Peroxynitrite anion stimulates arginine release from cultured rat astrocytes

The biosynthesis of the physiological messenger nitric oxide ((NO)-N-.) in neuronal cells is thought to depend on a glial-derived supply of the (NO)-N -. synthase substrate arginine. To expand our knowledge of the mechanism re sponsible for this glial-neuronal interaction, we studied the possible role s of peroxynitrite anion (ONOO-), superoxide anion (O2(.-)), (NO)-N-., and H2O2 in L-[H-3]arginine release in cultured rat astrocytes. After 5 min of incubation at 37 degrees C, initial concentrations of 0.05-2 mM ONOO- stimu lated the release of arginine from astrocytes in a concentration-dependent way; this effect was maximum from 1 mM ONOO- and proved to be similar to 40 0% as compared with control cells. ONOO--mediated arginine release was prev ented by arginine transport inhibitors, such as L-lysine and N-G-monomethyl -L-arginine, suggesting an involvement of the arginine transporter in the e ffect of ONOO-. In situ xanthine/xanthine oxidase-generated O-2(.-) (20 nmo l/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 inhibi tors. (NO)-N-. donors, such as sodium nitroprusside, S-nitroso-N-acetylpeni cillamine, 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)-N-. synthase activity may be neuro toxic due to ONOO- formation, our results suggest that ONOO--mediated argin ine release from astrocytes may contribute to replenishing neuronal arginin e, hence avoiding further generation of ONOO- within these cells.