Aldosterone and PCO2 enhance K-dependent chloride absorption in rat distal colon.
Aldosterone and PCO2 enhance K-dependent chloride absorption in rat distal colon.
复制标题
醛固酮和 PCO2 增强大鼠远端结肠中钾依赖性氯离子吸收。
DOI：
10.1007/bf00370607
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
McBride,DE
中科院分区：
文献类型：
--
作者：
Perrone,RD;McBride,DE
We have previously demonstrated that, in the absence of Na+in vitro, the rate of colonic K+absorption is increased by increasingPCO2. Chronic secondary hyperaldosteronism induced by dietary Na-depletion further stimulated K+absorption under these conditions. Because the observed increments in CO2-dependent K+absorption were not accompanied by corresponding changes in short-circuit current, macroscopic electroneutrality must have been maintained either by anion absorption or by cation secretion. Colonic Cl−absorption is known to respond to increasedPCO2both in vivo and in vitro, but its response under Na-free conditions and the relationship to K+absorption have not been examined. To determine the relationship of Cl−absorption to K+, we measured unidirectional fluxes of36Cl and the response toPCO2in voltage-clamped segments of rat distal colon. Our findings indicate that the rate of Cl−absorption is increased by increasing CO2, both in the presence and absence of Na+. Under Na-free conditions, Cl−absorption is inhibited by acetazolamide and by the absence of K+; K+absorption (86Rb or42K flux) is inhibited in a reciprocal fashion by the absence of Cl−. The rates of K+and Cl−absorption are similar in controls and after secondary hyperaldosteronism due to a Na-deficient diet. These findings suggest that K+and Cl−absorption are closely coupled under Na-free conditions, most likely due to the operation of parallel, aldosterone-responsive H+-K+and Cl−-HCO3−exchange pathways.
