Effect of high-level spinal cord injury on myocardial energy metabolism in rats

Objective To evaluate the effect of high-level spinal cord injury (SCI) on the myocardial energy metabolism in rats. Methods Sixty healthy male Sprague-Dawley rats, weighing 250-300 g, were randomly divided into 2 groups (n=30 each) using a random number table: sham operation (group S) and SCI group. SCI was induced in anesthetized rats by dropping a 10 g weight onto C7 spinal cord from 5 cm height falling freely inside a vertical hollow glass tube. At 6, 12, 24, 48 and 72 h after SCI, 6 rats in each group were chosen and arterial blood samples were taken for measurement of serum creatine kinase (CK) and creatine kinase isoenzyme-MB (CK-MB) activities. The rats were then sacrificed and myocardial specimens were obtained for examination of myocardial ultrastructure and for determination of ATP weight ratio, levels of Na+-K+-ATPase, Ca2+-Mg2+-ATPase, non-esterified fatty acids (NEFA) and lactic acid (LD), and expression of peroxisome proliferator-activated receptor alpha (PPARα) mRNA and protein (using fluorescent quantitative PCR and Western blot). Results Compared with group S, the serum CK and CK-MB activities were significantly increased, the ATP weight ratio, activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase and levels of NEFA and LD were decreased, and the expression of PPAR-α mRNA and protein was down-regulated in SCI group. No pathological changes of myocardium were found in group S, and the pathological changes of myocardium were obvious in SCI group. Conclusion High-level SCI can lead to decrease in the myocardial energy metabolism in rats, and down-regulated expression of PPARα is involved in the mechanism. Key words: Spinal cord injuries; Myocardium; Energy Metabolism; Peroxisome proliferators