Protein synthesis in the overloaded mammalian heart

Abstract

Protein synthesis was studied in the guinea pig heart in vitro perfused with uniformly labeled lysine-C14 in Krebs-Hensleit solution. Protein content decreased in the absence of supplemental amino acids, but was maintained at control levels when the supplements were added. In the presence of supplemental amino acids, increased fluid load to the left ventricle or increased aortic pressure with normal fluid load resulted in left ventricular distention and increased contractile action and was associated with an increase in lysine-C14 incorporation into myocardial protein after 3 hr. of continued load. Incorporation of lysine-C14 into protein also appeared to increase when coronary flow increased. The data suggest that overload to the ventricle, as well as coronary flow and pressure, play important roles as stimuli for myocardial protein synthesis.