FIGURE 5.

Role of PI3K in collagen-induced Ca²⁺ responses under flow in the absence of secondary mediators. PPACK-anti-coagulated blood, containing 10% autologous Fluo-3-loaded platelets, was preincubated with Me₂SO vehicle (control), PIK-75, TGX-221, or wortmannin (each 1 μm). A, single cell Ca²⁺ responses during flow of blood over collagen in the presence of indicated inhibitor at a shear rate of 1000 s⁻¹. Upper panels: mean overlays of [Ca²⁺]_i traces from >27 individual platelets; lower panels: traces from representative single platelets. B, quantification of increases in [Ca²⁺]_i at 20 s (gray) or 60 s (dark gray) after initial platelet activation. Means ± S.E. (n = 27–50); *, p < 0.05 compared with control.