Reduced GPIIb/IIIa expression in platelets hyposensitive to catecholamines when activated with TRAP

Introduction: A previous report assigned 35 healthy Koreans into five groups (groups A to E) based on their platelet responsiveness to catecholamines (CA). The present work aimed to elucidate the possible mechanism of heterogeneous responsiveness to CA in normal subjects. Materials and methods: The degrees of aggregation in platelet rich plasma (PRP) were measured with a turbidimetric method. The expression of platelet glycoprotein and activation maker was analyzed with flow cytometric method in whole blood. Results and conclusions: The degrees of aggregation in response to other aggregation inducing agents (AA, ADP, and U46619) were significantly lower in platelets hyporesponsive to CA. The flow cytometric analysis showed that GPIIb, GPIIIa and GPIIb/IIIa expressions were 20.1%, 25.7%, and 38.2%, respectively, higher in the CA-responsive group than in the CA-hyporesponsive group when the groups were in a TRAP activated state, while no differences were observed between the two groups when in a resting state. (C) 2009 Elsevier Ltd. All rights reserved.