Effect of acute alcohol intoxication on the in vivo rate of protein synthesis in skeletal muscle from young and mature rats. Rats were injected intraperitoneally with either ethanol or saline (control) and protein synthesis in the fast-twitch gastrocnemius muscle was determined 2.5 h thereafter by incorporation of [3H]-phenylalanine (Phe) into protein. Two groups of mature rats were used in this study; rats in group 1 received the same amount of alcohol normalized to body weight as young rats (i.e., 75 mmol/kg), while rats in group 2 were injected with alcohol at a dose of 90 mmol/kg. The approximate blood alcohol concentration achieved in each of the three groups is presented at the bottom of the graph and the absolute values (means ± SEM) are presented in the text. Values for protein synthesis are means ± SEM where the sample size was 10, 10, 6, 7, 9, and 9 for the six groups, respectively. Values with different letters are significantly different from each other, P < 0.05. Values which share a common letter are not statistically different.