The relationship between ciliary neurotrophic factor (CNTF) genotype and motor unit physiology: preliminary studies.
The relationship between ciliary neurotrophic factor (CNTF) genotype and motor unit physiology: preliminary studies.
复制标题
DOI：
10.1186/1472-6793-5-15
复制
发表时间：
2005-09-23
期刊：
影响因子：
--
通讯作者：
Metter EJ
中科院分区：
文献类型：
--
作者：
Conwit RA;Ling S;Roth S;Stashuk D;Hurley B;Ferrell R;Metter EJ
睫状神经营养因子（CNTF）对神经元和肌肉发育非常重要，CNTF基因的遗传变异与肌肉力量有关。CNTF对神经发育的影响表明CNTF基因型可能通过影响运动单位的大小和放电模式与力的产生有关。本研究的目的是检查CNTF基因型是否差异影响运动单位激活股内侧肌增加等长力量在膝关节伸展。对69例健康受试者进行CNTF基因G和A（无效）等位基因分型（n = 57 G/G，12 G/A）。他们在次最大等长膝关节伸展收缩期间使用测力计进行测试，收缩幅度为他们最大力量的10-50%。在收缩过程中，使用表面和肌内肌电图与尖峰触发平均法研究股内侧肌，以评估表面检测到的运动单位电位（SMUP）面积和识别的运动单位的平均放电率（mFR）。CNTF基因分型使用标准PCR技术从全血样品的白细胞获得的DNA进行。CNTF G/A基因型与较小的SMUP面积运动单位和较低的mFR在较高的力量水平，和更少，但更大的单位在较低的力量水平比G/G纯合子。两组使用不同大小和激活特征的运动单位，增加力量产生。虽然G/G科目倾向于使用更大的运动单位与增加的力量，G/A科目表现出相对较小的增加，在使用相对较大的单位在较低的力量水平。在更高的力量水平，G/A科目能够产生更多的力量，每运动单位的大小表明更有效的运动单位功能与增加肌肉力量。CNTF基因型在日常活动中使用的力量水平之间观察到差异运动单位反应。
Ciliary neurotrophic factor (CNTF) is important for neuronal and muscle development, and genetic variation in the CNTF gene has been associated with muscle strength. The effect of CNTF on nerve development suggests that CNTF genotype may be associated with force production via its influence on motor unit size and firing patterns. The purpose of this study is to examine whether CNTF genotype differentially affects motor unit activation in the vastus medialis with increasing isometric force during knee extension. Sixty-nine healthy subjects were genotyped for the presence of the G and A (null) alleles in the CNTF gene (n = 57 G/G, 12 G/A). They were tested using a dynamometer during submaximal isometric knee extension contractions that were from 10–50% of their maximal strength. During the contractions, the vastus medialis was studied using surface and intramuscular electromyography with spiked triggered averaging to assess surface-detected motor unit potential (SMUP) area and mean firing rates (mFR) from identified motor units. CNTF genotyping was performed using standard PCR techniques from DNA obtained from leucocytes of whole blood samples. The CNTF G/A genotype was associated with smaller SMUP area motor units and lower mFR at higher force levels, and fewer but larger units at lower force levels than G/G homozygotes. The two groups used motor units with different size and activation characteristics with increasing force generation. While G/G subjects tended to utilize larger motor units with increasing force, G/A subjects showed relatively less increase in size by using relatively larger units at lower force levels. At higher force levels, G/A subjects were able to generate more force per motor unit size suggesting more efficient motor unit function with increasing muscle force. Differential motor unit responses were observed between CNTF genotypes at force levels utilized in daily activities.