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dc.contributor.authorBusch, Stephen
dc.contributor.authorSimpson, Lydia
dc.contributor.authorSobierajski, Frances
dc.contributor.authorRiske, Laurel
dc.contributor.authorAinslie, Philip
dc.contributor.authorWillie, Chris
dc.contributor.authorStembridge, Mike
dc.contributor.authorMoore, Jonathan
dc.contributor.authorSteinback, Craig
dc.date.accessioned2020-01-07T12:29:39Z
dc.date.available2020-01-07T12:29:39Z
dc.date.issued2020-01-08
dc.identifier.citationBusch, S.A., Simpson, L.L., Sobierajski, F., Riske, L., Ainslie, P.N., Willie, C.K., Stembridge, M., Moore, J.P. and Steinback, C.D. (2020) 'Muscle Sympathetic Reactivity to Apneic and Exercise Stress in High-Altitude Sherpa', American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
dc.identifier.issn0363-6119
dc.identifier.issn1522-1490 online
dc.identifier.urihttp://hdl.handle.net/10369/10882
dc.descriptionArticle published in American Journal of Physiology-Regulatory, Integrative and Comparative Physiology on 08 January 2020, available at: https://doi.org/10.1152/ajpregu.00119.2019.en_US
dc.description.abstractLowland-dwelling populations exhibit persistent sympathetic hyperactivity at altitude that may alter vascular function. High altitude populations, such as Sherpa, exhibit greater peripheral blood flow in response to acute stress, suggesting Sherpas may exhibit lower sympathetic activity and reactivity to stress than Lowlanders. Muscle sympathetic activity (MSNA; microneurography) including frequency (bursts/min), incidence (bursts/100HB), amplitude (% of max burst), was measured at rest in Lowlanders (n=14; age=27±6yrs) at 344m and following a 8- 9 days of graded ascent to 5050m. Sherpa (age=32±11yrs) were tested at 5050m (n=8). Neurovascular reactivity (i.e., change in MSNA patterns) was measured during maximal end expiratory apnea, isometric hand-grip (IHG; 30% maximal voluntary contraction for 2 minutes) and post exercise circulatory occlusion (PECO; 3 minutes). Total normalized SNA (au/min) was calculated over 10 cardiac cycles during baseline and pre-volitional apnea breakpoint. Lowlander burst frequency (11±5 bursts/min to 30±7 bursts/min; Mean±SD; p<0.001) and burst incidence (25±13 bursts/100HB to 53±15 bursts/100HB; p<0.001) increased at 5050m. In contrast, Sherpas had lower burst frequency (23±11 bursts/min; p<0.05) and incidence (30±13 bursts/100HB; p<0.05) at 5050m. MSNA increases in Lowlanders and Sherpa during apnea at 5050m were significantly lower than Lowlanders at 344m (both P<0.05), with a possible sympathetic ceiling reached in Lowlanders at 5050m. MSNA increased similarly during the IHG/PECO in Lowlanders at 334m and 5050m altitude and Sherpa at 5050m. Sherpa demonstrate overall lower sympathetic activity and reactivity during severe stress. This may be a result of improved systemic hemodynamic function associated with evolutionary adaptations to permanent residency at altitude.en_US
dc.language.isoenen_US
dc.publisherAmerican Physiological Societyen_US
dc.relation.ispartofseriesAmerican Journal of Physiology-Regulatory, Integrative and Comparative Physiology;
dc.titleMuscle sympathetic reactivity to apneic and exercise stress in high-altitude Sherpaen_US
dc.typeArticleen_US
dc.identifier.doihttps://doi.org/10.1152/ajpregu.00119.2019
dcterms.dateAccepted2019-12-16
rioxxterms.funderCardiff Metropolitan Universityen_US
rioxxterms.identifier.projectCardiff Metropolian (Internal)en_US
rioxxterms.versionAMen_US
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/under-embargo-all-rights-reserveden_US
rioxxterms.freetoread.startdate2021-01-08
rioxxterms.funder.project37baf166-7129-4cd4-b6a1-507454d1372een_US


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