骨骼肌条肌质网Ca^2＋释放功能的间接测量方法  

Indirect Evaluation of Sarcoplasmic Reticulum Ca^(2+) Release Function in Skeletal Muscle Strips

作　　者：圣娟娟[1] 李全[1] 余志斌[1] 

机构地区：[1]第四军医大学航空航天医学教育部重点实验室,第四军医大学航空航天生理教研室,陕西西安710032

出　　处：《航天医学与医学工程》2010年第1期10-14,共5页Space Medicine & Medical Engineering

基　　金：国家自然科学基金资助课题(30770805)

摘　　要：目的本实验拟建立测量骨骼肌肌质网(SR)钙离子释放功能的简便方法。方法分析大鼠离体比目鱼肌肌条间断强直收缩张力峰值到75%恢复的时间(TR75),TR75呈先延长然后缓慢缩短。以延长至最大时的TR75除以第一次强直收缩的TR75,获得TR75延长比值(R-TR75)。结果增加刺激电压或用5mmoL/L Caffeine灌流(增加SR Ca2+释放通道开放几率)比目鱼肌肌条,R-TR75从对照组的2.5倍均增加到3.0倍。相反,5 mmol/L硫酸镁灌流抑制SR Ca2+释放通道,使R-TR75明显减小。间隔60 min的2次间断强直疲劳收缩,其R-TR75间无明显差别,但间隔5或10 min,再次进行间断强直疲劳收缩期间的R-TR75呈显著减小。萎缩比目鱼肌间断强直疲劳收缩期间,R-TR75增加2.9倍,明显高于对照组。结论比目鱼肌肌条间断强直疲劳收缩期间,在肌质网Ca2+-ATP酶活性没有改变的条件下,TR75延长比值可间接反映SR钙释放功能。另外,去负荷2周萎缩比目鱼肌的R-TR75增加提示其SR钙释放功能可能增强。Objective To set up a simple method to measure the SR Ca^2＋ release function in skeletal muscle strips. Methods The time from peak tension to 75 % relaxatidn （TRTi） during intermittent tetanic contraction （fatigue contraction ） of isolated museulus soleus strips was analyzed. It was prolonged rapidly, and then shortened slowly. The ratio of maximal TR75 to initial TR7s （R-TR75） indicated a balance between SR Ca^2＋ release and uptake. If the SR Ca^2＋-ATPase （SERCA） activity and inhibition extent of SERCA in fatigue contraction were identical, R-TR75 should be an index for SR Ca^2＋ release functionl Results Higher stimulation voltage or 5 mmoL/L caffeine perfusion which increased the SR Ca^2＋ release channel open probability induced an increase of R-TR75 from 2.5 in control to 3.0. On the contrary, inhibition of SR Ca^2＋ release with 5 mmoL/ L magnesium sulfate perfusion significantly decreased R-TR75. Inhibition of SR Ca^2＋ release by metabolites during fatigue contraction was recovered slowly. So R-TR75 at the second fatigued contraction was reduced after 5 or 10 min of recovery, but no significant difference after 60 min of recovery. During intermittent tetanic contraction R-TR75 was increased to be 2.9 times of normal in unloaded soleus. Conclusion The above results suggest that R-TR75 during muscle strip fatigue contraction without any change of SERCA activity can indirectly reflected SR Ca^2＋ release function. In 2-week unloaded soleus, the enhanced R-TR75 indicates an increase in SR Ca^2＋ release function.

关 键 词：失重模拟 尾吊 肌质网 钙释放 TR75 

分 类 号：R852.22[医药卫生—航空、航天与航海医学] R337.2[医药卫生—临床医学]