Studies on Myocardial Protein Metabolism in Cardiac Hypertrophy
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概要
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In order to study myocardial protein metabolism in cardiac hypertrophy and failure, the changes in concentrations of various proteins, nucleic acids, and amino acids, and in activities of protein synthetic enzymes and transaminases were observed in the heart muscle of dogs with experimentally produced cardiac hypertrophy.Cardiac hypertrophy, especially left ventricular hypertrophy, which was ascertained by measurement of the ratio of heart to body weight, right to left ventricular weight and RNA to DNA, was produced by aortic valve lesion.(1) In the early stage of hypertrophy and in acute failure hydration of myocardium proceeds.(2) The myocardial concentrations of total, noncollagen and contractile protein were decreased due to hydration of the myocardium in the early stage, but the total contents of them were increased progressively except a temporary initial decrease in total protein.(3) The concentrations of soluble protein, microsomal protein and mitochondrial protein were elevated throughout the course of time.(4) The activities of GOT and GPT in the myocardium were elevated both in the early and late stage of hypertrophy. This tendency is similar to those of some amino acids.(5) The activities of amino acid activating enzyme were elevated early, and returned rapidly to the control level. They were, however, lowered in another group of dogs which were in the acute and chronic cardiac decompensation tsage.(6) The changes in the myocardial concentrations of free amino acids were varied with its sort. In the acute phase, increases in fraction A1 and N3 were noticeable, and in relatively stable phase of hypertrophy decreases in fraction A1, N2, N4 and N5 were remarkable.(7) The increased concentrations of mitochondrial and cytoplasmic protein, RNA, transaminases, some amino acid fractions (A2, N3) and the increased activity of amino acid activating enzyme are suggestive of increased energy metabolism and of accerelated protein synthesis.
- International Heart Journal刊行会の論文