Characterization of amino acid metabolism by cultured rat kidney cells: study with 15N.
Characterization of amino acid metabolism by cultured rat kidney cells: study with 15N.
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培养大鼠肾细胞的氨基酸代谢特征：15N 研究。
DOI：
10.1152/ajprenal.1987.253.6.f1243
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Segal,S
中科院分区：
文献类型：
--
作者：
Nissim,I;States,B;Yudkoff,M;Segal,S
本研究评价了谷氨酰胺和谷氨酸的代谢正常大鼠肾（NRK）细胞。本研究旨在探讨急性酸中毒对体外培养的NRK细胞氨基酸代谢和氨生成的影响。在pH 7.0或7.4下，用补充有1 mM [5- 15 N]谷氨酰胺、[2- 15 N]谷氨酰胺或[15 N]谷氨酸盐的磷酸盐缓冲盐水进行实验。与谷氨酰胺或谷氨酸作为前体的孵育表明，氨和葡萄糖的产生在pH 7.0与7.4相比显著增加。谷氨酰胺和谷氨酸盐的消失[校正]在任一pH值下孵育60分钟期间呈线性。在[5- 15 N]谷氨酰胺的实验中，我们发现约57%和43%的氨态氮分别来自pH 7.4和7.0下的5-N谷氨酰胺。用[2- 15 N]谷氨酰胺或[15 N]谷氨酸盐的实验表明，在pH 7.0下，约43%和47%的2-N谷氨酰胺和谷氨酸盐N利用率分别由氨产生占。类似地，28%和29%的NH3通过谷氨酸脱氢酶在pH 7.4下的活性来自谷氨酰胺或谷氨酸N的2-N。除了15NH_3的形成外，[2- 15 N]谷氨酰胺或[15 N]谷氨酸的代谢主要有三条途径：1）转氨反应，包括[15 N]天冬氨酸和[15 N]丙氨酸的非pH依赖性形成; 2）[6- 15NH_2]腺嘌呤核苷酸的合成，这一过程在pH7.4比7.0更活跃;（3）由[15 N]谷氨酸合成谷氨酰胺，特别是在pH7.4时。数据表明，NRK细胞在培养中消耗谷氨酰胺和谷氨酸，并产生氨和各种氨基酸，这取决于培养基中的H+浓度。这些研究表明，这些细胞系可能提供了一个有用的模型，用于研究pH值对大鼠肾氨生成的影响的各个方面。
The present study evaluates the metabolism of glutamine and glutamate by normal rat kidney (NRK) cells. The major aim was to evaluate the effect of acute acidosis on the metabolism of amino acid and ammonia formation by cultured NRK cells. Experiments at either pH 7.0 or 7.4 were conducted with phosphate-buffered saline supplemented with either 1 mM [5-15N]glutamine, [2-15N]glutamine, or [15N]glutamate. Incubation with either glutamine or glutamate as a precursor showed that production of ammonia and glucose was increased significantly at pH 7.0 vs. 7.4. The disappearance [corrected] of glutamine and glutamate was linear during a 60-min incubation at either pH. In experiments with [5-15N]glutamine, we found that approximately 57 and 43% of ammonia N was derived from 5-N of glutamine at pH 7.4 and 7.0, respectively. Experiments with [2-15N]glutamine or [15N]glutamate indicated that approximately 43 and 47% of 2-N glutamine and glutamate N utilization, respectively, was accounted for by ammonia production at pH 7.0. Similarly, 28 and 29% of NH3 was derived from 2-N of glutamine or glutamate N by activity of glutamate dehydrogenase at pH 7.4. In addition to 15NH3 formation, three major metabolic pathways of [2-15N]glutamine or [15N]glutamate disposal were identified: 1) transamination reactions involving the pH-independent formation of [15N] aspartate and [15N]alanine; 2) the synthesis of [6-15NH2]adenine nucleotide, a process more active at pH 7.4 vs. 7.0; and 3) glutamine synthesis from [15N]glutamate, especially at pH 7.4. The data indicate that NRK cells in culture consume glutamine and glutamate and generate ammonia and various amino acids, depending on the H+ concentration in the media. The studies suggest that these cell lines may provide a useful model for studying various aspects of the effect of pH on rat renal ammoniagenesis.