Altitude Hypoxia

About: Altitude Hypoxia is a research topic. Over the lifetime, 166 publications have been published within this topic receiving 2552 citations.

The 2018 Lake Louise Acute Mountain Sickness Score.

Abstract: Roach, Robert C., Peter H. Hackett, Oswald Oelz, Peter Bartsch, Andrew M. Luks, Martin J. MacInnis, J. Kenneth Baillie, and The Lake Louise AMS Score Consensus Committee. The 2018 Lake Louise Acute Mountain Sickness Score. High Alt Med Biol 19:1-4, 2018.- The Lake Louise Acute Mountain Sickness (AMS) scoring system has been a useful research tool since first published in 1991. Recent studies have shown that disturbed sleep at altitude, one of the five symptoms scored for AMS, is more likely due to altitude hypoxia per se, and is not closely related to AMS. To address this issue, and also to evaluate the Lake Louise AMS score in light of decades of experience, experts in high altitude research undertook to revise the score. We here present an international consensus statement resulting from online discussions and meetings at the International Society of Mountain Medicine World Congress in Bolzano, Italy, in May 2014 and at the International Hypoxia Symposium in Lake Louise, Canada, in February 2015. The consensus group has revised the score to eliminate disturbed sleep as a questionnaire item, and has updated instructions for use of the score.

Acute hypoxia and hypoxic exercise induce DNA strand breaks and oxidative DNA damage in humans

Abstract: The present study investigated the effect of a single bout of exhaustive exercise on the generation of DNA strand breaks and oxidative DNA damage under normal conditions and at high-altitude hypoxia (4559 meters for 3 days). Twelve healthy subjects performed a maximal bicycle exercise test; lymphocytes were isolated for analysis of DNA strand breaks and oxidatively altered nucleotides, detected by endonuclease III and formamidipyridine glycosylase (FPG) enzymes. Urine was collected for 24 h periods for analysis of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a marker of oxidative DNA damage. Urinary excretion of 8-oxodG increased during the first day in altitude hypoxia, and there were more endonuclease III-sensitive sites on day 3 at high altitude. The subjects had more DNA strand breaks in altitude hypoxia than at sea level. The level of DNA strand breaks further increased immediately after exercise in altitude hypoxia. Exercise-induced generation of DNA strand breaks was not seen at sea level. In both environments, the level of FPG and endonuclease III-sensitive sites remained unchanged immediately after exercise. DNA strand breaks and oxidative DNA damage are probably produced by reactive oxygen species, generated by leakage of the mitochondrial respiration or during a hypoxia-induced inflammation. Furthermore, the presence of DNA strand breaks may play an important role in maintaining hypoxia-induced inflammation processes. Hypoxia seems to deplete the antioxidant system of its capacity to withstand oxidative stress produced by exhaustive exercise.

The effect of altitude hypoxia on glucose homeostasis in men.

Abstract: 1. Exposure to altitude hypoxia elicits changes in glucose homeostasis with increases in glucose and insulin concentrations within the first few days at altitude. Both increased and unchanged hepatic glucose production (HGP) have previously been reported in response to acute altitude hypoxia. Insulin action on glucose uptake has never been investigated during altitude hypoxia. 2. In eight healthy, sea level resident men (27 +/- 1 years (mean +/- S.E.M); weight, 72 +/- 2 kg; height, 182 +/- 2 cm) hyperinsulinaemic (50 mU min-1 m-2), euglycaemic clamps were carried out at sea level, and subsequently on days 2 and 7 after a rapid passive ascent to an altitude of 4559 m. 3. Acute mountain sickness scores increased in the first days of altitude exposure, with a peak on day 2. Basal HGP did not change with the transition from sea level (2.2 +/- 0.2 mg min-1 kg-1) to altitude (2.0 +/- 0.1 and 2.1 +/- 0.2 mg min-1 kg-1, days 2 and 7, respectively). Insulin-stimulated glucose uptake rate was halved on day two compared with sea level (4.5 +/- 0.6 and 9.8 +/- 1.1 mg min-1 kg-1, respectively; P < 0.05), and was partly restored on day 7 (7.4 +/- 1.4 mg min-1 kg-1; P < 0.05 vs. day two and sea level). Concentrations of glucagon and growth hormone remained unchanged, whereas glucose, C-peptide and cortisol increased on day 2. Noradrenaline concentrations increased during the stay at altitude, while adrenaline concentrations remained unchanged. In response to insulin infusion, catecholamines increased on day 2 (noradrenaline and adrenaline) and day 7 (adrenaline), but not at sea level. 4. In conclusion, insulin action decreases markedly in response to two days of altitude hypoxia, but improves with more prolonged exposure. HGP is always unchanged. The changes in insulin action may in part be explained by the changes in counter-regulatory hormones.

Hypoxemia increases serum interleukin-6 in humans.

Abstract: Serum concentrations of interleukin (IL) 1 beta, IL-1 receptor antagonist (IL-1ra), IL-6, tumor necrosis factor (TNF) alpha, and C-reactive protein (CRP) were determined in ten healthy men at sea level and during four days of altitude hypoxia (4350m above sea level). The mean (SD) arterial blood oxygen saturations were 78.6 (7.3)%, 82.4 (4.9)%, and 83.4 (5.3)% in the first, second, and third days at altitude, respectively. A symptom score of acute mountain sickness (AMS) revealed that the subjects had mostly light symptoms of AMS. Mean serum IL-6 increased from 1.36 (1.04) pg x ml(-1) at sea level to 3.10 (1.65), 4.71 (2.81), and 3,54 (2.17) pg x ml(-1) during the first three days at altitude, and to 9.96 (8.90) pg x ml(-1) on the fourth day at altitude (ANOVA p = 0.002). No changes occurred in serum concentrations of IL-1 beta, IL-1ra, TNF alpha, or CRP. The serum IL-6 were related to SaO2, (r = -0.45, p = 0.003), but not to heart rates or AMS scores. In conclusion, human serum concentrations of IL-6 increased during altitude hypoxia whereas the other proinflammatory cytokines remained unchanged. The major role of IL-6 during altitude hypoxia seem not to be mediation of inflammation, instead, the role of IL-6 could be to stimulate the erythropoiesis at altitude.

Adaptation to Altitude-Hypoxia in Vertebrates

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