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首页> 外文期刊>American Journal of Physiology >In rat inner medullary collecting duct, NH uptake by the Na,K-ATPase is increased during hypokalemia.
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In rat inner medullary collecting duct, NH uptake by the Na,K-ATPase is increased during hypokalemia.

机译：在大鼠内髓收集管中，低钾血症期间Na，K-ATPase对NH的吸收增加。

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摘要

In rat terminal inner medullary collecting duct (tIMCD), the Na,K-ATPase mediates NH uptake, which increases secretion of net H(+) equivalents. K(+) and NH compete for a common binding site on the Na,K-ATPase. Therefore, NH uptake should increase during hypokalemia because interstitial K(+) concentration is reduced. We asked whether upregulation of the Na,K-ATPase during hypokalemia also increases basolateral NH uptake. To induce hypokalemia, rats ate a diet with a low K(+) content. In tIMCD tubules from rats given 3 days of dietary K(+) restriction, Na,K-ATPase beta(1)-subunit (NK-beta(1)) protein expression increased although NK-alpha(1) protein expression and Na,K-ATPase activity were unchanged relative to K(+)-replete controls. However, after 7 days of K(+) restriction, both NK-alpha(1) and NK-beta(1) subunit protein expression and Na,K-ATPase activity increased. The magnitude of Na,K-ATPase-mediated NH uptake across the basolateral membrane (J) was determined in tIMCD tubules perfused in vitro from rats after 3 days of a normal or a K(+)-restricted diet. J was the same in tubules from rats on either diet when measured at the same extracellular K(+) concentration. However, in either treatment group, increasing K(+) concentration from 10 to 30 mM reduced J >60%. In conclusion, with 3 days of K(+) restriction, NH uptake by Na,K-ATPase is increased in the tIMCD primarily from the reduced interstitial K(+) concentration.
机译：在大鼠末梢内髓收集管（tIMCD）中，Na，K-ATPase介导NH吸收，这增加了净H（+）等效物的分泌。 K（+）和NH在Na，K-ATPase上竞争一个共同的结合位点。因此，由于间质K（+）浓度降低，因此在低钾血症期间应增加NH的吸收。我们问低钾血症期间Na，K-ATPase的上调是否还会增加基底外侧NH的吸收。为了诱发低血钾症，大鼠饮食中的K（+）含量低。在大鼠的tIMCD小管中，给予3天的饮食K（+）限制，Na，K-ATPase beta（1）-亚基（NK-beta（1））蛋白表达增加，尽管NK-alpha（1）蛋白表达和Na相对于K（+）完全对照，K-ATPase活性没有变化。但是，在7天的K（+）限制后，NK-alpha（1）和NK-beta（1）亚基蛋白表达和Na，K-ATPase活性均增加。在正常或K（+）限制饮食3天后，从大鼠体内灌注的tIMCD小管中确定了Na，K-ATPase介导的跨基底外侧膜的NH吸收量（J）。当以相同的细胞外K（+）浓度测量时，两种饮食的大鼠小管中的J均相同。但是，在任一治疗组中，将K（+）浓度从10 mM增加到30 mM都会使J> 60％。总之，在3天的K（+）限制下，tIMCD中Na，K-ATPase对NH的吸收增加主要是由于间质K（+）浓度降低。

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