Heliox Saturation Diving to 500kPa. Effects of Saturation Diving on Oxidative Stress in a Rat Model

Abstract

Formation of vascular gas bubbles following decompression has for a long time been considered to be the main initiator of decompression related illness. However, the presence of silent bubbles may suggest another underlying cause to the problem. Oxygen has toxic properties that are particularly prominent under hyperbaric conditions, producing reactive oxygen species (ROS) that alter physiological functions. Aim and hypotheses: The aim of this study was to examine the effects of hyperbaric conditions on oxidative stress in a rat model. It was hypothesized that lipid peroxidation would increase, and antioxidant concentrations of SOD and catalase would decrease in response to simulated saturation diving. Methods: Forty rats were divided into four groups; two diving groups and two respective control groups. Heart and pulmonary artery of the rats were scanned for vascular gas bubbles, in vivo, for one or four hours after surfacing to indicate decompression stress. Blood was drawn and serum measurements of TBARS, SOD and catalase were performed. Results: No vascular gas bubbles were detected, except for one rat with maximum bubble grade 2-3. There were no significant differences in TBARS or SOD concentrations between the four groups. Catalase concentrations did however differ, with significantly lower concentrations in diving groups compared to the respective control groups. Conclusion: Bubble formation, lipid peroxidation and SOD were not significantly affected by hyperbaric exposure, thus the applied dive profile did not seem to cause excessive oxidative stress to the rats.