Takeda M, Imaizumi Y, Watanabe M
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Eur J Pharmacol. 1991 Feb 14;193(3):375-8. doi: 10.1016/0014-2999(91)90155-j.
A transient outward current (Ito) was elicited by depolarization in single smooth muscle cells isolated from guinea-pig vas deferens under whole-cell voltage-clamp conditions. The peak amplitude of Ito was markedly decreased by over 80% within 10 s after application of 10 microM noradrenaline. When the pipette solution contained low molecular weight heparin (0.3-5 mg/ml), the inhibitory effect of 10 microM noradrenaline on Ito was apparently reduced. Our results strongly suggest that the noradrenaline-induced suppression of Ito is an event subsequent to Ca2+ release and depletion of available Ca2+ stored in the sarcoplasmic reticulum (SR) by myo-inositol 1,4,5-trisphosphate (InsP3), an event which is blocked by low molecular weight heparin.
在全细胞膜片钳条件下，豚鼠输精管分离出的单个平滑肌细胞去极化可诱发一过性外向电流（Ito）。施加10微摩尔去甲肾上腺素后10秒内，Ito的峰值幅度显著降低超过80%。当移液管溶液含有低分子量肝素（0.3 - 5毫克/毫升）时，10微摩尔去甲肾上腺素对Ito的抑制作用明显减弱。我们的结果强烈表明，去甲肾上腺素诱导的Ito抑制是肌醇1,4,5 - 三磷酸（InsP3）导致的Ca2+释放和肌浆网（SR）中可用Ca2+耗竭后的一个事件，而低分子量肝素可阻断该事件。
