title: Role of prostaglandins and histamine in reactive hyperemia: in-vivo studies on single mesenteric arterioles.
abstract: Direct, in vivo microcirculatory experiments were undertaken with anesthetized rats to determine whether prostaglandin (PG)-like compounds and histamine may mediate post-occlusion hyperemia in single mesenteric arterioles. Superfusion of the mesenteric vasculature with two structurally different PG synthetase inhibitors, indomethacin and 5,8,11,14-eicosatetraynoic acid (ETA), was found to markedly inhibit postocclusion vasodilator responses in arterioles 20-22 micrometer i.d. Superfusion of mesentery with an H2-histamine receptor antagonist, metiamide, resulted in a 40% inhibition of the postocclusion vasodilator responses in arterioles. Superfusion of the mesenteric vasculature with a combination of indomethacin and metiamide resulted in a 95% suppression of the postocclusion dilator responses. Administration of either the PG synthetase inhibitors, metiamide, or a combination of both types of drugs did not, however, influence resting arteriolar tone or responsiveness to PGE1 or epinephrine. Although the results of these experiments implicate a role for PG-like substances and histamine in reactive or postocclusion hypermia, they do not provide evidence for a role of these humoral substances in the normal moment-to-moment regulation of arteriolar tone.
mesh_terms: D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000503:physiopathology*; D001160:Arterioles / Q000503:physiopathology*; D016861:Cyclooxygenase Inhibitors; D006632:Histamine / Q000502:physiology*; D006940:Hyperemia / Q000503:physiopathology*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008638:Mesenteric Arteries / Q000503:physiopathology; D008785:Metiamide / Q000494:pharmacology; D011453:Prostaglandins / Q000502:physiology*; D051381:Rats; D014664:Vasodilation
chemical_list: D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; D015117:5,8,11,14-Eicosatetraynoic Acid; D008785:Metiamide; D006632:Histamine; D007213:Indomethacin