| Abstract: | The study involved the relationship of Factor V lability due to pH to pH variations in the performance of the one-stage prothrombin time. Samples of blood were drawn from ten patients on long-term, coumarin-derivative therapy. The pH of each sample was decreased progressively from 7.79 to 6.05 with lactic acid and the prothrombin time was determined. Each sample was then incubated for 4 hours at 37 degrees C and the pH and prothrombin time were measured again on each sample. Factor V activity and lactic acid were added to the samples in varying order. The addition of lactic acid after incubation did not alter the prothrombin time. The addition of Factor V activity without changing the pH brought the prothrombin time to values less than at pre-incubation time. The optimal pH for maximal enzyme activity and the mechanism for Factor V lability in the incubated plasma are briefly discussed. |
|---|
