MEMBRANE ELECTRICAL-PROPERTIES AND PREDICTION OF MOTOR-UNIT TYPE OF MEDIAL GASTROCNEMIUS MOTONEURONS IN THE CAT
MEMBRANE ELECTRICAL-PROPERTIES AND PREDICTION OF MOTOR-UNIT TYPE OF MEDIAL GASTROCNEMIUS MOTONEURONS IN THE CAT
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DOI：
10.1152/jn.1985.53.5.1323
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发表时间：
1985-01-01
影响因子：
2.5
通讯作者：
MUNSON, JB
中科院分区：
文献类型：
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作者：
ZENGEL, JE;REID, SA;MUNSON, JB
测定了猫内侧腓肠肌（MG）运动单元运动神经元的膜电特性[时间常数、超极化后动作电位（AHP）、流变碱、输入电阻和轴突传导速度]。运动单元根据其机械反应分为快速抽搐、快速疲劳（FF）；快速抽动，具有中等的抗疲劳性（FI）；快速抽搐，抗疲劳（FR）；或缓慢抽搐，抗疲劳（S; 11,22）。从长（50-100 ms）电流脉冲开始或结束时的电压响应估计并根据电压响应非线性进行校正的运动神经元膜时间常数（32）发现，在主要运动单元类型之间存在显著差异，其增加顺序为FF小于FR小于S。超极化后，快速运动单元（FF + FI + FR）的幅度、半衰减时间和持续时间均显著大于慢速运动单元(S)。AHP半衰减时间与整个运动神经元群和S型运动神经元群内的肌肉单位抽搐时间相关。在FF型和FR型运动单元群体中，抽动时间与AHP半衰减时间无显著相关。与之前的研究一致，我们发现在主要运动单元类型中，流变基和输入电阻都存在显著差异，流变基的增加顺序为S小于FR小于FF，输入电阻的减少顺序为S大于FR大于FF。输入电阻的差异在电压响应非线性校正前后都存在（32）。与先前的研究一致，快速运动单元（FF + FI +和FR）的平均轴突传导速度明显快于慢运动单元(S)。这些数据被用来单独检查运动单元类型的特性，传统上是根据肌肉单元的机械特性来定义的（11,22）。我们使用判别分析程序对73个机械类型的运动单元进行分类，我们测量了流变酶、输入电阻、膜时间常数和AHP半衰减时间。该模型能够对该数据集的73个运动单元中的71个进行正确的分类，表明该数据集的运动单元可以根据其流变基、输入电阻、膜时间常数和AHP半衰减时间分为三类，代表三种主要的运动单元类型（FF、FR和S）。（摘要删节为400字）
Membrane electrical properties [time constant, action potential afterhyperpolarization (AHP), rheobase, input resistance, and axonal conduction velocity] were measured in motoneurons of cat medial gastrocnemius (MG) motor units. Motor units were classified on the basis of their mechanical responses as fast twitch, fast fatiguing (FF); fast twitch with intermediate fatigue resistance (FI); fast twitch, fatigue resistant (FR); or slow twitch, fatigue resistant (S; 11, 22). Motoneuron membrane time constant, estimated from the voltage response at the onset or termination of long (50-100 ms) current pulses and corrected for voltage-response nonlinearities (32), was found to differ significantly among the major motor-unit types, increasing in the order FF less than FR less than S. Afterhyperpolarization magnitude, half-decay time, and duration were all significantly greater for the fast (FF + FI + FR) versus the slow (S) motor units. The AHP half-decay time was correlated with muscle unit twitch time over the entire motoneuron population and within the type S motor-unit population. There was no significant correlation between twitch time and AHP half-decay time among the types FF and FR motor-unit populations. In agreement with previous studies, we found a significant difference in both rheobase and input resistance among the major motor-unit types, with rheobase increasing in the order S less than FR less than FF and input resistance decreasing in that order (S greater than FR greater than FF). The differences in input resistance were present both before and after correcting for voltage-response nonlinearities (32). Also in agreement with previous studies, the mean axonal conduction velocity was significantly faster among the fast (FF + FI + and FR) compared with the slow (S) motor units. These data were used to examine the properties alone to determine motor-unit type, which has traditionally been defined on the basis of the muscle unit's mechanical properties (11, 22). We used a discriminant analysis program to classify 73 mechanically typed motor units for which we had measures of rheobase, input resistance, membrane time constant, and AHP half-decay time. This model was able to properly classify 71 of the 73 motor units of this data set, indicating that the motor units of this data set could be grouped into three categories representing the three major motor-unit types (FF, FR, and S) on the basis of their rheobase, input resistance, membrane time constant, and AHP half-decay time.(ABSTRACT TRUNCATED AT 400 WORDS)