['Glucose, insulin, and potassium solution improves left ventricular function in refractory pump failure. Direct effects of insulin on the heart cannot be determined in vivo. We hypothesized that insulin has a direct positive inotropic effect on the reperfused heart.', 'Isolated working rat hearts were perfused with buffer containing glucose (5 mmol/L) plus oleate (1.2 mmol/L). Hearts were subjected to 15 minutes of ischemia and reperfused with or without insulin (100 microU/mL) for 40 minutes. Epinephrine (1 micromol/L) was added for the last 20 minutes.', 'Hearts recovered 51.1% of preischemic cardiac power in the absence and 76.4% in the presence of insulin (p < 0.05). Whereas oleate oxidation remained unchanged, glucose uptake and oxidation increased during reperfusion with epinephrine (p < 0.01). This increase was significantly greater when hearts were reperfused in the presence of insulin (p < 0.01). Insulin also prevented an epinephrine-induced glycogen breakdown during reperfusion (p < 0.05).'] Does insulin improve functional and metabolic recovery of reperfused working rat heart?