Changes Of Lipid Metabolism And Its Mechanism During Myocardial Ischemia-reperfusion In Human Cardiopulmonary Bypass

Objective: To explore the changes of lipid metabolism and its mechanism during myocardial ischemia-reperfusion in human cardiopulmonary bypass.Methods: A total of 40 patients with congenital heart disease treated by extracorporeal circulation were collected.According to the aortic block time,it was divided into two groups.The aortic block time in group A was ?30 minutes(20patients),and that in group B was >30 minutes(20 patients).During the operation,specimens were collected: 1.Blood specimens: The arterial blood and coronary sinus venous blood were collected at T1(3 minutes)and T2(15 minutes),T3(45 minutes)and T4(75 minutes).The concentrations of plasma glucose,insulin,glucagon,growth hormone,TNF-?,and free fatty acids were measured by ELISA.2.Myocardial tissue specimens: 100 mg of myocardial specimens were collected T1(3 min)and T3(45min).The expression of FAT/CD36 was detected by RT-PCR and immunohistochemistry.Results: 1.Glucose concentration and myocardial glucose uptake in plasma of arterial and venous blood: During myocardial ischemia and reperfusion in cardiopulmonary bypass,glucose concentrations in both arterial and venous blood were elevated,which were observed in both groups.The blood glucose concentration at T2(15 minutes)was significantly higher than that before the blockade(P <0.01).Compared with group A,the time when the blood glucose concentration returned to normal was higher in group B,which was longer in the ascending aorta.The glucose intakes of T2(15 minutes),T3(45 minutes)and T4(75 minutes)in group A and B decreased compared with that in the T1(3 minutes)time point,and the difference was statistically significant(P <0.01).Myocardial glucose intake in group B was less than that of group A,and the difference was statistically significant(P <0.01).2 Changes in the concentrations of plasma insulin,glucagon,growth hormone and TNF-?: the concentrations of plasma insulin,glucagon,growth hormone and TNF-? increased significantly,and reached to the peak of at T2(15 minutes),and the differences were statistically significant(P <0.01)compared with that in the T1(3minutes).Compared with group A,the concentrations of plasma insulin,glucagon,growth hormone and TNF-? alerted more but recovered slower to normal in group B(P <0.05 or P <0.01).3.Insulin resistance index(IRI)changes: During myocardial ischemia and reperfusion in cardiopulmonary bypass,the insulin resistance index increased and reached a maximum at T2(15 min),compared with that at T1(3 min),and the difference was statistically significant(P <0.01).The insulin resistance index in group B costed more time to recover to normal compared with that of group A,and the difference was statistically significant(P <0.01).4.Changes in free fatty acids and myocardial fat intake in the plasma of the arteries and veins: The concentrations of free fatty acids in the blood of the venous and venous blood of the two groups peaked at T2(15 minutes).At the same time,the myocardial fatty acids uptake in the two groups also peaked at T2,but then decreased followingly.At T3 and T4,the fatty acid concentrations in the arterial and myocardial fat intake in group B were more than those in group A,and the differences were statistically significant(P <0.01).5.The expressions of FAT/CD36 m RNA and protein in cardiomyocytes: The expression of FAT/CD36 m RNA was higher at T3(45 min)than that at T1(3 min),with statistical difference(P <0.01).Compared with group A,the protein expression of FAT/CD36 in group B was higher at T3(45 min),and there was statistical difference(P <0.01).Conclusion: During myocardial ischemia reperfusion with myocardial insulin resistance in cardiopulmonary bypass,there is a significant lipid metabolism disorder,which may be related to the abnormal expression of fatty acid translocation enzyme FAT/CD36.