抄録
The concentration of platelets in flowing blood is known to attain maximum near the vessel wall, and this phenomenon is referred to as "Near Wall Excess (NWE)". Although NWE is evidently important and expedient in hemostatic functions of the platelets, its mechanism has not been fully elucidated yet. In order to understand NEW from a mechanical point of view, we measured the distribution of platelet-sized latex beads in a mixed suspension with human red cells flowing through microchannels, by using a confocal laser scanning microscope. The results indicated that the distributions of beads of various diameters were nonuniform in the presence of red cells, whereas their distributions in the absence of red cells were uniform in the channel cross-section. In the mixed suspensions of beads and red cells, the concentration profiles of beads of 3μm diameter showed sharp peaks near the channel walls at hematocrits of 20% and 44%, and the extent of this NWE was larger for larger hematocrits in the range examined. On the other hand, the beads of 1μm diameter exhibited NWE only slightly at similar hematocrits, and instead, they showed a distinct tendency to concentrate near the channel centerline.
