Oxy-inflammation after repetitive "open circuit" dives in the Baltic Sea

SCUBA diving involves exposure to a hyperbaric environment that can induce oxidative stress and inflammation. This study investigates the evolution of oxy-inflammation status in divers who performed repetitive dives in cold water.

In the Baltic Sea, nine expert divers were recruited to perform five dives (T1-T5). Urine and saliva were collected before (A) and after (B) each dive. Reactive Oxygen Species (ROS), total antioxidant capacity (TAC), lipid peroxidation (8-iso-PGF2α), DNA damage (8-OH-dG), inflammatory status (IL-6), nitric oxide metabolites, neopterin, and electrolyte balance changes were investigated.

Pre-dive values showed significant increases at the fourth to fifth days in ROS (+45 and +89%) and consequently in lipid peroxidation (+65%) at the fourth day and in DNA damage (+49 and +61%) at the fourth to fifth days, respectively, compared to the first day value. Post-dive significant increases were recorded at the fourth to fifth days in ROS (+83 % and +146%), and at the fifth day in lipid peroxidation (+59%) and DNA damage (+41%) with respect to the post-dive value of the first day. TAC showed a decrease from the fourth to fifth days post-dive (-15% and -24%) compared to the value on the first day post-dive. Finally, IL-6 increased at the basal level of the fifth day (+183%) and post dive (+154%) with respect to the corresponding values of the first day.

Repetitive dives in cold water induced a progressive increase in pre-dive ROS, 8-iso-PGF2α, 8-OH-dG, and IL-6. Oxidative stress was only partially contained by activation of endogenous antioxidant defenses, while IL-6 variation resulted from diving-related physical effort or oxy-inflammation. We did not find notable changes in the electrolyte balance, probably because all subjects examined were well- trained and experienced divers.