Abstract
We have devised a microcomputer-based filtration technique for erythrocyte deform ability studies. The system receives the output from a pressure transducer and can continuously vary the flow rate or the filtration pressure via a programmable pump. Measurement may be performed either at constant flow rate or at constant pressure under feedback control. The initial steady state relative filtration pressure (iRFP) at constant flow rate or initial relative flow rate at constant pressure (iRFR) may be used to assess erythrocyte deformability. Blood was anticoagulated with, either heparin or EDT A. Leucocytes and platelets were removed by pre-filtration through Imugard cotton wool. For deformability studies, erythrocyte suspensions at 5% haematocrit were filtered through Hemafil PC membranes with 4.7 micron pores. The mean iRFP value from 33 experiments was 1.335 ± 0.049. When 5 µM dipyridamole was present in the cell suspension, the iRFP was reduced to 1.224 ± 0.057 (p<0.0001). Similar results were obtained from filtrations at constant pressure. This finding suggests that dipyridamole may be beneficial when impaired erythrocyte deformability contributes to microcirculatory pathology. Leucocyte and platelet removal was more efficient with heparin than with EDT A and the filtration results were also more improved. Heparin which does not deplete Ca++, may be the anticoagulant of choice for erythrocyte deformability studies.
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