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Article: Responses of respiratory modulated and tonic units in the retrotrapezoid nucleus to CO 2

TitleResponses of respiratory modulated and tonic units in the retrotrapezoid nucleus to CO 2
Authors
Issue Date1993
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/resphysiol
Citation
Respiration Physiology, 1993, v. 94 n. 1, p. 35-50 How to Cite?
AbstractWe hypothesized that the retrotrapezoid nucleus (RTN) contains both respiratory modulated (RM) and non-respiratory modulated (NRM) neurons which participate in the ventilatory response to increased CO 2. We made extracellular recordings of the activity of 46 single units in the RTN of 9 decerebrate, paralyzed, ventilated cats (5 intact; 4 with carotid body and sinus ablation) under eucapnic (P(CO 2) = 34.2 ± 3.5 mmHg; mean ± SD) and hypercapnic (P(CO 2) = 47.4 ± 3.4 mmHg) conditions. To define a RM unit, we used the η 2 statistic which is the ratio of the variance of the unit firing rate within respiratory cycles to that across respiratory cycles. We classified the units as RM (N = 17) if the η 2 values in eucapnia or hypercapnia were ≥0.25 and as NRM (N = 29) if the values were <0.25. Overall, 19/46 units (41%) increased their firing rate with increased CO 2, 5 decreased their firing rate, and 22 had no significant change in firing rate. Of 17 RM units, 8 (47%) increased their mean firing rate with hypercapnia from 7.6 ± 3.9 to 23.2 ± 6.8 spikes/sec. These included 5 inspiratory units, 2 inspiratory units that had an onset of firing in late expiration (Pre-I/I), and 1 expiratory unit. Seven of these also changed their discharge pattern (eucapnic η 2 = 0.02 to 0.12; hypercapnic η 2 = 0.34 to 0.79). Of 29 NRM units, 11 (38%) showed a significant increase in mean firing rate with CO 2 stimulation from 19.8 ± 7.2 to 31.3 ± 8.2 spikes/sec. The RTN has RM units which change their discharge pattern and firing rate in response to increased CO 2, as do units within the medulla and pons, and it has NRM units which are also responsive to increased CO 2. These data indicate that some neurons of the RTN are involved in the central chemoreceptor response but they provide no direct evidence that chemoreception resides within the RTN.
Persistent Identifierhttp://hdl.handle.net/10722/171589
ISSN
2001 Impact Factor: 2.197
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorNattie, EEen_US
dc.contributor.authorFung, MLen_US
dc.contributor.authorLi, Aen_US
dc.contributor.authorSt John, WMen_US
dc.date.accessioned2012-10-30T06:15:51Z-
dc.date.available2012-10-30T06:15:51Z-
dc.date.issued1993en_US
dc.identifier.citationRespiration Physiology, 1993, v. 94 n. 1, p. 35-50en_US
dc.identifier.issn0034-5687en_US
dc.identifier.urihttp://hdl.handle.net/10722/171589-
dc.description.abstractWe hypothesized that the retrotrapezoid nucleus (RTN) contains both respiratory modulated (RM) and non-respiratory modulated (NRM) neurons which participate in the ventilatory response to increased CO 2. We made extracellular recordings of the activity of 46 single units in the RTN of 9 decerebrate, paralyzed, ventilated cats (5 intact; 4 with carotid body and sinus ablation) under eucapnic (P(CO 2) = 34.2 ± 3.5 mmHg; mean ± SD) and hypercapnic (P(CO 2) = 47.4 ± 3.4 mmHg) conditions. To define a RM unit, we used the η 2 statistic which is the ratio of the variance of the unit firing rate within respiratory cycles to that across respiratory cycles. We classified the units as RM (N = 17) if the η 2 values in eucapnia or hypercapnia were ≥0.25 and as NRM (N = 29) if the values were <0.25. Overall, 19/46 units (41%) increased their firing rate with increased CO 2, 5 decreased their firing rate, and 22 had no significant change in firing rate. Of 17 RM units, 8 (47%) increased their mean firing rate with hypercapnia from 7.6 ± 3.9 to 23.2 ± 6.8 spikes/sec. These included 5 inspiratory units, 2 inspiratory units that had an onset of firing in late expiration (Pre-I/I), and 1 expiratory unit. Seven of these also changed their discharge pattern (eucapnic η 2 = 0.02 to 0.12; hypercapnic η 2 = 0.34 to 0.79). Of 29 NRM units, 11 (38%) showed a significant increase in mean firing rate with CO 2 stimulation from 19.8 ± 7.2 to 31.3 ± 8.2 spikes/sec. The RTN has RM units which change their discharge pattern and firing rate in response to increased CO 2, as do units within the medulla and pons, and it has NRM units which are also responsive to increased CO 2. These data indicate that some neurons of the RTN are involved in the central chemoreceptor response but they provide no direct evidence that chemoreception resides within the RTN.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/resphysiolen_US
dc.relation.ispartofRespiration Physiologyen_US
dc.subject.meshAnimalsen_US
dc.subject.meshCarbon Dioxide - Analysis - Blood - Pharmacologyen_US
dc.subject.meshCatsen_US
dc.subject.meshFemaleen_US
dc.subject.meshHypercapnia - Blood - Physiopathologyen_US
dc.subject.meshMaleen_US
dc.subject.meshMedulla Oblongata - Drug Effects - Physiologyen_US
dc.subject.meshNeurons - Drug Effects - Physiologyen_US
dc.subject.meshPulmonary Alveoli - Chemistry - Physiologyen_US
dc.subject.meshRespiration - Drug Effects - Physiologyen_US
dc.titleResponses of respiratory modulated and tonic units in the retrotrapezoid nucleus to CO 2en_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.doi10.1016/0034-5687(93)90055-Fen_US
dc.identifier.pmid8272580-
dc.identifier.scopuseid_2-s2.0-0027423541en_US
dc.identifier.volume94en_US
dc.identifier.issue1en_US
dc.identifier.spage35en_US
dc.identifier.epage50en_US
dc.identifier.isiWOS:A1993MA98300004-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridNattie, EE=7005019384en_US
dc.identifier.scopusauthoridFung, ML=7101955092en_US
dc.identifier.scopusauthoridLi, A=7403292086en_US
dc.identifier.scopusauthoridSt John, WM=36831054200en_US

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