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Differential kinetics of the cardiac, ventilatory, and gas exchange variables during walking under moderate hypoxia.

ABSTRACT: We investigated the effects of moderate hypoxia (FiO2 = 15%) on different kinetics between pulmonary ventilation ([Formula: see text]) and heart rate (HR) during treadmill walking. Breath-by-breath [Formula: see text], oxygen uptake ([Formula: see text]), carbon dioxide output ([Formula: see text]), and HR were measured in 13 healthy young adults. The treadmill speed was sinusoidally changed from 3 to 6 km·h-1 with four oscillation periods of 1, 2, 5, and 10 min. The amplitude (Amp), phase shift (PS) and mean values of these kinetics were obtained by harmonic analysis. The mean values of all of these responses during walking at a sinusoidally changing speed became greater under hypoxia compared to normoxia (FiO2 = 21%), indicating that moderate hypoxia could achieve an increased energy expenditure (increased [Formula: see text] and [Formula: see text]) and hyperventilation. The Amp values of the [Formula: see text], [Formula: see text], and [Formula: see text] kinetics were not significantly different between normoxia and hypoxia at most periods, although a significantly smaller Amp of the HR was observed at faster oscillation periods (1 or 2 min).The PS of the HR was significantly greater under hypoxia than normoxia at the 2, 5, and 10 min periods, whereas the PS of the [Formula: see text], [Formula: see text], and [Formula: see text] responses was not significantly different between normoxia and hypoxia at any period. These findings suggest that the lesser changes in Amp and PS in ventilatory and gas exchange kinetics during walking at a sinusoidally changing speed were remarkably different from a deceleration in HR kinetics under moderate hypoxia.

SUBMITTER: Ebine N

PROVIDER: S-EPMC6059434 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Differential kinetics of the cardiac, ventilatory, and gas exchange variables during walking under moderate hypoxia.

Ebine Naoyuki N Aoki Tomoko T Itoh Masahiro M Fukuoka Yoshiyuki Y

PloS one 20180725 7

We investigated the effects of moderate hypoxia (FiO2 = 15%) on different kinetics between pulmonary ventilation ([Formula: see text]) and heart rate (HR) during treadmill walking. Breath-by-breath [Formula: see text], oxygen uptake ([Formula: see text]), carbon dioxide output ([Formula: see text]), and HR were measured in 13 healthy young adults. The treadmill speed was sinusoidally changed from 3 to 6 km·h-1 with four oscillation periods of 1, 2, 5, and 10 min. The amplitude (Amp), phase shift ...[more]

PMID: 30044809

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Project description:Background: HIV infection is associated with impaired gas transfer in the lung as indicated by a low diffusing capacity (DLCO). Mechanisms for reduced DLCO in the setting of HIV infection are not well understood. We hypothesized that HIV-associated gas exchange impairment is indicative of system-wide perturbations that could be reflected by alterations in peripheral blood gene expression. Methods: A total of 40 HIV-infected (HIV+) and uninfected (HIV-) men with preserved versus reduced DLCO were selected from a larger cohort study of lung function. All subjects were current smokers and those with acute illness, lung diseases other than COPD or asthma were excluded. Total RNA was extracted from peripheral blood leukocytes (PBLs) and hybridized to whole-genome microarrays. Gene set enrichment analysis (GSEA) was performed between HIV+ vs. HIV- subjects with preserved DLCO and those with impaired DLCO to identify differentially activated pathways. Results: Using pathway-based analyses we found that in subjects with preserved DLCO, HIV infection is associated with activation of processes involved in immunity, cell cycle, and apoptosis. When we applied a similar analysis to subjects with low DLCO, we identified a much broader repertoire of inflammatory and immune-related pathways in HIV+ patients relative to HIV- subjects, with up-regulation of multiple interleukin pathways, interferon signaling, Toll-like receptor signaling, and T cell/B cell receptor signaling. We confirmed elevated circulating levels of IL-6 in HIV+ patients with reduced DLCO relative to the other groups. Conclusions: Our findings reveal that PBLs of subjects with HIV infection and low DLCO are distinguished by widespread enrichment of immuno-inflammatory programs. Activation of these pathways may alter the biology of circulating leukocytes and play a role in the pathogenesis of HIV-associated pulmonary gas exchange impairment. Total RNA was isolated from peripheral blood leukocytes in four subject groups: 1. HIV-, low DLCO (N = 11); 2. HIV+, low DLCO (N = 10); 3. HIV-, preserved DLCO (N = 9); 4. HIV+, preserved DLCO (N = 9). Each sample was hybridized to an Affymetrix PrimeView Human Gene Expression microarray for a total of 39 experiments.

Dataset Information

Differential kinetics of the cardiac, ventilatory, and gas exchange variables during walking under moderate hypoxia.

Publications

Differential kinetics of the cardiac, ventilatory, and gas exchange variables during walking under moderate hypoxia.

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