RESUMO
Objective To evaluate the effect of high-level spinal cord injury(SCI)on the expression of mitochondrial voltage-dependent anion channel 2(VDAC2)in rat cardiomyocytes.Methods Forty-eight pathogen-free healthy adult male Sprague-Dawley rats,weighing 200-250 g,were divided into 2 groups(n=24 each)using a random number table:sham operation group(group S)and high-level SCI group(group H).The animals were anesthetized with intraperitoneal chloral hydrate and subjected to SCI using the modified Allen weight-drop method in group H.The spinal cord was only exposed in group S.At 6,12,24 and 48 h after SCI(T1-4),6 rats in each group were randomly selected and sacrificed,and myocardial specimens were collected from the cardiac apex for microscopic examination of the cell morphology(with a transmission electron microscope) and for determination of cell apoptosis(by TUNEL assay),expression of Bax,Bcl-2 and VDAC2 protein and mRNA in cardiomyocytes(by Western blot and real-time polymerase chain reaction,respectively).The apoptosis rate and ratios of Bax/Bcl-2 protein and mRNA were calculated.Results Compared with group S,the apoptosis rate and ratios of Bax/Bcl-2 protein and mRNA were significantly increased at T1-4,the expression of VDAC2 protein and mRNA was significantly down-regulated at T2-4(P<0.05 or 0.01),and the pathologic changes of cardiomyocytes were aggravated in group H.Conclusion The mechanism of myocardial damage is related to down-regulation of mitochondrial VDAC2 expression in cardiomyocytes and promotion of cell apoptosis in rats with high-level SCI.
