MECHANISM OF MYOCARDIAL CATECHOLAMINE DEPLETION IN CARDIAC HYPERTROPHY AND FAILURE IN RABBITS

Abstract

The myocardial catecholamine metabolism was investigated to elucidate the mechanism of the depletion of myocardial catecholamine stores in hypertrophied and failing hearts of rabbits. Myocardial catecholamine concentration was already reduced in early stage of cardiac hypertrophy, and similar time course changes were observed in the activity of tyrosine hydroxylase, the rate-limiting enzyme in the biosynthesis of catecholamine. These findings suggest that the depression of tyrosine hydroxylase activity is a main factor contributing to the depletion of myocardial catecholamine stores. The changes of the enzymatic destruction, the release and the uptake of catecholamine in hypertrophied and failing hearts were also observed and discussed.