Energy metabolism during reperfusion following ischemia.

Insulin treatment of hearts during aerobic reperfusion following transient ischemia in the working rat heart preparation significantly improved the recovery of myocardial function. This improvement was reflected both by a shorter time required for the heart to resume beating, and to increase heart rate and peak systolic pressure after resumption of beating. The beneficial effects of insulin may be related to improved energy metabolism secondary to small increases in pyruvate production during the early phase of reperfusion. It was also associated with an increased rate of restoration of cellular K+. Pyruvate addition to the perfusate also improved resumption of spontaneous beating of the heart and restoration of normal rate and pressure development. This effect of pyruvate was also associated with increased cellular levels of K+. Both insulin and pyruvate may improve ATP production during the first few minutes of reperfusion when glycolysis and oxidation of fatty acids are inhibited, but ATP levels were not increased after 30 min of reperfusion.