Myocardial protein turnover in patients with coronary artery disease. Effect of branched chain amino acid infusion.
Open Access
- 1 February 1991
- journal article
- Published by American Society for Clinical Investigation in JCI Insight
- Vol. 87 (2), 554-560
- https://doi.org/10.1172/JCI115030
Abstract
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.This publication has 34 references indexed in Scilit:
- Ischemia of the dog heart induces the appearance of a cardiac mRNA coding for a protein with migration characteristics similar to heat-shock/stress protein 71.Circulation Research, 1986
- Removal of infused amino acids by splanchnic and leg tissues in humansAmerican Journal of Physiology-Endocrinology and Metabolism, 1986
- Regulation of myocardial amino acid balance in the conscious dog.JCI Insight, 1985
- Influence of starvation and total protein deprivation on cardiac mRNA levelsBasic Research in Cardiology, 1985
- Rates of protein turnover in vivo and in vitro in ventricular muscle of hearts from fed and starved ratsBiochemical Journal, 1984
- Measurement of branched chain amino acids and branched chain α-ketoacids in plasma by high-performance liquid chromatographyJournal of Chromatography B: Biomedical Sciences and Applications, 1982
- The disposal of an intravenously administered amino acid load across the human forearmMetabolism, 1982
- Effects of insulin, glucose, and amino acids on protein turnover in rat diaphragm.Online Journal of Public Health Informatics, 1975
- Significance of Ammonia in Myocardial MetabolismJapanese Circulation Journal, 1969
- Myocardial metabolism of glucose, lactic acid, amino acids and fatty acids in healthy human individuals at rest and at different work loads.1961