Fig. 2.

Agonist-induced activation of integrin α_IIbβ₃ and aggregation in platelets from sphk1^−/− and sphk1^+/+ mice. A: arithmetic means ± SE (n = 6) of activated integrin α_IIbβ₃ determined by flow cytometry in platelets from sphk1^+/+ (black bars) and sphk1^−/− (grey bars) mice in response to CRP (μg/ml), thrombin (mU/ml), or ADP/U-46 (μM) at the indicated concentrations. *P < 0.05, **P < 0.01, ***P < 0.001, statistically significant difference from sphk1^+/+ platelets. B: representative tracings of aggregometry after stimulation of platelets from either sphk1^+/+ (black) or sphk1^−/− (grey) mice with 0.25 μg/ml CRP (top) or 5 mU/ml thrombin (bottom). C: arithmetic means ± SE (n = 7) of aggregometry after stimulation of platelets from either sphk1^+/+ (black bars) or sphk1^−/− (gray bars) mice with either 0.25 μg/ml CRP or 5 mU/ml thrombin. *P < 0.05, statistically significant difference from sphk1^+/+ platelets. D: representative tracings of spontaneous platelet aggregation before and after addition of fibrinogen (100 μg/ml)/Ca²⁺ (1 mM) in platelets from sphk1^+/+ (black line) and sphk1^−/− (dark grey line) mice or the appropriate vehicle control (light grey line). E: arithmetic means ± SE (n = 6) of spontaneous platelet aggregation in the presence of fibrinogen (100 μg/ml)/Ca²⁺ (1 mM) in platelets from sphk1^+/+ (black bar) and sphk1^−/− (dark grey bar) mice or the appropriate vehicle control (light grey bar).