EARLY CHANGES IN MYOCARDIAL PROTEIN-SYNTHESIS INVIVO IN RESPONSE TO RIGHT VENTRICULAR PRESSURE OVERLOAD IN THE DOG

Pulmonary artery stenosis was produced by inflation of a cuff positioned around the artery in dogs. Right ventricular pressures averaged 40 ± 2 (s.e.) mmHg before inflation and 72 ± 3 mmHg 1 day after inflation of the cuff. After 1 day stenosis the mass of the right ventricle averaged 12% above that in control dogs in which the cuff was not inflated. The protein synthesis rate was measured in both ventricles at this time by a continuous intravenous infusion of [14C]-tyrosine. Stenosis resulted in an increase in the specific radioactivity of tyrosine in protein while that of the tissue free tyrosine was unchanged. The rate of mixed protein synthesis in the right ventricle increased from 7.2%/day to 13.9%/day after 1 day of stenosis. Myofibrillar and sarcoplasmic protein fractions showed similar increases. © 1979.