Change in activity of factor XIII in the plasma during platelet aggregation

Abstract

During platelet aggregation induced by ADP or thrombin, a reduction in the activity of factor XIII is observed in platelet-enriched rat plasma. On the addition of active factor XIII (XIIIa) to this plasma, besides the increased ADP-induced aggregation, activity of factor III in the plasma is reduced. In the case of thrombin-induced platelet aggregation, addition of factor XIIIa is accompanied by a marked decrease in its activity in the plasma. The degree of aggregation under these circumstances is lower than in control samples. The observed differences in the character of aggregation taking place in the presence of factor XIIIa, when different aggregants (ADP and thrombin) are used, are evidently due to interaction between active factor XIII and thrombin added to the plasma as the aggregant.