Cationized ferritin による血小板形質膜陰性荷電の標識

抄録

The distribution of anionic sites on the platelet membranes was studied under the different conditions by using cationized ferritin (CF).
Experiment I; Human platelet rich plasma (PRP) was fixed in 2.5% glutaraldehyde at room temperature for 30min, and followed by washing with 0.01 M phosphate buffered saline (PBS). Samples of PRP were incubated with CF at 37°C for 30min. After washing with same PBS twice, the specimen was prepared for electron microscopy. CF were observed as evenly distributed dense particles on the cell surface of the platelet.
Experiment II; PRP was washed with 0.01 M PBS containing sodium citrate, and then resuspended in the solution (suspension of washed platelets: SWP). After incubation of the SWP with CF at 37°C, each specimen obtained at 1-45min was similarly washed with the PBS and prepared for observation. In the incubation for less than 15min, a large amount of the particles were clustered on several sites of the cell surface. The platelet incubated for more than 30min, showed an uptake of most particles into the dilated open canalicular system (OCS). A small amount of clustered particles, however, were left on the surface behind.
Experiment III; Immediately after fixation, the SWP was washed with the PBS, and incubated with CF at 37°C for 30min. The specimen was washed with the PBS and prepared for observation. The cell surface was evenly studded with the dense particles.
In each experiment, the control specimen revealed no presence of binding site for the native ferritin particles on the surface of the plasma membrane or the membrane of OCS.
It is concluded that the anionic sites on the platelet surface may be mobile in the fluid state and glutaraldehyde fixation may have some effects on the arrangement of CF particles as well. Furthermore, when the CF particles are taken up into the OCS, the anionic sites on the membrane systems may also undergo electrical changes, probably due to the secretion reaction of platelets stimulated by CF particles.