Analogues of vasoactive intestinal peptide (VIP) contract the guinea-pig uterine artery but do not antagonize VIP-induced relaxations.

European journal of pharmacology1989PMID: 2542061

Plain Language Summary

Two VIP antagonists, including a modified GRF peptide, were tested on guinea-pig uterine artery segments but failed to block VIP-induced relaxation of the blood vessel. Instead, at high concentrations, the antagonists themselves caused brief contractions. These unexpected findings suggest the uterine artery has two distinct types of VIP receptors with opposite effects on vessel tone, and that VIP antagonists developed for other tissues may not work at this particular vascular site.

Abstract

Guinea-pig vasoactive intestinal peptide (gpVIP-(1-28] in the concentration range 3 x 10(-9)-3 x 10(-7) mol.1-1 relaxed precontracted segments of the guinea-pig uterine artery. Porcine VIP-(10-28) (pVIP-(10-28], [4-Cl-D-Phe6,Leu17]VIP, or [N-Ac-Tyr1, D-Phe2]GRF-(1-29)-NH2 did not antagonize VIP-induced relaxations of the artery, but high concentrations of the two VIP analogues produced large, transient contractions of the artery. In some preparations 10(-5) mol.1-1 gpVIP-(1-28) also caused transient arterial contractions. These data indicate the presence of two distinct receptors for VIP on the guinea-pig uterine artery, mediating opposite effects on vascular tone.

Authors

Morris, J L; Murphy, R