Hemodynamically induced blood platelet deposits in branched, curved, and constricted glass tubes.

Branched, curved, and constricted glass tubes were perfused with bovine platelets/platelet rich plasma (50000 platelets/μl activated by 2.5 x 10-6 M ADP; at 37°C) for 3 to 12 min. Straight tube flow does not lead to adhesions on the tube wall. As a rule, deposits start with individual adherent platelets and are observed at following sites: on both sides of and distally from the orifice of the side branch (main tube ID (inside diameter) 3 mm, side branch ID 1.5 mm; rectangular); on the outer wall of a 180° curved tube (ID 3 mm, curve radius 6.5 mm); and on the beginning of the constriction (ID 4 mm constricted to 2.1 mm over 4 mm). The deposits form streaks following the streamlines. A minimum flow rate and ADP concentration is necessary to produce deposits; these values are higher in curved and constricted tubes than in a branched tube. High flow rates prevent mural adhesion. Addition of washed red blood cells up to a concentration of 10 fold the platelet concentration does not alter the platelet deposits. It was shown earlier that red blood cells deposit in contrary in the stagnation water opposite the orifice of the side branch if a rectangular branched tube is perfused with a suspension of sticky red blood cells. At this site platelet aggregations rarely and not yet reproducible deposit on the wall