Abstract
We discuss the mechanism of prevented platelet activation on microdomain-structutured surface in terms of [Ca2+]i On PSt, [Ca2+]i in platelets increased rapidly to reach maximum within 2 min. The platelets on PHEMA, however, showed a gradual increase in [Ca2+]i. On the other hand, the [Ca2+]i showed few increase in the case of the HEMA-St block copolymer (Block). This result indicates that platelets activation is preventing when contacting with Block from early stage of activation. Then the platelets on polymer were activated by thrombin and calcium ionophore. Platelets on Block exhibited almost the same response in thrombin activation as those on homopolymer. This result indicates that the activation mechanism is different from receptor mediated one. By ionophore, [Ca2+]i in the platelets on PHEMA showed higher level than any other polymrs. These results suggest that the membrane fluidity could be increased by contacting with PHEMA. Therefore, the platelet activation mechanism by contacting with PSt and PHEMA are different from each other. The Block prevent platelets activation by the formation of microdomain structures.
