ABSTRACT
BACKGROUND:
Several mechanisms allow
humans to resist the extreme conditions encountered during breath-hold
diving. Available
nitric oxide (NO) is one of the major contributors to such complex adaptations at depth and
oxidative stress is one of the major collateral effects of
diving. Due to technical difficulties, these
biomarkers have not so far been studied in vivo while at depth. The aim of this study is to investigate
nitrate and
nitrite (NOx) concentration, total
antioxidant capacity (TAC) and
lipid peroxidation (
TBARS) before, during, and after repetitive breath-hold dives in
healthy volunteers. MATERIALS AND
METHODS:
Blood plasma, obtained from 14 expert breath-hold divers, was tested for differences in NOx, TAC, and
TBARS between pre-dive, bottom, surface, 30 and 60 min post-dive samples.
RESULTS:
We observed a statistically significant increase of NOx
plasma concentration in the "bottom
blood draw" as compared to the pre-dive condition while we did not find any difference in the following samples We found a statistically significant decrease in TAC at the bottom but the value returned to
normality immediately after reaching the surface. We did not find any statistically significant difference in
TBARS.
DISCUSSION:
The increased
plasma NOx values found at the bottom were not observed at surface and post dive sampling (T0, T30, T60), showing a very rapid return to the pre-dive values. Also TAC values returned to pre-
diving levels immediately after the end of hyperbaric exposure, probably as a consequence of the activation of
endogenous antioxidant defenses.
TBARS did not show any difference during the protocol.
