Abstract
An elevation of cytoplasmic free calcium levels ([Ca2+]i) in platelets in contact with polystyrene latex particles was examined in comparison with those by thrombin and calcium ionophore (A23187). Benzyl alcohol-treated platelets showed much higher [Ca2+]i by A23187 but lower by thrombin and polystyrene, which suggests that elevation of [Ca2+]i by polystyrene surface is not due to an increase in membrane fluidity. Serratia protease-treated plateletes showed a steep increase in [Ca2+]i by polystyrene but gradual increase by thrombin, which suggests that polystyrene surface can initiate platelet activation independent of glycocalicin of GPIb. Dibucaine-treated platelets showed few increase in [Ca2+]i by polystyrene, which indicates that microfilament assembly including the binding of GPIb with actin binding protein should be required for platelet activation by polystyrene surface. Thus, a change in membrane glycoproteins-cytoskeleton networks can be dominant in initiating platelet activation by polymer surfaces.
