Modulation of rank-ordered recruitment of motor units in the jaw-closing movement by leak K+ channels

对三叉神经运动核运动神经元（MNs）的免疫组化分析显示，TASK1和TASK3分别在MNs的体细胞和树突中互补表达。实时RT - PCR结果显示，与小于20微米的小纳米颗粒相比，大纳米颗粒（bbb35微米）表达更多的TASK1/cell和TASK3。因此，与较小的mn相比，较大的mn具有较小的输入电阻（IR）和更多的超极化静息膜电位（RMP）。PKG激活可增强TASK1的活性，抑制TASK3的活性。随着MN尺寸的减小，PKG的激活进一步降低了红外光谱，并使RMP超极化。α - mns大小的频率分布呈现由较小的α - mns和较大的α - mns组成的双峰分布，而γ - mns则呈现较小的单峰分布。这些发现为下颌闭合运动中运动单位的有序招募提供了重要的分子和细胞基础。

The immunohistochemical analysis of motoneurons (MNs) in the trigeminal motor nucleus that innervates jaw-closing muscles revealed that TASK1 and TASK3 are complementary expressed in the soma and dendrites of MNs, respectively. The real-time RT PCR revealed that large MNs (>35 microm) expressed more TASK1/cell and TASK3 compared to small MNs (<20 microm). Consequently, larger MNs had smaller input resistance (IR) and more hyperpolarized resting membrane potentials (RMP) compared to smaller MNs. PKG activation enhanced TASK1 activity while it inhibited TASK3 activity. As the MN size becomes smaller, PKG activation more decreased the IR and hyperpolarized the RMP. The frequency distribution of sizes of alpha-MNs was found to display a bimodal distribution composed of smaller and larger alpha-MNs while gamma-MNs displayed a unimodal patter of smaller size. These finding provide crucial molecular and cellular bases of the rank-ordered recruitment of motor units in the jaw-closing movement.