| Abstract: | DNA synthesis and system A-mediated amino acid transport were studied in primary culture of adult rat hepatocytes maintained as a monolayer. Potent growth promoting activity and inducibility of system A-mediated amino acid transport could be found in human newborn sera but not in human adult sera. The maximal activity to promote DNA synthesis was about the same level as insulin (10(-7) M) plus epidermal growth factor (EGF, 20 ng/ml). These results suggest the presence of a hepatocyte-specific growth factor in human newborn sera controlling the amino acid metabolism during the newborn period. |
