The role of oxygen and reduced oxygen species in nitric oxide-mediated cytotoxicity:: Studies in the yeast Saccharomyces cerevisiae model system

The cytotoxicity of nitric oxide (NO) is well established, yet the mechanism(s) of its cytotoxicity is (are) still undefined and a matter of significant interest and speculation. Many of the previously proposed mechanisms for NO-mediated cytotoxicity involve interactions between NO and molecular oxygen (O-2) and/or O-2-derived species such as O-2(-) and H2O2. The yeast Saccharomyces cerevisiae represents a useful model system for evaluating the role of O-2 and O-2-derived species in NO-mediated cytotoxicity. This study examines the contribution of O-2 and O-2-derived species to NO-mediated cytotoxicity in the yeast S. cerevisiae. NO-mediated cytotoxicity was determined to be O-2-dependent. However, this O-2 dependence was only minimally due to the generation of O-2-derived species such as O-2(-) and/or H2O2. (C) 2000 Academic Press.