Nampt overexpression attenuates HFD-induced oxidative stress. (A) Nampt overexpression attenuates HFD-induced GSH oxidation. The levels of GSH and GSSG and the GSH/GSSG ratio were examined in Tg-Nampt mice after 3 months of HFD consumption. (B-C) Nampt overexpression attenuates HFD-induced inhibition of Trx1 substrates. Heart lysates were prepared from NTg and Tg-Nampt mice after 3 months of HFD consumption. Western blot analyses were performed with indicated antibodies. (D) Nampt promotes palmitic acid (PA)-induced autophagy. After 2 days of adenovirus transduction of Nampt and GFP-LC3, cardiomyocytes were treated with 100 μM PA and 10 μM chloroquine for 4 hours. GFP-LC3 dots per cell were counted. (E) Nampt promotes PA-induced mitophagy in an NADK-dependent manner. After 3 days of adenovirus transduction of Nampt and Mito-Keima, NADK was knocked down with shNADK. After 3 days, the cardiomyocytes were treated with 100 μmol/L PA for 24 hours. Areas with high 561/457 nm ratios, indicating mitophagy, were measured. (F-G) The effect of Nampt overexpression upon myocardial contents of various lipid species in the presence or absence of HFD consumption. (F) The effect upon the total amount of indicated lipid species. (G) The effect upon several specific subspecies of dihydroceramide, ceramide and hexosylceramide. Statistical significance was determined with ANOVA (A (GSH and GSSG), and C-E) and the Kruskal-Wallis test (A (GSH/GSSG), F and G.