Myocardial protein turnover in patients with coronary artery disease. Effect of branched chain amino acid infusion.
Myocardial protein turnover in patients with coronary artery disease. Effect of branched chain amino acid infusion.
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冠状动脉疾病患者的心肌蛋白质周转。
DOI：
10.1172/jci115030
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Barrett,EJ
中科院分区：
文献类型：
--
作者：
Young,LH;McNulty,PH;Morgan,C;Deckelbaum,LI;Zaret,BL;Barrett,EJ
人类心脏中蛋白质代谢的调节以前没有被研究过。在10例吸收后冠心病患者中，从静脉输注的L-[ring-2，6 - 3 H]苯丙氨酸（PHE）的提取和同位素稳态下其在心脏中的比活度的稀释同时估计心脏蛋白质的合成和降解。随后，我们研究了支链氨基酸（BCAA）输注对这些患者心脏蛋白质周转和氨基酸和支链酮酸（BCKA）的心肌平衡的影响。在吸收后状态下，有苯丙氨酸的净释放（动-心静脉[PHE] = -1.71 +/-0.32nmol/ml，P <0.001;平衡= -116 +/- 21 nmol PHE/min，P小于0.001），反映蛋白质降解（142 +/- 40 nmol PHE/min）超过合成（24 +/- 42 nmol PHE/min）和净心肌蛋白质催化剂。在BCAA输注过程中，蛋白质合成增加到与降解速率相等（分别为106 +/- 24和106 +/- 28 nmol PHE/min），苯丙氨酸平衡从阴性变为中性（动脉-心脏静脉[PHE] = 0.07 +/- 0.36 nmol/ml;平衡= 2 +/- 25 nmol PHE/min）（P = 0.01）。BCAA输注刺激心肌摄取BCAA（P <0.005）和它们的酮酸结合物（P <0.001），与它们的循环浓度成比例。BCAA的净摄取量大大超过了其他必需氨基酸，表明BCAA和BCKA作为代谢燃料的作用。血浆胰岛素水平、心脏双功、冠状动脉血流量和心肌耗氧量无变化。这些结果表明，吸收后的人类心肌处于负蛋白质平衡，并表明BCAA对人类心脏的主要合成代谢作用。图片
The regulation of protein metabolism in the human heart has not previously been studied. In 10 postabsorptive patients with coronary artery disease, heart protein synthesis and degradation were estimated simultaneously from the extraction of intravenously infused L-[ring-2,6-3H]phenylalanine (PHE) and the dilution of its specific activity across the heart at isotopic steady state. We subsequently examined the effect of branched chain amino acid (BCAA) infusion on heart protein turnover and on the myocardial balance of amino acids and branched chain ketoacids (BCKA) in these patients. In the postabsorptive state, there was a net release of phenylalanine (arterial-cardiac venous [PHE] = -1.71 +/- 0.32 nmol/ml, P less than 0.001; balance = -116 +/- 21 nmol PHE/min, P less than 0.001), reflecting protein degradation (142 +/- 40 nmol PHE/min) in excess of synthesis (24 +/- 42 nmol PHE/min) and net myocardial protein catabolism. During BCAA infusion, protein synthesis increased to equal the degradation rate (106 +/- 24 and 106 +/- 28 nmol PHE/min, respectively) and the phenylalanine balance shifted (P = 0.01) from negative to neutral (arterial-cardiac venous [PHE] = 0.07 +/- 0.36 nmol/ml; balance = 2 +/- 25 nmol PHE/min). BCAA infusion stimulated the myocardial uptake of both BCAA (P less than 0.005) and their ketoacid conjugates (P less than 0.001) in proportion to their circulating concentrations. Net uptake of the BCAA greatly exceeded that of other essential amino acids suggesting a role for BCAA and BCKA as metabolic fuels. Plasma insulin levels, cardiac double product, coronary blood flow, and myocardial oxygen consumption were unchanged. These results demonstrate that the myocardium of postabsorptive humans is in negative protein balance and indicate a primary anabolic effect of BCAA on the human heart.Images