Postnatal changes in motoneurone electrotonic coupling studied in the in vitro rat lumbar spinal cord.
Postnatal changes in motoneurone electrotonic coupling studied in the in vitro rat lumbar spinal cord.
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在体外大鼠腰脊髓中研究运动神经元电紧张耦合的出生后变化。
DOI：
10.1113/jphysiol.1991.sp018426
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Navarrete,R
中科院分区：
文献类型：
--
作者：
Walton,KD;Navarrete,R
1. 使用从大鼠出生 (P0) 到 13 天 (P13) 之间分离的体外脊髓后肢制剂的细胞内记录，研究了支配踝关节屈肌和伸肌的运动神经元之间以及未识别的腰椎运动神经元之间的电紧张耦合。 2.分级的腹侧根刺激可以引起分级的短潜伏期去极化(SLD)，其在逆向动作电位之前、同时或之后。这些 SLD 通过其潜伏期、对膜电位变化的相对不敏感性以及对以下一种或多种的抵抗力被鉴定为电紧张连接电位：(1) 高频刺激，(2) 与离体动作电位的碰撞，(3) 从沐浴溶液中去除 Ca2+。 3. 在 162 个神经元中进行了研究，在 P0 至 P3 大鼠 (n = 57) 的制剂中，77.2% 的细胞中发现了 SLD，但在 P8 至 P13 (n = 39) 中，仅在 30.8% 的细胞中发现了 SLD。 4. SLD 在最年轻的动物（P0 至 P3）中最大，从 P8 至 P13 的平均值 1.31 mV（+/- 0.17，n = 34）降至 0.56 mV（+/- 0.10，n = 7）。根据 20 次碰撞实验确定，SLD 包含 2 到 8 个 (4.3 +/- 0.36) 个全或无组件。 5.运动神经元之间的电紧张耦合具有特异性。 SLD 可以通过刺激同名运动神经元引起，但不能通过刺激其拮抗肌神经引起。 6. 这些结果表明，新生动物腰椎运动神经元之间的电紧张耦合表现出高度的特异性，并且根据 SLD 发生的幅度和频率判断，其重要性在出生后以与运动神经元和肌肉系统的功能成熟度相关的速率下降。
1. Electrotonic coupling between motoneurones innervating ankle flexor and extensor muscles, as well as between unidentified lumbar motoneurones, was studied using intracellular recordings in an in vitro spinal cord‐hindlimb preparation isolated from rats between birth (P0) and 13 days (P13). 2. Graded ventral root stimulation could elicit graded, short latency depolarizations (SLD) which preceded, coincided with, or followed the antidromic action potential. These SLDs were identified as electrotonic junctional potentials by their latency, relative insensitivity to changes in membrane potential and their resistance to one or more of the following: (1) high‐frequency stimulation, (2) collision with a somatofugal action potential, (3) removal of Ca2+ from the bathing solution. 3. SLDs were studied in 162 neurones and were identified in 77.2% of the cells in preparations from P0 to P3 rats (n = 57), but only in 30.8% at P8 to P13 (n = 39). 4. SLDs were largest in the youngest animals (P0 to P3), decreasing from a mean of 1.31 mV (+/‐ 0.17, n = 34) to 0.56 mV (+/‐ 0.10, n = 7) at P8 to P13. The SLDs comprised two to eight (4.3 +/‐ 0.36) all‐or‐none components as determined from twenty collision experiments. 5. Electrotonic coupling between motoneurones was specific. SLDs could be elicited in given motoneurones by stimulation of their homonymous but never of their antagonistic muscle nerves. 6. These results indicate that electrotonic coupling between lumbar motoneurones in neonatal animals exhibits a high degree of specificity and that its significance, as judged by the amplitude and frequency of occurrence of SLDs, decreases postnatally at a rate that can be correlated with the functional maturity of the motoneurones and the muscular system.