THE EFFECT OF SHEAR RATE ON THE ADHESION ACTIVATION OF HUMAN PLATELETS IN FLOW-THROUGH A CLOSED-LOOP POLYMERIC TUBULAR SYSTEM/

Three polymers, produced as reference materials of a European Communit ies program, namely PE, PP, and PVC, in tubular form, were comparative ly evaluated for their hemocompatibilily. In particular, the following parameters: platelet retention index, beta-thromboglobulin (beta-TG) release from activated platelets, and expression of the platelet prote in GMP 140 (PADGEM) were measured as a function of time for whole anti coagulated human blood flowing in a closed-loop system under two diffe rent shear rates of 2000 and 500 s(-1). Data up to 20 min (afterwards there was hemolysis) showed a fluctuating platelet retention index as time increased for PE and PVC and an increasing value for PP. Platelet aggregation and dislodgment fi:om the surface could not be differenti ated. Activation of platelets as expressed with beta-TG release were h igher for both PE and PP in both shear rates in comparison to PVC whic h elicited a higher response at the high shear rate. Finally, PADGEM e stimations seem to indicate a more stable platelet retention layer for PP than PE or PVC.