Abstract
Glass bead column methods are widely employed for the estimation of the adhesiveness of the blood platelets. However, light and scanning electron microscopic studies as well as biochemical studies have shown that the retention rate by these methods represents not the pure adhesion but a combination of adhesion and aggregation. In order to devise a method to estimate more pure adhesiveness, a series of experiments were performed on inhibiting the aggregation in the glass bead column and on obtaining an adequate normal range. The platelets on the beads were examined by scanning electron microscopy by our method and the retention rate was calculated as usually.
EDTA-2K (0.1% at final concentration) was proved to almost completely inhibit the aggregation or to dissociate the aggregates on the beads in the columns by Hellem II method as in an aggregometer, whereas adenosine did not so completely. The adhered (spread) platelets, however, were changed to spheres with pseudopods by EDTA, but spread again after washing out EDTA by infusion of saline. This suggests that the platelets retained in the column in the presence of EDTA are adhered ones. The adhesiveness (retention rate) with EDTA-blood was elevated with the increase of length of the column (glass bead amount) and also with the decrease of the infusion speed.
To minimize the blood amount neccessary a short and thick tube, 2.5ml in inner capacity, was connected to a 80cm long column, 3mm in inner diameter, containing 7.8gr of glass beads with diameter of 0.5mm. At measurement about 2ml of EDTA-blood was injected to fill the short tube and a disporsable syringe containing 0.85% saline was connected to the tube and set on a Harvard infusion pump 975. The EDTA-blood was thus indirectly infused by the saline at speed of 27sec/ml into the long column which was held perpendicularly to avoid mixture of blood with saline. The retention rate was calculated from the platelet counts in the control sample and in the first 1ml of the effluent from the column. The retention rate was 50-80% in normal subjects. This method is hoped to give us a new information on the behaviour of normal and pathological platelets.
