Action of Tonin on the Response of Rat on Mesenteric Vessels to Norepinephrine 1

Abstract

Summary

Infusion into the rat mesen-teric artery of tonin, an enzyme which forms angiotensin II directly from a natural protein plus the tetradecapeptide renin substrate, significantly potentiated the vasoconstrictor response to norepineph-rine. This effect was not inhibited by the simultaneous administration of an inhibitor of angiotensin I-converting enzyme or by Sar 1 Ala⁸angiotensin II. These substances block the pressor effect of the angi-otensins I and II, respectively.

The authors wish to thank Mrs. V. Lacombe for secretarial work.

The synthetic saralasin, antagonist of angiotensin II (P 113), was kindly supplied by Eaton Laboratories, Nowrich, New York.