钡对蟾蜍膀胱中钠离子转运的抑制作用。

Barium inhibition of sodium ion transport in toad bladder.

作者信息

Ramsay A G, Gallagher D L, Shoemaker R L, Sachs G

出版信息

Biochim Biophys Acta. 1976 Jul 1;436(3):617-27. doi: 10.1016/0005-2736(76)90445-4.

Abstract

The effect of Ba2+ on Na+ transport and electrical characteristics of toad bladder was determined from change produced in short circuit current (Isc), epithelial, apical and basal-lateral potentials (psit, psia, psib), epithelial and membrane resistances (Rt, Ra, Rb) and shunt resistance (Rs). Mucosal Ba2+ had no effect. Serosal Ba2+ reduced Isc, psit, psia, and psib, but had no effect on Rt, Ra, Rb and Rs. Minimal effective Ba2+ concentration was 5-10(-5) M. The phenomenon was reversed by Ba2+ removal, but not by 86 mM serosal K+. Ba2+ inhibition of Isc did not impair the response to vasopressin which was quantitatively the same as controls. Psia with Ba2+ equalled psib. After Ba2+ inhibition, ouabain produced no further decrease in psit and Isc. Ba2+ exposure after ouabain did not decrease psit and Isc. The results suggest that Ba2+ inhibits the basal-lateral electrogenic Na+ pump.

摘要

通过测定蟾蜍膀胱的短路电流（Isc）、上皮电位、顶端电位和基底外侧电位（ψit、ψia、ψib）、上皮电阻和膜电阻（Rt、Ra、Rb）以及分流电阻（Rs）的变化，来确定Ba2+对蟾蜍膀胱Na+转运和电特性的影响。黏膜Ba2+无作用。浆膜Ba2+降低了Isc、ψit、ψia和ψib，但对Rt、Ra、Rb和Rs无影响。最小有效Ba2+浓度为5×10(-5) M。去除Ba2+可使该现象逆转，但86 mM浆膜K+不能。Ba2+对Isc的抑制并不损害对血管加压素的反应，其反应在数量上与对照相同。存在Ba2+时的ψia等于ψib。Ba2+抑制后，哇巴因不再使ψit和Isc进一步降低。哇巴因处理后再暴露于Ba2+不会降低ψit和Isc。结果表明，Ba2+抑制基底外侧生电Na+泵。