Naitoh T, Toyo-Oka T, Sugimoto T
The Second Department of Internal Medicine, University of Tokyo, Japan.
Biochem Biophys Res Commun. 1990 Sep 28;171(3):1205-10. doi: 10.1016/0006-291x(90)90813-3.
To elucidate the action of tentative endogenous Ca2+ channel activator, endothelin (ET)-1, on a voltage-dependent Ca2+ channel in the heart, a dihydropyridine (DHP)-binding protein was solubilized from porcine ventricular muscle, partially purified by wheat germ agglutinin-affinity chromatography and reconstituted into proteoliposomes. Ca2+ flux into the proteoliposomes was determined using a fluorescent probe, Quin-2. The initial Ca2+ entry rate was dose-dependently activated by either a K(+)-depolarization or a synthetic Ca2+ channel agonist, Bay K8644, and inhibited by several Ca2+ entry blockers or cadmium ions. Using the same reconstituted system, it was demonstrated that sufficient dose of ET-1 yielded no effect on the Ca2+ channel function, indicating that the ET-1 action was not directly mediated by the voltage-dependent, DHP-sensitive Ca2+ channel.
为了阐明内源性钙通道激活剂内皮素（ET）-1对心脏电压依赖性钙通道的作用，从猪心室肌中溶解二氢吡啶（DHP）结合蛋白，通过麦胚凝集素亲和层析进行部分纯化，然后重构成蛋白脂质体。使用荧光探针喹啉-2测定进入蛋白脂质体的钙通量。初始钙进入速率可被钾去极化或合成钙通道激动剂Bay K8644剂量依赖性激活，并被几种钙进入阻滞剂或镉离子抑制。使用相同的重构系统证明，足够剂量的ET-1对钙通道功能无影响，这表明ET-1的作用不是由电压依赖性、DHP敏感的钙通道直接介导的。
