Alcohol-induced depression of albumin synthesis: reversal by tryptophan.

The influence of alcohol on albumin synthesis was studied in the isolated perfused rabbit liver. Carbonate-(14)C was used to label the intracellular arginine pool which serves as the precursor of both the carbon of urea and the guanido carbon of arginine in albumin. The control group synthesized albumin at a rate of 33 mg/100 g of wet liver weight during 2.5 hr of perfusion. When alcohol, 220 mg/100 ml, was added to the perfusate, albumin synthesis decreased to between 7 and 11 mg, less than one-third the control rate. The addition of 10 mM tryptophan to perfusates containing alcohol prevented most of the inhibitory effects and albumin synthesis increased to average 24 mg. Further, the addition of alcohol to the perfusate decreased the hepatic protein/DNA ratio from 70 to 54 and the RNA/DNA ratio from 2.3 to 1.8, changes equivalent to those seen after a 24 hr fast. The addition of tryptophan to the perfusate prevented these findings in both instances. Endoplasmic membrane-bound polysomes were examined for aggregation. Alcohol decreased the quantity of heavier aggregates. Reaggregation occurred when tryptophan was added but quantitative changes in albumin synthesis could not be related to the degree of reaggregation.