Competitive apnea diving sessions induces an adaptative antioxidant response in mononucleated blood cells

Abstract

The aim was evaluating the effects of hypoxia/reoxygenation repetitive episodes during 5 days of apnea diving (3-day training/2-day competition) on peripheral blood mononuclear cells (PBMCs) antioxidant defenses, oxidative damage, and plasma xanthine oxidase activity. Blood samples, from seven professional apnea divers, were taken under basal conditions the previous morning to the first training session (pre-diving basal), 4 h after ending the competition (4 h post-diving) and the following morning (15 h after last dive) in basal conditions (post-diving basal). Glucose levels significantly decreased whereas triglycerides increased at 4 h post-diving, both returning to basal values at post-diving basal. Glutathione reductase and catalase activity significantly increased after 4 h post-diving remaining elevated at post-diving basal. Glutathione peroxidase and superoxide dismutase activities and catalase protein levels progressively increased after diving with significant differences respect to initial values at post-diving basal. No significant differences were observed in circulating PBMCs and oxidative damage markers. Plasma xanthine oxidase activity and nitrite levels, but not the inducible nitric oxide synthetase, significantly increased 4 h post-diving, returning to the basal values after 15 h. In conclusion, chronic and repetitive episodes of diving apnea during five consecutive days increased plasma xanthine oxidase activity and nitric oxide production which could enhance the signalling role of reactive oxygen and nitrogen species for PBMCs antioxidant adaptation against hypoxia/reoxygenation.

Physiology, pathophysiology and (mal)adaptations to chronic apnoeic training: a state-of-the-art review

“…Once breathing is reinstated following a hypoxaemic bout, reactive hyperaemia and systemic reoxygenation results in increased free radical and associated reactive oxygen species (ROS) production alongside a state of oxidative stress (Li and Jackson 2002). Similarly, repeated maximal apnoeic attempts have been documented to upregulate the production of ROS in the systemic circulation (Joulia et al 2002(Joulia et al , 2003, accentuating that repeated apnoeic bouts can aggravate systemic oxidative stress levels (Mrakic-Sposta et al 2019;Sureda et al 2004bSureda et al , 2015Theunissen et al 2013). Interestingly, following sustained static and dynamic apnoeic activity EBHDs exhibited lower post-exercise blood acidosis and oxidative stress (i.e., thiobarbituric acid reactive substances [TBARS], reduced glutathione [GSH] and reduced ascorbic acid) compared with NDs, despite attaining significantly greater (302 ± 30 s vs. 104 ± 10 s) apnoeic performances (Joulia et al 2002)-an observation that was later ascribed to a training-induced adaptation (Joulia et al 2003).…”

“…Moreover, after five static apnoeic repetitions, circulating antioxidant concentrations (i.e., bilirubin and uric acid) were reduced while antioxidant enzyme activity (i.e., SOD and GPx) was enhanced without causing an increase in oxidative stress (i.e., malondialdehyde) (Bulmer et al 2008 ). More recently, Sureda et al ( 2015 ) evaluated for the first time the cumulative effects of daily apnoeic exposures on ROS generation, oxidative stress and antioxidant enzyme activity. Following a series of repeated apnoeic dives (i.e., ~ 200 dives performed over a period of 5 days) xanthine oxidase activity, an enzyme responsible for the generation of ROS, was significantly elevated (+ 98%) (Sureda et al 2015 ).…”

“…More recently, Sureda et al ( 2015 ) evaluated for the first time the cumulative effects of daily apnoeic exposures on ROS generation, oxidative stress and antioxidant enzyme activity. Following a series of repeated apnoeic dives (i.e., ~ 200 dives performed over a period of 5 days) xanthine oxidase activity, an enzyme responsible for the generation of ROS, was significantly elevated (+ 98%) (Sureda et al 2015 ). However, concomitant increases in antioxidant enzyme activity (i.e., catalase, GPx, glutathione reductase and SOD) and protein levels (i.e., catalase), primarily observed 15 h after the last hypoxaemic bout, inhibited xanthine oxidase-derived ROS generation (i.e., supported by the lack of changes in malondialdehyde and protein carbonyl derivates levels) and protected cells from oxidative damage.…”

Six weeks of dynamic apnoeic training stimulates erythropoiesis but does not increase splenic volume

“…Oxidative stress has been documented to incite haemolysis and to dictate the magnitude of this response in a dose-dependent manner; with considerable evidence indicating that oxidative damage may be the primary mechanism by which erythrocytes age (Clark 1988;Mohanty et al 2014;Pigeolet and Remacle 1991;Seppi et al 1991;Smith 1995;Telford et al 2003). Interestingly, repeated maximal apnoeic epochs have been evidenced to upregulate the production of reactive oxygen species (ROS) (Joulia et al 2002(Joulia et al , 2003 and aggravate systemic oxidative stress levels (Rousseau et al 2006;Sureda et al 2004Sureda et al , 2015. Therefore, the presently recorded marked increases in circulating iron concentrations following session one may be indicative of an oxidative stress-induced haemolysis (Reardon and Allen 2009;Reeder and Wilson 2005;Schümann et al 2005).…”

“…In contrast, no changes were observed in iron following session twelve and twenty-four. Considering that long-term apnoeic training lowers post-apnoeic oxidative stress (Joulia et al 2003;Sureda et al 2015), it is tempting to speculate that the lack of iron changes following session twelve and twenty-four may, at least in part, relate to a training-induced adaptation that lowers the degree of oxidative stress-induced haemolysis. Howbeit, it is imperative that additional research is conducted to fully elucidate the underlining mechanisms that dictated the presently recorded iron fluctuations.…”