CHARACTERIZATION OF CONTRACTILE ENDOTHELIN AND ANGIOTENSIN RECEPTORS IN HUMAN RESISTANCE ARTERIES - EVIDENCE FOR 2 ENDOTHELIN AND ONE ANGIOTENSIN RECEPTOR

Endothelin-1 (ET-1) and angiotensin II (AII) are potent vasoconstrictor hormones which regulate tissue perfusion and blood pressure. We pharmacologically characterized endothelin and angiotensin receptors mediating contractions of human mammary resistance arteries in myographs for isometric tension recording. ET-1 caused potent contractions. The concentration response curve was shifted to the right by ET(A) antagonist FR 139317, but a high sensitivity, low efficacy component remained. After incubation with ET(B) agonist sarafotoxin (S6c) this component of the concentration response curve resistant to FR 139317 disappeared. The ET(A)/ET(B)-receptor antagonist bosentan shifted the entire concentration response curve to the right. AI and AII caused marked contractions, The effects of AI were reduced by the ACE inhibitor benazeprilat, while those of AII were prevented by valsartan, an AT(1) antagonist. In summary, in human resistance arteries, contractions to ET-1 are mediated by ET(A)- and ET(B)-receptors while those to AII are exclusively mediated by AT(1)-receptors. 1994 Academic Inc. Press,