搏窦房结制剂的电生理作用。Bunazosin （10 μM以上）降低了心跳频率、最大上升速率和动作电位幅值。舒张期去极化斜率（第4期）也被药物降低，而50%复极化时的动作电位持续时间延长。布纳唑嗪降低慢向内电流（Isi）和随时间变化的钾向外电流（IK）。然而，主要的影响是Isi的减少。结果表明，α-肾上腺素受体拮抗剂布那佐辛通过抑制Ca通道抑制窦房结的动作电位和自动性。
The electrophysiological effects of bunazosin, a novel α-adrenoceptor antagonist, were examined on isolated spontaneously beating sinoatrial node preparations of the rabbit by means of a double-microelectrode voltage clamp method. Bunazosin (above 10 μM) reduced the beating frequency, and the maximum rate of rise and the amplitude of action potentials. The slope of the diastolic depolarization (phase 4) was also decreased by the drug whereas the action potential duration at 50% repolarization was prolonged. Bunazosin decreased the slow inward current (Isi) and the time-dependent potassium outward current (IK). However, the major effect was the reduction of Isi. The results indicate that bunazosin, an α-adrenoceptor antagonist, depresses the action potential and automaticity of the sinoatrial node by inhibition of Ca channels.