A Plasma Factor Enhances Activity of Vitamin K-Dependent Coagulation Proteins

Abstract

A plasma factor, "coagulopoietin", present in animals with depleted vitamin K-dependent coagulation factors, appears to enhance activity of these factors in normal animals. We have investigated the effects of "coagulopoietin" on synthesis of certain coagulation proteins by the isolated rat liver perfused for eight hours. Liver donor rats received plasma injections from vitamin K-deficient rats or from normal rats 24 hr before sacrifice. Coagulation activity of Factor VII and Factor II in liver perfusate samples was measured with a coagulation assay; Factor II synthesis was also measured by rocket immunoelectrophoresis and by activation with E. carinatus venom. Cumulative hepatic synthesis of Factor VII coagulation activity was increased by 43% when rat liver donors received vitamin K-deficient rat plasma compared to normal rat plasma. Cumulative synthesis of Factor II coagulation activity was increased by 51%, but synthesis of the protein measured immunologically or by activation with venom was not affected. The "coagulopoietin" factor in these studies appears to increase measurable coagulation factor activity without increasing total protein synthesis.