Contribution of Adenosine in the Physiological Changes and Injuries Secondary to Exposure to Extreme Oxygen Pressure in Healthy Subjects

Abstract

Climbers and aviators are exposed to severe hypoxia at high altitudes, whereas divers are exposed to hyperoxia at depth. The aim of this study was to report changes in the adenosinergic system induced by exposure to extreme oxygen partial pressures. At high altitudes, the increased adenosine concentration contributes to brain protection against hypoxia through various mechanisms such as stimulation of glycogenolysis for ATP production, reduction in neuronal energy requirements, enhancement in 2,3-bisphosphoglycerate production, and increase in cerebral blood flow secondary to vasodilation of cerebral arteries. In the context of mountain illness, the increased level of A2AR expression leads to glial dysfunction through neuroinflammation and is involved in the pathogenesis of neurological disorders. Nonetheless, a high level of adenosine concentration can protect against high-altitude pulmonary edema via a decrease in pulmonary arterial pressure. The adenosinergic system is also involved in the acclimatization phenomenon induced by prolonged exposure to altitude hypoxia. During hyperoxic exposure, decreased extracellular adenosine and low A2A receptor expression contribute to vasoconstriction. The resulting decrease in cerebral blood flow is considered a preventive phenomenon against cerebral oxygen toxicity through the decrease in oxygen delivery to the brain. With regard to lung oxygen toxicity, hyperoxia leads to an increase in extracellular adenosine, which acts to preserve pulmonary barrier function. Changes in the adenosinergic system induced by exposure to extreme oxygen partial pressures frequently have a benefit in decreasing the risk of adverse effects.

Highlighting of the interactions of MYD88 and NFKB1 SNPs in rats resistant to decompression sickness: toward an autoimmune response

“…Without being exhaustive, we must also remember that previous studies, one of which involves this same strain of rat, evoke reshuffles at the energy level and therefore mitochondria ( Blatteau et al, 2018 ; de Maistre et al, 2020 ; Vallee et al, 2021 ; Boussuges et al, 2022 ; Desruelle et al, 2022 ), whereas the mitochondria is itself a major player in the immune response. These studies also propose the idea of a reorganization of the microbial communities ( de Maistre et al, 2016a ; de Maistre et al, 2016b ; de Maistre et al, 2018 ; de Maistre et al, 2020 ; Vallee et al, 2021 ; Desruelle et al, 2022 ), which have two particularities: interacting with the immune system ( Korach-Rechtman et al, 2019 ) and being sensitive to oxygen (presence of anerobic species).…”