GSNO induction and HEL TUNEL assay.

(A) HEL cells treated with cytokines to stimulate the expression of iNOS and TUNEL-positive cells (YOYO-1 DNA stain; 40× magnification). (B) HEL cells treated with cytokines to stimulate expression of iNOS and incubated with 100 μmol/L L-NMMA showing decreased TUNEL-positive cell staining (YOYO-1 DNA stain; 40× magnification). (C) Percentage of apoptotic cells that were visible by TUNEL assay. 5 to 10 random fields were examined to calculate the percentages in each case, and each bar in the plot represents the average of 3 experiments (*P < .05).