title: Endothelium-dependent contractions to oxygen-derived free radicals in the canine basilar artery.
abstract: Experiments were designed to determine the effect of oxygen-derived free radicals in isolated canine basilar arteries. Rings with and without endothelium were suspended for isometric tension recording in modified Krebs-Ringer bicarbonate solution bubbled with 95% O2-5% CO2 (temperature = 37 degrees C; pH = 7.4). A radioimmunoassay technique was used to measure production of prostaglandins and thromboxane B2. Xanthine oxidase (1-9 mU/ml, in the presence of 10(-4) M xanthine) and hydrogen peroxide (10(-6) to 10(-4) M) caused concentration-dependent contractions. The removal of endothelium reversed these contractions into relaxations. Contractions to xanthine oxidase and hydrogen peroxide were inhibited in the presence of superoxide dismutase (150 U/ml), catalase (1,200 U/ml), indomethacin (10(-5) M), and SQ 29548 (10(-6) M) but not in the presence of deferoxamine (10(-4) to 10(-3) M) and dimethyl sulfoxide (10(-4) M). NG-monomethyl-L-arginine (3 x 10(-5) M) augmented the contractions to hydrogen peroxide. Xanthine oxidase stimulated production of 6-ketoprostaglandin F1 alpha, prostaglandin F2 alpha, prostaglandin E2, and thromboxane B2. The stimulatory effect was prevented by the removal of endothelial cells. These studies suggest that xanthine oxidase causes endothelium-dependent contractions mediated by: 1) hydrogen peroxide-induced stimulation of the endothelial metabolism of arachidonic acid via the cyclooxygenase pathway, leading to activation of prostaglandin H2-thromboxane A2 receptors, and 2) inactivation of basal production of nitric oxide by superoxide anions.
authors.affiliation: Department of Anesthesiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
authors.forename: Z S
authors.initials: ZS
authors.lastname: Katusić
authors.forename: J
authors.initials: J
authors.lastname: Schugel
authors.forename: F
authors.initials: F
authors.lastname: Cosentino
authors.forename: P M
authors.initials: PM
authors.lastname: Vanhoutte
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001488:Basilar Artery / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D004285:Dogs; D004730:Endothelium, Vascular / Q000502:physiology*; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008469:Meclofenamic Acid / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D011453:Prostaglandins / Q000096:biosynthesis; D013482:Superoxide Dismutase / Q000494:pharmacology; D013929:Thromboxane B2 / Q000096:biosynthesis; D019820:Xanthine; D014969:Xanthine Oxidase / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology; D019323:omega-N-Methylarginine
chemical_list: D005609:Free Radicals; D011453:Prostaglandins; D014970:Xanthines; D019820:Xanthine; D019323:omega-N-Methylarginine; D008469:Meclofenamic Acid; D013929:Thromboxane B2; D001120:Arginine; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010100:Oxygen; D007213:Indomethacin