Turnover of platelets adhered to fibrinogen-coated surfaces.

The dynamic interactions between platelets and fibrinogen-coated surfaces were investigated by using a tube-flow device and a rotating rod device. The net platelet accumulation to the fibrinogen-coated surfaces in both devices reached maximal values of 30-40 platelets/1000 um2. This adhesion phenomenon was completely inhibited by EDTA. In the tube-flow device, the density of platelets adhered to the tube surface increased with flow time and decreased with distance from the tube inlet. These adhered platelets were difficult to be washed off the tube surface and showed little turnover. The platelet accumulation kinetics in a rotating rod device increased with rotation speed from 300 rpm to 1200 rpm. At 1200 rpm, about half of these platelets adhered to the rod were exchangeable with platelets in the suspension whereas the rest of them were permanent. The detachment of platelets from the rod surface depended on the presence of erythrocytes and platelets in the suspension and it was facilitated by the presence of EDTA in the suspension. These observations suggest that the turnover of platelets adhered to fibrinogen-coated surfaces depends on experimental conditions.