Figure 4.

Mitochondrial respiratory parameters and ATP synthesis rates are decreased by induction of GLUT4 following short-term hyperglycemia with minor changes in mitochondrial number and structure. Mitochondrial respiration in saponin-permeabilized cardiac fibers examining V₀, V_ADP, and V_Oligo oxygen utilization with glutamate/malate (GM) (A) (n = 7–9), pyruvate/malate (PM) (B) (n = 6–9), or palmitoylcarnitine/malate (PC) (C) (n = 4–6) as substrates (fiber weight [FW]). ATP synthesis rates (D–F) and ATP/O ratios (G–I) in comparably treated fibers from the same mice as in A–C. J: Representative electron micrographs of cardiac tissue; left, low magnification, and right, high magnification of different heart sections. K: Mitochondrial number per high-power field (hpf) (n = 3 hearts). L: Mitochondrial volume density as a percentage (n = 3 hearts). Quantitative data are means ± SEM. *P < 0.05 or **P < 0.01 vs. Con-Veh.