Thromb Haemost 1989; 62(04): 1116-1120
DOI: 10.1055/s-0038-1647129
Original Article
Platelets
Schattauer GmbH Stuttgart

Eicosapentaenoic Acid Interferes with U46619-Stimulated Formation of Inositol Phosphates in Washed Rabbit Platelets

N Chetty
1   The Department of Haematology, Coagulation Research Unit, South African Institute for Medical Research, Johannesburg, South Africa
,
J D Vickers
The Department of Pathology, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
,
R L Kinlough-Rathbone
The Department of Pathology, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
,
M A Packham
2   The Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
,
J F Mustard
The Department of Pathology, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
› Author Affiliations
Further Information

Publication History

Received 23 May 1989

Accepted after revision 26 September 1989

Publication Date:
24 July 2018 (online)

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Summary

Eicosapentaenoic acid (EPA) inhibits platelet responsiveness to aggregating agents. To investigate the reactions that are affected by EPA, we examined the effect of preincubating aspirintreated rabbit platelets with EPA on stimulation of inositol phosphate formation in response to the TXA2 analogue U46619. Stimulation of platelets with U46619 (0.5 μM) caused aggregation and slight release of dense granule contents; aggregation and release were inhibited by preincubation of the platelets with EPA (50 μM) for 1 h followed by washing to remove unincorporated EPA. Incubation with EPA (50 μM) for 1 h did not cause a detectable increase in the amount of EPA in the platelet phospholipids. When platelets were prelabelled with [3H]inositol stimulation with U46619 of control platelets that had not been incubated with EPA significantly increased the labelling of mos1tol phosphates. The increases in inositol phosphate labelling due to U46619 at 10 and 60 s were partially inhibited by premcubat10n of the platelets with 50 μM EPA. Since the activity of cyclo-oxygenase was blocked with aspirin, inhibition of inositol phosphate labelling in response to U46619 indicates either that there may be inhibition of signal transduction without a detectable change in the amount of EPA in platelet phospholipids, that changes in signal transduction require only minute changes in the fatty acid composition of membrane phospholipids, or that after a 1 h incubation with EPA, activation of phospholipase C is affected by a mechanism that is not directly related to incorporation of EPA.