Acute tolerance to ethanol in the rat.

Male Wistar rats were examined on the moving belt test at approximately 10, 30 and 60 min after administration of ethanol in doses ranging from 1.0-2.8 g/kg. Immediately after the test, each animal was sacrificed and ethanol concentrations were measured. The regression line of impairment as a function of brain alcohol concentration showed a progressive shift toward higher brain levels with increasing time after alcohol administration. The results confirm the existence of acute tolerance to ethanol, as defined by reduced impairment of function for a given blood level on the falling versus the rising arm of the blood alcohol curve. Confusion of interpretation due to arterio-venous differences in alcohol concentration was ruled out by simultaneous measurements in arterial blood and brain. Practice effects were ruled out by testing each animal only once.