EFFECTS OF A VASOPRESSIN ANTAGONIST WITH COMBINED ANTIPRESSOR AND ANTIANTIDIURETIC ACTIVITIES IN RATS WITH LEFT-VENTRICULAR DYSFUNCTION

These experiments assessed the hemodynamic and aquaretic effects of an arginine vasopressin (AVP) antagonist with dual V1V2-receptor inhibiting properties in rats with congestive heart failure resulting from ischemic cardiomyopathy. The compound d(CH2)5-D-Tyr(Et)VAVP was used in these studies. Rats with limited or extensive myocardial infarcts (i.e., with <50% or >66% necrosis of the left ventrical wall, respectively, induced by left coronary ligation) and sham-operated controls received the AVP antagonist (100 μg/kg i.v.) 4 weeks later. This agent produced an 18% increase in cardiac output (p < 0.05) and 13% decrease in systemic vascular resistance in the severely damaged rats, both changes being significantly different from those seen in the normal controls or the rats with limited infarcts. All animals exhibited increases in urinary output of 4-10-fold over baseline. We conclude that the hemodynamic and renal effects of this agent are beneficial in animals with left ventricular dysfunction.