Acute Hyperbaric Oxygenation, Contrary to Intermittent Hyperbaric Oxygenation, Adversely Affects Vasorelaxation in Healthy Sprague-Dawley Rats due to Increased Oxidative Stress

Figure 2

Mechanisms of AChIR response of isolated rat aorta rings in the CTRL (a), A-HBO₂ (b), 24H-HBO₂ (c), and 4D-HBO₂ (d) groups of rats. Used concentrations: ACh 10⁻⁹ to 10⁻⁵ M, L-NAME 3 × 10⁻⁴ M, and TEMPOL 100 μM. Half maximal effective concentration (EC50) presents the concentration of ACh (M) which induces a response halfway between the baseline and maximum. The presence of L-NAME significantly reduced AChIR of isolated rat aortic rings in all experimental groups. TEMPOL administration significantly increased the AChIR response in the A-HBO₂ group of rats, while it did not induce any significant change in the AChIR of isolated rat aortic rings in other groups. Data were compared by two-way ANOVA and Bonferroni post hoc tests. Tables within figures present sensitivity of aortic rings to ACh in the CTRL (a), A-HBO₂ (b), 24H-HBO₂ (c), and 4D-HBO₂ (d) groups of rats. Sensitivity to ACh in the presence of L-NAME was significantly decreased compared to the basic response or response to ACh in the presence of TEMPOL in all experimental groups of rats. LogEC50 values were compared by one-way ANOVA followed by a Holm-Sidak pairwise multiple comparison.

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