抄録
Measurements of Factor X clotting activity by using tissue thromboplastin (T. T.) and Russell's viper venom (R. V. V.) showed the correlated result for normal rabbit plasma and human plasmas from healthy persons and patients with liver disease. However the clotting activity of Factor X in plasmas from the rabbits and patients given warfarin become variable according to the assay methods, the activity assayed by T. T. was decreased, whereas it was not so by using R. V. V.
Plasma samples are tested in a series of dilutions (D) and the coagulation time (t) measured with assay system using T. T., R. V. V. and hepaplastin test (H. T.).
When t is plotted against D, a straight line was obtained. Extrapolation to infinite substrate concentration gives the minima coagulation time (tmin). Normal or liver disease plasma display the same value for tmin, when using any assay systems. Plasma from persons or rabbits given warfarin display the same value for tmin when using R. V. V. or H. T., but not by T. T.
These results show that clotting activity of Factor X assayed by T. T. is disturbed with competitive inhibitors probably Protein Induced by Vitamin K Absence or Antagonists (PIVKA) but assayed by R. V. V. or H. T. is not inhibited, as suggested by HEMKER.
The value of amidolytic activity of Factor X is higher than that of its clotting activity assayed by R. V. V. for plasma from the persons or rabbits given warfarin.
It is likely that there might be some substances which have no clotting activity but amidolytic activity associated with Factor X.
Further studies might be necessary to clarify the relationship between the clotting activity and the amidolytic activity of Factor X.
