Blue Native gel WT (n=4), OGT TG (n=4), OGT x OGA TG (n=4) stained for a. complex I activity, and b. Coomassie stain for total mitochondrial protein expression from heart (1 heart/lane), and c. Complex I activity spectrophotometer assay summary data. d. Measurement of isolated mitochondria OCR after sequential addition of ADP, oligomycin, FCCP and rotenone/ antimycin A in the presence of substrates pyruvate, glutamate, and malate from all genotypes (WT, OGT TG, OGA TG n = 6, OGT x OGA TG n = 5). e. OCR measurement before ADP addition (the first time point in 6d) f. OCR measurement after ADP addition (the third time point in 6d). Data are represented as mean ± SEM, significance was determined using a 1 way ANOVA with Tukey’s multiple comparisons test. (**P<0.01, *P<0.05, ns=not significant).