title: Ascorbic acid supplementation diminishes microparticle elevations and neutrophil activation following SCUBA diving.
abstract: Predicated on evidence that diving-related microparticle generation is an oxidative stress response, this study investigated the role that oxygen plays in augmenting production of annexin V-positive microparticles associated with open-water SCUBA diving and whether elevations can be abrogated by ascorbic acid. Following a cross-over study design, 14 male subjects ingested placebo and 2-3 wk later ascorbic acid (2 g) daily for 6 days prior to performing either a 47-min dive to 18 m of sea water while breathing air (∼222 kPa N2/59 kPa O2) or breathing a mixture of 60% O2/balance N2 from a tight-fitting face mask at atmospheric pressure for 47 min (∼40 kPa N2/59 kPa O2). Within 30 min after the 18-m dive in the placebo group, neutrophil activation, and platelet-neutrophil interactions occurred, and the total number of microparticles, as well as subgroups bearing CD66b, CD41, CD31, CD142 proteins or nitrotyrosine, increased approximately twofold. No significant elevations occurred among divers after ingesting ascorbic acid, nor were elevations identified in either group after breathing 60% O2. Ascorbic acid had no significant effect on post-dive intravascular bubble production quantified by transthoracic echocardiography. We conclude that high-pressure nitrogen plays a key role in neutrophil and microparticle-associated changes with diving and that responses can be abrogated by dietary ascorbic acid supplementation.
authors.affiliation: Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland; and.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Otto F
authors.initials: OF
authors.lastname: Barak
authors.affiliation: Department of Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Dujic
authors.affiliation: Department of Physiology, University of Split School of Medicine, Split, Croatia.
authors.forename: Dennis
authors.initials: D
authors.lastname: Madden
authors.affiliation: Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland; and.
authors.forename: Veena M
authors.initials: VM
authors.lastname: Bhopale
authors.affiliation: Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland; and.
authors.forename: Jasjeet
authors.initials: J
authors.lastname: Bhullar
authors.affiliation: Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland; and sthom@smail.umaryland.edu.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Thom
mesh_terms: D001205:Ascorbic Acid / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D018592:Cross-Over Studies; D003665:Decompression Sickness / Q000097:blood / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D019587:Dietary Supplements; D004242:Diving / Q000009:adverse effects*; D004618:Embolism, Air / Q000000981:diagnostic imaging / Q000209:etiology; D006801:Humans; D008297:Male; D018375:Neutrophil Activation / Q000187:drug effects*; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D053668:Syndecan-1 / Q000097:blood; D013997:Time Factors; D016896:Treatment Outcome; D014443:Tyrosine / Q000031:analogs & derivatives / Q000097:blood; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; C508241:SDC1 protein, human; D053668:Syndecan-1; C002744:3-nitrotyrosine; D014443:Tyrosine; D001205:Ascorbic Acid
keywords: decompression; microparticles; neutrophil activation; oxidative stress