engleski

Acute hyperbaric oxygenation, contrary to intermittent hyperbaric oxygenation, adversely affects vasorelaxation in healthy Sprague- Dawley rats due to increased oxidative stress

Present study aimed to assess endothelium- dependent vasorelaxation, to measure superoxide production in aorta and femoral artery, and to determine antioxidative enzymes expression and activity in aortas of male Sprague-Dawley rats (N=135), randomized to: A-HBO2 group exposed to single hyperbaric oxygenation session (120’ of 100% O2 at 2.0 bars) ; 24H-HBO2 group (single session, examined 24h after exposure) ; 4D-HBO2 group (4 consecutive days of single sessions) and CTRL (untreated group). Vasorelaxation of aortic rings in response to acetylcholine (AChIR) and to reduced pO2 (HIR) were tested in vitro in the absence/presence of NOS inhibitor L-NAME and superoxide scavenger TEMPOL. eNOS, iNOS, antioxidative enzymes and NADPH oxidase mRNA expression was assessed by qPCR. Serum oxidative stress markers and enzymes activity were assessed by spectrometry, and superoxide production was determined by DHE flourescence. Impaired AChIR and HIR in A-HBO2 group was restored by TEMPOL. LNAME inhibited AChIR in all groups. Serum oxidative stress and superoxide production were increased in A-HBO2 group compared to all other groups. mRNA expression of iNOS was decreased in A-HBO2 and 24H-HBO2 groups while SOD1, 3 and NADPH oxidase were increased in 4D-HBO2 group. Expression and activity of catalase and gluthation peroxidase were increased in 4D-HBO2 group as well. AChIR was NO-dependent. Acute HBO2 transiently impaired vasorelaxation due to increased oxidative stress. Vasorelaxation was restored and oxidative stress was normalized 24h after the treatment.

acetylcholine, hyperbaric oxygenation, hypoxia, oxidative stress

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