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Highs and lows of sympathetic neurocardiovascular transduction: influence of altitude acclimatization and adaptation

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dc.contributor.author Berthelsen, L.F.
dc.contributor.author Fraser, G.M.
dc.contributor.author Simpson, L.L.
dc.contributor.author Vanden Berg, E.R.
dc.contributor.author Busch, S.A.
dc.contributor.author Steele, A.R.
dc.contributor.author Meah, V.L.
dc.contributor.author Lawley, J.S.
dc.contributor.author Figueroa-Mujíca, R.J.
dc.contributor.author Vizcardo-Galindo, G.
dc.contributor.author Villafuerte, F.
dc.contributor.author Gasho, C.
dc.contributor.author Willie, C.K.
dc.contributor.author Tymko, M.M.
dc.contributor.author Ainslie, P.N.
dc.contributor.author Stembridge, M.
dc.contributor.author Moore, J.P.
dc.contributor.author Steinback, C.D.
dc.date.accessioned 2020-12-14T16:06:09Z
dc.date.available 2020-12-14T16:06:09Z
dc.date.issued 2020
dc.identifier.uri https://hdl.handle.net/20.500.12866/8668
dc.description.abstract High-altitude (>2,500 m) exposure results in increased muscle sympathetic nervous activity (MSNA) in acclimatizing lowlanders. However, little is known about how altitude affects MSNA in indigenous high-altitude populations. Additionally, the relationship between MSNA and blood pressure regulation (i.e., neurovascular transduction) at high-altitude is unclear. We sought to determine 1) how high-altitude effects neurocardiovascular transduction and 2) whether differences exist in neurocardiovascular transduction between low- and high-altitude populations. Measurements of MSNA (microneurography), mean arterial blood pressure (MAP; finger photoplethysmography), and heart rate (electrocardiogram) were collected in 1) lowlanders (n = 14) at low (344 m) and high altitude (5,050 m), 2) Sherpa highlanders (n = 8; 5,050 m), and 3) Andean (with and without excessive erythrocytosis) highlanders (n = 15; 4,300 m). Cardiovascular responses to MSNA burst sequences (i.e., singlet, couplet, triplet, and quadruplet) were quantified using custom software (coded in MATLAB, v.2015b). Slopes were generated for each individual based on peak responses and normalized total MSNA. High altitude reduced neurocardiovascular transduction in lowlanders (MAP slope: high altitude, 0.0075 ± 0.0060 vs. low altitude, 0.0134 ± 0.080; P = 0.03). Transduction was elevated in Sherpa (MAP slope, 0.012 ± 0.007) compared with Andeans (0.003 ± 0.002, P = 0.001). MAP transduction was not statistically different between acclimatizing lowlanders and Sherpa (MAP slope, P = 0.08) or Andeans (MAP slope, P = 0.07). When resting MSNA is accounted for (ANCOVA), transduction was inversely related to basal MSNA (bursts/minute) independent of population (RRI, r = 0.578 P < 0.001; MAP, r = -0.627, P < 0.0001). Our results demonstrate that transduction is blunted in individuals with higher basal MSNA, suggesting that blunted neurocardiovascular transduction is a physiological adaptation to elevated MSNA rather than an effect or adaptation specific to chronic hypoxic exposure.NEW & NOTEWORTHY This study has identified that sympathetically mediated blood pressure regulation is reduced following ascent to high-altitude. Additionally, we show that high altitude Andean natives have reduced blood pressure responsiveness to sympathetic nervous activity (SNA) compared with Nepalese Sherpa. However, basal sympathetic activity is inversely related to the magnitude of SNA-mediated fluctuations in blood pressure regardless of population or condition. These data set a foundation to explore more precise mechanisms of blood pressure control under conditions of persistent sympathetic activation and hypoxia. en_US
dc.language.iso eng
dc.publisher American Physiological Society
dc.relation.ispartof urn:issn:1522-1539
dc.rights info:eu-repo/semantics/restrictedAccess
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/4.0/deed.es
dc.subject UNAVAILABLE en_US
dc.title Highs and lows of sympathetic neurocardiovascular transduction: influence of altitude acclimatization and adaptation en_US
dc.type info:eu-repo/semantics/article
dc.identifier.doi https://doi.org/10.1152/ajpheart.00364.2020
dc.subject.ocde https://purl.org/pe-repo/ocde/ford#3.02.00 es_PE
dc.subject.ocde https://purl.org/pe-repo/ocde/ford#3.01.08
dc.subject.ocde https://purl.org/pe-repo/ocde/ford#3.02.04

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