Effects of some new angiotensin II analogs on the reactivity of small arterioles in the mesentery of rat intestine

Abstract

The influence of nine new angiotensin II analogs: Asp-Arg-Val-Tyr-Gly-His-Pro-Phe (1-RP), Asp-Arg-Val-DL-p-ClPhe-Ile-His-Pro-Phe (2-RP), epsilon Ahx-Arg-Val-Tyr-Ile-His-Pro-Phe (3-RP), Asp-Arg-Val-Tyr-beta Ala-His-Pro-Ile (4-RP), Asp-Arg-Val-Tyr-Ile-Pro-Phe (5-RP), beta Ala-Arg-Val-Tyr-D-Val-His-Pro-Lac (6-RP), beta Ala-Arg-Val-Tyr-Ile-His-Pro-Lac (7-RP), epsilon Ahx-Val-Tyr-Ile-His-Pro-Phe (8-RP) and Arg-Val-Tyr-Ile-His-Pro-Thr (9-RP) on the contractility of small arterioles in the rat intestinal mesentery was investigated. All the peptides had weaker contractile activity than angiotensinamide. The most potent new peptides presented 56% (1-RP), 67% (3-RP) and 78% (8-RP) of the agonistic activity of angiotensinamide. None of the new angiotensin II analogs had antagonistic activity. Compounds 1-RP and 3-RP presented the tendency to cause tachyphylaxis.