| Abstract: | Kianicka, Irenej, Véronique Diaz, Sylvain Renolleau,Emmanuel Canet, and Jean-Paul Praud. Laryngeal and abdominal muscle electrical activity during periodic breathing in nonsedated lambs. J. Appl. Physiol. 84(2):669-675, 1998. We recently reported that glottic closure waspresent throughout central apneas in awake lambs. The present studytested whether glottic closure was also observed during periodicbreathing (PB). We attempted to induce PB in 21 nonsedated lambs onreturn from hypocapnic hypoxia to room air. Airflow and thyroarytenoid(a laryngeal constrictor, n = 16),cricothyroid (a laryngeal dilator, n = 10), and abdominal (n = 9) muscleelectrical activity (EMG) were monitored continuously. PB was observedin 16 lambs, with apneic phases in 8 lambs. Thyroarytenoid muscle EMGwas observed at the nadir of PB, either throughout apnea or withprolonged expiration during the lowest respiratory efforts. Phasicinspiratory cricothyroid muscle EMG and phasic expiratory abdominal EMGdisappeared at the nadir of PB. Active glottic closure at the nadir ofPB, without abdominal muscle contraction, could be a beneficialmechanism, preserving alveolar gas stores for continuing gas exchangeduring the apneic/hypopneic phase of PB. However, consequences ofactive glottic closure on ventilatory instability, either enhancing orreducing, are unknown. |
