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Article: Reflex recruitment of medullary gasping mechanisms in eupnoea by pharyngeal stimulation in cats

TitleReflex recruitment of medullary gasping mechanisms in eupnoea by pharyngeal stimulation in cats
Authors
Issue Date1994
PublisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751
Citation
Journal Of Physiology, 1994, v. 475 n. 3, p. 519-529 How to Cite?
Abstract1. Mechanical stimulation of the naso- and oropharynx causes the replacement of the eupnoeic ventilatory pattern by a brief, but large, burst of activity of the phrenic nerve. Our purpose was to define whether these changes in phrenic activity represent a switch to gasping. 2. In decerebrate, vagotomized, paralysed and ventilated cats, mechanical stimulation of the pharynx was performed during eupnoea, apneusis and gasping. The latter two ventilatory patterns were produced by ventilating the experimental animal with 10% carbon monoxide in air or with 100% nitrogen. Eupnoea could be re-established by a recommencement of ventilation with oxygen. 3. The rate of rise of phrenic activity and its peak height were much greater following mechanical stimulation of the pharynx than the phrenic bursts of eupnoea or apneusis. The durations of phrenic burst and the period between these were much less following pharyngeal stimulation. In contrast, these variables of phrenic activity were the same during pharyngeal stimulation and in gasping. 4. Previous studies had established that activity within a region of the lateral tegmental field of medulla is critical for the manifestation of gasping. Hence, electrical stimulation of this region during gasping elicits premature gasps whereas its ablation irreversibly eliminates gasping. 5. We positioned a multibarrelled pipette in the critical medullary region for gasping. Its location was verified, once gasping was established in hypoxia or anoxia, by the elicitation of premature gasps following electrical stimulation. Neurons in this region were destroyed by microinjections of the neurotoxin kainic acid; in a few experiments the region was destroyed by electrolytic lesions. 6. Following destruction of the region of the lateral tegmental field, gasping could no longer be provoked in anoxia. In contrast, the eupnoeic pattern of phrenic activity continued. However, mechanical stimulation of the pharynx no longer caused any changes in the on-going pattern of phrenic activity. 7. We conclude that mechanical stimulation of the pharynx elicits a powerful reflex by which eupnoea is suppressed and gasping is elicited. Stated differently, the changes in phrenic activity during this pharyngeal stimulation in fact represent gasps. 8. Gasps are dependent upon activity within a region of the lateral tegmental field of the medulla. This region plays no role in the neurogenesis of eupnoea. Hence, our results provide additional support for the concept that there are multiple sites for ventilatory neurogenesis in the mammalian brainstem.
Persistent Identifierhttp://hdl.handle.net/10722/171612
ISSN
2015 Impact Factor: 4.731
2015 SCImago Journal Rankings: 2.670
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorFung, MLen_US
dc.contributor.authorSt John, WMen_US
dc.contributor.authorTomori, Zen_US
dc.date.accessioned2012-10-30T06:15:58Z-
dc.date.available2012-10-30T06:15:58Z-
dc.date.issued1994en_US
dc.identifier.citationJournal Of Physiology, 1994, v. 475 n. 3, p. 519-529en_US
dc.identifier.issn0022-3751en_US
dc.identifier.urihttp://hdl.handle.net/10722/171612-
dc.description.abstract1. Mechanical stimulation of the naso- and oropharynx causes the replacement of the eupnoeic ventilatory pattern by a brief, but large, burst of activity of the phrenic nerve. Our purpose was to define whether these changes in phrenic activity represent a switch to gasping. 2. In decerebrate, vagotomized, paralysed and ventilated cats, mechanical stimulation of the pharynx was performed during eupnoea, apneusis and gasping. The latter two ventilatory patterns were produced by ventilating the experimental animal with 10% carbon monoxide in air or with 100% nitrogen. Eupnoea could be re-established by a recommencement of ventilation with oxygen. 3. The rate of rise of phrenic activity and its peak height were much greater following mechanical stimulation of the pharynx than the phrenic bursts of eupnoea or apneusis. The durations of phrenic burst and the period between these were much less following pharyngeal stimulation. In contrast, these variables of phrenic activity were the same during pharyngeal stimulation and in gasping. 4. Previous studies had established that activity within a region of the lateral tegmental field of medulla is critical for the manifestation of gasping. Hence, electrical stimulation of this region during gasping elicits premature gasps whereas its ablation irreversibly eliminates gasping. 5. We positioned a multibarrelled pipette in the critical medullary region for gasping. Its location was verified, once gasping was established in hypoxia or anoxia, by the elicitation of premature gasps following electrical stimulation. Neurons in this region were destroyed by microinjections of the neurotoxin kainic acid; in a few experiments the region was destroyed by electrolytic lesions. 6. Following destruction of the region of the lateral tegmental field, gasping could no longer be provoked in anoxia. In contrast, the eupnoeic pattern of phrenic activity continued. However, mechanical stimulation of the pharynx no longer caused any changes in the on-going pattern of phrenic activity. 7. We conclude that mechanical stimulation of the pharynx elicits a powerful reflex by which eupnoea is suppressed and gasping is elicited. Stated differently, the changes in phrenic activity during this pharyngeal stimulation in fact represent gasps. 8. Gasps are dependent upon activity within a region of the lateral tegmental field of the medulla. This region plays no role in the neurogenesis of eupnoea. Hence, our results provide additional support for the concept that there are multiple sites for ventilatory neurogenesis in the mammalian brainstem.en_US
dc.languageengen_US
dc.publisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751en_US
dc.relation.ispartofJournal of Physiologyen_US
dc.subject.meshAnimalsen_US
dc.subject.meshCatsen_US
dc.subject.meshElectric Stimulationen_US
dc.subject.meshElectrophysiologyen_US
dc.subject.meshFemaleen_US
dc.subject.meshMaleen_US
dc.subject.meshMedulla Oblongata - Physiologyen_US
dc.subject.meshPharynx - Physiologyen_US
dc.subject.meshPhrenic Nerve - Physiologyen_US
dc.subject.meshRecruitment, Neurophysiologicalen_US
dc.subject.meshReflexen_US
dc.subject.meshRespiration - Physiologyen_US
dc.titleReflex recruitment of medullary gasping mechanisms in eupnoea by pharyngeal stimulation in catsen_US
dc.typeArticleen_US
dc.identifier.emailFung, ML:fungml@hkucc.hku.hken_US
dc.identifier.authorityFung, ML=rp00433en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.pmid8006833-
dc.identifier.scopuseid_2-s2.0-0028350930en_US
dc.identifier.volume475en_US
dc.identifier.issue3en_US
dc.identifier.spage519en_US
dc.identifier.epage529en_US
dc.identifier.isiWOS:A1994ND61700013-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridFung, ML=7101955092en_US
dc.identifier.scopusauthoridSt John, WM=36831054200en_US
dc.identifier.scopusauthoridTomori, Z=7005413045en_US

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