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Conference Paper: Intermittent hypoxia increases AT1 receptor and oxidative stress in the rat carotid body

TitleIntermittent hypoxia increases AT1 receptor and oxidative stress in the rat carotid body
Authors
Issue Date2004
PublisherMary Ann Liebert, Inc.
Citation
The 6th World Congress on Mountain Medicine & High Altitude Physiology, Xining, China, 12-20 August 2004. In High Altitude Medicine & Biology, 2004, v. 5 n. 2, p. 238 Abstract no. 127 How to Cite?
AbstractThe carotid body (CB) plays an important role in cardiorespiratory changes in intermittent hypoxia. Recent data suggest an involvement of angiotensin II (AT) and reactive oxygen species in the pathophysiological development. The aim of this study was to examine the expression of AT1 receptor and the by-products of oxidative stress in the CB of rats exposed to intermittent hypoxia (IH, cyclic between air and 5% O2 per minute, 8 hour/day) or in isobaric chamber breathing 10% O2 for chronic hypoxia (CH, 24 hour/day) for up to 4 weeks. Immunohistochemical (IHC) studies revealed that, in the IH and CH groups, the immunoreactivity (IR) of AT1 receptor was mainly observed in glomic clusters of the CB. The AT1 receptor expression was markedly elevated in the 3- day IH group but not in the CH, and it reached a plateau at day 7. Also, intracellular calcium response to AT was enhanced in the fura-2 loaded dissociated glomus cells from 3-day IH rats when compared with the normoxic controls. Levels of oxidative stress in the CB were assessed by IHC method using specific antibody against nitrotyrosine (NTR) and ELISA for the detection of total 8-isoprostane (IPT) in the serum. NTR-IR and IPT levels were significantly elevated in 7-day IH group and returned to normoxic levels by day 14, whereas mild expression of NTR and IPT were observed in the CH and normoxic controls throughout the time course. These data suggest that oxidative stress occurred within the first week in the IH but not with the CH group. In conclusion, the upregulation of the AT1 receptor expression may play a role in the enhancement of CB excitability during IH and this is associated with oxidative stress during an early time course. (Supported by research grants from Research Grants Council, HKSAR and the University of Hong Kong)
Persistent Identifierhttp://hdl.handle.net/10722/95123
ISSN

 

DC FieldValueLanguage
dc.contributor.authorLam, SSYen_HK
dc.contributor.authorTipoe, GLen_HK
dc.contributor.authorTjong, YWen_HK
dc.contributor.authorLiong, ECen_HK
dc.contributor.authorFung, MLen_HK
dc.date.accessioned2010-09-25T15:52:22Z-
dc.date.available2010-09-25T15:52:22Z-
dc.date.issued2004en_HK
dc.identifier.citationThe 6th World Congress on Mountain Medicine & High Altitude Physiology, Xining, China, 12-20 August 2004. In High Altitude Medicine & Biology, 2004, v. 5 n. 2, p. 238 Abstract no. 127en_HK
dc.identifier.issn1557-8682-
dc.identifier.urihttp://hdl.handle.net/10722/95123-
dc.description.abstractThe carotid body (CB) plays an important role in cardiorespiratory changes in intermittent hypoxia. Recent data suggest an involvement of angiotensin II (AT) and reactive oxygen species in the pathophysiological development. The aim of this study was to examine the expression of AT1 receptor and the by-products of oxidative stress in the CB of rats exposed to intermittent hypoxia (IH, cyclic between air and 5% O2 per minute, 8 hour/day) or in isobaric chamber breathing 10% O2 for chronic hypoxia (CH, 24 hour/day) for up to 4 weeks. Immunohistochemical (IHC) studies revealed that, in the IH and CH groups, the immunoreactivity (IR) of AT1 receptor was mainly observed in glomic clusters of the CB. The AT1 receptor expression was markedly elevated in the 3- day IH group but not in the CH, and it reached a plateau at day 7. Also, intracellular calcium response to AT was enhanced in the fura-2 loaded dissociated glomus cells from 3-day IH rats when compared with the normoxic controls. Levels of oxidative stress in the CB were assessed by IHC method using specific antibody against nitrotyrosine (NTR) and ELISA for the detection of total 8-isoprostane (IPT) in the serum. NTR-IR and IPT levels were significantly elevated in 7-day IH group and returned to normoxic levels by day 14, whereas mild expression of NTR and IPT were observed in the CH and normoxic controls throughout the time course. These data suggest that oxidative stress occurred within the first week in the IH but not with the CH group. In conclusion, the upregulation of the AT1 receptor expression may play a role in the enhancement of CB excitability during IH and this is associated with oxidative stress during an early time course. (Supported by research grants from Research Grants Council, HKSAR and the University of Hong Kong)-
dc.languageengen_HK
dc.publisherMary Ann Liebert, Inc.-
dc.relation.ispartofHigh Altitude Medicine & Biologyen_HK
dc.titleIntermittent hypoxia increases AT1 receptor and oxidative stress in the rat carotid bodyen_HK
dc.typeConference_Paperen_HK
dc.identifier.emailLam, SSY: lam.sy.sylvia@gmail.comen_HK
dc.identifier.emailTipoe, GL: tgeorge@hkucc.hku.hken_HK
dc.identifier.emailTjong, YW: jefftjong@yahoo.com.hken_HK
dc.identifier.emailLiong, EC: eclionga@HKUCC.hku.hken_HK
dc.identifier.emailFung, ML: fungml@hkucc.hku.hken_HK
dc.identifier.authorityTipoe, GL=rp00371en_HK
dc.identifier.authorityFung, ML=rp00433en_HK
dc.identifier.hkuros104410en_HK
dc.identifier.volume5en_HK
dc.identifier.issue2en_HK
dc.identifier.spage238en_HK

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