Repeated obstructive apneas induce long-term facilitation of genioglossus muscle tone.

The respiratory network is sensitive to both chemical and mechanosensory feedback and exhibits considerable plasticity when exposed to repeated respiratory perturbations. One example of respiratory plasticity is long-term facilitation (LTF) - a long-term enhancement in respiratory activity induced by intermittent hypoxia. Although intermittent hypoxia ranging from 5-min to 10-s has been shown to trigger respiratory LTF, it is unknown whether brief repeated airway obstruction as experience in obstructive sleep apnea could trigger LTF of respiratory motor outflow. Here we show that brief (15-s), repeated apneas trigger LTF of genioglossus muscle tone in rats. We also show that vagal feedback is important for the expression of apnea-induced LTF because it was not inducible when vagal feedback was impaired. Our results demonstrate a novel mechanism for triggering respiratory neuroplasticity and may have implications for maintenance of airway patency during sleep.