5HT对STA2介导的血小板聚集和解释反应的双重影响

目的：研究５－ＨＴ对ＳＴＡ２血小板聚集和释放反应的影响及可能的分子机制。方法：以透光法，介质中ＡＴＰ含量及荧光图像法评介血小板变形，聚集反应和［Ｃａ＾］ｉ水平。结果：（１）５－ＨＴ预处理可消除ＳＴＡ２的血小板变形，ＳＴＡ２ ０．３μｍｏｌ·Ｌ＾－１的聚集增强，１－２ｍｏｌ·Ｌ＾－１的聚集不变，释放反应抑制。（２）５－ＴＨ预处理增加ＳＴＡ２ ０．３μｍｏｌ·Ｌ＾－１的［Ｃａ＾２＋］ｉ降低３μｍｏｌ·

Dual effects of 5-hydroxytryptamine on stable analogue of thromboxane A2-induced aggregation and release reaction in rabbit platelets.

AIM: To study the effects of 5-hydroxytryptamine (5-HT) on stable analogue of thromboxane A2 (STA2)-induced platelet shape, aggregation, and release reaction. METHODS: Platelet shape change and aggregation were quantified by the light transmission through platelet-rich plasma (PRP). Release reaction was evaluated by the amount of ATP in the medium and cytosolic-free Ca2+ was measured by fluorescent imaging. RESULTS: (1) STA2 0.3-3 mumol.L-1-induced shape change followed by aggregation. When STA2 1 or 3 mumol.L-1 was added to PRP, the release reaction was occurred. Pretreatment of PRP with 5-HT 3 mumol.L-1, the shape change by STA2 was abolished and the aggregation by STA2 0.3 mumol.L-1 was enhanced (P < 0.01), STA2 1 or 3 mumol.L-1-induced aggregation was not affected, but the release reaction was partially suppressed (P < 0.01). (2) STA2 0.3 mumol.L-1-induced Ca2+]i elevation was further increased by 5-HT pretreatment, but the Ca2+]i mobilizations by STA2 3 mumol.L-1 was decreased by 5-HT, especially the peak level. (3) The aggregation without release reaction was increased from 3.4 +/- 2.1 to 25.6 +/- 1.8% (P < 0.01) with 10 s interval and the enhancement was declined with the prolongation of the intervals. The aggregation with release reaction was not affected by changing the intervals, but the release reaction was decreased in the same treatment. CONCLUSION: The dual effects of 5-HT on STA2-induced aggregation and release reaction and the molecular mechanism of this effect was probably through the regulative action of 5-HT on Ca2+]i mobilization by STA2.