Details

Autor(en) / Beteiligte

• Xia, Yong
• Dawson, Valina L.
• Dawson, Ted M.
• Snyder, Solomon H.
• Zweier, Jay L.

Titel

Nitric Oxide Synthase Generates Superoxide and Nitric Oxide in Arginine-Depleted Cells Leading to Peroxynitrite-Mediated Cellular Injury

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1996-06, Vol.93 (13), p.6770-6774

Ort / Verlag

United States: National Academy of Sciences of the United States of America

Erscheinungsjahr

1996

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Besides synthesizing nitric oxide (NO), purified neuronal NO synthase (nNOS) can produce superoxide (·O2-) at lower L-Arg concentrations. By using electron paramagnetic resonance spin-trapping techniques, we monitored NO and ·O2- formation in nNOS-transfected human kidney 293 cells. In control transfected cells, the Ca2+ ionophore A23187 triggered NO generation but no ·O2- was seen. With cells in L-Arg-free medium, we observed ·O2- formation that increased as the cytosolic L-Arg levels decreased, while NO generation declined. ·O2- formation was virtually abolished by the specific NOS blocker, N-nitro-L-arginine methyl ester (L-NAME). Nitrotyrosine, a specific nitration product of peroxynitrite, accumulated in L-Arg-depleted cells but not in control cells. Activation by A23187 was cytotoxic to L-Arg-depleted, but not to control cells, with marked lactate dehydrogenase release. The cytotoxicity was largely prevented by either superoxide dismutase or L-NAME. Thus, with reduced L-Arg availability NOS elicits cytotoxicity by generating ·O2- and NO that interact to form the potent oxidant peroxynitrite. Regulating arginine levels may provide a therapeutic approach to disorders involving ·O2-/NO-mediated cellular injury.