The Effects Of GLUT4 Signal Channel In The Myocardial Energy Metabolism Following Early High-level Spinal Cord Injury In Rats

Objective To explore the expression in insignaling molecular expression of myocardial GLUT4 signal channel in myocardial injury induced by high-level spinal cord injury(SCI),clarifying whether myocardial injury after SCI is related to the changes of myocardial energy metabolism.Methods 36 healthy male Sprague-Dawley rats,weighing 250-300 g,were randomly divi-ded into five groups: the control check group(CK group),the sham operation control group(Sham group),4 h after high spinal cord injury group(SCI1 group),12 h after high spinal cord injury group(SCI2 group),24 h after high spinal cord injury group(SCI3 group)and 48 h after high spinal cord injury group(SCI4 group).The rats in the group of SCI were treated by a modified Allen's combat method.The post-operative features were investigated and recorded and the myocardium tissue was taken at each time point for the further test.Transmission electron microscopy is used to assess ultrastructure in the myocardium.Western Blot is used to assess the level of tyrosine phosphorylation in insulin receptor substrate-1(IRS-1)and the content of GLUT4 on cardiac myocyte membrane.Also,realtime fluorescence quantitative PCR is used to assess the ex-pression quantity of GLUT4 m RNA.Results(1)The shock point of spinal cord turned grey immediately after the modified Allen's combat.And the rats showed a detection of activity amount,flaccid paralysis of the lower.Extremities and inability to urinate and defecate autonomously postoperation.(2)Transmission electron microscopy showed that myocardial cells exhibited normally in Sham group,similar to CK group,whlie the changes in myocardial ultrastructure were apparent in SCI group,including damaged meshy scaffold structure outside cytomembrance,lysosome accumulation inside cytomem-brance,the appearance of cell vacuolar structure and the shift of mitochondria.(3)The results of Western blot showed that there are no significant differences in the level oftyrosine phosphorylation in IRS-1 between Sham,SCI1,SCI4 and CK group(P>0.05),and it appeared decline at SCI 12 h and 24h(P<0.05)?The content of GLUT4 on cardiac myocyte membrane at each time point after SCI were lower than those of the Sham group and CK group(P<0.05),which is prominent in SCI2(P<0.01).(4)The results of PCR showed the GLUT4 m RNA expression quantity in Sham and CK group is similar,and were significantly lower than those of Sham and CK group in SCI group rats(P<0.05).(5)The trend in rate of decline between the GLUT4 cytomembrance content and the GLUT4 m RNA expression quantity is the same,but the later is larger than the former,it appeared decline at SCI 12 h and 24h(P<0.05).Conclusion After high-level spinal cord injury,the changes in myocardial ultrastructure were apparent,the level of tyrosine phosphorylation was decreased,the GLUT4 m RNA expression quantity was reduced and the ability of GLUT4 transposition is abnormal,which indicated that high-level SCI hinder GLUT4 signal channel,lead to insulin resistance and disturb glucose metabolism in heart.