葡萄糖和酮体对大鼠离体半膈肌中支链氨基酸氧化的调节作用。

Modulation of branched-chain amino acid oxidation in rat hemidiaphragms in vitro by glucose and ketone bodies.

作者信息

Palmer T N, Caldecourt M A, Warner J P, Sugden M C

出版信息

Biochem Int. 1985 Sep;11(3):407-13.

Abstract

Branched-chain amino acid metabolism in hemidiaphragms from 40 h-starved rats is influenced by the provision of glucose as co-substrate. Glucose inhibits 14CO2 production from [l-14C]valine and [U-14C]valine but stimulates 14CO2 production from [l-14C]leucine, [U-14C]leucine and [U-14C]isoleucine. In the presence of glucose, ketone bodies inhibit alanine release and 14CO2 production from [l-14C]valine, [l-14C]leucine and [U-14C]isoleucine, but inhibition is not observed in the absence of glucose as cosubstrate. Glucose-dependent inhibition by ketone bodies of branched-chain amino acid oxidation via inhibition of the branched-chain 2-oxo acid dehydrogenase complex or branched-chain amino acid aminotransferase may account in part for the reported hypoalanaemic action of ketone bodies in vivo.

摘要

40小时饥饿大鼠半膈中支链氨基酸代谢受葡萄糖作为共底物供应的影响。葡萄糖抑制[l-14C]缬氨酸和[U-14C]缬氨酸生成14CO2，但刺激[l-14C]亮氨酸、[U-14C]亮氨酸和[U-14C]异亮氨酸生成14CO2。在有葡萄糖存在时，酮体抑制丙氨酸释放以及[l-14C]缬氨酸、[l-14C]亮氨酸和[U-14C]异亮氨酸生成14CO2，但在没有葡萄糖作为共底物时未观察到抑制作用。酮体通过抑制支链2-氧代酸脱氢酶复合体或支链氨基酸转氨酶对支链氨基酸氧化的葡萄糖依赖性抑制可能部分解释了酮体在体内所报道的低丙氨酸血症作用。