title: Effects of bradykinin and leukotrienes B4 and D4 on the bovine bronchial artery in vitro: role of the endothelium.
abstract: The effects of bradykinin, leukotriene (LT) B4 and LTD4 on the bovine bronchial artery were studied using isolated, perfused vessel segments. Intrapulmonary bronchial arteries were precontracted to the EC50 of 5-hydroxytryptamine in the organ bath, after which increasing concentrations of bradykinin, LTB4 or LTD4 were perfused through the vessel lumen. In arteries with intact endothelium, bradykinin induced a concentration-dependent relaxation beginning at 1 pmol/l (p less than 0.01), whereas LTD4 and LTB4 had no significant effect. Indomethacin (10 mumol/l) significantly (p less than 0.01) inhibited bradykinin-induced relaxation with an increase in the IC50 from 0.11 +/- 0.08 nmol/l to 0.51 +/- 0.10 nmol/l (p less than 0.05). In endothelium-denuded arteries bradykinin had no observed effect, whereas LTB4 and LTD4 significantly increased tone with threshold concentrations of 50 pmol/l (p less than 0.025) and 5 pmol/l (p less than 0.05), respectively. The data indicate that in the bronchial artery: 1) bradykinin is a potent vasodilator; 2) bradykinin-induced relaxation is endothelium-dependent and only partially blocked by a cyclooxygenase inhibitor; 3) removal of the endothelium unmasks a potent contractile effect of LTB4 and LTD4.
authors.affiliation: Department of Pharmacology and Toxicology, University of Western Ontario, London, Canada.
authors.forename: W R
authors.initials: WR
authors.lastname: Tracey
authors.forename: P
authors.initials: P
authors.lastname: Eyre
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D001981:Bronchial Arteries / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D002417:Cattle; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007975:Leukotriene B4 / Q000494:pharmacology*; D008297:Male; D013189:SRS-A / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D013189:SRS-A; D007975:Leukotriene B4; D012701:Serotonin; D001920:Bradykinin; D007213:Indomethacin