CONVERSION OF ANGIOTENSIN-I TO ANGIOTENSIN-II IN THE HUMAN FETOPLACENTAL VASCULAR BED

  • 1 January 1985
    • journal article
    • research article
    • Vol. 84  (1) , 237-241
Abstract
Pressor effects of angiotensin I (AI) and angiotensin II (AII) on the human fetoplacental vasculature were compared in dual-perfused term placental cotyledons in which fetoplacental perfusion pressure was monitored. Arterial injections of 1 nmol doses of AI and AII caused marked increases in perfusion pressure; the mean pressor response to AI was 92.9 .+-. 5.8% (mean .+-. standard error of the mean [SEM]) of the AII response. The angiotensin-converting enzyme inhibitor captopril at 2.2 .mu.M reversibly reduced the AI response to 13.7 .+-. 3.2% (mean .+-. SEM) of the AII response, which was unaffected. Saralasin, an AII receptor blocker, at 94 nM reversibly antagonized both AI- and AII-induced increases in fetoplacental perfusion pressure. Fetoplacental vasoconstriction elicited by AI is due to its conversion to AII by angiotensin-converting enzyme present in the fetoplacental bed.