Blood pressure, acid-base and blood gas status and indicators of oxidative stress in healthy male rats exposed to acute hyperbaric oxygenation.

Different protocols of hyperbaric oxygenation (HBO2) are used for research purposes; however, data on the changes in blood pressure, oxidative stress and acid-base and gas status induced by various oxygenation protocols are scarce and conflicting. The aim of this study was to examine the effects of an acute session of HBO2 [2 bar (200 kPa) for two hours] on arterial systolic and diastolic blood pressure, arterial blood gases and acid-base status, and oxidative stress in rats. Sprague-Dawley rats (12-15 weeks) were examined prior to, immediately and 24 hours after a two-hour HBO2 exposure at 2 bars. The femoral artery was cannulated to determine blood pressure, and blood samples were collected to measure blood gases and acid-base status, Ferric reducing antioxidant power ability of plasma (FRAP) and thiobarbituric acid reactive substances (TBARS). Immediately after HBO2 systolic and diastolic blood pressure significantly decreased (from 138 +/- 14/103 +/- 13 to 113 +/- 12/72 +/- 16 mmHg). However, these values were still inside the normal physiological range. pH decreased (from 7.34 +/- 0.05 to 7.28 +/- 0.05), pCO2 decreased (from 7.07 +/- 0.89 to 5.76 +/- 0.50 kPa), pO2 increased (from 12.48 +/- 0.88 to 13.68 +/- 2.4 kPa), plasma bicarbonate decreased (from 27.04 +/- 3.25 to 20.52 +/- 3.02 mmol/L). Exposure to HBO2 immediately increased TBARS levels (from 0.17 +/- 0.09 to 21.79 +/- 1.05 microM/MDA), while FRAP levels were not significantly changed. Measurements on separate animals 24 hours after a single HBO2 exposure showed no differences in comparison to control animals, except for pO2, which was significantly lower (11.10 +/- 0.31 kPa). The results define values of important parameters, serving as a necessary basis for complex analysis of HBO2 effects in research on rat animal models.