Effect of streptozotocin and ALDH2 on myocardial apoptosis and mitochondrial membrane potential using TUNEL staining and JC-1 fluorescence. TUNEL-positive nuclei were visualized with fluorescein (green) in panels (A) FVB, (C) FVB-STZ, (E) ALDH2 and (G) ALDH2-STZ. All nuclei were stained with 4'-6-diamidino-2-phenylindole (blue) in panels (B) FVB, (D) FVB-STZ, (F) ALDH2 and (H) ALDH2-STZ. Original magnification × 400. (I) Quantified data. (J) Quantitative analysis of cardiomyocyte mitochondrial membrane potential using JC-1 ratio in FVB and ALDH2 mice treated with or without STZ (10 μM carbonyl cyanide m-chlorophenylhydrazone was used as a positive control). (K) Representative JC-1 fluorochrome images depicting mitochondrial membrane potential in cardiomyocytes. Mean ± SEM, n = 12 and 7 fields from three mice per group for panel I and J, respectively. *P < 0.05 versus FVB group; #
P < 0.05 versus FVB-STZ group.