Role of distinct collagen receptors in mediating platelet attachment under flow to reconstituted (banded) and pepsin-solubilized (nonbanded) type I collagen. Blood was perfused through the parallel plate chamber as described in the legend to Fig 2. Control blood or blood containing monoclonal antibodies to block specifically the function of platelet ₂β₁ and _IIbβ₃ concurrently with inhibition of plasma vWF binding to collagen was perfused over pepsin-solubilized (nonbanded) type I collagen or reconstituted collagen derived from the former, as indicated. Note the complete inhibition of platelet interaction with pepsin-solubilized (nonbanded) collagen when platelet ₂β₁ and _IIbβ₃function were blocked concurrently with inhibition of plasma vWF binding to collagen, compared with the stable attachment of single platelets at 100 s⁻¹ and 500 s⁻¹ under the same conditions with reconstituted type I collagen. Representative images of 6 separate experiments with blood from different donors are shown.