Thromb Haemost 2001; 85(03): 514-520
DOI: 10.1055/s-0037-1615614
Review Article
Schattauer GmbH

Rho-kinase Is Involved in the Sustained Phosphorylation of Myosin and the Irreversible Platelet Aggregation Induced by PAR1 Activating Peptide

K. Missy
1   INSERM, Unité 326, Institut Fédératif de Recherche 30, Hôpital Purpan, Toulouse, France
,
M. Plantavid
1   INSERM, Unité 326, Institut Fédératif de Recherche 30, Hôpital Purpan, Toulouse, France
,
P. Pacaud*
,
C. Viala
1   INSERM, Unité 326, Institut Fédératif de Recherche 30, Hôpital Purpan, Toulouse, France
,
H. Chap
1   INSERM, Unité 326, Institut Fédératif de Recherche 30, Hôpital Purpan, Toulouse, France
,
B. Payrastre
1   INSERM, Unité 326, Institut Fédératif de Recherche 30, Hôpital Purpan, Toulouse, France
› Author Affiliations
Further Information

Publication History

Received 25 May 2000

Accepted after resubmission 12 October 2000

Publication Date:
08 December 2017 (online)

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Summary

We have addressed the role of Rho-kinase in the different steps of thrombin receptor agonist peptide (TRAP) -induced platelet activation. Interestingly, under physiological conditions, incubation of platelets with increasing concentrations of the specific Rho-kinase inhibitor Y-27632 resulted in a dose-dependent reversion of the aggregation induced by 10 μM TRAP, without affecting serotonin secretion. Addition of Y-27632 after three minutes of TRAP stimulation, when the maximal aggregation was reached, resulted in a rapid disaggregation of platelets. Accordingly, the early peak of myosin light chain (MLC) phosphorylation induced by TRAP was not affected by Y-27632 but its sustained phosphorylation, observed during the irreversible phase of aggregation, was dependent of Rho-kinase activity. The rapid decrease in MLC phosphorylation upon Y-27632 treatment correlated well with the specific disappearance of myosin heavy chain from the cytoskeleton and preceded platelet disaggregation. Finally, we provide evidence that secreted ADP, known to play a key role in TRAP-induced irreversible phase of aggregation, was involved in the sustained MLC phosphorylation through Rho-kinase and could be replaced by epinephrine.

* INSERM, Unité 533, Faculté des Sciences et Techniques de Nantes, Nantes, France