Synthesis And Catabolism Of Human Prothrombin And Pivka-II

The synthesis and catabolism of both prothrombin and PIVKA-II were studied in patients with stable stage of various thromboembolic disorders. Laboratory examinations revealed that their hemostatic and fibrinolytic activities were within normal range. Thirty mg of warfarin was administered orally to patients, which was followed by daily U to 8 mg of warfarin to maintain one stage prothrombin time in therapeutic range. Fifty mg of vitamin K was administered intravenously to these anticoagulated patients. PIVKA-II was determined as prothrombin related antigen in the BaSO^ adsorbed plasma by the method of Ganrot using anti-human prothrombin antibody.

After the administration of 30 mg of warfarin, prothrombin clotting activity(FII:C) decreased exponentialy with the half life(T 1/2) of 74 hrs on an average. Rapid increase of PIVKA-II was observed in the early phase of warfarin administration, though in the later phase an increasing tendency slowed down. The changes of PIVKA-II in the early phase could be analyzed easier by following up the changes in the value of (100 - PIVKA-II activity)%. As the progress of time after the administration of warfarin, their values decreased exponentialy with the T 1/2 of 64 hrs on an average. After the administration of vitamin K, FII:C increased rapidly in the initial phase, then slowly returned to normal level. Similarly to the case of PIVKA-II after the administration of warfarin , values of (100 - FII:C activity)% decreased exponentialy with the T 1/2 of 45 hrs on an average. PIVKA-II decreased rapidly after the administration of vitamin K, describing exponential curve with the T 1/2 of 40 hrs on an average.

From the results described above, it is suggested that the catabolism of PIVKA-II is much more faster than that of FII:C.