ENDOTHELIN IS BLOOD VESSEL SELECTIVE: STUDIES ON A VARIETY OF HUMAN AND DOG VESSELS IN VITRO AND ON REGIONAL BLOOD FLOW IN THE CONSCIOUS RABBIT

Abstract

1. Endothelin (Et), a vasoconstrictor peptide, was 5–10‐fold more potent (lower EC50) on isolated ring segments of large veins than on large arteries removed from dog coronary, mesenteric, femoral, renal and internal mammary vasculature and from the human internal mammary pedicle. 2. In the dog large coronary artery, Et (10–30 nmol/L) caused transient relaxations partway through the generation of a concentration‐contraction curve. These relaxations were endothelium dependent. 3. In conscious rabbits treated with mecamylamine, Et (0.025–0.4 nmol/kg) caused a marked rise in renal vascular resistance but hindquarter vasodilation. Under the same conditions angiotensin II constricted both beds. 4..