Reactive Oxygen Species, Mitochondria, and Endothelial Cell Death during In Vitro Simulated Dives.
OBJECTIVE
Excessive reactive oxygen species (ROS) is considered a consequence of hyperoxia and a major contributor to diving-derived vascular endothelial damage and decompression sickness. The aims of this work were: 1) to directly observe endothelial ROS production during simulated air dives as well as its relation with both mitochondrial activity and cell survival; and 2) to determine which ambient factor during air diving (hydrostatic pressure or oxygen and/or nitrogen partial pressure) is responsible for the observed modifications.


METHODS
In vitro diving simulation was performed with bovine arterial endothelial cells under real-time observation. The effects of air diving, hydrostatic, oxygen and nitrogen pressures, and N-acetylcysteine (NAC) treatment on mitochondrial ROS generation, mitochondrial membrane potential and cellular survival during simulation were investigated.


RESULTS
Vascular endothelial cells performing air diving simulation suffered excessive mitochondrial ROS, mitochondrial depolarization, and cell death. These effects were prevented by NAC: after NAC treatment, the cells presented no difference in damage from nondiving cells. Oxygen diving showed a higher effect on ROS generation but lower impacts on mitochondrial depolarization and cell death than hydrostatic or nitrogen diving. Nitrogen diving had no effect on the inductions of ROS, mito-depolarization, or cell death.


CONCLUSIONS
This study is the first direct observation of mitochondrial ROS production, mitochondrial membrane potential and cell survival during diving. Simulated air SCUBA diving induces excessive ROS production, which leads to mitochondrial depolarization and endothelial cell death. Oxygen partial pressure plays a crucial role in the production of ROS. Deleterious effects of hyperoxia-induced ROS are potentiated by hydrostatic pressure. These findings hold new implications for the pathogenesis of diving-derived endothelial dysfunction.
Laboratory ORPHY, Department of UFR Sciences and Technologies, European University of Bretagne, University of Brest, Brest, FRANCE.
Qiong
Q
Wang
François
F
Guerrero
Aleksandra
A
Mazur
Kate
K
Lambrechts
Peter
P
Buzzacott
Marac
M
Belhomme
Michaël
M
Theron
D000111:Acetylcysteine / Q000494:pharmacology; D000388:Air; D000818:Animals; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004242:Diving; D042783:Endothelial Cells / Q000473:pathology*; D004730:Endothelium, Vascular / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000494:pharmacology; D018496:Hyperoxia / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology*; D023421:Models, Animal; D009584:Nitrogen; D010100:Oxygen; D017382:Reactive Oxygen Species / Q000378:metabolism*
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D009584:Nitrogen; D010100:Oxygen; D000111:Acetylcysteine