A study of potassium transport mechanism in rabbit distal tubules.

家兔远曲小管钾转运机制的研究。

基本信息

批准号：
06671148
负责人：
TABEI Kaoru
金额：
$ 1.22万
依托单位：
Jichi Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

It has been known that cortical collecting duct plays a most important role to regulate renal potassium metabolism, which is confirmed by in vivo clearance study, in vivo micropuncture study, and in vitro microperfu study. In regulation of potassium transport in CCD,aldosterone and luminal volume flow are the main regulator however, other regulator should be considered. Thus I evaluate the regulatory factors affecting potassium transport CCD,by using in vitro isolated tubular microperfusion.1) The acidification of bathing medium, by reducing bicarbonate concentration from 25 to 5 mEq/L,markedly reduced potassium secretion in rabbit CCD.The suppression of potassium secretion is induced by several transport pathways, such as Na-K ATPase dependent and independent, K channel dependent and independent, Bicarbonate independent, and independent of sodium reabsorption.2) In the experiment, stated above, I observed that potassium secretion increased by the elimination of bicarbon from bathing m … More edium. To evaluate the mechanism of this phenomenon, intracellular pH was measured by fluorescence technique. Intracellular pH in CCD was 7.2 n the basal condition, and it increases markedly by the elimination of bicarbonate to 7.6. These findings suggest that intracellular pH is the important regulator of potassium secretion in rabbit CCD.3) Morphologically, connecting duct cells preexist to CCD,and in CNT a bulk of potassium is secrelted. In vi condition, luminal potassium concentration goes up from 5.0 mEq/L to 10 to 15mEq/L,at a perfusion rate of 10 nl/min, indicating that in vivo condition, luminal potassium concentration might be higher than the condition, w usually in vitro experimentally used. To evaluate the effect of luminal potassium concentration changes on potassium secretion, the changes of potassium secretion rate was examined in vitro microperfusion, using differen perfusate containing 5.0 to 15.0 mEq/L potassium concentration. The increase of potassium concentration in perfusate induced hyperpolarization of transepithelial voltage and decrease of potassium secretion. These findings indicate that the function of CNT to secrete potassium is another regulator of potassium secretion in CCD. Less

肾脏代谢，体内微插入研究和体外微孔系的研究是肾脏代谢的最重要作用。通过使用体外孤立的管状微灌注来评估影响钾含量CCD的调节因素。1）通过将碳酸氢盐浓度从25 mEq /l降低至5 mEq /l，显着降低了兔CCD中的钾分泌。严重性途径TPase依赖性和独立，K通道依赖性和独立，独立于碳酸氢盐独立，并且独立于钠的重吸收。2）在实验中，我观察到通过消除碳碳从沐浴中消除碳的分泌。通过荧光技术在CCD中进行测量。基础条件是7.2 n，通过消除碳酸氢盐至7.6，它显着增加在CNT中，钾的含量为posrassium is is IS。可能高于该条件，通常在体外使用，以评估钾分泌率的钾浓度变化在体外微灌注中，使用较大的灌注液含量。钾的电压和钾分泌