Acute Hyperbaria and Hyperoxia Effects on Oxidative Stress Kinetic Response: A Simulated Study

Abstract

This study aims to investigate the effects hyperoxia/hyperbaria on both oxidative stress and antioxidant response. To this purpose two different protocols were performed at rest conditions: (1) fifteen male divers (age of 28.9 ± 5.3 years) simulated immersions at resting conditions in a hyperbaric chamber (HBO) at a depth of 40 m seawater for 30 min; (2) nine healthy male subjects (age of 25.3 ± 1.2 years) breathed pure oxygen for 30 min. Oxidative stress biomarkers in the plasma were monitored before and during the 3 h after the exposure. Total antioxidant capacity significantly decreased immediately at the end of both HBO and pure oxygen exposures (‒19% and ‒16%, respectively; p < 0.001), and thereafter increased during the recovery period. Concentrations of protein carbonyls, assessed as a marker of protein oxidation, significantly increased after both HBO (+52%, p < 0.001) and pure oxygen (+65%, p < 0.05) exposures, but following different kinetic pathways. A significant increase (+21%; p < 0.0001) in thiobarbituric acid-reactive substances, assessed as a marker of lipid peroxidation, was found only after HBO, attaining the maximum concentration at about 1 h after the end of exposure. The values of all the examined parameters returned back to the basal levels within 3 h of the recovery phase. HBO exposure probably resulted in a more pronounced ROS formation, and this can be explained by taking into account that ROS leakage by mitochondria is believed to increase in direct proportion to the oxygen pressure rise.