Glucose-insulin-potassium reduces infarct size when administered during reperfusion

Coronary reperfusion improves ventricular function and survival after infar ction, but the metabolic conditions at this time may not be optimal to prot ect the heart. The objective of this study was to evaluate if metabolic sup port with glucose-insulin-potassium (GIK) administered at the time of coron ary reperfusion could elicit the same cardioprotection as GIK infusion duri ng the entire ischemia/reperfusion period. Three groups of anesthetized, op en-chest rats were subjected to 30 minutes of regional ischemia and 180 min utes of reperfusion. Groups 1 (controls) and 2 (GIK(IR)) received saline or GIK, respectively, throughout the whole experimental period, whereas a thi rd group (GIK(R)) received GIK from the onset of reperfusion only. Infarct size was significantly reduced in the GIK-treated groups, compared with con trols (GIK(IR) 44 +/- 5% and GIK(R) 45 +/- 5% vs. control 66 +/- 4%; P < 0. 05). Postischemic recovery of cardiac function improved when GIK was only a dministered during the reperfusion phase. Furthermore, infusion of GIK resu lted in reduced plasma concentrations of free fatty acids and increased pla sma glucose (both P < 0.05) compared with controls. This study demonstrates that glucose-insulin-potassium administration at the onset of the postisch emic reperfusion period is as cardioprotective as administration of GIK dur ing the entire ischemia/reperfusion period.