HUMAN INTERNAL MAMMARY ARTERY RESPONSES TO NON‐PEPTIDE VASOPRESSIN ANTAGONISTS

Abstract

1. OPC‐21268 and OPC‐31260 are newly developed orally active non‐peptide vasopressin (AVP) V1 and V2 receptor antagonists, respectively. The effects of the two compounds on human vessels have not been studied. 2. The effects of the two compounds on AVP‐induced contraction of human internal mammary arteries (IMA) were investigated. Their effects were compared with the peptide V1 and V2 antagonists d(CH2)sSar7AVP (SAVP) and d(CH2)5D‐Ileu211eu4AVP (Ileu2 Ileu4AVP), respectively. 3. The V1 antagonist OPC‐21268 failed to antagonize AVP‐induced contraction at low concentrations and potentiated the contraction at higher concentration (3 × 10−‐7 mol/L, P<0.05). It also caused a mild direct contracti..