心肌钙敏感受体在高位脊髓损伤大鼠心肌损伤中的作用

目的 探讨心肌钙敏感受体(CasR)在高位脊髓损伤大鼠心肌损伤中的作用.方法 健康雄性SD大鼠18只,体重250 ～ 300 g,采用随机数字表法,将大鼠随机分为2组:假手术组(S组,n＝6)和高位脊髓损伤组(SCI组,n＝12).采用砝码(10 g)从5 cm高处沿中空玻璃管垂直自由落下撞击C7脊髓的方法制备高位脊髓损伤模型.SCI组于高位脊髓损伤后12和24h(T1,2)时,S组于T1时取血样,测定血清肌酸激酶(CK)和CK-MB活性,取心肌组织,在透射电镜下观察心肌超微结构,分别采用荧光定量PCR法和Western blot法检测心肌CaSR mRNA及其蛋白的表达水平.结果 与S组比较,SCI组血清CK和CK-MB活性升高,心肌CaSR mRNA及其蛋白表达上调(P<0.05)；与T1时比较,SCI组T2时血清CK活性升高,CK-MB活性降低,心肌CaSR mRNA表达上调(P<0.05),CaSR蛋白表达差异则无统计学意义(P＞0.05).SCI组T1,2时心肌超微结构呈现不同程度的损伤改变.结论 大鼠高位脊髓损伤后心肌CaSR表达上调,该变化可能是高位脊髓损伤后心肌损伤的机制之一.

Role of myocardial calcium-sensing receptor in a rats model of high-level spinal cord injury

Objective To investigate the role of myocardial calcium-sensing receptor (CaSR) in a rat model of high-level spinal cord injury (SCI).Methods Eighteen healthy male SD rats weighing 250-300 g were randomly divided into 2 groups:sham operation group(group S,n ＝6) and SCI group(n ＝ 12).SCI model was induced by dropping a 10 g weight onto spinal cord (C7) in freely vertical falling along the hollow glass tube from 5 cm height.The blood samples were taken 12 and 24 h after SCI in group SCI and 12 h after SCI in group S,and serum activity of creatine kinase(CK) and MB isoenzyme of creatine kinsse(CK-MB) were measured.Then myocardium specimens were obtained for uhrastructure examination and determination of CaSR mRNA and protien expression by fluorescence quantitative RCR and Western blot.Results Serum activities of CK and CK-MB and CaSR mRNA and protein expression were higher in group SCI than in group S.Serum activity of CK and CaSR mRNA expression were higher,and serum activity of CK-MB was lower at 24 h after SCI than that at 12 h after SCI.There was no significantly difference in CaSR protein expression between the two time points in group SCI.The ultrastructure examination showed that myocardial injury was found in group SCI.Conclusion The expression of CaSR is up-regulated after SCI in rats,which might be the mechanism of myocardial injury after SCI.