Peroxynitrite anion stimulates arginine release from cultured rat astrocytes.
The biosynthesis of the physiological messenger nitric oxide (*NO) in neuronal cells is thought to depend on a glial-derived supply of the *NO synthase substrate arginine. To expand our knowledge of the mechanism responsible for this glial-neuronal interaction, we studied the possible roles of peroxynitrite anion (ONOO-), superoxide anion (O2*-), *NO, and H2O2 in L-[3H]arginine release in cultured rat astrocytes. After 5 min of incubation at 37 degrees C, initial concentrations of 0.05-2 mM ONOO- stimulated the release of arginine from astrocytes in a concentration-dependent way; this effect was maximum from 1 mM ONOO- and proved to be approximately 400% as compared with control cells. ONOO(-)-mediated arginine release was prevented by arginine transport inhibitors, such as L-lysine and N(G)-monomethyl-L-arginine, suggesting an involvement of the arginine transporter in the effect of ONOO-. In situ xanthine/xanthine oxidase-generated O2*- (20 nmol/min) stimulated arginine release to a similar extent to that found with 0.1 mM ONOO-, but this effect was not prevented by arginine transport inhibitors. *NO donors, such as sodium nitroprusside, S-nitroso-N-acetylpenicillamine, or 1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium+ ++-1,2-diolate, and H2O2 did not significantly modify arginine release. As limited arginine availability for neuronal *NO synthase activity may be neurotoxic due to ONOO- formation, our results suggest that ONOO(-)-mediated arginine release from astrocytes may contribute to replenishing neuronal arginine, hence avoiding further generation of ONOO- within these cells.
Vega-Agapito
V
V
Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Spain.
Almeida
A
A
Heales
S J
SJ
Medina
J M
JM
Bolaños
J P
JP
D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000378:metabolism*; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002956:Citrulline / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008239:Lysine / Q000494:pharmacology; D009566:Nitrates / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000378:metabolism
D009566:Nitrates; D020030:Nitric Oxide Donors; D016877:Oxidants; C039642:peroxynitric acid; D002956:Citrulline; D018698:Glutamic Acid; D012694:Serine; D001120:Arginine; D006861:Hydrogen Peroxide; D008239:Lysine