Physiological and Biochemical Parameters of Normobaric Hypoxia Stress in Humans

The aim of the study is to examine the dynamics of the sympathoadrenal and adrenocortical components of acute normobaric hypoxia stress and their correlation with some physiological and biochemical parameters characterizing the energy metabolism in humans. Materials and methods. Fourteen trial subjects were exposed to 40-minute hypoxia while breathing nitrogen-oxygen mixture containing 9 % of oxygen. At 5th, 10th, 20th, and 40th minutes of hypoxia, blood was taken from the cubital vein for further analysis. The authors determined a number of physiological parameters, such as pulse rate; blood pressure; oxygen consumption; rheographic index of cerebral blood flow. We also evaluated epinephrine, norepinephrine, cortisol, lactate and glucose blood levels at the time of sampling. The authors estimated the increase in parameters at control points compared to baseline, as well as the correlation of the increase in various indicators. Results. A significant increase in blood epinephrine (max. min 20), norepinephrine (max. min 10) and lactate (max. min 40) was found in trial subjects under hypoxia compared to baseline parameters. A significant increase in oxygen consumption and rheographic index of cerebral blood flow was established under hypoxia (max. min 40). The longer the trial subject was exposed to hypoxia, the more the degree of conjugation in the dynamics of sympathoadrenal response, cerebral blood flow, and energy metabolism (lactate, glucose) was. Conclusion. The obtained facts prove the heterochrony of sympathoadrenal and adrenocortical stress components in the dynamics of the human body response to acute normobaric hypoxia. With hypoxia development, the impact of the adrenergic component on mobilizing the energy of glycolytic processes increases.