Oxygen consumption at E9.5.

<p><b>A.</b> Representative recording of oxygen consumption in cardiac tissue homogenates (approximately 12.5 µg protein in 0.3 ml respiration buffer). The red recording represents the experiment and the arrows indicate the addition of 2 mM succinate (Succ.), 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. <b>B.</b> Bar graph illustrating oxygen consumption at baseline (BL), after the addition of substrate (V_o Succ and V_o MG) and ADP (V_max). <b>C.</b> Respiratory control ratio, calculated as V_max/V_o. A–C: n = 9, for each experiment 7–8 hearts were pooled. <b>D.</b> Representative recording of the inhibition of oxygen consumption by potassium cyanide (KCN) added in 20 µM increments. <b>E.</b> Summary of KCN inhibition (n = 3, 9–10 hearts were pooled per experiment).