title: Impairment of autoregulatory vasodilation by NAD(P)H oxidase-dependent superoxide generation during acute stage of subarachnoid hemorrhage in rat pial artery.
abstract: This study assessed the mechanism(s) by which the autoregulatory vasodilation of rat pial artery in response to acute hypotension during the acute phase of subarachnoid hemorrhage (SAH) was markedly blunted. Increased superoxide production from the cerebral vessels in response to NAD(P)H at 24 hours after SAH + NG-nitro-l-arginine methyl ester (l-NAME) (10 mg/kg) was inhibited by intracisternal administration of a tyrosine kinase inhibitor genistein (10 micromol/L) and Rac inhibitor Clostridium difficile toxin B (1 ng/mL) and a flavoenzyme inhibitor diphenyleneiodonium (10 micromol/L). The expression of gp91phox was enhanced by SAH + l-NAME from 12 to 24 hours, which was inhibited by genistein and toxin B, but not the p22phox. Increased membrane translocation of Rac after SAH + l-NAME was attenuated by both genistein and toxin B, whereas increased tyrosine kinase activity was blocked by genistein, but not by toxin B. The blunted autoregulatory vasodilation to acute hypotension was effectively recovered by genistein and C. difficile toxin B as well as by diphenyleneiodonium. In conclusion, SAH during acute stage causes an increase in NAD(P)H oxidase-dependent superoxide formation in cerebral vessels, which is due to activation of tyrosine phosphorylation-dependent increased expression of gp91phox mRNA and translocation of Rac protein, thereby resulting in a significant reduction of autoregulatory vasodilation.
authors.affiliation: Department of Pharmacology, College of Medicine, Research Institute of Genetic Engineering, Pusan National University, Korea.
authors.forename: Hwa Kyoung
authors.initials: HK
authors.lastname: Shin
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Kim
authors.forename: Chi Dae
authors.initials: CD
authors.lastname: Kim
authors.forename: Won Suk
authors.initials: WS
authors.lastname: Lee
authors.forename: Byung Yong
authors.initials: BY
authors.lastname: Rhim
authors.forename: Ki Whan
authors.initials: KW
authors.lastname: Hong
mesh_terms: D000818:Animals; D001158:Arteries; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D006706:Homeostasis; D007022:Hypotension / Q000503:physiopathology; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D026901:Membrane Transport Proteins; D009249:NADP / Q000494:pharmacology; D009252:NADPH Dehydrogenase / Q000494:pharmacology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010750:Phosphoproteins / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology*; D013481:Superoxides / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects*; D020744:rac GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C031815:toxB protein, Clostridium difficile; D013481:Superoxides; D009249:NADP; D019833:Genistein; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C086986:CYBA protein, human; D009252:NADPH Dehydrogenase; D011505:Protein-Tyrosine Kinases; D020744:rac GTP-Binding Proteins; D019331:NG-Nitroarginine Methyl Ester