INVITRO ACTIVITIES OF SOME SYNTHETIC SUBSTANCE-P ANALOGS

Abstract

Substance P (SP) and several analogs and fragments were synthesized and evaluated on non-stimulated and stimulated guinea pig ileum. In the former test system the potency order was as follows: SP(4-11) > SP = [Tyr7]-SP = [Eth11]-SP = [Nle11]-SP > [DA1a9]-SP > SP(7-11) = [Tyr7]-SP(7-11) > [Eth11]-SP(7-11) > [DA1a9]-SP(7-11) > [Ne1e11]-SP(7-11) > SP(1-7). The spasmogenic activity of SP and analogs was preserved in the same potency order on stimulated guinea-pig ileum; none of the modifications caused an analog with narcotic-like activity. A hypothetical SP receptor in extravascular smooth muscle is discussed.