MEDLINE Journals

    Platelet-activating factor is a weak platelet agonist: evidence from normal human platelets and platelets with congenital secretion defects.

    Authors
    Rao AK, Willis J, Hassell B, et al. 
    Source
    Am J Hematol 1984 Aug; 17(2) :153-65.
    Abstract

    We have examined the effects of a novel platelet agonist, platelet activating factor (PAF), on human platelets. Irreversible aggregation and 14C-serotonin secretion in response to PAF (10(-5) M) was found to be dependent on both thromboxane production and secreted adenosine diphosphate (ADP). Liberation of arachidonic acid (AA) from membrane-bound phospholipids is a prerequisite step in platelet thromboxane production. Studies with 3H-AA-labeled platelets revealed that PAF (10(-5) M) was a weak stimulus for the mobilization of AA. In addition, PAF (10(-5) M) was found to be a weak inducer of thromboxane synthesis (mean = 6 pmol/10(8) platelets) as compared to thrombin 5 U/ml (mean = 177 pmol/10(8) platelets), measured using a radioimmunoassay for thromboxane B2. Formation of phosphatidic acid is an early step in stimulus-response coupling in platelets. Our studies indicate that PAF is a weak stimulus for phosphatidic acid formation as well. To obtain further insights into its action, we examined the effect of PAF on platelets from three groups of patients with congenital secretion defects: patients with the storage pool deficiency, those with impaired thromboxane synthesis due to impaired liberation of AA from phospholipids, and those with impaired secretion despite normal granule stores and thromboxane production. The response to PAF was impaired in all patients, providing further evidence that PAF-induced platelet activation is dependent on secreted ADP and thromboxane A2 synthesis, and occurs by mechanisms common to a number of agonists. Overall, these studies indicate that PAF is a weak platelet agonist.

    Mesh
    Adenosine
    Adenosine Triphosphate
    Arachidonic Acid
    Arachidonic Acids
    Blood Platelet Disorders
    Humans
    Platelet Activating Factor
    Platelet Aggregation
    Serotonin
    Thrombin
    Thromboxanes
    Language

    eng

    Pub Type(s)
    Journal Article Research Support, U.S. Gov't, P.H.S.
    PubMed ID

    6431801

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