Interaction of ascorbic acid with the neurotoxic effects of nmda and sodium nitroprusside

We have previously shown that ascorbic acid (AA) protects cortical neurons in culture from the toxic effects of NMDA. In the present study, we examined the interactions of AA with toxicity produced by nitric oxide (NO) that is generated from the breakdown of sodium nitroprusside (SNP), and with NMDA toxicity measured 24 h later. AA enhanced SNP toxicity, but it reduced toxicity of NMDA. We propose that these data support a model wherein AA produces neuroprotection by an action at the NMDA receptor, and indirectly with respect to NO. This effect occurs probably by antagonizing Ca2+ influx starting the cascade of biochemical events that lead to the production of NO.