Effect of propranolol upon protein and proteolytic synthesis activity in hypertrophic myocardium.

The aim of the study was to investigate the effect of propranolol upon protein synthesis and degradation processes in cell-free subfractions of rat myocardium in experimental cardiac hypertrophy induced by aortic stenosis. It was found that hypertrophy stimulates incorporation of 3H-amino acids by the postmitochondrial supernatant (PMS) by 17 +/- 4% (mean +/- SE). Propranolol 10 6M inhibited protein synthesis in the control and experimental groups by 37 +/- 5% and 34 +/- 7%, respectively. At a concentration of 5 X 10 6M, propranolol-induced inhibition in each group was 74 +/- 4% and 58 +/- 5%, respectively. The activity of neutral proteases in PMS of hypertrophic hearts increased up to 255 +/- 29 IU in comparison to 154 +/- 10 IU in controls; in the cytosol it was unchanged. Propranolol had no effect upon the activity of proteases in both fractions. Activity of calcium-activated neutral proteases (CANP) remained at the same level in control and hypertrophic hearts and was unaffected by propranolol.