Metabolic fate of glutamate carbon in rat renal tubules. Studies with 13C nuclear magnetic resonance and gas chromatography-mass spectrometry.
Metabolic fate of glutamate carbon in rat renal tubules. Studies with 13C nuclear magnetic resonance and gas chromatography-mass spectrometry.
复制标题
大鼠肾小管中谷氨酸碳的代谢命运。
DOI：
10.1042/bj2410361
复制
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;Yudkoff,M;Segal,S
13 c-n.m.r。采用光谱学和气相色谱-质谱法测定谷氨酸碳在大鼠肾脏中的代谢命运。研究慢性代谢性酸中毒对谷氨酸碳利用的影响。取正常和慢性酸中毒大鼠肾小管，置于pH 7.4的Krebs缓冲液中，加入2.5 mM-[3-13C]谷氨酸。在孵育过程中，酸性大鼠组织中总葡萄糖和NH3浓度显著升高（P < 0.05）。对照组织中部分三羧酸循环中间体含量较高（P < 0.05）。在对照组织中，13C-n.m.r。光谱显示天冬氨酸、谷氨酰胺和[2,4-13C]谷氨酸的13C出现率显著提高。然而，在酸中毒中，[13C]葡萄糖碳原子的共振明显更高。在对照组中，大约。[13C]葡萄糖形成占谷氨酸碳的15%，而慢性酸中毒占30%。然而，在对照组织中，44%的谷氨酸碳利用是通过谷氨酸再循环和形成天冬氨酸、谷氨酰胺和GABA来实现的。而在酸中毒中，只有11%的人能痊愈。在2.5 mM-[15N]谷氨酸孵育过程中对15NH3形成的分析表明，在对照组和酸中毒中，[13C]葡萄糖和15NH3的出现之间存在正相关。这些数据表明，酸中毒中糖异生和氨作用的控制，部分是由于α -氧葡萄糖酸盐的还原性胺化反应速率、转氨化反应速率和谷氨酰胺合成速率的降低。
13C-n.m.r. spectroscopy and g.c.-m.s. were used to determine the metabolic fate of glutamate carbon in rat kidney. The main purpose was to characterize the effect of chronic metabolic acidosis on the utilization of glutamate carbon. Renal tubules obtained from normal and chronically acidotic rats were incubated in Krebs buffer, pH 7.4, in the presence of 2.5 mM-[3-13C]glutamate. During the course of incubation the concentrations of total glucose and NH3 were significantly (P less than 0.05) higher in tissue from acidotic rats. The levels of some tricarboxylic-acid-cycle intermediates were higher (P less than 0.05) in control tissue. In control tissue, 13C-n.m.r. spectra demonstrated a significantly higher rate of 13C appearance of aspartate, glutamine and [2,4-13C]glutamate. However, in acidosis the resonances of [13C]glucose carbon atoms were significantly higher. In the control, approx. 15% of glutamate carbon was accounted for by [13C]glucose formation as against 30% in chronic acidosis. However, in control tissue, 44% of glutamate carbon utilization was accounted for by recycling to glutamate and formation of aspartate, glutamine and GABA. In acidosis, only 11% was so recovered. Analysis of 15NH3 formation during the course of incubation with 2.5 mM-[15N]glutamate demonstrated a positive association between the appearance of [13C]glucose and 15NH3 both in the control and in acidosis. The data suggest that the control of gluconeogenesis and ammoniagenesis in acidosis is, in part, referable to a diminution in the rate of the reductive amination of alpha-oxoglutarate, that of the transamination reaction and that of glutamine synthesis.