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. 2021 Jul 9:12:692204.
doi: 10.3389/fphys.2021.692204. eCollection 2021.

Endothelial Nitric Oxide Production and Antioxidant Response in Breath-Hold Diving: Genetic Predisposition or Environment Related?

Danilo Cialoni  1   2   3 , Andrea Brizzolari  2   4 , Michele Samaja  4 , Gerardo Bosco  1 , Matteo Paganini  1 , Nicola Sponsiello  3 , Valentina Lancellotti  5 , Alessandro Marroni  2
Affiliations

Endothelial Nitric Oxide Production and Antioxidant Response in Breath-Hold Diving: Genetic Predisposition or Environment Related?

Danilo Cialoni et al. Front Physiol. .

Abstract

Introduction: Nitric oxide (NO) is an essential signaling molecule modulating the endothelial adaptation during breath-hold diving (BH-diving). This study aimed to investigate changes in NO derivatives (NOx) and total antioxidant capacity (TAC), searching for correlations with different environmental and hyperbaric exposure.

Materials and methods: Blood samples were obtained from 50 breath-hold divers (BH-divers) before, and 30 and 60 min after the end of training sessions performed both in a swimming pool or the sea. Samples were tested for NOx and TAC differences in different groups related to their hyperbaric exposure, experience, and additional genetic polymorphism.

Results: We found statistically significant differences in NOx plasma concentration during the follow-up (decrease at T30 and increase at T60) compared with the pre-dive values. At T30, we found a significantly lower decrease of NOx in subjects with a higher diving experience, but no difference was detected between the swimming pool and Sea. No significant difference was found in TAC levels, as well as between NOx and TAC levels and the genetic variants.

Conclusion: These data showed how NO consumption in BH-diving is significantly lower in the expert group, indicating a possible training-related adaptation process. Data confirm a significant NO use during BH-diving, compatible with the well-known BH-diving related circulatory adaptation suggesting that the reduction in NOx 30 min after diving can be ascribed to the lower NO availability in the first few minutes after the dives. Expert BH-divers suffered higher oxidative stress. A preliminary genetic investigation seems to indicate a less significant influence of genetic predisposition.

Keywords: breath hold diving; diving; genetic prone; nitric oxide; oxidative stress.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Subjects showed a lower NOx concentration at T30 suggesting a lower NO availability after dives, and a higher NOx concentration at T60 suggesting a NO availability re-balance effect. *p < 0.05, ***p < 0.001.
FIGURE 2
FIGURE 2
Data at T30 show lower NO usage in highly exposed and experienced subjects indicating adaptation in the management of hyperbaric-related vascular changes. Swimming Pool vs. sea BH-diving data showed no significant differences. *p < 0.05.
FIGURE 3
FIGURE 3
Data at T60 show a rebound effect with an increase of NO available probably to compensate for the higher underwater consumption. This rebound effect was larger in the subject who shows a higher diving exposure and experience and in sea diving as compared with the swimming pool diving. *p < 0.05, **p < 0.01.
FIGURE 4
FIGURE 4
No statistical difference in TAC levels were found between pre- and post-dive values at T30 and T60.
See this image and copyright information in PMC

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