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dc.contributor.authorSimpson, Lydia
dc.contributor.authorBusch, Stephen
dc.contributor.authorOliver, Samuel
dc.contributor.authorAinslie, Philip
dc.contributor.authorStembridge, Mike
dc.contributor.authorSteinback, Craig
dc.contributor.authorMoore, Jonathan
dc.date.accessioned2019-03-20T11:30:33Z
dc.date.available2019-03-20T11:30:33Z
dc.date.issued2019-03-20
dc.identifier.citationSimpson, L.L., Busch, S.A., Oliver, S.J., Ainslie, P.N., Stembridge, M., Steinback, C.D. and Moore, J.P. (2019) 'Baroreflex control of sympathetic vasomotor activity and resting arterial pressure at high altitude: insight from Lowlanders and Sherpa', The Journal of Physiology.https://doi.org/10.1113/JP277663
dc.identifier.issn1469-7793
dc.identifier.urihttp://hdl.handle.net/10369/10385
dc.descriptionArticle published in Journal of Physiology available at https://doi.org/10.1113/JP277663en_US
dc.description.abstractExposure to high altitude (HA) is characterized by heightened muscle sympathetic neural activity (MSNA); however, the effect on arterial baroreflex control of MSNA is unknown. Furthermore, arterial baroreflex control at HA may be influenced by genotypic and phenotypic differences between lowland and highland natives. Fourteen Lowlanders (10 male) and 9 male Sherpa underwent haemodynamic and sympathetic neural assessment at low altitude (Lowlanders, LA; 344m, Sherpa, KT; 1400m) and following gradual ascent to 5050m. Beat-by-beat haemodynamics (photoplethysmography) and MSNA (microneurography) were recorded lying supine. Indices of vascular sympathetic baroreflex function were determined from the relationship of diastolic blood pressure (DBP) and corresponding MSNA at rest (i.e. DBP ‘operating pressure’ and MSNA ‘operating point’), and during a modified Oxford baroreflex test (i.e. ‘gain’). Operating pressure and gain were unchanged for Lowlanders during HA exposure; however, the operating point was reset upwards (48 ± 16 vs 22 ± 12 bursts·100HB-1, P=0.001). Compared to Lowlanders at 5050m, Sherpa had similar gain and operating pressure, but operating point was lower (30 ± 13 bursts·100HB-1P=0.02); MSNA burst frequency was lower for Sherpa (22 ± 11 versus 30 ± 9 bursts·min-1 P = 0.03). Breathing 100% oxygen did not alter vascular sympathetic baroreflex function for either group at HA. For Lowlanders, upward baroreflex resetting promotes heightened sympathetic vasoconstrictor activity and maintains blood pressure stability, at least during early HA exposure; mechanisms other than peripheral chemoreflex activation could be involved. Sherpa adaptation appears to favour lower sympathetic vasoconstrictor activity than Lowlanders for blood pressure homeostasis.en_US
dc.description.sponsorshipThis study was supported by the Natural Sciences and Engineering Research Council of Canada (CDS, PNA), a Canada Research Chair in Cerebrovascular Physiology grant (PNA), and a University of Alberta, Presidents Grant for the Creative and Performance Arts – Human Performance Scholarship (CDS)en_US
dc.language.isoenen_US
dc.publisherWileyen_US
dc.relation.ispartofseriesJournal of Physiology;
dc.titleBaroreflex control of sympathetic vasomotor activity and resting arterial pressure at high altitude: insight from Lowlanders and Sherpaen_US
dc.typeArticleen_US
dc.identifier.doihttps://doi.org/10.1113/JP277663
dcterms.dateAccepted2019-03-18
rioxxterms.versionAMen_US
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/under-embargo-all-rights-reserveden_US
rioxxterms.licenseref.startdate2019-03-20
rioxxterms.freetoread.startdate2020-03-20


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