Murine platelet Itga2: surface density and function. (A) Murine platelet glycoprotein levels were determined by flow cytometry. The surface content of platelet glycoproteins αIIbβ3, GPIbα, GPVI, α5β1, and α2β1 was determined in citrated whole blood using rat antimouse monoclonal antibodies. The level of bound FITC- or PE-conjugated rat antibody was expressed as the geometric mean fluorescence intensity and is indicated on the ordinate. Each bar represents the mean ± SD of 6 separate measurements using whole blood pooled from 5 to 6 male mice in each measurement. The results from 5 representative inbred strains are depicted. Three strains bear haplotype 1 (BALB/cJ, C57BL/6J, and 129/SvJ), whereas 2 strains express haplotype 2 (FVB/NJ and A/J). In the bottom right-hand panel, the levels of α2β1 were normalized with respect to the levels of α5β1 where [α2β1(n) = GMFI (α2β1)/GMFI (α5β) × 100]. (B) Platelet adhesion under high shear measured by the PFA-100. Citrated whole blood was pooled from 5 to 6 male mice of each of the 5 representative strains (see panel A) on 3 independent occasions. The CT in seconds was recorded and is indicated on the ordinate. The left-hand side depicts the results when blood was perfused over cartridge membranes impregnated with collagen plus ADP (CT-CADP); for the right-hand side, the findings shown when blood was perfused over cartridge membranes impregnated with collagen plus epinephrine (CT-CEPI). Each entry represents the mean ± SD.