脊椎动物光感受器中钠泵的作用机制。

Mechanism of action of the sodium pump in vertebrate photoreceptors.

作者信息

Marroni P, Alpigiani V, Cervetto L, Torre V

出版信息

Rev Can Biol Exp. 1983 Nov;42(3):257-61.

Abstract

Membrane potential and photoresponse of rods in the isolated toad retina was recorded while changing the ionic composition of the extracellular medium. In the presence of 10 mM external Cs+ the bright flash response consisted of an initial fast component of about 35 mV followed by a much slower component as large as 50 mV. The slow component of the photoresponse was blocked by micromolar amounts of both ouabain and strophanthidin. The effects induced by the latter were almost completely irreversible. The effects induced by changing the external concentrations of Na+, K+ and Ca2+ were analysed assuming that the amplitude of the slow component of voltage photoresponse reflects the activity of Na+--K+ pump. It is shown that external Na+, K+ and Ca2+ have the same effect on the amplitude of the slow component as on the Na+-K+ pump activity of other tissues.

摘要

在改变细胞外介质离子组成的同时，记录了分离的蟾蜍视网膜中视杆细胞的膜电位和光反应。在存在10 mM外部Cs+的情况下，明亮闪光反应由约35 mV的初始快速成分和高达50 mV的慢得多的成分组成。光反应的慢成分被微摩尔量的哇巴因和毒毛花苷K阻断。后者诱导的效应几乎完全不可逆。假设电压光反应慢成分的幅度反映了Na+-K+泵的活性，分析了改变外部Na+、K+和Ca2+浓度所诱导的效应。结果表明，外部Na+、K+和Ca2+对慢成分幅度的影响与对其他组织Na+-K+泵活性的影响相同。