Different effects of two thromboxane A2/prostaglandin H2 receptor ligands, U46619 and S-145, on rabbit platelets |
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Authors: | T Nakano K Hanasaki H Arita |
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Affiliation: | Shionogi Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan. |
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Abstract: | Stimulation of rabbit platelets with U46619 induced platelet shape change, aggregation and secretion of ATP. However, S-145, which specifically binds to the thromboxane A2/prostaglandin H2 receptor like U46619, induced only shape change. Both compounds rapidly elevated cytoplasmic Ca2+ concentration although only U46619 evoked the formation of inositol phosphates. Chelating external Ca2+ with EGTA did not affect the S-145-induced platelet shape change while intracellular Ca2+ movement was severely reduced. These results suggest an essential role of phospholipase C in the induction of platelet aggregation and secretion and that some factor other than Ca2+ and phospholipase C participates in platelet shape change. |
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