胃窦的特性。III. 分流电导的选择性与修饰

Properties of gastric antrum. III. Selectivity and modification of shunt conductance.

作者信息

Bajaj S C, Spenney J G, Sachs G

出版信息

Gastroenterology. 1977 Jan;72(1):72-7.

Abstract

The permselectivity of the paracellular pathway of amphibian (Necturus and bullfrog) antrum was investigated with respect to intracationic selectivity and the K+ and Cl- permeability ratio as a function of mucosal pH. The intracationic selectivity sequence was Rb+ greater than K+ greater than Cs+ greater than Na+ greater than Li+. Both antra showed weak cationic selectivity at pH 7.4, and at pH 4.4 for bullfrog and pH 3.0 for Necturus, the ratio Pk+/P Cl- was unity. At lower mucosal pH the tissues were anion selective. Treatment of the tissue with a water-soluble carbodiimide enhanced anion selectivity at higher pH; carbenoxolone, a weak acid, resulted in maintained cation selectivity at lower pH. These data suggest that carboxyl groups play a role in determining shunt selectivity; the increase in anion selectivity below pH 2.0 suggests that phosphate or sulfate groups could also be involved.

摘要

针对阳离子内选择性以及钾离子（K⁺）与氯离子（Cl⁻）渗透比随黏膜pH值变化的情况，研究了两栖动物（美西螈和牛蛙）胃窦旁细胞途径的通透选择性。阳离子内选择性顺序为铷离子（Rb⁺）＞钾离子（K⁺）＞铯离子（Cs⁺）＞钠离子（Na⁺）＞锂离子（Li⁺）。在pH 7.4时，两种胃窦均表现出弱阳离子选择性，在牛蛙pH 4.4和美西螈pH 3.0时，K⁺/Cl⁻渗透率比值为1。在较低的黏膜pH值下，组织具有阴离子选择性。用水溶性碳二亚胺处理组织可增强较高pH值下的阴离子选择性；弱酸性药物生胃酮在较低pH值下可维持阳离子选择性。这些数据表明，羧基在决定分流选择性方面发挥作用；pH值低于2.0时阴离子选择性增加表明磷酸基团或硫酸基团也可能参与其中。