适应海水环境的海湾蟾鱼中，碳酸氢根刺激的氯离子外流。

HCO3-stimulated Cl efflux in the gulf toadfish acclimated to sea water.

作者信息

Kormanik G A, Evans D H

出版信息

J Exp Zool. 1979 Apr;208(1):13-6. doi: 10.1002/jez.1402080103.

DOI:10.1002/jez.1402080103

Abstract

Unidirectional efflux of Cl was examined in the Gulf toadfish, Opsanus beta, in artificial seawater solutions with modified concentrations of Cl and HCO3. Removal of Cl HCO3 reduced Cl efflux. Addition of HCO3 at typical seawater concentrations stimulated Cl efflux, independent of changes in the transepithelial potential. This active, HCO3-stimulated Cl efflux is saturable, with a Km of 2.4 mM, typical of the concentration of HCO3 found in sea water, and independent of external pH. Active extrusion of Cl offsets the net diffusional and oral gain of Cl faced by O. beta in sea water.

摘要

在人工海水溶液中，通过改变氯离子（Cl）和碳酸氢根离子（HCO₃）的浓度，研究了海湾蟾鱼（Opsanus beta）中氯离子的单向流出情况。去除氯离子和碳酸氢根离子会降低氯离子流出。在典型海水浓度下添加碳酸氢根离子会刺激氯离子流出，且与跨上皮电位的变化无关。这种由碳酸氢根离子刺激的主动氯离子流出是可饱和的，其米氏常数（Km）为2.4 mM，这是海水中碳酸氢根离子的典型浓度，并且与外部pH无关。氯离子的主动外排抵消了海湾蟾鱼在海水中面临的氯离子净扩散和经口摄入。