Four important features distinguished hearts that were perfused in the presence of octanoate from hearts that were perfused with oleate alone: (1) decreased rates of glucose oxidation, especially in the first minutes of reperfusion; (2) slower mitochondrial rates of ADP-stimulated respiration; (3) increased time to recovery of aortic pressure post-ischemia, and (4) mitigation of mitochondrial ROS generation during reperfusion in UCP3-deficient hearts. Here, UCP3 is linked to ischemia.