Unaltered platelet responses to thrombin and collagen in α2A–/– mice. (A) Diluted whole blood was incubated with different concentrations of thrombin and CRP, as indicated. Activation of αIIbβ3 and P-selectin expression (not shown) was analyzed by flow cytometry. Results are presented as mean ± SD of 5 mice per group. (B) Heparinized PRP was stimulated with indicated concentrations of fibrillar collagen (“Coll”), and light transmission was recorded on a Fibrintimer 4-channel aggregometer. Results shown are representative of 6 individual experiments. (C) Whole blood was perfused over a “Horm-type” collagen-coated coverslip at high shear (1000 seconds–1). Representative phase-contrast images were taken at the end of the experiment. Images were captured with a Zeiss Axiovert 200 inverted microscope (Carl Zeiss, Jena, Germany) with a 63 ×/0.75 Ph2 objective, a 100-W HBO fluorescent lamp source, and a CCD camera (CV-M300; Visitron Systems, Puchheim, Germany) connected to an AG-7355 S-VHS video camera (Panasonic, Matsushita Electric, Osaka, Japan). Videotaped images were evaluated using a computer-assisted image analysis program, Meta View Version 5.0 (Visitron Systems).
