Reduced platelet life span in Adap^−/−mice. (A) Platelet life span was analyzed by injection of a Dylight488 anti−GPIX antibody and the fluorescently labeled platelet population was measured over 5 days by flow cytometry. (B) αIIbβ3 integrin activation was analyzed by JON/A-PE binding under resting (rest) conditions and upon stimulation with 1 µM U46619 (U46; thromboxane analog), 10 µM epinephrine (epi) alone and in combination. Relative platelet count was determined after (C) splenectomy or (F) macrophage depletion by flow cytometry. *Significance between the control groups; #significance between the macrophage depletion groups. (D) Desialylation of Adap^+/+ and Adap^−/− platelets in washed blood was determined with fluorescein isothiocyanate (FITC)-labeled ECL binding by flow cytometry. Platelets were treated with neuraminidase (Neu) or untreated (rest). (E) Ratio of lectin binding between neuraminidase treated and untreated samples. (A-F) Values are mean ± SD (at least n = 5). ***P < .001; **P < .01; *^/#P < .05.