VASCULAR EFFECTS AND CYCLIC-AMP PRODUCTION PRODUCED BY VIP, PHM, PHV,PACAP-27, PACAP-38, AND NPY ON RABBIT OVARIAN ARTERY

The relationship between vessel tone and cAMP production induced by va soactive intestinal polypeptide (VIP), peptide histidine methionine (P HM), peptide histidine valine (PHV), pituitary adenylate cyclase activ ating polypeptide (PACAP-27 and PACAP-38), and neuropeptide Y (NPY) wa s investigated in rabbit ovarian arteries in vitro. VIP, PHM, PHV, PAC AP-27, and PACAP-38 added in single-dose experiments (10(-9), 10(-8), 10(-7), and 10(-6) M) induced all a significant dose-related relaxatio n of noradrenaline (NA)-precontracted vessels and displayed similar po tencies. VIP, PHM, PHV, PACAP-27, and PACAP-38 all increased cyclic ad enosine monophosphate (cAMP) accumulation. The cAMP accumulation induc ed by PACAP-27 and PACAP-38 was five times higher than the cAMP conten t induced by the other three peptides. The peptide-induced smooth musc le relaxation did not correlate to the cAMP accumulation. NPY (10(-7) M) markedly reversed the relaxations induced by VIP, PHM, PHV, PACAP-2 7, and PACAP-38, but did not influence the cAMP production induced by these peptides. In conclusion, the relaxation induced by VIP, PHM, PHV , PACAP-27, and PACAP-38 and the contraction induced by NPY are not so lely related to the changes of cAMP contents. These findings indicate that in addition to cAMP, another intracellular signal transduction pa thway may be involved in the relaxation and contraction induced by the se peptides in rabbit ovarian artery.