Gronda C, Rossi J P, Gagliardino J J
Centro de Endocrinología Experimental y Aplicada (UNLP-CONICET), Facultad de Ciencias Médicas, La Plata, Argentina.
Acta Physiol Pharmacol Latinoam. 1987;37(2):245-56.
A simple procedure to measure plasma-membrane Ca2+-ATPase in rat islet homogenate, in a medium containing low Ca2+ and Mg2+ concentrations and in the absence of K+ ions, is described. The Ca2+-ATPase activity detected is inhibited with high affinity by vanadate and compound 48/80 (a specific anticalmodulin drug). The curve of Ca2+ -ATPase activity as a function of Ca2+ concentration shows two components, one with high apparent affinity and low maximum velocity and the other with low apparent affinity and high maximum velocity. The kinetic parameters for these two components are similar to those measured in partially purified islet-membranes. These results suggest that the main Ca2+-ATPase activity detected in these conditions belongs to the islet plasma-membrane. The islets obtained from 48 h fasted rats show a simultaneous and significant decrease both in their insulin response to glucose and in their Ca2+ -ATPase activity. These results suggest that Ca2+-ATPase activity of the islet plasma membrane might participate in the regulatory process of insulin secretion.
本文描述了一种在低钙和低镁浓度且无钾离子的培养基中，测量大鼠胰岛匀浆中质膜钙ATP酶的简单方法。检测到的钙ATP酶活性可被钒酸盐和化合物48/80（一种特异性抗钙调蛋白药物）高亲和力抑制。钙ATP酶活性随钙浓度变化的曲线显示出两个组分，一个具有高表观亲和力和低最大速度，另一个具有低表观亲和力和高最大速度。这两个组分的动力学参数与在部分纯化的胰岛膜中测得的参数相似。这些结果表明，在这些条件下检测到的主要钙ATP酶活性属于胰岛质膜。从禁食48小时的大鼠获得的胰岛，其对葡萄糖的胰岛素反应和钙ATP酶活性同时显著降低。这些结果表明，胰岛质膜的钙ATP酶活性可能参与胰岛素分泌的调节过程。
