| It has long been demonstrated both in clinical observations and experimental researches that hemorheologic changes are one of the most important reactions to myocardial ischemia. Abnormal hemorheologic changes have been found in acute myocardial infarction (AMI). In recent years, many large-scale clinical trials and studies have demonstrated that high dose glucose-insulin-potassium (GIK) plus myocardium reperfusion can significantly decrease the mortality in AMI. Though elevated blood glucose level was reported in acute period in AMI patients, there has been no report on the effects of intravenous infusion of GIK on the changes of hemorheologic parameters and the glucose level.This study was aimed to investigating the effects of high dose GIK and GK without insulin on the changes of hemorheologic paramters andblood glucose level in myocardial ischemia/reperfusion dogs and to study the role of the insulin in G IK. We studied the myocardial ultrastructure in the injured areas of the myocardial ischemia/ reperfusion myocardium in dogs. 1 Methods1.1 Animal model Twenty four dogs were anaesthetized with sodium pentobarbital (30mg/kg) via saphenous veins. The myocardial ischemia was induced by partial occlusion (80% reduction in its blood flow ) of the left anterior descending coronary artery (LAD) for 50 min, followed by 4 h reperfusion. The dogs were then randomly divided into 3 groups: saline (0.9% NaCl, n=8), GIK (glucose: 50 g/L, insulin: 60 U/L, potassium: 80 mmol/L, n=8) and GK (glucose:250 g/L, potassium: 80 mmol/L, n=8). Blood was obtained via coronary arteriovenous sinus. The hemorheological parameters and blood glucose levels were measured 50 min before and after myocardial ischemia and 1 h, 2 h and 4 h following reperfusion.1.1.1 The changes of hematoxrit (HCT), blood viscosity at high shear rate( η bh), blood viscosity at low shear rate ( η bl), erythrocyte aggregation index (EA1) and blood glucose were observed after ischemia/reperfusion.1.1.2 The changes of the hemorheologic parameters in systemic circulation and those of the coronary veins were compared before and after ischemia/reperfusion.1.1.3 The myocardial ultrastructural changes were observed by Transmission electron microscopy.2 Results2.1 Compared with saline control, there were no significant changes of hemorheological parameters in GIK group, while HCT at 2 h and 4 h after reperfusion increased in GK group.2.2 After acute myocardial ischemia, the blood glucose levelsignificantly decreased in all groups. Following reperfusion, blood glucose level did not change significantly in GIK group compared with that in saline control but the blood glucose level increased significantly at 2 h and 4 h after reperfusion in GK group.2.3 Following occlusion, significant changes in hemorheologic parameters were observed, with HCT, n bh and 1 bl significantly elevating in both coronary arteriovenous sinus and systemic circulation. Erythrocyte deformability index (EDI) exhibited significant decrease and H bh and blood viscosity significant elevated in n. bh in coronary arteriovenous sinus compared with that in systemic circulation.2.4 GIK had no significant effects on the ultrastructure of unischemic myocardium, while GK had significant effects on the ultrastructure of unischemic myocardium.3 Conclusion3.1 The high-dose of GIK used in this study has no significant effects on both the blood glucose level and hemoreological parameters in MI/R dogs. The data of this study also indicate that the infusion of large-dose of glucose may be harmful to MI patients.3.2 After coronary occlusion, the increase of the blood viscosity indicates a very important change in hemoreological parameters in...
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