Highs and Lows of Sympathetic Neuro-cardiovascular Transduction: Influence of Altitude Acclimatization and Adaptation
Vanden Berg, Emily
Busch, Stephen A.
Steele, Andrew R.
Meah, Victoria L.
Tymko, Michael M.
Ainslie, Philip N.
Moore, Jonathan P.
Steinback, Craig D.
American Physiological Society
MetadataDangos cofnod eitem llawn
High-altitude (>2500m) exposure results in increased muscle sympathetic nervous activity (MSNA) in acclimatizing lowlanders. However, little is known about how altitude affects MSNA in 66 indigenous high-altitude populations. Additionally, the relationship between MSNA and blood 67 pressure regulation (i.e., neurovascular transduction) at high-altitude is unclear. We sought to 68 determine 1) how high-altitude effects neuro-cardiovascular transduction and 2) whether 69 differences exist in neuro-cardiovascular transduction between low and high-altitude 70 populations. Measurements of MSNA (microneurography), mean arterial blood pressure (MAP; 71 finger photoplethysmography), and heart rate (electrocardiogram) were collected in: I) 72 lowlanders (n=14) at low (344m) and high-altitude (5050m), II) Sherpa highlanders (n=8; 73 5050m), and III) Andean (with and without excessive erythrocytosis) highlanders (n=15; 74 4300m). Cardiovascular responses to MSNA burst sequences (i.e. singlet, couplet, triplet, and 75 quadruplets) were quantified using custom software (coded in MATLAB, v2015b). Slopes were 76 generated for each individual based on peak responses and normalized total MSNA. High 77 altitude reduced neuro-cardiovascular transduction in lowlanders (MAP slope: high-altitude, 78 0.0075±0.0060 vs low-altitude, 0.0134±0.080; p=0.03). Transduction was elevated in Sherpa 79 (MAP slope, 0.012±0.007) compared to Andeans (0.003±0.002; p=0.001). MAP transduction 80 was not statistically different between acclimatizing lowlanders and Sherpa (MAP slope, p=0.08) 81 or Andeans (MAP slope, p=0.07). When accounting for resting MSNA (ANCOVA), transduction 82 was inversely related to basal MSNA (bursts/min) independent of population (RRI, r= 0.578 83 p<0.001; MAP, r= -0.627 p<0.0001). Our results demonstrate transduction is blunted in 84 individuals with higher basal MSNA, suggesting blunted neuro-cardiovascular transduction is a 85 physiological adaptation to elevated MSNA rather than an effect or adaptation specific to 86 chronic hypoxic exposure.
American Journal of Physiology - Heart and Circulatory Physiology;
Berthelsen, L.F., Fraser, G.M., Simpson, L.L., Vanden Berg, E.R., Busch, S.A., Steele, A.R., Meah, V.L., Lawley, J.S., Figueroa-Mujíca, R., Vizcardo Galindo, G.A., Villafuerte, F.C., Gasho, C., Willie, C., Tymko, M., Ainslie, P., Stembridge, M., Moore, J.P. & Steinback, C.D. (2020) 'Highs and Lows of Sympathetic Neuro-cardiovascular Transduction: Influence of Altitude Acclimatization and Adaptation', American Journal of Physiology-Heart and Circulatory Physiology. https://doi.org/10.1152/ajpheart.00364.2020
Dynodwr Gwrthrych Digidol (DOI)https://doi.org/10.1152/ajpheart.00364.2020
Article published in AJP- Heart and Circulatory Physiology, available at https://doi.org/10.1152/ajpheart.00364.2020
Cardiff Metropolitan University (Grant ID: Cardiff Metropolian (Internal))
- Sport Research Groups 
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Steele, Andrew; Tymko, Michael; Meah, Victoria L.; Simpson, Lydia; Gasho, Christopher; Dawkins, Tony; Villafuerte, Francisco; Ainslie, Philip N.; Stembridge, Mike; Moore, Jonathan P.; Steinback, Craig D. (American Physiological Society, 2020-09-30)Early acclimatization to high-altitude is characterized by various respiratory, hematological, and cardiovascular adaptations that serve to restore oxygen delivery to tissue. However, less is understood about renal function ...
Short-term adaptation and chronic cardiac remodelling to high altitude in lowlander natives and Himalayan Sherpa Stembridge, Mike; Ainslie, Philip; Shave, Rob (Wiley, 2014-10-18)New Findings - What is the topic of this review? At high altitude, the cardiovascular system must adapt in order to meet the metabolic demand for oxygen. This review summarizes recent findings relating to short‐term and ...
Adenosine receptor dependent signaling is not obligatory for normobaric and hypobaric hypoxia-induced cerebral vasodilation in humans Holland, Ryan; Bain, Anthony; Tymko, Michael; Rieger, Mathew; Howe, Connor; Willie, Christopher; Hansen, Alex; Fluck, Daniela; Wildfong, Kevin; Stembridge, Mike; Subedi, Prajan; Anholm, James; Ainslie, Philip (American Physiological Society, 2017-01-12)Hypoxia increases cerebral blood flow (CBF) with the underlying signaling processes potentially including adenosine. A randomized, double-blinded, placebo controlled design, was implemented to determine if adenosine receptor ...