Vascular responses to vasopressin antagonists in man and rat

Abstract

1. The effects of the non-peptide arginine vasopressin V1 receptor antagonist (OPC-21268) and the nonpeptide V2 receptor antagonist (OPC-31260) on vasopressin-induced contraction of human internal mammary arteries and rat mesenteric resistance arteries were investigated, 2. In human internal mammary arteries, the nonpeptide V, receptor antagonist, OPC-21268, failed to antagonize vasopressin-induced contraction at low concentrations and potentiated the contraction at higher concentrations (300 nmol/l, P < 0.05), A peptide selective V1 receptor antagonist {[d(CH2)5, sarcosine7]arginine vasopressin} potently inhibited the vasopressin-induced contraction, indicating the presence of functionally ..