Studies on tolerance development in inbred and heterogeneous stock National Institutes of Health rats.

The rate of development of environment-independent tolerance was assessed in seven inbred strains of rats, in randomly bred Sprague-Dawley rats, and in the heterogeneous stock (HS) animals developed from the inbred strains. The results demonstrated significant differences in rates of tolerance development between the various groups of inbred animals. A relationship between the initial sensitivity of an animal to the incoordinating effects of ethanol and the rate of tolerance development was also demonstrated. Animals displaying the greatest initial sensitivity to ethanol were found to develop tolerance at a faster rate than those displaying greater resistance to the incoordinating effects of ethanol. The HS animals developed from the inbred strains were demonstrated to embody the full range of rates of tolerance development exemplified by the parental inbred strains.