Arginine vasopressin increases the rate of protein synthesis in isolated perfused adult rat heart via the V1 receptor

Arginine vasopressin (AVP) is known to contribute significantly to the pathogenesis of congestive heart failure and hypertension. However, little is known about its effect on the myocardium. The present study was conducted to determine whether AVP directly increases the rate of protein synthesis in isolated, perfused rat heart, and, if so, the mechanism involved. Elevation of the aortic pressure from 60 to 120 mmHg in perfused rat heart accelerated the rate of protein synthesis which was associated with increases in cAMP levels and Ca2+ uptake. AVP (100 mu M) increased Ca2+ uptake and accelerated the rate of protein synthesis without a change in cAMP concentration. The latter events were inhibited by OPC-21268 (100 mu M), a selective V-1 receptor antagonist, or amiloride (100 mu M), an inhibitor of the Na+/H+ exchange system. However, increases in cAMP concentrations, Ca2+ uptake, and rates of protein synthesis associated with the elevated aortic pressure were not inhibited by amiloride. Thus, AVP directly increased the rate of protein synthesis via the V-1 receptor that is sensitive to amiloride, a mechanism that differs from the cAMP-dependent mechanism that is responsible for the cardiac hypertrophy induced by pressure overload.