| Abstract: | On addition to rat plasma, platelet-enriched, of active factor XIII (XIIIa), there occurred along with increase in the aggregation induced by ADP, a reduction in the activity of factor XIII in the plasma. Addition to the plasma of inactive factor XIII failed to influence either the degree of aggregation, or the change in the activity of factor XIII in the plasma in comparison with control samples. In platelet aggregation induced by thrombin, addition of factor XIII was accompanied by a marked fall of its activity in the plasma. In comparison with control, the extent of aggregation in this case decreased. The observed differences in the character of aggregation coursing in the presence of factor XIIIa when different aggregating agents (ADP and thrombin) were used were apparently due to the interaction of active factor XIII with thrombin added to the plasma in the capacity of an aggregating agent. |
