A compartmental model of platelet aggregation in vitro: the kinetics of single platelets.

A compartmental model of platelet aggregation which accurately describes both reversible and irreversible aggregation in vitro is presented. This model is substantiated by correlative analyses of agonist-induced aggregation as monitored by both routine aggregometry and resistive counting of single platelets. Previously unresolved differences in the reported reaction order of the aggregation process are explained. The model suggests that aggregation includes, in addition to the association and dissociation of platelets, the stabilization of aggregates. We find reversible aggregation requires that single platelets associate more rapidly than aggregates stabilize. For irreversible aggregation, our results suggest the presence of subpopulations of single platelets which associate at different rates. As an unexpected consequence of this study, quantitative relationships between photometric and resistive methods of monitoring platelet aggregation are elucidated.