Bubbles, microparticles, and neutrophil activation: changes with exercise level and breathing gas during open-water SCUBA diving

• Published in: Journal of applied physiology (1985) 2013-05, Vol.114 (10), p.1396-1405
• Main Authors: Thom, Stephen R, Milovanova, Tatyana N, Bogush, Marina, Yang, Ming, Bhopale, Veena M, Pollock, Neal W, Ljubkovic, Marko, Denoble, Petar, Madden, Dennis, Lozo, Mislav, Dujic, Zeljko
• Format: Article
• Language: English
• Subjects: Air; Annexin A5 - metabolism; Blood Platelets - metabolism; Decompression Sickness - metabolism; Decompression Sickness - physiopathology; Diving - physiology; Exercise; Exercise - physiology; Female; Gases - metabolism; Humans; Male; Membrane Proteins - metabolism; Neutrophil Activation - physiology; Neutrophils - metabolism; Neutrophils - physiology; Nitrogen; Nitrogen - metabolism; Oxygen; Oxygen - metabolism; Respiration; Scuba & skin diving
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00106.2013

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.