The mechanism of the excretion of ammonia in the dog.
The mechanism of the excretion of ammonia in the dog.
复制标题
狗体内氨的排泄机制。
DOI：
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发表时间：
1956
影响因子：
15.9
通讯作者：
R. Berliner
中科院分区：
文献类型：
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作者：
J. Orloff;R. Berliner
氨的排泄取决于几个因素：摄入酸的量和持续时间，可能会影响细胞内酶活性的变化（1-3），形成氨的前体的可用性（4-6），以及尿液的pH值（7-9）。关于尿液pH值的影响，氨的排泄类似于一些有机碱的排泄，如奎宁（10）、尼古丁（11）、普鲁卡因（12）、阿塔布林@（13）和某些4-氨基喹啉衍生物（13）。所有这一切出现在尿尿率负相关博士的实验报告是为了重新审视这一现象和比较氨排泄与选择有机基地为了提供信息关于1)氨的过程的本质进入尿液,2)生产的氨通过肾小管细胞,3)其他弱电解质的分泌机制,这是依赖于尿液pH值的输出,4)对氨排泄和尿ph之间的定量关系作出解释。由于影响有机碱运输的因素与影响氨进入尿液的因素相似，因此预计这些碱的排泄可能被用作独立评估影响氨运输的因素的手段，而不是影响细胞内生产的因素。在急性实验中发现，奎宁的清除率达到了这一目的，因为它只受pH值的影响，而氨的排泄受尿液pH值和可能被认为影响生产速度的环境的影响。然而，不可能将这些原则扩展到慢性实验，因为在不同的实验中，在相同的pH值下，奎宁清除率的绝对水平以不可预测的方式变化。研究结果与（9,14）的观点一致，即在小管细胞中形成的氨几乎完全以不带电状态进入尿液，即以游离碱NH3的形式进入尿液，并以NH3、+的形式积累。在尿pH值的酸性范围内，积累的程度可能受到氨生成速率的限制。在较高的pH值下，氨的产生是无限制的，排泄速率取决于小管尿中氨与小管细胞中氨的平衡。类似的考虑也适用于尿中其他弱电解质的流失，这些电解质的排泄被尿液pH值的变化所改变，但在酸性范围内，扩散速率而不是产生速率可能是限制因素。这些数据进一步被解释为表明尿量的最终变化受到小管中超过最终氨含量的位置的水的提取的影响。
The excretion of ammonia is dependent upon several factors: the amount and duration of acid intake, presumably affecting variations in intracellular enzyme activity (1-3), the availability of precursors from which ammonia can be formed (4-6), and the pH of the urine (7-9). With respect to the effect of urine pH, the excretion of ammonia resembles that of a number of organic bases, such as quinine (10), nicotine (11), procaine (12), Atabrine@ (13), and certain derivatives of 4-aminoquinoline (13), all of which appear in the urine at a rate inversely related to urine pH. The experiments to be reported were designed to reexamine this phenomenon and to compare ammonia excretion with that of selected organic bases in order to provide information concerning 1) the nature of the process by which ammonia enters the urine, 2) the production of ammonia by the cells of the renal tubules, 3) the mechanism of excretion of other weak electrolytes, the output of which is dependent upon urine pH, and 4) to yield an interpretation of the quantitative relations between ammonia excretion and urine pH. Since the factors which affect the transport of the organic bases are similar to those affecting the movement of ammonia into the urine, it was anticipated that the excretion of these bases might be used as a means of independently evaluating the factors affecting the transport of ammonia as contrasted with those affecting intracellular production. In acute experiments the clearance of quinine was found to serve this purpose since it was influenced by pH only and the excretion of ammonia by both urine pH and by circumstances which might be presumed to influence rate of production. However, it was not possible to extend these principles to chronic experiments since the absolute level of quinine clearance varied at the same pH in different experiments in an unpredictable fashion. The results of the studies are in accord with the view (9, 14) that ammonia formed in the tubule cell enters the urine almost exclusively in the uncharged state, i.e., as the free base NH3, and accumulates as NH,+. The extent of accumulation is probably limited in the acid range of urine pH by the rate of ammonia production. At higher pH's, production of ammonia is non-limiting and the rate of excretion is dependent upon equilibration of ammonia in the tubule urine with that in tubule cell. Similar considerations also apply to the urinary loss of other weak electrolytes whose excretion is modified by changes in urine pH except insofar as rate of diffusion, rather than rate of production, is presumably the limiting factor in the acid range. The data have further been interpreted to indicate that final changes in urine volume are effected by abstraction of water in the tubule at a site beyond which final ammonia content is achieved.