Attempts to physiologically classify human thenar motor units.
Attempts to physiologically classify human thenar motor units.
复制标题
尝试对人类大鱼际运动单位进行生理学分类。
DOI：
10.1152/jn.1991.65.6.1501
复制
发表时间：
1991
影响因子：
2.5
通讯作者：
Bigland-Ritchie,B
中科院分区：
文献类型：
--
作者：
Thomas,CK;Johansson,RS;Bigland-Ritchie,B
1. 本研究旨在确定人类大鱼际运动单元是否可以按照与其他哺乳动物肢体运动单元相同的生理标准进行分类，并考虑这种分类是否与功能相关。2. 在常规的2分钟疲劳试验中，对25个人体大鱼际单个运动单元的运动轴突进行1 ~ 100 Hz和40 Hz间歇刺激，观察其收缩反应。测定抽搐力、强直力及各种收缩率指标。3. 抽搐收缩次数和强直下与最大强直力之比均呈连续分布。张力的“凹陷”在未融合的力剖面中不明显。因此，这些单位不能按照传统的收缩率标准分为快慢两类。4. 大部分单元具有抗疲劳性能，力疲劳指数（FI）在0.33 ~ 1.14之间。均不能归类为疲劳（FI小于0.25）。7个单位（28%）属于疲劳-中间（FI = 0.25-0.75）类别，而18个单位（72%）的FI大于0.75，即它们是抗疲劳单位。然而，这些单位不能按照传统的FI和收缩率标准进行分类，因为抗疲劳和疲劳中间单位具有相似的收缩率。5. 计算额外的FI来描述收缩速率的变化。在疲劳试验中，单元表现为以下三种方式之一：1)力或速率变化不大；2)在收缩和松弛阶段收缩变慢，很少或没有力损失；或者3)力和速率都降低。（摘要删节250字）
1. This study was designed to determine whether human thenar motor units can be classified into types by the same physiological criteria used for other mammalian limb motor units and to consider whether such classification is functionally relevant. 2. Contractile responses of 25 human thenar single motor units were examined when their motor axons were stimulated intraneurally at rates from 1 to 100 Hz and intermittently at 40 Hz in a conventional 2-min fatigue test. Twitch and tetanic forces were measured together with various indexes of contractile rate. 3. Twitch contraction times and subtetanic to maximum tetanic force ratios were both distributed continuously. "Sag" in tension was not evident in unfused force profiles. Thus these units could not be divided into fast and slow types by the use of traditional contractile rate criteria. 4. Most units were fatigue resistant, with force fatigue indexes (FI) ranging from 0.33 to 1.14. None could be classified as fatiguable (FI less than 0.25). Seven units (28%) fell into the fatigue-intermediate (FI = 0.25-0.75) category, whereas 18 units (72%) had FI greater than 0.75, i.e., they were fatigue-resistant units. However, these units could not be classified by conventional FI and contractile rate criteria, because fatigue-resistant and fatigue-intermediate units had similar contractile rates. 5. Additional FI were calculated to describe changes in contractile rate. During the fatigue test, units behaved in one of three ways, showing 1) little change in either force or rate; 2) contractile slowing during the contraction and relaxation phases, with little or no force loss; or 3) both force and rate reduction.(ABSTRACT TRUNCATED AT 250 WORDS)