The Influence of Red Blood Cell Hemolysate (RBCH) on Platelet Aggregation (PA) and Release of Serotonin and β-Thromboglobulin (β-TG) in Heparinized Platelet Rich Plasma (PRP)

As hemolysis occurs preferentially in artificial internal organs (AIO), and thromboembolic complications are frequently seen in AIO, the influence of liberated RBC-contents on PA was investigated. To perform the experiments under the most physiological conditions, heparin was used as anticoagulant and the platelets were kept at 37°C during withdrawal, preparation, storage and aggregometry. The lysed RBC were freed of membranes and stored at 0°C until use. PA was quantitatively monitored in a defined homogenous shear field in a Couette-chamber by turbidimetry. Dense granule release was assayed using ¹⁴C-Serotonin labelled platelets. Alpha granule release was assessed via β-TG radioimmunoassay. PRP samples with added RBCH were compared with samples with ADP added in doses equivalent to that of the samples with RBCH. PA, Serotonin, and β-TG release were found to be positively correlated to the concentration of RBCH In PRP, An increase of PA and release as compared to control samples was observed above RBCH-concentratlons of ea. 0.3 g/L hemoglobin, a concentration frequently found during use of AIO. The addioion of ADP in hemolysate-equivalent doses proved to be less effective. Chromatographic assays showed that ATP, which is found in concentration about tenfold of ADP In the RBC, is broken down to ADP in PRP, thus augmenting the ADP-pool acting on platelets.