TY - JOUR T1 - The Possible Role of TASK Channels in Rank-Ordered Recruitment of Motoneurons in the Dorsolateral Part of the Trigeminal Motor Nucleus JF - eneuro JO - eneuro DO - 10.1523/ENEURO.0138-16.2016 VL - 3 IS - 3 SP - ENEURO.0138-16.2016 AU - Keiko Okamoto AU - Norihito Emura AU - Hajime Sato AU - Yuki Fukatsu AU - Mitsuru Saito AU - Chie Tanaka AU - Yukako Morita AU - Kayo Nishimura AU - Eriko Kuramoto AU - Dong Xu Yin AU - Kazuharu Furutani AU - Makoto Okazawa AU - Yoshihisa Kurachi AU - Takeshi Kaneko AU - Yoshinobu Maeda AU - Takashi Yamashiro AU - Kenji Takada AU - Hiroki Toyoda AU - Youngnam Kang Y1 - 2016/05/01 UR - http://www.eneuro.org/content/3/3/ENEURO.0138-16.2016.abstract N2 - Because a rank-ordered recruitment of motor units occurs during isometric contraction of jaw-closing muscles, jaw-closing motoneurons (MNs) may be recruited in a manner dependent on their soma sizes or input resistances (IRs). In the dorsolateral part of the trigeminal motor nucleus (dl-TMN) in rats, MNs abundantly express TWIK (two-pore domain weak inwardly rectifying K channel)-related acid-sensitive-K+ channel (TASK)-1 and TASK3 channels, which determine the IR and resting membrane potential. Here we examined how TASK channels are involved in IR-dependent activation/recruitment of MNs in the rat dl-TMN by using multiple methods. The real-time PCR study revealed that single large MNs (>35 μm) expressed TASK1 and TASK3 mRNAs more abundantly compared with single small MNs (15–20 μm). The immunohistochemistry revealed that TASK1 and TASK3 channels were complementarily distributed in somata and dendrites of MNs, respectively. The density of TASK1 channels seemed to increase with a decrease in soma diameter while there were inverse relationships between the soma size of MNs and IR, resting membrane potential, or spike threshold. Dual whole-cell recordings obtained from smaller and larger MNs revealed that the recruitment of MNs depends on their IRs in response to repetitive stimulation of the presumed Ia afferents. 8-Bromoguanosine-cGMP decreased IRs in small MNs, while it hardly changed those in large MNs, and subsequently decreased the difference in spike-onset latency between the smaller and larger MNs, causing a synchronous activation of MNs. These results suggest that TASK channels play critical roles in rank-ordered recruitment of MNs in the dl-TMN. ER -