Decrease in the rate of RNA and protein synthesis and degradation in the myocardium under long-term compensatory hyperfunction and on aging.
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Aging↗
Biomedical subjects
M P Javich
Publications and source records attributed to M P Javich.
Metabolism of poly (A)-containing mRNA in myocardium under normal physiological conditions and compensatory cardiac hyperfunction.
Two fractions of mRNA poly A+ and poly A- mRNA have been found in rat heart muscle by the method of affinity chromatography. These fractions amount to 30 and 70% of the total RNA respectively. The relationship between poly A+ and poly A-mRNA in myocardium does not alter in heart hyperfunction and aging. The life-span of mRNA reduces to 2-3 hours in the beginning of the process of myocardium hyperfunction development; the lifespan of mRNA does not differ from the controls in prolonged heart hyperfunction (6 months). The rate of poly A+mRNA synthesis increases by 70% compared to controls in the early stage of heart hyperfunction; it falls below the control level in long-term hypertrophied myocardium. This decreases in the rate of mRNA transcription in compensatory heart hypertrophy can play an important role in wear of the organ and in premature development of aging changes in the heart.
Animals↗
Isoenzyme pattern and activity of myocardial creatine phosphokinase under heart adaptation to prolonged overload.
Three isoenzymes of creatine phosphokinase (CPK) were detected in rat heart myocardium after electrophoretic separation of the enzyme in agarose gel: MM isozyme, MB isozyme and BB isozyme. The ratio of their activities was 60:30:5. Total activity of CPK per unit mass of myocardium was increased concomitant with transformation of its isoenzyme spectrum during the early stage of heart adaptation to the increased loading caused by aortic constriction. By the third day of cardiac hyperfunction, relative BB isozyme activity in the heart had increased to 15%, relative activity of the hybrid MB isozyme was increased to 40%, and relative activity of the main muscle MM isozyme was decreased to 45%. The relative increase in the activity of BB isozyme appears to reflect a preference for accumulation of the most functionally effective, short-lived isoenzymes-which play the key role in adaptation of tissues and systems to long-term loading.
Animals↗