title: Thrombin induces serotonin secretion and aggregation independently of inositol phospholipids hydrolysis and protein phosphorylation in human platelets permeabilized with saponin.
abstract: We have observed that the addition of Ca2+ to platelets, permeabilized with saponin, promotes a drastic dephosphorylation of proteins and polyphosphoinositides without inducing platelet responses. Subsequent addition of thrombin could promote secretion of serotonin and aggregation in the absence of phospholipase C-induced breakdown of the inositol phospholipids and protein phosphorylation. This information indicates that activation of saponized platelets by thrombin is independent of the formation of second messengers derived from the phospholipase C-induced breakdown of the inositol phospholipids. The implications of this result for intact platelets are discussed.
authors.forename: E G
authors.initials: EG
authors.lastname: Lapetina
authors.forename: J
authors.initials: J
authors.lastname: Silió
authors.forename: M
authors.initials: M
authors.lastname: Ruggiero
mesh_terms: D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D006801:Humans; D006868:Hydrolysis; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects; D012503:Saponins / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D012503:Saponins; D012701:Serotonin; D010738:Type C Phospholipases; D013917:Thrombin; D002118:Calcium