补充肌酸对老龄大鼠骨骼肌收缩特性的影响

Effects of Creatine Supplements on Contractile Properties of Skeletal Muscle in Elder Rats

目的研究补充肌酸对老年大鼠骨骼肌收缩特性的影响。方法 18月龄雄性Sprague-Dawley大鼠20只,分为对照组和肌酸补充组(0.3 g/kg),每组10只。使用高效液相色谱法测定肌组织中肌酸和磷酸肌酸含量;离体比目鱼肌和趾长伸肌30℃灌流方法,测量其单次收缩和强直收缩力。结果肌酸补充组大鼠比目鱼肌和趾长伸肌中肌酸和磷酸肌酸含量比对照组增加(P<0.05)。比目鱼肌最大收缩力(Pt)和最大强直收缩力(P0)增大,达到最大收缩力使用时间(TPT)以及最大收缩力舒张一半时间(TPR50)缩短,但只有TPR50与对照组具有显著性差异(P<0.05)。趾长伸肌Pt和P0增大、TPT缩短,且与对照组具有显著性差异(P<0.05),时间参数TPR50虽缩短,但与对照组无显著性差异(P>0.05)。肌酸补充组比目鱼肌抗疲劳性提高(P<0.05),而趾长伸肌的抗疲劳性没有明显提高。但是在抗疲劳测试中,在刺激开始的20-30 s肌酸补充组趾长伸肌张力增加幅度大于对照组(P<0.05)。结论肌酸补充对老年大鼠比目鱼肌和趾长伸肌收缩特性具有良好的作用,但影响具有肌纤维类型依赖性。

Objective To investigate the effects of creatine supplement on contractile properties of soleus （SOL） and extensor digitorum longus （EDL） in elder rat. Methods 20 male Sprague-Dawley rats were randomly divided into control group and creatine supplement group with 10 rats in each group. After 6 weeks, the content of creatine and phosphocreatine were detected by high performance liquid chromatography, and contractile properties were examined in SOL and EDL in vitro at 30℃. Results The content of creatine and phosphocreatine both in SOL and EDL were higher in the creatine supplement group than in the control group （P〈0.05）. In SOL, creatine supplements increased the maximum twitch tension （Pt）, maximum titanic tension（P0）, decreased time to maximum twitch tension （TPT）, but only time from maxi- mum twitch to half relaxation （TPRs0） significantly decreased, compared with the control group. In EDL, creatine supplements significantly increased P,, Po and decreased TPT （P〈0.05）. But there was no significant difference in TPRs0 between 2 groups （P〉0.05）. Creatine supple- ments significantly increased the fatigue resistance of the SOL and there was no significant effect on EDL. The force potentiation which oc- curred in EDL during the initial 20-30 s of the fatigue test significantly increased （P〈0.05）. Conclusion Creatine supplement is effective on the contractile properties of SOL and EDL in elder rats, but the effect is dependent on the fiber types.