[abstract] REACTIVE OXYGEN AND NITROGEN SPECIES GENERATION BY HYPERBARIC STRESS IN NAIVE VERSUS EXPERIENCED DIVERS.

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[abstract] REACTIVE OXYGEN AND NITROGEN SPECIES GENERATION BY HYPERBARIC STRESS IN NAIVE VERSUS EXPERIENCED DIVERS.

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Title: [abstract] REACTIVE OXYGEN AND NITROGEN SPECIES GENERATION BY HYPERBARIC STRESS IN NAIVE VERSUS EXPERIENCED DIVERS.
Author: Cameron, BA; McLellan, TC; Eaton, DJ; Rhind, SG
Abstract: BACKGROUND: Reactive oxygen (ROS; O2-) and nitrogen species (RNS; NO- and ONOO-) are potent signalling molecules that regulate inflammatory response. Venous gas emboli (VGE) during decompression may elicit vascular endothelial reaction via flow disruption/injury thereby activating acute inflammatory responses. Animal models suggest that VGE may activate polymorphonuclear neutrophils (PMN) to release ROS, contributing to oxidative tissue damage and the pathogenesis of decompression sickness (DCS). The aim of this study was to compare the effects of 3 different levels of hyperbaric stress on ROS/RNS generation in experienced divers vs. naive subjects. MATERIALS AND METHODS: Naive (n=10) and experienced-to-hyperbaric-stress (n=12) subjects underwent three 30-min hyperbaric stress exposures [180 kPa (18 msw); 300 kPa (30 msw); 450 kPa (45 msw)] each separated by 1 week. Blood samples were drawn pre-dive and at 20 and 60 min post-dive. PMN ROS production was quantified flow cytometrically [median fluorescence intensity (MdFI)] using DHR 123; circulating concentrations of NO- and tyrosine nitration of amino acids (N-Tyr; stable marker of ONOO-) were measured by enzyme immunoassay. RESULTS: ROS generation was greatly enhanced in experienced divers after all three dives, with peak levels observed at 60 min post-dive 45m. Similarly, pre-dive NO- concentrations were higher in experienced vs. naïve, with maximal increases detected at post-dive 45m. Immunoreactivity of plasma N-Tyr residues in experienced divers did not change significantly from pre-dive levels (6 nM) after dives to 18m, 30m or 45m. In contrast, pre and post-dive N-Tyr levels in naive divers were consistently higher (12 nM) after all three dives. CONCLUSIONS: Whereas PMN ROS generation and plasma NO- levels were higher in experienced divers, their N-Tyr levels were lower than that in naive subjects. This suggests that experienced divers may be conferred with a degree of physiological adaptation to the inflammatory response.
Description: Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held June 14-16, 2007. Ritz-Carlton Kapalua Maui, Hawaii (http:www.uhms.org)
URI: http://archive.rubicon-foundation.org/5191
Date: 2007

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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