Interaction between norepinephrine, NPY and VIP in the ovarian artery

Abstract

The in vitro effect and the interaction between norepinephrine (NE), neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) were studied in dissected segments of the rabbit ovarian artery. In addition, the structural requirement of the NPY receptor was investigated using NPY peptide analogs. NE induced a dose-dependent vasoconstriction with an E max of 131.4±2.9% of K +-induced constriction. The vasoconstrictor effect of NPY was less than 5% of K +-induced vasoconstriction. Incubation of the artery with 10 −7 M NPY for 4 min induced a significant potentiation of NE-induced contractions. The selective NPY Y 1 receptor agonist [Leu 31,Pro 34]NPY was also able to potentiate the NE response at the half-maximum contraction level, but not NPY(11–36), an NPY peptide fragment predominantly stimulating the NPY Y 2 receptor. NPY exerted a dose-dependent vasoconstrictor effect on vessels contracted for 20 min with 10 −6 M NE. VIP induced a dose-dependent relaxation of vessels contracted with 10 −6 M NE. The VIP-induced relaxation could be reversed by NPY. In conclusion, receptors capable of interacting with NPY, presumably of the Y 1 type, and VIP are present in the rabbit ovarian artery, and activation of these receptors may profoundly influence the response of the artery to norepinephrine.