Role of Cu,Zn-SOD in the synthesis of endogenous vasodilator hydrogen peroxide during reactive hyperemia in mouse mesenteric microcirculation in vivo.
We have recently demonstrated that endothelium-derived hydrogen peroxide (H2O2) is an endothelium-derived hyperpolarizing factor and that endothelial Cu/Zn-superoxide dismutase (SOD) plays an important role in the synthesis of endogenous H2O2 in both animals and humans. We examined whether SOD plays a role in the synthesis of endogenous H2O2 during in vivo reactive hyperemia (RH), an important regulatory mechanism. Mesenteric arterioles from wild-type and Cu,Zn-SOD(-/-) mice were continuously observed by a pencil-type charge-coupled device (CCD) intravital microscope during RH (reperfusion after 20 and 60 s of mesenteric artery occlusion) in the cyclooxygenase blockade under the following four conditions: control, catalase alone, N(G)-monomethyl-L-arginine (L-NMMA) alone, and L-NMMA + catalase. Vasodilatation during RH was significantly decreased by catalase or L-NMMA alone and was almost completely inhibited by L-NMMA + catalase in wild-type mice, whereas it was inhibited by L-NMMA and L-NMMA + catalase in the Cu,Zn-SOD(-/-) mice. RH-induced increase in blood flow after L-NMMA was significantly increased in the wild-type mice, whereas it was significantly reduced in the Cu,Zn-SOD(-/-) mice. In mesenteric arterioles of the Cu,Zn-SOD(-/-) mice, Tempol, an SOD mimetic, significantly increased the ACh-induced vasodilatation, and the enhancing effect of Tempol was decreased by catalase. Vascular H(2)O(2) production by fluorescent microscopy in mesenteric arterioles after RH was significantly increased in response to ACh in wild-type mice but markedly impaired in Cu,Zn-SOD(-/-) mice. Endothelial Cu,Zn-SOD plays an important role in the synthesis of endogenous H(2)O(2) that contributes to RH in mouse mesenteric smaller arterioles.
Yada
Toyotaka
T
Department of Medical Engineering and Systems Cardiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192 Japan. yada@me.kawasaki-m.ac.jp
Shimokawa
Hiroaki
H
Morikawa
Keiko
K
Takaki
Aya
A
Shinozaki
Yoshiro
Y
Mori
Hidezo
H
Goto
Masami
M
Ogasawara
Yasuo
Y
Kajiya
Fumihiko
F
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000378:metabolism / Q000503:physiopathology; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D002374:Catalase / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006940:Hyperemia / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008643:Mesentery / Q000098:blood supply*; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010100:Oxygen / Q000097:blood; D013113:Spin Labels; D013152:Splanchnic Circulation / Q000187:drug effects; D013482:Superoxide Dismutase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000378:metabolism* / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D003497:Cyclic N-Oxides; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D013113:Spin Labels; D014665:Vasodilator Agents; D002245:Carbon Dioxide; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D002374:Catalase; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D000109:Acetylcholine; D010100:Oxygen; C001803:tempol; D007213:Indomethacin