Retention of Platelets by Foreign Surfaces and its Modification by Chemical Substances

For investigation of platelet retention from streaming citrated (3.8%) blood by foreign surfaces a test system has been developed consisting of a peristaltic pump by which anticoagulated blood is passed continuously through silicone tubing connected with glass bead and charcoal filters. Maximum retention in glass bead filters as well as in filters packed with charcoal particles was observed when citrated blood was passed through dry filters (mean ± S.D.: 30.3±10.5% and 37.4±10.5% at a passage time of 10 min.). By prior coating the fiTter particles with saline or 20% albumin retention was reduced to 24.B ±12.9% (n.s.) and 14.B±3.9% (p 0.01), respectively in glass bead filters and to 22.9±5.9% (p 0,01) and 13.9±B.2 % (p<0.01), respectively in charcoal filters. Coating of the glass beads with 0.6% fibrinogen and 80 μM/1 ADP significantly (p <0.01) increased retention while addition of 0.25 mg/ml of RA 233 to citrated blood significantly (p < 0.01) reduced retention in charcoal filters (67.1±15.B%, 42.3±12.1% and 10.2±6.7%). Further the kinetics of retention, the rate of hemolysis and the effect of passage on platelet metabolism was investigated.