Analysis of platelet function. (A) Aggregation of washed platelets from WT and APP-KO mice induced by the indicated agonists. Aggregation induced by adenosine 5′-diphosphate (ADP) was measured on addition of purified fibrinogen, as indicated. (B-C) Flow cytometry analysis of agonist-induced integrin αIIbβ3 activation, measured as binding of fluorescein isothiocyanate-labeled fibrinogen (B) and granule secretion as P-selectin exposure (C). Red bars, WT platelets; blue bars, APP-deficient platelets. Results are the mean ± SEM of 3 different experiments. (D) Tail bleeding time determined in groups of 10 mice for each genotype and expressed as time required for bleeding cessation (i) and amount of blood hemoglobin lost (ii). Each symbol represents 1 animal.