Platelet activation increased in WT and Nbeal2^−/− hypoxic mice. (A) Representative western blot of platelet lysates for PF4. (B) Quantification of western blot demonstrates platelet PF4 is reduced in Nbeal2^−/− mice compared with WT mice at baseline. (C) Platelet PF4 levels are reduced in Nbeal2^−/− mice compared with WT mice at baseline. Platelet PF4 is decreased in hypoxic WT mice at days 3 and 21 but not Nbeal2^−/− mice. (D) Plasma PF4 was decreased at baseline in Nbeal2^−/− compared with WT mice. Plasma PF4 increased in hypoxic WT and Nbeal2^−/− at day 3. Hypoxia-induced increase in plasma PF4 was attenuated in Nbeal2^−/− mice. (E) The percentage of P-selectin expressing platelets increased in hypoxic WT and Nbeal2^−/− mice at day 3. Hypoxia-induced increase in P-selectin expressing platelets was attenuated in Nbeal2^−/− compared with WT mice. (F) The percentage of activation of αIIBβ3 (JONA) expressing platelets increased in hypoxic WT and Nbeal2^−/− mice at day 3. The hypoxia-induced increase in the percentage of platelets expressing activated αIIBβ3 (JONA) was attenuated in Nbeal2^−/− compared with WT mice. (G-I) PLAs are increased in hypoxic WT mice at day 3 but not Nbeal2^−/− mice. PMAs and PNAs are similar between WT and Nbeal2^−/− mice at baseline and unchanged in hypoxia. Statistics: P ≤.05 by 2-way ANOVA with Tukey post hoc analysis. Comparisons: (∗) WT compared with WT baseline, (#) Nbeal2^−/− compared with Nbeal2^−/− baseline, (^) WT compared with Nbeal2^−/−. NMX, normoxia.