Platelet adhesion and thrombus formation on subendothelium, epon, gelatin and collagen under arterial flow conditions

In an annular perfusion chamber, subendothelium, Epon, gelatin and collagen coated on gelatin were exposed to rabbit blood flowing at 160 ml/min, under shear rates comparable to those found in the major arteries, for a period ranging from 1 to 40 minutes. Morphologic examination determined platelet contact, spreading and thrombus formation on these surfaces. On Epon, the major platelet interaction was contact, and spreading and release of granules were almost completely inhibited. Platelet-platelet accumulations were absent; after 10 minutes of exposure platelet adhesion consisted of a monolayer of individual platelets covering 10-30% of the surface; this adhesion pattern did not vary with time. On gelatin, platelet adhesion reached 45% surface coverage after 40 minutes; 70% of interactions were contact and few platelet-platelet accumulations were observed. On subendothelium, spread platelets covered 100% of the surface after 40 minutes. Spread platelets had lost more than 90% of their granule content and platelet thrombi reached a maximum surface coverage after 10 minutes and then disappeared. On collagen-coated gelatin, spread platelets almost completely covered the surface after 40 minutes, at a slightly slower rate than on subendothelium. However, platelet thrombi persisted for exposure times of as long as 40 minutes. Transition of the platelet from contact to the spread form and release of subcellular contents are associated with maximal platelet attachment and thrombus formation on surfaces. Among the surfaces tested, only subendothelium and collagen coated on gelatin promote spreading, release and maxiamal platelet attachment.