The rapid development of functional tolerance to ethanol by mice

A method is described in which the development of tolerance to ethanol in individual mice can be measured during the inhalation of ethanol vapour. This method has been used with two behavioural end-points, loss of righting reflex and loss of rotarod performance. It demonstrates that, in the adult male, TO Swiss mouse, peak tolerance, in which approximately 2 X the original effective blood ethanol concentration is required to produce the behavioural end-point, can develop in 3--5 h. After this time the ability of the animals to perform normally in the presence of continued high concentrations of ethanol in blood begins to fall. The results are discussed in relation to current concepts of tolerance to central nervous system depressant drugs.