Comparative effects of PGD2 and PGE2 on vasoconstrictor responses in the feline intestinal vascular bed

The effects of prostaglandins (PG) D2 and E2 on vascular resistance and vasoconstrictor responses were compared in the feline mesenteric vascular bed under conditions of controlled flow so that changes in perfusion pressure directly reflect changes in vascular resistance. Infusions of PGD2 into the superior mesenteric artery significantly dilated the mesenteric vascular bed and inhibited vasoconstrictor responses to sympathetic nerve stimulation and intra-arterial injections of norepinephrine and angiotensin II. The inhibitory effects of PGD2 were reversible and dose-dependent. PGD2 inhibited responses to sympathetic nerve stimulation to a greater extent than responses to the pressor hormones. Infusion of PGE2 at similar doses dilated the mesenteric vascular bed but had little or no effect on vasoconstrictor responses to sympathetic nerve stimulation or pressor hormones. These data suggest that PGD2 possesses the ability to modulate responses to nerve stimulation and pressor hormones by both pre- and post-junctional actions in the feline mesenteric vascular bed.