Amy S Jordan, Michael J Woods, Jennifer M Cori, Julia K M Chan, Christian L Nicholas, John Semmler, John Trinder
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引用次数: 0
Abstract
High activity of upper airway dilator muscles is thought to be critical in preventing sleep-related upper airway collapse. To date, most of the research regarding upper airway dilator muscles has focused on the genioglossus muscle, which protrudes the tongue and opens the retroglossal airway. However, collapse commonly occurs in the retropalatal region. We, therefore, aimed to examine the motor control of the palatoglossus muscle as well as investigate breathing route-related changes in genioglossus and palatoglossus motor units. Single motor unit recordings of the genioglossus and palatoglossus were made simultaneously in healthy individuals during wakefulness while breathing through the nose with the mouth closed (NMC), nose with mouth open (NMO), or orally (OMO). The palatoglossus was found to have all five motor unit firing patterns that have been observed in other upper airway dilator muscles, but during nasal breathing had a higher proportion of tonically active but inspiratory modulated motor units as compared with the genioglossus (67% vs. 30%). When still breathing nasally but with the mouth open, the units with an expiratory firing pattern in genioglossus, and all firing patterns in palatoglossus, increased their firing rates compared with nasal breathing with the mouth closed [genioglossus (GG): 17.8 ± 4.9 vs. 23.1 ± 4.8 Hz, palatoglossus (PG): 17.0 ± 4.0 vs. 19.3 ± 4.0 Hz]. Finally, oral breathing resulted in dramatic reductions in the number of palatoglossal motor units that were firing (35 units vs. 92 during nasal breathing). Palatoglossal activity may contribute importantly to airway collapsibility and may provide an alternate pathway for preventing sleep-related airway collapse.NEW & NOTEWORTHY The firing patterns of motor units in the palatoglossus have until now not been investigated, and how they and motor units in the genioglossus change with breathing route alteration was not known. This study has shown that the palatoglossus contains motor units with all the firing patterns observed in the genioglossus but in different proportions. Furthermore, breathing route changes alter units with different firing patterns differentially in the two muscles.
期刊介绍:
The Journal of Applied Physiology publishes the highest quality original research and reviews that examine novel adaptive and integrative physiological mechanisms in humans and animals that advance the field. The journal encourages the submission of manuscripts that examine the acute and adaptive responses of various organs, tissues, cells and/or molecular pathways to environmental, physiological and/or pathophysiological stressors. As an applied physiology journal, topics of interest are not limited to a particular organ system. The journal, therefore, considers a wide array of integrative and translational research topics examining the mechanisms involved in disease processes and mitigation strategies, as well as the promotion of health and well-being throughout the lifespan. Priority is given to manuscripts that provide mechanistic insight deemed to exert an impact on the field.