title: Bubbles, microparticles, and neutrophil activation: changes with exercise level and breathing gas during open-water SCUBA diving.
abstract: The study goal was to evaluate responses in humans following decompression from open-water SCUBA diving with the hypothesis that exertion underwater and use of a breathing mixture containing more oxygen and less nitrogen (enriched air nitrox) would alter annexin V-positive microparticle (MP) production and size changes and neutrophil activation, as well as their relationships to intravascular bubble formation. Twenty-four divers followed a uniform dive profile to 18 m of sea water breathing air or 22.5 m breathing 32% oxygen/68% nitrogen for 47 min, either swimming with moderately heavy exertion underwater or remaining stationary at depth. Blood was obtained pre- and at 15 and 120 min postdive. Intravascular bubbles were quantified by transthoracic echocardiography postdive at 20-min intervals for 2 h. There were no significant differences in maximum bubble scores among the dives. MP number increased 2.7-fold, on average, within 15 min after each dive; only the air-exertion dive resulted in a significant further increase to 5-fold over baseline at 2 h postdive. Neutrophil activation occurred after all dives. For the enriched air nitrox stationary at depth dive, but not for other conditions, the numbers of postdive annexin V-positive particles above 1 μm in diameter were correlated with intravascular bubble scores (correlation coefficients ∼0.9, P < 0.05). We conclude that postdecompression relationships among bubbles, MPs, platelet-neutrophil interactions, and neutrophil activation appear to exist, but more study is required to improve confidence in the associations.
authors.affiliation: Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA. sthom@mail.med.upenn.edu
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Thom
authors.forename: Tatyana N
authors.initials: TN
authors.lastname: Milovanova
authors.forename: Marina
authors.initials: M
authors.lastname: Bogush
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Veena M
authors.initials: VM
authors.lastname: Bhopale
authors.forename: Neal W
authors.initials: NW
authors.lastname: Pollock
authors.forename: Marko
authors.initials: M
authors.lastname: Ljubkovic
authors.forename: Petar
authors.initials: P
authors.lastname: Denoble
authors.forename: Dennis
authors.initials: D
authors.lastname: Madden
authors.forename: Mislav
authors.initials: M
authors.lastname: Lozo
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Dujic
mesh_terms: D000388:Air; D017304:Annexin A5 / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism; D003665:Decompression Sickness / Q000378:metabolism / Q000503:physiopathology; D004242:Diving / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005740:Gases / Q000378:metabolism*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012119:Respiration
chemical_list: D017304:Annexin A5; D005740:Gases; D008565:Membrane Proteins; C041364:nitrox; D009584:Nitrogen; D010100:Oxygen
keywords: CD41; antigen sharing; decompression sickness; integrins; intravascular bubble; leukocytes; platelets; ultrasound