S100B protein in conscious carbon monoxide-poisoned rats treated with normobaric or hyperbaric oxygen.

OBJECTIVE

To evaluate S100B, an astroglial structural protein, during normobaric and hyperbaric oxygen therapy of conscious carbon monoxide (CO)-poisoned rats. So far, the usefulness of hyperbaric oxygen therapy in conscious CO-poisoned patients has been shown with neuropsychological testing. The S100B protein has been demonstrated as a possible biochemical marker and prognostic parameter in CO-poisoned rats.

DESIGN

Randomized, controlled interventional trial.

SETTING

University laboratory.

SUBJECTS

: Male Wistar rats weighing 254 +/- 14 g.

INTERVENTIONS

The rats were exposed to a mixture of 3,000 ppm CO in air for 60 mins. After CO exposure, the first group of eight conscious rats was exposed to ambient air for 30 mins, the second group of six conscious rats was exposed to 100% normobaric oxygen for 30 mins, and the third group of six conscious rats was exposed to 100% hyperbaric oxygen at 3 bars for 30 mins. Blood samples were taken from the jugular vein just before CO exposure and immediately after oxygen therapy. The level of consciousness was evaluated at the end of exposure, and the survival rate was monitored for 14 days. The S100B concentrations were measured with a commercial immunoluminometric assay.

MEASUREMENTS AND MAIN RESULTS

Analyses of differences in S100B levels between different kinds of therapy before and after treatment showed a global significant difference (p = .002). The post hoc test results showed that S100B levels after therapy of the first group treated with ambient air (0.16 +/- 0.07 microg/L) and the second group treated with normobaric oxygen (0.19 +/- 0.05 microg/L) were similar (p = .741), and both of them were significantly different, with much higher values of S100B levels after therapy, from the third group treated with hyperbaric oxygen (0.06 +/- 0.03 microg/L; p = .018 and p = .002, respectively). All the rats survived.

CONCLUSIONS

S100B is elevated in conscious CO-poisoned rats left on ambient air or treated with normobaric oxygen, but not in conscious CO-poisoned rats treated with hyperbaric oxygen.