论文部分内容阅读
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 ,以及肌肉电兴奋性改变所导致
OBJECTIVE: To observe the dynamic characteristics of tetanus (SOL) tonic contractility after tail suspension for 4 weeks and to explore its possible mechanism. Methods In vitro and long extensor digitorum longus (EDL) perfusion method was used to measure the single and tetanic contractile tension. Results The tail suspension simulation simulated weight loss for 4 weeks, with a significant atrophy of the rat SOL, but the EDL weight remained unchanged. The maximal tension of single contraction of suspended rats decreased obviously, and had obvious stimulation voltage dependence; the time to reach peak tension and relaxation was significantly shortened. EDL single contraction although the maximum tension was significantly reduced, but no significant voltage-dependent stimulation, the time parameters have not changed. The maximum tension of tetanic contraction of suspended rats SOL was significantly reduced and a rapid decline occurred. Tensions of the tetanic contractions had been reduced by 73% at 33 seconds of tetanic contractility. Dynamic curves of tetanic contractile tension in suspension rats were similar to EDL. EDL tetanus contraction maximum tension also significantly reduced, but the rate of decay did not change. CONCLUSIONS: The maximal tension of tetanic contractility of SOL rats after 4-week suspension is declining and easily decayed. The former may be related to the reduction of systolic unit per unit area and the decrease of productivity of each transversal bridge. The latter may be due to the occurrence of contractile and regulatory protein isoforms Conversion, and changes in muscle electrical excitability