Evidence for a possible synergism between pituitary adenylate cyclase activating polypeptide and calcitonin gene‐related peptide in porcine ophthalmic artery

Abstract

ABSTRACT. The activities of pituitary adenylate cyclase activating polypeptide (PACAP) and calcitonin gene-related peptide (CGRP) were investigated in isolated segments of porcine ophthalmic artery. In artery segments pre-contracted by prostaglandin FZa, PACAP induced a concentration dependent relaxation, but was clearly less potent than CGRP. When 2 X M CGRP (relaxation 4.3 f 0.8%, n = 11) and lo-* M PACAP (relaxation 12.4 k 3.8%, n = 10) were added together, the subsequent relaxation was substantially increased (33.6 f 5.6%, p<0.0005). In addition, the rate of relaxation was increased. The results indicate that there is synergism between low concentrations of CGRP and PACAP in isolated porcine ophthalmic artery.

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

“…A few PACAP-positive perikarya are also present in the sphenopalatine and otic ganglia (Uddman et al, 1991b(Uddman et al, , 1999. In the eye, PACAP-LI is present in fibers innervating the iris sphincter and in cell bodies scattered in the ciliary ganglia (Wang et al, 1995;Elsås and White, 1997;Olianas et al, 1997;Samuelsson-Almén and Nilsson, 1999). In the retina, PACAP is found in fibers of the ganglion cell and nerve fiber layer Seki et al, 1997Seki et al, , 2000 and in amacrine cells in the inner nuclear layer (Seki et al, 2000).…”

“…Although PACAP is able to exert an indirect hypertensive action mediated through the release of catecholamines (Ishizuka et al, 1992;Minkes et al, 1992a), this peptide, in very much the same way as VIP, is mainly considered as a highly potent vasorelaxant factor (Hirata et al, 1985;Ross-Ascuitto et al, 1993;Tong et al, 1993;Ascuitto et al, 1996). This vasodilatory activity, which can be ascribed at least in part to its activity on arterial smooth muscle cells Naruse et al, 1993;Steenstrup et al, 1996;Bruch et al, 1997), is well documented in various organs, including the brain (Tong et al, 1993;Anzai et al, 1995), the eye (Nilsson, 1994;Elsås and White, 1997;Dorner et al, 1998), the pulmonary vascular bed (Minkes et al, 1992b;Cheng et al, 1993;Foda et al, 1995), the mesentery (Wilson and Warren, 1993), the pancreas (Bertrand et al, 1996;Ito et al, 1998), the testis (Lissbrant et al, 1999), the ovary (Steenstrup et al, 1994;Yao et al, 1996), the vagina (Steenstrup et al, 1994;Giraldi et al, 2002;Aughton et al, 2008), the kidney (Gardiner et al, 1994), the gastrointestinal tract (Portbury et al, 1995;Badawy and Reinecke, 2003), and the skin (Wallengren, 1997).…”