Involvement of platelet-derived 5-hydroxytryptamine in thromboxane A2-induced aggregation in cat platelets
作者:
T Ogawa,
A Sugidachi,
F Asai,
H Koike,
期刊:
Blood Coagulation and Fibrinolysis
(OVID Available online 1998)
卷期:
Volume 9,
issue 3
页码: 233-240
ISSN:0957-5235
年代: 1998
出版商: OVID
关键词: 5-HT;5-HT2receptor;TXA2;U-46619;cat;platelet aggregation;ketanserin
数据来源: OVID
摘要:
The present study was undertaken to examine the involvement of platelet-derived serotonin (5-hydroxytryptamine; 5-HT) in thromboxane A2(TXA2)-induced platelet aggregation. Pharmacological experiments with 5-HT2and TXA2inhibitors were conducted on platelet aggregation in platelet-rich plasma from cats. Exogenously added 5-HT, U-46619 (a stable TXA2analogue) and collagen caused platelet aggregation in a concentration-dependent manner. The combination of low concentrations of 5-HT and U-46619 caused full platelet aggregation, whereas each agent alone, at these concentrations, caused a transient aggregation. 5-HT-induced aggregation was inhibited by ketanserin (0.01–0.3 µmol/l), a 5-HT2receptor antagonist, in a concentrationdependent manner. Collagen-induced platelet aggregation was also inhibited by ketanserin, whereas the inhibition by indomethacin was modest even at the highest concentration tested (300 µmol/l). U-46619 triggered platelet aggregation in a biphasic manner. Ketanserin inhibited only the second phase of the aggregation. The inhibition of U-46619-induced aggregation by ketanserin occurred at a concentration range similar to that for 5-HT-induced platelet aggregation. Likewise, platelet aggregation induced by the combination of low concentrations of 5-HT and U-46619 was fully inhibited by ketanserin. These data suggest a major involvement of platelet-derived 5-HT in TXA2-dependent aggregation in cat platelets.
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