A and B. Tissue homogenate (TH, approximately 55 µg protein) and isolated mitochondria (Mito) from E13.5 embryos. Hearts of 31 embryos were used to isolate 30 µg of mitochondrial protein for this experiment. C and D. Tissue homogenate (TH, adult) and isolated mitochondria (Mito, adult). 100 µg protein were used per experiment. In all panels the red recordings represents the experiment and the arrows indicate the addition of 3 mM malate and 5 mM glutamate (MG), 1 mM ADP and 0.1 mM ATR. The yellow bars indicate the slopes used to calculate oxygen consumption. The black recording represents the tissue homogenate in the respiration medium, but no additions to stimulate oxygen consumption are made. The green recording represents the buffer only. E. Summary of V0, Vmax and the RCR of E13.5 and adult samples, where n is the number of experiments, BL baseline, MG malate/glutamate, RCR respiratory control ratio. BL, Vo and Vmax are calculated as nmol O2/min/mg.