Fersiynau electronig

Dangosydd eitem ddigidol (DOI)

  • Joshua C Tremblay
  • Geoff B Coombs
    University of British Columbia, Okanagan
  • Connor A Howe
    University of British Columbia, Okanagan
  • Gustavo A Vizcardo-Galindo
    Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígeno
  • Rómulo J Figueroa-Mujíca
    Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígeno
  • Daniela Bermudez
    Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígeno
  • Michael M Tymko
    University of British Columbia, Okanagan
  • Francisco C Villafuerte
    Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígeno
  • Philip N Ainslie
    University of British Columbia, Okanagan
  • Kyra E Pyke
    Queen's University

Excessive erythrocytosis [EE; hemoglobin concentration (Hb) ≥ 21 g/dL in adult men] is a maladaptive high-altitude pathology associated with increased cardiovascular risk and reduced reactive hyperemia flow-mediated dilation (FMD); however, whether a similar impairment occurs in response to more commonly encountered sustained increases in shear stress [sustained stimulus (SS)-FMD] over a range of overlapping stimuli is unknown. We characterized SS-FMD in response to handgrip exercise in Andeans with and without EE in Cerro de Pasco, Peru (4,330 m). Andean highlanders with EE (n = 17, Hb = 23.2 ± 1.2 g/dL) and without EE (n = 23, Hb = 18.7 ± 1.9 g/dL) performed 3 min of rhythmic handgrip exercise at 20, 35, and 50% of maximum voluntary contraction (MVC). Duplex ultrasound was used to continuously record blood velocity and diameter in the brachial artery, and blood viscosity was measured to accurately calculate shear stress. Although baseline shear stress did not differ, Andeans with EE had 22% lower shear stress than Andeans without at 50% MVC (P = 0.004). At 35 and 50% MVC, SS-FMD was 2.1 ± 2.0 and 2.8 ± 2.7% in Andeans with EE compared with 4.1 ± 3.4 and 7.5 ± 4.5% in those without (P = 0.048 and P < 0.001). The stimulus-response slope (∆shear stress vs. ∆diameter) was lower in Andeans with EE compared with Andeans without (P = 0.028). This slope was inversely related to Hb in Andeans with EE (r2 = 0.396, P = 0.007). A reduced SS-FMD in response to small muscle mass exercise in Andeans with EE indicates a generalized reduction in endothelial sensitivity to shear stress, which may contribute to increased cardiovascular risk in this population.NEW & NOTEWORTHY High-altitude excessive erythrocytosis (EE; hemoglobin concentration ≥ 21 g/dL) is a maladaptation to chronic hypoxia exposure and is associated with increased cardiovascular risk. We examined flow-mediated dilation (FMD) in response to sustained elevations in shear stress achieved using progressive handgrip exercise [sustained stimulus (SS)-FMD] in Andean highlanders with and without EE at 4,330 m. Andeans with EE demonstrated lower SS-FMD compared with those without. Heightened hemoglobin concentration was related to lower SS-FMD in Andeans with EE.

Allweddeiriau

Iaith wreiddiolSaesneg
Tudalennau (o-i)H991-H1001
CyfnodolynAmerican Journal of Physiology - Heart and Circulatory Physiology
Cyfrol317
Rhif y cyfnodolyn5
Dynodwyr Gwrthrych Digidol (DOIs)
StatwsCyhoeddwyd - 1 Tach 2019
Cyhoeddwyd yn allanolIe
Gweld graff cysylltiadau