title: N-Ethylmaleimide induces disaggregation of platelets preaggregated by ADP and thrombin and decreases cytoplasmic calcium level.
abstract: The effect of N-ethylmaleimide (NEM, 1-200 microM) on ADP- and thrombin-induced platelet aggregation and thrombin-induced increase in intracellular Ca2+ concentration was studied. Addition of NEM to platelets preaggregated with ADP or thrombin induces platelet disaggregation. The anti-aggregant activity of NEM was different for ADP- and thrombin-induced aggregations. At 200 microM concentration, NEM completely disaggregated ADP-induced aggregates and only partially disaggregated thrombin-aggregated platelets. NEM did not influence the thrombin-induced increase in cytoplasmic Ca2+ and had no effect on the basal level of Ca2+ in the cytosol of non-activated platelets. However, NEM decreased the level of thrombin-mobilized Ca2+ in the cytosol of activated platelets. Thus, NEM can induce disaggregation of ADP- and thrombin-preaggregated platelets by activating a system which removes Ca2+ from the platelet cytosol.
authors.affiliation: Department of Biophysics, Belarus State University, Minsk, 220050, Belarus. samal@phys.bsu.unibel.by.
authors.forename: A B
authors.initials: AB
authors.lastname: Samal
authors.forename: E N
authors.initials: EN
authors.lastname: Loiko
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000097:blood*; D003593:Cytoplasm / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology
chemical_list: D000244:Adenosine Diphosphate; D013917:Thrombin; D005033:Ethylmaleimide; D002118:Calcium