Daily alcohol intake during the 2-h alcohol-access period prior to onset of drug treatment in Study 1 averaged 1.3 ± 0.2 g/kg BW/2 h, which is lower than the intake seen in some of our previous studies using 2-h alcohol access in P rats. This is likely because the rats in the current study were older and larger than those we have previously used (which have averaged only about 350–400 g BW and have consumed approximately 2.0 g alcohol/kg BW during 2 h of alcohol access). Weight gain above 400 g in rats is due to addition of fat; fat tissue has poor blood supply, low water content, and only 10–20% of the alcohol concentration found in blood, so reporting alcohol intake in g/kg BW in fat rats underestimates alcohol intake (Bloom, Lad, Pittman, & Rogers, 1982; Westerfeld & Schulman, 1959; York, 1983).
