title: Reoxygenation-induced constriction in murine coronary arteries: the role of endothelial NADPH oxidase (gp91phox) and intracellular superoxide.
abstract: Previous work suggests that superoxide mediates hypoxia/reoxygenation (H/R)-induced constriction of isolated mouse coronary arteries (CA). To determine the source of superoxide overproduction during H/R we studied CA obtained from transgenic (Tg) mice overexpressing human CuZn-superoxide dismutase (SOD) and mice lacking gp91(phox) using an in vitro vascular ring bioassay. We found that under normoxic conditions CA isolated from wild type (wt) mice, CuZn-SOD Tg mice and gp91(phox) knock-out mice had similar contractile responses to U46619 and hypoxia and similar dilation responses to acetylcholine. In wt CA, 30 min of hypoxia (1% O(2)) followed by reoxygenation (16% O(2)) resulted in further coronary vasoconstriction (internal diameter from 105 +/- 11 to 84.5 +/- 17.9 microm), whereas this response was completely blocked in both CuZn-SOD Tg and gp91(phox) knock-out CA (104.3 +/- 10.5 to 120.7 +/- 14 microm and 143.3 +/- 15.3 to 172.7 +/- 12.5 microm, respectively, p < 0.01). Furthermore, we show that H/R enhances the generation of superoxide radicals in wt CA (25.8 +/- 0.7 relative light units per second (RLU/s)), whereas CuZn-SOD Tg CA (12.2 +/- 0.8 RLU/s, p < 0.01) and gp91(phox) CA (12.5 +/- 0.9 RLU/s, p < 0.01) show reduced levels. These results demonstrate that H/R-induced vasoconstriction is mediated by intracellular superoxide overproduction via endothelial NADPH oxidase gp91(phox). Therefore, increasing endogenous levels of CuZn-SOD in CA may provide a novel cardioprotective strategy for maintaining coronary perfusion under conditions of H/R.
authors.affiliation: Department of Medicine, Division of Pulmonary, Allergy, and Critical Care, Duke University Medical Center, Durham, North Carolina 27710, USA. john.liu@duke.edu
authors.forename: John Q
authors.initials: JQ
authors.lastname: Liu
authors.forename: Igor N
authors.initials: IN
authors.lastname: Zelko
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Folz
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001158:Arteries / Q000378:metabolism*; D001681:Biological Assay; D003331:Coronary Vessels / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia; D008163:Luminescent Measurements; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008954:Models, Biological; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D014661:Vasoconstriction
chemical_list: D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D013481:Superoxides; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D013482:Superoxide Dismutase; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D000109:Acetylcholine; D010100:Oxygen