Hyperbaric ethanol antagonism in mice: time course.

C57BL/6J mice were injected intraperitoneally with 3.6 g/kg ethanol and exposed to 1 ATA air or to 1 or 12 ATA helium-oxygen immediately, 5, 10 or 20 minutes after injection. Immediate and delayed hyperbaric exposure produced similar significant reductions in sleep-times and increases in wake-up brain ethanol concentrations. These findings demonstrate the effectiveness of delayed hyperbaric treatment in reducing ethanol sleep-time and eliminate decreased absorption and altered distribution as critical factors mediating the antagonism. The results are consistent with current theories of anesthesia and support a direct mechanism involving brain cellular membranes.