S-nitroso-N-acetylpenicillamine and nitroprusside induce apoptosis in a neuronal cell line by the production of different reactive molecules

CHP212 neuroblastoma cells were exposed to two different nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine and sodium nitroprusside. Apoptosis and necrosis were determined with flow cytometric analysis of annexin V bi nding and propodium iodide uptake. Both S-nitroso-N-acetylpenicillamine and sodium nitroprusside induced apoptosis, but with a different time dependen cy. Oxyhemoglobin (NO scavenger) attenuated the toxicity of S-nitroso-N-ace tylpenicillamine, but had no effect on the toxicity of sodium nitroprusside . By contrast, deferoxamine (iron chelator) attenuated the toxicity of sodi um nitroprusside, but had no effect on the toxicity of S-nitroso-N-acetylpe nicillamine. Urate (ONOO- scavenger) did not influence the toxicity of eith er S-nitroso-N-acetylpenicillamine or sodium nitroprusside, but protected f rom SIN-1 (3-morpholinosydnonimine, ONOO- donor). It was shown that both di thiothreitol and ascorbic acid affected the toxicity of S-nitroso-N-acetylp enicillamine and sodium nitroprusside in opposite ways. In the presence of dithiothreitol, superoxide dismutase and catalase decreased the toxicity of sodium nitroprusside. In the presence of cells, but not in their absence, S-nitroso-N-acetylpenicillamine decomposed with a half-life of about 4 h as assessed by the production of nitrite and absorbance reduction at 335 nm. Sodium nitroprusside decomposed Very slowly in the presence of cells as ass essed by the production of ferrocyanide. It can be concluded that (1) slow and sustained release of NO from S-nitroso-N-acetylpenicillamine at the cel l surface causes apoptosis in CHP212 cells, probably without the involvemen t of ONOO-, (2) sodium nitroprusside causes apoptosis by the production of H2O2 and/or iron, rather than NO, and probably has to be taken up by the ce ll for decomposition. (C) 2000 Elsevier Science B.V. All rights reserved.