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Effect of various excitatory agonists on the secretion of 5‐hydroxytryptamine from permeabilised human platelets induced by Ca 2+ in the presence or absence of GTP
Author(s) -
Knight D.E.,
Scrutton M.C.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80823-1
Subject(s) - gtp' , chemistry , thrombin , phospholipase c , platelet , excitatory postsynaptic potential , g protein , biophysics , secretion , phorbol , medicine , receptor , endocrinology , signal transduction , biochemistry , biology , protein kinase c , enzyme
Addition of GTP markedly enhances the ability of thrombin to cause a leftward shift in the Ca 2+ dose/ response curve for 5‐hydroxytryptamine secretion from permeabilised human platelets. Little effect is observed on addition of GTP in the absence of thrombin. Neither ADP nor adrenaline, in the presence or absence of GTP, causes such a shift, whereas 5‐hydroxytryptamine does so to a small extent but only in the presence of GTP. The leftward shift in the Ca 2+ dose/response curve induced by 12‐ O ‐tetradecanoyl‐phorbol‐13‐acetate or 1‐oleyl‐2‐acetylglycerol is not enhanced by addition of GTP. The thrombin concentration required for half‐maximal enhancement of the responce to Ca 2+ is markedly reduced by addition of GTP. The results support the postulate that the effects of excitatory agonists in this system correlate with their ability to activate phospholipase C and provide further evidence for a role for GTP in signal transduction between the receptor and phospholipase C.