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[摘要]：The membrane microparticle (MP) formation and phosphatidylserine (PS) exposure evoked by platelet activation provide Catalytic Surfaces for thrombin generation. Several reports have indicated the effects of cAMP-elevating agents on agonist-induced MP formation and PS exposure; however, the mechanism still remains Unclear. Here we show that inhibition of basal cyclic AMP-dependent protein kinase (PKA) activity incurred platelet MP formation and PS exposure. Pretreatment of platelets with cAMP-elevating agent, forskolin, abolished thrombin plus collagen-induced MP formation and PS exposure, and obviously decreased calcium ionophore-evoked MP shedding. Moreover, the inhibitory effects of forskolin on agonists-induced MP formation and PS exposure were reversed by the PKA inhibitor H89. PKA inhibitor-induced MP formation was dose-dependently inhibited by calpain inhibitor MDL28170. and forskolin abrogated thrombin Plus collagen-induced calpain activation. In conclusion, PKA plays key roles in the regulation of platelet MP formation and PS exposure. PKA-mediated MP shedding is dependent oil calpain activation. (C) 2009 Elsevier Inc. All rights reserved. |
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