Abstract
The present study examined the direct effect of bencyclane on the human platelet by means of electron microscopy.
Fresh platelet-rich plasma (PRP) was prepared for respective experiment from heparinized human blood by centrifugation at 1, 000 r. p. m. for 10min. at 4°C.
Either one of the following concentration of bencyclane (0.2ml, 1, 000, 500, 250, 125 and 62. 5μg/ml) or saline (0.2ml) was added to the PRP (1.8ml) at room temperature. After an incubation of the mixture for 30min. ribbons of platelets were obtained by centrifugation at 3, 500 r. p. m. for 15min.
In saline control qroup, the platelet showed round or spindle in shape with a few short pseudopods. The cytoplasmic organelles were relatively well preserved.
Ruthenium red stain revealed the surface layer measuring of 300-1, 200 Å in thickness on the outer leaflet of the plasma membrane of the platelet.
In experimental group, bencyclane in final concentration of either one of 1, 000, 500 or 250μg/ml made the contour of the platelet round and caused destruction of the plasma membrane. Deprival of the uneven surface layer and gathering of the cytoplasmic organelles to the center or periphery also occured in the cytoplasm of the platelet. Cytotoxic effects of bencyclane on the platelet was obvious in such a high concentration. Although bencyclane in concentration of 125 and 100μg/ml had kept the plasma membrane intact, a slight decrease in the surface layer appeared in the round platelet. Dilatation of the “canalicular system” occured characteristically in the center, but is obscure in the periphery of the platelet. Well preserved granules were fairly seen in the platelet.
No structural change was visible in the platelet treated with bencyclane in concentration of 62.5μg/ml. The surface layer stained by ruthenium red was not detected on the plasma membrane of the platelet under the effect of bencyclane in concentartion of either one of 1, 000, 500 or 250μg/ml.
These findings seemed to indicate that bencyclane acts not only on the plasma membrane but also on the membrane of the canalicular system of the platelet. Roundness of the platelet could be brought about by an interception of the canalicular system.
Eventually, antithrombotic activity of bencyclane appeared to cause these three changes in the platelet.
