Effects of ethanol on body temperature of rats at high ambient pressure

Separately, ethanol and high ambient pressure cause hypothermia in laboratory animals. However, ethanol and high pressure have mutually antagonistic effects on several biological functions and the present experiments investigate their combined action on body temperature. Rats given saline, 1.5 g/kg ethanol or 3.5 g/kg ethanol were exposed to 1 bar air at 25-26 degrees C, 1 bar helium-oxygen at 30-31 degrees C, or 48 bar helium-oxygen at 33.5-34.5 degrees C. Ambient, colonic and tail-skin temperatures were monitored for 60 min. There were no significant differences in mean ambient or tail-skin temperatures between groups belonging to the same ambient condition. Colonic temperatures under the 1 bar conditions were 1.5-2 degrees C lower in the 3.5 g/kg ethanol group than in the saline and 1.5 g/kg ethanol groups, while no significant differences were observed between the groups at 48 bar. Comparisons of the colonic temperatures at the end of the observation period, i.e., 60 min after administration of ethanol, demonstrated that their values at 48 bar were significantly lower than at 1 bar after saline, significantly higher after 3.5 g/kg ethanol and identical across conditions in the 1.5 g/kg groups. The results suggest that high ambient pressure may counteract rather than potentiate the hypothermic effect of ethanol.