"Am J Physiol Regul Integr Comp Physiol. 2015 Jun 17:ajpregu.00155.2015. doi: 10.1152/ajpregu.00155.2015. [Epub ahead of print]
Ascorbic acid supplementation diminishes microparticle elevations and neutrophil activation following SCUBA diving.
Yang M1, Barak OF2, Dujic Z2, Madden D2, Bhopale VM3, Bhullar J4, Thom SR5.
Predicated on evidence that diving-related microparticle generation is an oxidative stress response, this study investigated the role 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 weeks later ascorbic acid (2 g) daily for 6 days prior to performing either a 47 minute dive to 18 meters 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 minutes (~ 40 kPa N2/59 kPa O2). Within 30 minutes after the 18 meter dive in the placebo group, neutrophil activation and platelet-neutrophil interactions occurred, and total number of microparticles as well as sub-groups bearing CD66b, CD41, CD31, CD142 proteins or nitrotyrosine increased approximately 2-fold. 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 trans-thoracic 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."