| Phrenic long-term facilitation is robust to hypercapnia and hypocapnia but not hyperventilatory hypotension under PEEP. | |
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MedLine Citation:
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PMID: 17331813 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Phrenic long-term facilitation (LTF) has been extensively studied in anesthetized animals under well-defined physiological conditions but the factors underlying its possible manifestation under clinically relevant conditions are not well understood. Here, we examine the stability of LTF in the face of hypercapnic or hypocapnic challenges in anesthetized, paralyzed and mechanically ventilated rats. Sixty minutes after induction of phrenic LTF by intermittent hypoxia the animal was exposed to one of four conditions for 5 min with or without positive end-expiratory pressure (PEEP, 3-4 cmH(2)O): hypocapnic apnea, hypocapnia (5 Torr below resting level), 5% CO(2) and 10% CO(2). LTF at 60 min post-intermittent hypoxia was approximately 39% above baseline. Following the above CO(2) tests, LTF almost invariably returned to the corresponding pre-test level after recovery for 20 min. The only exception was the combination of hypocapnic apnea and PEEP, which resulted in a marked decrease in mean arterial pressure (to 38-55mmHg) during test and a subsequent paradoxical sustained attenuation of LTF (to approximately 8% above baseline) even after mean arterial pressure had fully recovered. The results suggest that LTF, once developed, is highly robust to changes in CO(2) levels and is attenuated only after severe hypotension secondary to excessive hyperventilation under PEEP. |
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Authors:
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Michelle McGuire; Shawna M MacDonald; Gang Song; Chi-Sang Poon |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2007-02-03 |
Journal Detail:
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Title: Respiratory physiology & neurobiology Volume: 158 ISSN: 1569-9048 ISO Abbreviation: Respir Physiol Neurobiol Publication Date: 2007 Aug |
Date Detail:
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Created Date: 2007-06-25 Completed Date: 2007-09-18 Revised Date: 2011-09-26 |
Medline Journal Info:
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Nlm Unique ID: 101140022 Medline TA: Respir Physiol Neurobiol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 107-11 Citation Subset: IM |
Affiliation:
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Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Bldg. 56-046, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Anoxia / physiopathology, therapy Disease Models, Animal Hypercapnia / physiopathology* Hyperventilation / etiology, physiopathology* Hypocapnia / physiopathology* Hypotension / physiopathology* Long-Term Potentiation / physiology* Phrenic Nerve / physiopathology* Positive-Pressure Respiration* Rats Sleep Apnea Syndromes / physiopathology, therapy |
| Grant Support | |
ID/Acronym/Agency:
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HL067966/HL/NHLBI NIH HHS; HL072849/HL/NHLBI NIH HHS; R01 HL067966-04/HL/NHLBI NIH HHS; R01 HL072849-03/HL/NHLBI NIH HHS |
| Comments/Corrections | |
Comment In:
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Respir Physiol Neurobiol. 2007 Aug 15;158(1):112-3
[PMID:
17412653
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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