尼卡地平作为一种钙离子通道阻滞剂作用于单个藤壶肌纤维。

Nicardipine as a Ca2+ channel blocker in single barnacle muscle fibers.

作者信息

Xie H, Bittar E E

机构信息

Department of Physiology, University of Wisconsin, Madison.

出版信息

Biochim Biophys Acta. 1989 Nov 20;1014(2):207-9. doi: 10.1016/0167-4889(89)90036-0.

DOI:10.1016/0167-4889(89)90036-0

PMID:2554978

Abstract

A study has been made of the efficacy of nicardipine as a Ca2+ channel blocker by determining the magnitude of its effect on the stimulatory response of the ouabain-insensitive Na+ efflux in single barnacle muscle fibers to 100 mM external K+. The results show that nicardipine (at pH 6.5) is a potent inhibitor, the minimal effective concentration being approx. 10(-7) M and the IC(50) about 5.10(-6) M. Nicardipine, however, is not as potent as verapamil (at pH 6.5) on an equimolar basis. This is explained by assuming that the number of dihydropyridine receptors in the t-tubule membranes of barnacle fibers is not high or that verapamil is able to block the sarcoplasmic reticulum Ca2+ release channel in addition to the voltage-dependent Ca2+ channels.

摘要

通过测定尼卡地平对单个藤壶肌纤维中哇巴因不敏感的Na⁺外流对100 mM细胞外K⁺刺激反应的影响程度，对其作为Ca²⁺通道阻滞剂的疗效进行了研究。结果表明，尼卡地平（在pH 6.5时）是一种强效抑制剂，最小有效浓度约为10⁻⁷ M，IC₅₀约为5×10⁻⁶ M。然而，在等摩尔基础上，尼卡地平不如维拉帕米（在pH 6.5时）有效。这可以通过假设藤壶纤维横管膜中二氢吡啶受体的数量不高，或者维拉帕米除了能阻断电压依赖性Ca²⁺通道外，还能阻断肌浆网Ca²⁺释放通道来解释。