Effects of arginase isoforms on NO Production by nNOS.
Both arginase isoforms (AI and AII) regulate high-level NO production by the inducible NOS, but whether the arginase isoforms also regulate low-level NO production by neuronal NOS (nNOS) is not known. In this study, 293 cells that stably overexpress nNOS gene (293nNOS cells) were transfected with rat AI (pEGFP-AI) or AII (pcDNA-AII) plasmids, and nitrite production was measured with or without supplemental L-arginine. Transfection with pEGFP-AI increased AI expression and activity 10-fold and decreased intracellular l-arginine by 50%. Nitrite production was inhibited by >80% when no l-arginine was supplemented but not when 1 mM L-arginine was present. The inhibition was reversed by an arginase inhibitor, N(omega)-hydroxy-L-arginine. Transfection with pcDNA-AII increased AII expression and activity but had little effect on nitrite production even if no l-arginine was added. These results suggest that, in 293nNOS cells, AI was more effective in regulating NO production by nNOS, most likely by competing for L-arginine.
Que
Loretta G
LG
Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
George
Samuel E
SE
Gotoh
Tomomi
T
Mori
Masataka
M
Huang
Yuh-Chin T
YC
D000818:Animals; D001119:Arginase / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D051381:Rats; D014162:Transfection
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009569:Nitric Oxide; C068309:N(omega)-hydroxyarginine; D001120:Arginine; C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; C113162:Arg2 protein, rat; D001119:Arginase