| Phasic respiratory modulation of pharyngeal collapsibility via neuromuscular mechanisms in rats. | |
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MedLine Citation:
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PMID: 22052868 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Obstructive sleep apnea patients experience recurrent upper airway (UA) collapse due to decreases in the UA dilator muscle activity during sleep. In contrast, activation of UA dilators reduces pharyngeal critical pressure (Pcrit, an index of pharyngeal collapsibility), suggesting an inverse relationship between pharyngeal collapsibility and dilator activity. Since most UA muscles display phasic respiratory activity, we hypothesized that pharyngeal collapsibility is modulated by respiratory drive via neuromuscular mechanisms. Adult male Sprague-Dawley rats were anesthetized, vagotomized and ventilated (normocapnia). In one group, integrated genioglossal activity, Pcrit and maximal airflow (Vmax) were measured at 3 expiration and 5 inspiration time points within the breathing cycle. Pcrit was closely and inversely related to phasic genioglossal activity, with the value measured at peak inspiration being the lowest. In other groups, the variables were measured during expiration and peak inspiration, before and after each of 5 manipulations. Pcrit was 26% more negative (-15.0±1.0 cmH(2)O, -18.9±1.2; n=23), Vmax was 7% larger (31.0±1.0 ml/s, 33.2±1.1), nasal resistance was 12% bigger [0.49±0.05 cmH(2)O/(ml/s), 0.59±0.05] and latency to induced UA closure was 14% longer (55±4 ms, 63±5) during peak inspiration vs. expiration (all P<0.005). The expiration-inspiration difference in Pcrit was abolished with neuromuscular blockade, hypocapnic apnea or death, but was not reduced by the superior laryngeal nerve transection or altered by tracheal displacement. Collectively, these results suggest that pharyngeal collapsibility is moment-by-moment modulated by respiratory drive and this phasic modulation requires neuromuscular mechanisms, but not the UA negative pressure reflex or tracheal displacement by phasic lung inflation. |
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Authors:
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Ying Cao; Michelle McGuire; Chun Liu; Atul Malhotra; Liming Ling |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-11-3 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: - ISSN: 1522-1601 ISO Abbreviation: - Publication Date: 2011 Nov |
Date Detail:
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Created Date: 2011-11-4 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1UTHSC. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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