Increase in slow-wave vasomotion by hypoxia and ischemia in lowlanders and highlanders

Paolo Salvi, Andrea Faini, Paolo Castiglioni, Fausto Brunacci, Luca Montaguti, Francesca Severi, Sylvie Gautier, Enzo Pretolani, Athanase Benetos, Gianfranco Parati

Research output: Contribution to journalArticle

Abstract

The physiological relevance of slow-wave vasomotion is still unclear, even though it has been hypothesized that it could be a compensatory mechanism for enhancing tissue oxygenation in conditions of reduced oxygen supply. The aim of our study was to explore the effects of hypoxia and ischemia on slow-wave vasomotion in microcirculation. Peripheral oxygen saturation and forearm microcirculation flow (laser-Doppler flowmetry) were recorded at baseline and during postocclusive reactive hyperemia in the Himalaya region from 8 European lowlanders (6 men; aged 29-39 yr) at 1,350, 3,400, and 5,050 m and from 10 Nepalese male highlanders (aged 21-39 yr) at 3,400 and 5,050 m of altitude. The same measurements were also performed at sea level in 16 healthy volunteers (aged 23-61 yr) during a short-term exposure to normobaric hypoxia. In lowlanders, exposure to progressively higher altitude under baseline flow conditions progressively increased 0.06-0.15 Hz vasomotion amplitude [power spectral density % was expressed as geometric means (geometric standard deviation) = 14.0 (3.6) at 1,350 m; 87.0(2.3) at 3,400 m and 249.8 (3.6) at 5,050 m; P = 0.006 and P < 0.001 vs. 1,350 m, respectively]. In highlanders, low frequency vasomotion amplitude was similarly enhanced at different altitudes [power spectral density % = 183.4 (4.1) at 3,400 m vs. 236.0 (3.0) at 5,050 m; P = 0.139]. In both groups at altitude, it was further increased after ischemic stimulus ( P < 0.001). At baseline, acute short lasting normobaric hypoxia did not induce low frequency vasomotion, which was conversely induced by ischemia, even under normal oxygenation and barometric pressure. This study offers the demonstration of a significant increase in slow-wave vasomotion under prolonged hypobaric-hypoxia exposure at high altitude, with a further enhancement after ischemia induction. NEW & NOTEWORTHY This study offers the demonstration in humans of the occurrence of enhanced slow-wave vasomotion in microcirculation induced by exposure to hypobaric hypoxia, ischemia, and their combination. This phenomenon, where vasomotion can be hypothesized to behave as a "peripheral heart," may represent a compensating adaptive change aimed at improving peripheral flow and tissue oxygenation in conditions of reduced oxygen supply, such as altitude-induced hypobaric hypoxia and postocclusion ischemia.

Original languageEnglish
Pages (from-to)780-789
Number of pages10
JournalJournal of Applied Physiology
Volume125
Issue number3
DOIs
Publication statusPublished - Sep 1 2018

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