INSULIN STIMULATES AMMONIAGENESIS IN CANINE RENAL PROXIMAL TUBULAR SEGMENTS
INSULIN STIMULATES AMMONIAGENESIS IN CANINE RENAL PROXIMAL TUBULAR SEGMENTS
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DOI：
10.1152/ajprenal.1987.253.6.f1171
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发表时间：
1987-12-01
影响因子：
--
通讯作者：
HAMMERMAN, MR
中科院分区：
文献类型：
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作者：
CHOBANIAN, MC;HAMMERMAN, MR
为了表征胰岛素对肾近端小管中氨生成的影响，在用10 mM L-谷氨酰胺和不同浓度的胰岛素孵育的犬肾近端小管节段的悬浮液中测量氨生成。在120分钟内，氨的产生是时间的线性函数。胰岛素（10（-6）M）使2小时的氨产生增加34 +/-5%。与此同时，通过葡萄糖产生测量的异生作用降低了16 +/-2%。在用低至10（-9）M胰岛素孵育的节段悬液中，氨生成显著增强。半最大刺激发生在10（-9）和10（-8）M胰岛素之间。胰岛素也以浓度依赖性方式增加节段内细胞中L-谷氨酰胺的氧化。胰岛素增加氨的生产在段孵育在pH 7.5，但不是在7.0。在前一种情况下，胰岛素在细胞外[Na+]大于细胞内[Na+]的条件下增强近端肾小管段的氨生成，但当细胞外[Na+]等于细胞内[Na+]时则不然。我们的结论是胰岛素刺激犬肾近端小管段的悬浮液中的氨产生。体外氨生成的刺激可以反映胰岛素在体内增强近端肾小管氨生成的作用。
To characterize the effect of insulin on ammoniagenesis in renal proximal tubule, ammonia productions were measured in suspensions of canine renal proximal tubular segments incubated with 10 mM L-glutamine and varying concentrations of insulin. Productions of ammonia were linear functions of time for 120 min. Insulin (10(-6) M) increased ammonia production at 2 h by 34 +/- 5%. At the same time, gluconeogenesis, as measured by glucose production, was decreased by 16 +/- 2%. Significant enhancement of ammoniagenesis occurred in suspensions of segments incubated with as little as 10(-9) M insulin. Half-maximal stimulation occurred at between 10(-9) and 10(-8) M insulin. Oxidation of L-glutamine in cells within segments was also increased by insulin in a concentration-dependent manner. Insulin increased ammonia productions in segments incubated at pH 7.5 but not at 7.0. Under the former conditions, insulin enhanced ammoniagenesis in proximal tubular segments under conditions such that extracellular [Na+] was greater than intracellular [Na+], but not when extracellular [Na+] equaled intracellular [Na+]. We conclude that insulin stimulates ammonia production in suspensions of canine renal proximal tubular segments. Stimulation of ammonia production in vitro could reflect an action of insulin to enhance proximal tubular ammoniagenesis in vivo.