Modulation of rat skeletal muscle branched-chain alpha-keto acid dehydrogenase in vivo. Effects of dietary protein and meal consumption.
Modulation of rat skeletal muscle branched-chain alpha-keto acid dehydrogenase in vivo. Effects of dietary protein and meal consumption.
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体内大鼠骨骼肌支链α-酮酸脱氢酶的调节。
DOI：
10.1172/jci112961
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Buse,MG
中科院分区：
文献类型：
--
作者：
Block,KP;Aftring,RP;Mehard,WB;Buse,MG
研究了日粮蛋白质对骨骼肌支链α-酮酸脱氢酶（BCKAD）活性的影响。BCKAD对肌肉分解支链氨基酸（BCAA）具有限速作用;其活性受到磷酸化-去磷酸化的调节。在喂食足够蛋白质（25%酪蛋白）饮食的大鼠中，BCKAD在吸收后约为2%，在25%或50%蛋白质餐后分别增加至10%或16%。延长喂养的50%的蛋白质饮食增加吸收后BCKAD活性为7%，进一步增加到40%的餐后活动。在低蛋白（9%酪蛋白）饮食BCKAD保持约2%的活性，无论进餐喂养。低蛋白饮食可减弱吸收后大鼠静脉注射亮氨酸对BCKAD的剂量依赖性激活作用。我们的结论是，过量的膳食蛋白质增强了骨骼肌氧化BCAA的能力，当蛋白质摄入不足时，肌肉保存BCAA，骨骼肌可能在全身BCAA稳态中发挥重要作用。图片
The effects of dietary protein on the activity of skeletal muscle branched-chain alpha-keto acid dehydrogenase (BCKAD) were investigated. BCKAD is rate-limiting for branched-chain amino acid (BCAA) catabolism by muscle; its activity is modulated by phosphorylation-dephosphorylation. In rats fed an adequate protein (25% casein) diet, BCKAD was approximately 2% active postabsorptively and increased to 10% or 16% active after a 25% or 50% protein meal, respectively. Prolonged feeding of a 50% protein diet increased postabsorptive BCKAD activity to 7% with further increases to 40% active postprandially. On a low protein (9% casein) diet BCKAD remained approximately 2% active regardless of meal-feeding. Dose-dependent activation of BCKAD by intravenous leucine in postabsorptive rats was blunted by a low protein diet. We conclude that excesses of dietary protein enhance the capacity of skeletal muscle to oxidize BCAA, muscle conserves BCAA when protein intake is inadequate, and skeletal muscle may play an important role in whole-body BCAA homeostasis.Images