Fig. 4. Inhibition of NO production by L-NAME protects yeast cells from H₂O₂, but not from mammalian Bax expression, or acetic acid-induced apoptosis. (A) Comparison of the survival rate of wild-type cells upon H₂O₂ treatment with or without pre-incubation with L-NAME in order to inhibit NO production. ^*P0.03 versus wild type; t-test, n=3. (B) Comparison of the survival of wild-type cells upon acetic acid-induced apoptosis with or without pre-incubation with L-NAME. (C) Comparison of the survival of yeast cells (strain BY.bax) upon Bax expression for 15 hours (apoptotic inducing conditions), with or without pre-incubation with L-NAME. (D) Epifluorescence and phase-contrast micrographs of untreated and H₂O₂-treated (1.5 mM) wild-type cells, with or without pre-incubation with L-NAME, stained with dihydrorhodamine 123 (DHR123) as an indicator of high intracellular ROS accumulation. Bars, 5 µm.