Srsf3-null platelets are rapidly cleared from circulation. (A) The half-life of control and Pf4-Srsf3^Δ/Δ platelets as measured by the transplantation of CFSE- and CTV-labeled platelets, respectively, into wild-type mice. The data were fitted to a 1-phase exponential decay curve, and the half-life (t_1/2) for control (R² = 0.932) and Srsf3^Δ/Δ (R² = 0.937) platelets is depicted in the inset. (B) The clearance rate of control and Pf4-Srsf3^Δ/Δ platelets as measured by in vivo labeling of platelets by anti-CD42c DyLight488 antibody in control and Pf4-Srsf3^Δ/Δ mice. The data were fitted to a 1-phase exponential decay curve, and the rate constant K for control (R² = 0.991) and Srsf3^Δ/Δ (R² = 0.996) platelets is depicted in the inset. (C) The number of platelets in the spleen of control and Pf4-Srsf3^Δ/Δ mice. (D) Relative Caspase 3/7 activity in control and Pf4-Srsf3^Δ/Δ platelets. (E) Fraction of reticulated TO⁺ platelets in control and Pf4-Srsf3^Δ/Δ mice in the steady-state. (F) The fraction of TO⁺ platelets in control and Pf4-Srsf3^Δ/Δ mice following antiplatelet serum (APS) administration. The data are presented as mean plus or minus SEM. Two-tailed unpaired Student t test in panels C through E; 2-way ANOVA in panel F. ****P ≤ .0001; **P ≤ .01. CFSE, carboxyfluorescein succinimidyl ester; CTV, CellTrace™ Violet.