ROLE OF ALDOSTERONE AND DIETARY POTASSIUM IN POTASSIUM ADAPTATION IN THE DISTAL COLON OF THE RAT
ROLE OF ALDOSTERONE AND DIETARY POTASSIUM IN POTASSIUM ADAPTATION IN THE DISTAL COLON OF THE RAT
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DOI：
10.1016/s0016-5085(85)80130-x
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发表时间：
1985-01-01
期刊：
影响因子：
29.4
通讯作者：
BINDER, HJ
中科院分区：
文献类型：
--
作者：
FOSTER, ES;JONES, WJ;BINDER, HJ
本实验的目的是区分醛固酮和慢性钾负荷在结肠钾适应机制的影响，使用最近描述的动物模型，允许系统操作醛固酮和膳食钾。单向42 K通量在短路条件下进行跨离体远端结肠粘膜大鼠与完整的肾上腺和肾上腺切除，替代动物。在完整动物中，给予富钾饮食可将净钾吸收（+0.43 ± 0.10 μEq/h ·cm 2）逆转为净钾分泌（-0.76 ± 0.08 μEq/h ·cm 2）。在肾上腺切除的动物中输注醛固酮，其量相当于在完整大鼠中通过钾负荷产生的量，使1 netK降至零（−0.03 ± 0.06 μEq/h ·cm 2）。同样，当实验大鼠喂食富钾饮食并维持基础醛固酮水平时，观察到零净钾转运（−0.14 ± 0.08 μEq/h ·cm 2）。因此，升高的醛固酮水平和富钾饮食都对钾的净转运有影响，但都没有产生慢性钾负荷的全部效应。然而，当钾负荷和醛固酮水平升高相结合时，实验动物的净钾分泌增加（−0.57 ± 0.07 μEq/h ·cm 2）与完整的钾负荷动物相当。这些研究表明：（a）慢性钾负荷通过不依赖于醛固酮的机制改变了主动钾转运;（B）慢性钾适应机制代表了增加膳食钾和醛固酮的累加效应。
The present experiments were designed to differentiate the effects of aldosterone and chronic potassium loading in the mechanism of colonic potassium adaptation, using a recently described animal model that permits systematic manipulation of aldosterone and dietary potassium. Unidirectional42K fluxes were performed under short-circuit conditions across isolated distal colonic mucosa from rats with intact adrenal glands and in adrenal ectomized, hormone-replaced animals. Administration of a potassium-enriched diet reversed net potassium absorption (+0.43 ± 0.10 μEq/h · cm2) in intact animals to net potassium secretion (−0.76 ± 0.08 μEq/h · cm2). Infusion of aldosterone in adrenalectomized animals, in an amount equivalent to that produced by potassium loading in intact rats, reduced 1netKto zero (−0.03 ± 0.06 μEq/h · cm2). Similarly, zero net potassium transport (−0.14 ± 0.08 μEq/h · cm2) was observed when experimental rats were fed a potassium-enriched diet and maintained with basal aldosterone levels. Therefore, both elevated aldosterone levels and a potassium-enriched diet had an effect on net potassium transport, but neither produced the full effects of chronic potassium loading. An increase in net potassium secretion (−0.57 ± 0.07 μEq/h · cm2) comparable to that of intact potassiumloaded animals did, however, occur when potassium loading and elevated aldosterone levels were combined in experimental animals. These studies demonstrate that (a) chronic potassium loading alters active potassium transport by an aldosteroneindependent mechanism and (b) the mechanism of chronic potassium adaptation represents the additive effects of increased dietary potassium and aldosterone.