PROTHROMBIN SYNTHESIS IN RAT HEPATOMA H4IIEC3 CELLS - RESPONSE TO THEPROPOSED COAGULOPOIETIN FACTOR

Based on studies in intact animals, the presence of humoral factors, ' 'coagulopoietins'', which regulate the synthesis of vitamin K-dependen t plasma proteins has been proposed. These proposed factors are produc ed in response to vitamin K deficiency, coumarin treatment, or specifi c antibody depletion of vitamin K-dependent clotting factors. The prod uction of prothrombin by rat hepatoma H4IIEC3 cells has now been shown to be dependent on the source of bovine serum in the media. Cells gro wn in serum from cows treated with dicoumarol produce about 20% more p rothrombin in 24 h than those cells grown in control serum. The humora l factor causing this response is present early in the course of dicou marol treatment, and the increase in prothrombin production is depende nt on the amount of serum from a dicoumarol-treated cow in the media. Based on membrane filtration studies, the factor appears to be associa ted with the protein fraction of serum.