Phospholipid transverse mobility modifications in plasma membranes of activated platelets: an ESR study.
Spin labeled phospholipid analogs were used to directly study changes in aminophospholipid translocase activity in activated platelets. In thrombin-activated platelets, the translocase activity was slightly stimulated, whereas no vesicle formation or proteolysis of cytoskeletal protein occurred. Ca2+ ionophore A23187-mediated activation produced vesiculation and proteolysis. Additionally, the translocase activity was completely inhibited, probably due to a sharp rise the intracellular Ca2+ concentration, as shown when platelets were activated in the presence of various A23187 and Ca2+ concentrations and by the recovery of the translocase activity when Ca2+ was complexed with EGTA. No translocase activity was found in vesicles. Whereas vesiculation and translocase inhibition can occur independently of proteolysis, this later accentuated the shedding phenomenon.
Bassé
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URA 530 CNRS, Dept Biologie Santé, USTL, Montpellier, France.
Gaffet
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P
Rendu
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Bienvenüe
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D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D010743:Phospholipids / Q000097:blood*; D015539:Platelet Activation / Q000187:drug effects; D013113:Spin Labels; D013917:Thrombin / Q000494:pharmacology
D010743:Phospholipids; D013113:Spin Labels; D000001:Calcimycin; D004533:Egtazic Acid; D013917:Thrombin; D002118:Calcium