CAJ | 학술논문

目的：探讨肝硬化大鼠膈肌损伤及其发生机制。方法成年雄性Sprague-Dawley大鼠30只，随机分成对照组（CON组，n=10）和肝硬化组（LC组，n=20）。对照组给予正常饲料和自来水；肝硬化组采用CCl4复合因素建立肝硬化大鼠模型。第9周，测定两组大鼠体重和膈肌重/体重比；体外灌流大鼠膈肌条，测定其单收缩力(Pt)、最大强直力(Po)、峰值收缩时间(CT)、半舒张时间(1/2RT)和张力-频率曲线的变化，同时测定膈肌组织超氧化物歧化酶（SOD)和琥珀酸脱氢酶(SDH)的活性及丙二醛(MDA)和髓过氧化物酶(MPO)的含量；电镜观察膈肌超微结构的变化；RT-PCR检测膈肌组织中肌浆网钙泵（SERCA）及骨架蛋白titin， nebulin的基因表达。结果(1)与CON组相比，LC组大鼠体重和膈肌/体重比明显降低（P<0.01）；Pt和Po明显降低（P<0.01），CT和1/2RT明显延长（P<0.01）；在10、20、40、60、100 Hz刺激下，膈肌条张力明显降低（P<0.01）；(2)与CON组比较，LC组大鼠膈肌组织的SOD、SDH的活性明显降低（P<0.01），MDA、MPO的含量明显增高（P<0.01）；(3)与CON组比较，LC组的titin、nebulin和SERCA mRNA表达均明显降低（P<0.01）；(4)电镜显示LC组大鼠膈肌肌丝紊乱、断裂，Z线模糊或消失；线粒体数量减少，水肿。结论肝硬化引起大鼠膈肌自由基生成增多，炎症反应和脂质过氧化增强，损伤膈肌线粒体，骨架蛋白titin，nebulin和SERCA表达降低，导致膈肌功能障碍。
목적：탐토간경화대서격기손상급기발생궤제。방법성년웅성Sprague-Dawley대서30지，수궤분성대조조（CON조，n=10）화간경화조（LC조，n=20）。대조조급여정상사료화자래수；간경화조채용CCl4복합인소건립간경화대서모형。제9주，측정량조대서체중화격기중/체중비；체외관류대서격기조，측정기단수축력(Pt)、최대강직력(Po)、봉치수축시간(CT)、반서장시간(1/2RT)화장력-빈솔곡선적변화，동시측정격기조직초양화물기화매（SOD)화호박산탈경매(SDH)적활성급병이철(MDA)화수과양화물매(MPO)적함량；전경관찰격기초미결구적변화；RT-PCR검측격기조직중기장망개빙（SERCA）급골가단백titin， nebulin적기인표체。결과(1)여CON조상비，LC조대서체중화격기/체중비명현강저（P<0.01）；Pt화Po명현강저（P<0.01），CT화1/2RT명현연장（P<0.01）；재10、20、40、60、100 Hz자격하，격기조장력명현강저（P<0.01）；(2)여CON조비교，LC조대서격기조직적SOD、SDH적활성명현강저（P<0.01），MDA、MPO적함량명현증고（P<0.01）；(3)여CON조비교，LC조적titin、nebulin화SERCA mRNA표체균명현강저（P<0.01）；(4)전경현시LC조대서격기기사문란、단렬，Z선모호혹소실；선립체수량감소，수종。결론간경화인기대서격기자유기생성증다，염증반응화지질과양화증강，손상격기선립체，골가단백titin，nebulin화SERCA표체강저，도치격기공능장애。
Objective To investigate the molecular mechanisms of diaphragm injury in rats with liver cirrhosis. Methods Thirty adult male Sprague-Dawley rats were randomized into control group (n=10) and carbon tetrachloride-induced liver cirrhosis group (LC group, n=20). In the 9th week, the rat body weight and diaphragm to body weight ratio were measured, and the parameters of diaphragm contractility including peak twitch tension (Pt), maximum tetanic tension (Po), time to peak contraction (CT), half relaxation time (1/2RT), and force-frequency curve were assessed using a Medlab-U/4C biological signal collecting system. The activities of superoxide dismutase (SOD), succinic dehydrogenase (SDH) and myeloperoxidase (MPO) and malondiadehyde (MDA) content in the diaphragm were detected. The mRNA expression levels of sarcoplasmic reticulum calcium ATPase (SERCA) and cytoskeletal proteins (titin and nebulin) in the diaphragm were detected by RT-PCR, and the diaphragm ultrastructure was examined with electron microscopy. Results Compared with those in the control group, body weight, diaphragm to body weight ratio, Pt, Po, and tetanic force under the stimulus frequency of 10, 20, 40, 60, 100 Hz were all significantly decreased (P<0.01), while CT and 1/2RT were significantly prolonged in LC group (P<0.01). SOD and SDH activities were significantly lowered (P<0.01) while the contents of MDA and MPO activity were significantly increased in LC group (P<0.01) with significantly decreased SERCA, titin and nebulin mRNA expressions in the diaphragm (P<0.01). Electron microscopy of the diaphragm in LC group revealed myofibrillar degeneration, absence of the Z line, and mitochondria swelling and edema. Conclusions Liver cirrhosis increases free radicals and aggravates inflammatory response and lipid peroxidation in the diaphragm, thus leading to mitochondrial damages and decreased expressions of cytoskeletal proteins and SERCA to cause diaphragmatic dysfunction.