Animal Experiment Of Discrimination Between Injury Of Myocardium And Of Skeletal Muscle

BACKGROUND:Physical sports including physical exercise and military training not only cause the injury of the heart due to the increased demand of blood and oxygen but also induce skeletal muscle damage because of the more movement of the muscle. At present, most of the cardiac makers such as creatine kinase and myoglobin are lack of organ specificity because they exist both in myocardium and skeletal muscle. On the other hand, some biochemical markers for instance troponin, creatine kinase MB isoenzyme and so on, which is specific for injury of myocardium, rise only after the heart having micro-infarct, so they can not indicate the injury of myocardium earlier before heart having micro-infarct. Therefore it is the key to seek a indicator which is specific for myocardium and can also identify the injury of skeletal muscle in early phage for diagnose of myocardial damage at advance.OBJECTIVE:the aim of this study is to seek an indicator to discriminate the injury of myocardium from of skeletal muscle by observing the change of CK,CK-MB,Myo,H-FABP in serum and by calculating the ratio of myoglobin and H-FABP after the injury of myocardium and skeletal muscle.METHODS:45 rabbits were randomly divided into three groups:myocardium injured group, skeletal muscle injured group and sham-operate control group. Animal model were produced by ligating left ventricle branch of left coronary artery in myocardium injured group and by ligating the femoral arteries of the two hindlimbs in skeletal muscle injured group. The sham operated control group rabbits underwent the same protocol but the coronary artery and the femoral arteries were not ligated. The concentrations of Myo and H-FABP and the activity of CK and CK-MB enzyme in the serum pre-ligation and 2h,4h,6h,8h, 10h,12h post-ligation were measured and the ratio of Myo/H-FABP were calculated.RESULTES:In the myocardium injured group, the concentrations of Myo and H-FABP were increased at 2h when the differences were not significant and reached the peak at 4h after the ligation (P＜0.05), the concentrations of H-FABP rose significantly at 2h,CK rose significantly at 4h and 6h (P＜0.05), the value of CK-MB was significantly higher at 4h-8h post-ligation than pre-ligation(P＜0.05).In the skeletal muscle injured group, the concentrations of Myo were increased at 2h after the ligation (P＜0.05 2-6h, P＜0.01 8-12h). The levels of H-FABP were increased at 4h post-ligation too (P＜0.05 only at 4,6h); the CK and CK-MB also rose significantly during 8h-12h (P＜0.01)and 4h-8h post-ligation respectively(P＜0.05).In the sham-operate group, the activity of CK,CK-MB rose a little after the protocol, but the increase was insignificant(P＞0.05), and the levels of Myo and H-FABP were unchanged(P＞0.05).The differences of the levels of CK, CK-MB, Myo and H-FABP between any two of three groups pre-ligation is insignificant(P＞0.05).There were significant differences in the levels of CK, CK-MB, Myo and H-FABP between the myocardium injured group and the sham-operate control group (P＜0.05) and So were there the differences between the skeletal muscle injured group and the sham-operate control group(P＜0.05).There was significant differences in the concentrations of Myo between the myocardium injured group and skeletal muscle injured group except at 4h(P＜0.05), but the differences of levels of CK. CK-MB and H-FABP between myocardium injured group and skeletal muscle injured group at most time were not significant (P＞0.05).By calculating the ratio of Myo/H-FABP, we find there were significant differences between the myocardium injured group and the sham-operate control group (P＜0.05), between the skeletal injured group and the shame-operate control group (P＜0.05) and between myocardium injured group and skeletal muscle injured group post-ligation(P＜0.01).CONCLUSION:Compared to sham-operated group, the concentration of CK,CK-MB,Myo,H-FABP was increased after the ischemia of the myocardium and the skeletal muscle, but they can not be used to discriminate the two kinds of ischemia injuries. It is an effective way to calculating the ratio of Myo and H-FABP for discriminating the injury of myocardium from the injury of skeletal muscle.