Thromb Haemost 1975; 34(03): 917-918
DOI: 10.1055/s-0039-1689578
Abstracts
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The Role of Calcium Ions in the Activation of Blood Platelets

P. Massini
1   Theodor Kocher Institute, University of Berne, Postfach 99, CH-3000 Bern 9, Switzerland
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Further Information

Publication History

Publication Date:
22 May 2019 (online)

 

    The plasma membrane of the resting platelet is only slightly permeable to Ca2+-ions. Stimulation of platelets with thrombin or other activators induces an increased influx of 45Ca. The influx occurs simultaneously with the release of serotonin. The “Ca influx is inhibited when the energy supply of the platelets has been interrupted. Stimulation with thrombin increases the efflux of 46Ca in platelets which have been labelled with 45Ca for 24 hours.

    Ionophores for divalent cations (X-537 A, A 23187) induce the release reaction, aggregation, clot retraction and rapid shape change. The release reaction does not require external Ca2+-ions whereas clot retraction depends on a Ca2+-eontaining medium.

    These results strongly suggest that the reactivity of platelets to external stimuli is primarily mediated by an increase of the cytoplasmic concentration of Ca2+-ions.