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Circulation. 2002 May 28;105(21):2531-6.

Functional significance of adenosine 5'-diphosphate receptor (P2Y(12)) in platelet activation initiated by binding of von Willebrand factor to platelet GP Ibalpha induced by conditions of high shear rate.

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  • 1Division of Cardiology, Department of Medicine, Tokai University School of Medicine, Kanagawa, Japan. shinichi@is.icc.u-tokai.ac.jp

Abstract

BACKGROUND:

The role of the adenosine 5'-diphosphate receptor P2Y(12) in platelet activation initiated by the von Willebrand factor (VWF)-GP Ibalpha interaction under high shear rate was investigated.

METHODS AND RESULTS:

Blood samples were obtained from 11 donors. Shear-induced platelet aggregation was detected by optically modified cone-plate viscometer. Shear-induced VWF binding, P-selectin expression, and microparticle release were detected by flow cytometry. Platelet interaction with immobilized VWF was also investigated by parallel-plate flow chamber equipped with epifluorescent videomicroscopy. Effects of a selective P2Y(12) antagonist AR-C69931 MX were tested. AR-C69931 MX inhibited shear-induced platelet aggregation in a dose-dependent manner, achieving the maximum inhibition at 100 nmol/L. The extent of aggregation after exposure to a shear rate of 10 800 s(-1) for 6 minutes in the presence of 100 nmol/L AR-C69931 MX was 32.4+/-8.2% (mean+/-SD), which was significantly lower than the value in the controls of 69.7+/-9.6% (P<0.01). The inhibiting effects of AR-C69931 MX were reversed by exogenous addition of adenosine 5'-diphosphate. Shear-induced VWF binding and P-selectin surface translocation, which occurred in 4696+/-911 and 5964+/-784, respectively, of 10 000 measured platelets, was also inhibited by AR-C69931 MX (100 nmol/L) to 1948+/-528 and 2797+/-718, respectively (P=0.0018 and P=0.0009). Microparticle release was similarly inhibited. In a flow chamber experiment, firm platelet attachment on immobilized VWF was inhibited by AR-C69931 MX, whereas transient interaction was not influenced. All the above reactions were completely inhibited by blocking VWF-GP Ibalpha interaction.

CONCLUSIONS:

We have demonstrated that the stimulation of P2Y(12) is involved in platelet activation initiated by the binding of VWF to GP Ibalpha induced by a high shear rate.

PMID:
12034661
[PubMed - indexed for MEDLINE]
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