The kinetics of protein synthesis was studied in the cultures of rat hepatocytes on slides covered with collagen or fibronectin and kept in a serum-free medium 199 complemented by albumin and insulin. No protein synthesis rhythm was found in the cultures with markedly separated cells obtained from a diluted suspension of hepatocytes ("sparse cultures"). After 0.3-0.4 microM total gangliosides were added to the medium with such cultures, the rhythm was found in all experiments. Such an effect was earlier found under the influence of a medium conditioned by a monolayer on the sparse cultures. The results obtained suggest the involvement of gangliosides in synchronization of oscillations of the protein synthesis intensity and call for studies of the conditioned medium properties.
Animals Cells, Cultured