4周悬吊大鼠比目鱼肌强直收缩力降低及其机理分析  

Decrease in Tetanic Tension in 4-week Tail-suspended Rat Soleus and Analysis of Its Underlying Mechanisms.

作　　者：高放[1] 余志斌[1] 程九华[1] 冯汉忠[1] 张立藩[1] 

机构地区：[1]第四军医大学航空航天生理学教研室,陕西西安710032

出　　处：《航天医学与医学工程》2002年第4期255-259,共5页Space Medicine & Medical Engineering

基　　金：高等学校骨干教师资助计划项目部分资助 ;军队卫生科研基金重点项目 (98Z0 83 )部分资助

摘　　要：目的观测尾部悬吊 4周大鼠比目鱼肌 (SOL)强直收缩力降低的动态特征 ,并探讨其可能机理。方法采用离体SOL与趾长伸肌 (EDL)灌流方法 ,测量其单次与强直收缩张力。结果尾部悬吊模拟失重 4周 ,大鼠SOL明显萎缩 ,但EDL重量保持不变。悬吊大鼠SOL单次收缩的最大张力明显降低 ,且具有明显的刺激电压依赖性 ;达到张力峰值与舒张的时间明显缩短。EDL单次收缩的最大张力虽然显著降低 ,但未见明显的刺激电压依赖性 ,时间参数亦未发生改变。悬吊大鼠SOL强直收缩的最大张力显著降低 ,且发生迅速的衰退 ,在强直收缩的第 33秒时 ,其强直收缩的张力已降低了 73%。悬吊大鼠SOL强直收缩张力的动态曲线与EDL的相似。EDL的强直收缩最大张力也显著降低 ,但衰减速率未改变。结论悬吊 4周大鼠SOL强直收缩最大张力降低且易衰退 ,前者可能与单位面积内收缩装置减少以及每一横桥产力减少相关 ;后者则可能是由于收缩与调节蛋白异构体发生转化 。Objective To observe the dynamic changes in tetanic tension in 4 week tail suspended rat soleus (SOL) and extensor digitorum longus muscle (EDL)and to elucidate its underlying mechanisms. Method After 4 weeks of tail suspension SOL and EDL of the rats were isolated and perfused. Their isometric twitch and tetanic tensions were recorded. Result Atrophy occurred in the SOL, but not in the EDL. The maximum twitch tension(P t) decreased significantly and was more dependent on stimulation voltage in SOL of tail suspended rat.Time to maximum twitch tension(TPT) and time from maximum twitch tension to half relaxation(TR 50 ) were reduced in the SOL. P t also decreased in the EDL, but TPT and TR 50 did not change in the EDL. The maximum tetanic tension reduced in SOL and EDL of tail suspended rats. The decline rate of tetanic tension in SOL was faster than the control. The profile of tetanic contraction curve in atrophic SOL approached that in EDL. Conclusion The above results suggested that the underlying mechanisms of reduced maximum twitch and tetanic tension in 4 week tail suspended rat SOL may involve the reduction in number of cross bridge per cross section area or force produced per cross bridge. The rapid declinie rate in atrophic SOL may be related to the shift in myosin heavy chain and troponin I isoforms or to decrease in excitability.

关 键 词：悬吊 大鼠 比目鱼肌 强直收缩力 失重模拟 肌功能 单次收缩张力 

分 类 号：R852.22[医药卫生—航空、航天与航海医学]