Endocrine, inflammatory and immune responses and individual differences in acute hypobaric hypoxia in lowlanders

Abstract When lowlanders are exposed to hypobaric hypoxia (HH) environments such as high mountains, hemodynamic changes occur to maintain oxygen levels in the body. However, changes to other physiological functions under such conditions have yet to be clarified. This study aimed to investigate changes to endocrine, inflammatory and immune responses and individual differences during acute HH exposure using a climatic chamber (75 min of exposure to conditions mimicking 3500 m) in healthy lowlanders. Aldosterone and cortisol were significantly decreased and interleukin (IL)-6, IL-8 and white blood cell (WBC) count were significantly increased after HH. Lower peripheral oxygen saturation (SpO2) was associated with higher IL-6 and WBC count, and higher IL-8 was associated with higher cortisol. These results suggest that endocrine, inflammatory and immune responses are evoked even with a short 75-min exposure to HH and individuals with lower SpO2 show more pronounced responses. Our results provide basic data for understanding physiological responses and interactions of homeostatic systems with acute HH.