Liver growth after partial hepatectomy: Influence of phenobarbital administration

To elucidate if liver growing after partial hepatectomy retains its capacity to respond to the administration of phenobarbital, a substance known to stimulate tissue growth, the effect of this inducer on various parameters related to tissue growth was studied in liver of partially hepatectomized rats, 48 and 96 hr after surgery. At 48 hr, when cell proliferation is still sustained, phenobarbital induces a significant increase of the rate of protein synthesis, of the degree of polyribosomal aggregation, and of the activity of the microsomal enzyme, aminopyrine demethylase; the drug has instead no influence on relative liver weight, DNA, and protein content, and on the distribution of ribosomal RNA of various subcellular fractions. This indicates that at this time after surgery the capacity of the hepatocyte to respond to phenobarbital administration is present, though partially impaired. At 96 hr instead, when the rate of cellular proliferation is reduced, phenobarbital administration significantly influences all the parameters tested; this indicates that at this time after hepatectomy the capacity of the liver to respond to the administration of the drug is fully restored.