EFFECTS OF PHYSICAL FORCES ON PLATELETS

该计划的重点是阐明的动力学和 剪切场中血小板反应的机制。 人血小板 将在全血和许多不同的悬浮液中进行研究 加入和不加入激动剂，进行测量，已知水平的 剪切应力，并检查反应的证据。 旋转 将使用粘度计，以便在很宽的压力水平范围内， 可以在严格控制的条件下研究暴露时间。 基本 血小板反应的指标将包括剪切场中的聚集， 发布和功能变更。 大部分重点将放在其他方面 血小板反应的指标如下所述。 旋转粘度计将配备光学检测系统， 血小板反应可以在剪切场中直接监测。 三 监测血小板反应的指标：（1）聚集， 以光密度变化表示;（2）致密颗粒释放，随后 通过测量ATP -荧光素酶-荧光素酶发光;和（3） 细胞内钙离子动员，随后通过使用光探针。 剪切应力对花生四烯酸（AA）代谢率的影响 将建立吸收。 将对分布进行测量 在磷脂、中性脂质和游离脂肪酸中。 代谢物 将测量AA的浓度，并研究血小板受体的变化， 直接和间接的。 将研究血小板受体糖蛋白 通过使用针对特定血小板的单克隆抗体 受体。 其他研究将确定剪切场对 vWF（血管性血友病因子）多聚体形式与血小板的附着 在正常血浆中，产生了异常大的vWF多聚体， 由人内皮细胞分泌。

The proposed program is focused on elucidation of the kinetics and mechanisms of platelet response in a shear field. Human blood platelets will be studied in whole blood and in a number of different suspensions with and without added agonists, subjected to measured, known levels of shear stress, and examined for evidence of response. Rotational viscometers will be used so that a very wide range of stress levels and exposure times can be studied under closely controlled conditions. Basic indices of platelet response will include aggregation in the shear field, release and functional changes. Most of the emphasis will be on other indicators of platelet response as outlined below. A rotational viscometer will be fitted with optical detection systems so that platelet response can be monitored directly in the shear field. Three indicators of platelet response will be monitored: (1) aggregation, indicated by optical density changes; (2) dense granule release, followed by measuring ATP - luciferin - luciferase luminescence; and (3) intracellular calcium ion mobilization, followed through use of photoprobes. The influence of exposure to shear stress on rates of arachidonic acid (AA) uptake will be established. Measurements will be made of the distribution amongst phospholipids, neutral lipids, and free fatty acids. Metabolites of AA will be measured and platelet receptor changes will be studied both directly and indirectly. Platelet receptor glycoproteins will be studied by use of monoclonal antibodies directed against specific platelet receptors. Other studies will determine the influence of the shear field on the attachment to platelets of the vWF (von Willebrand Factor) multimeric forms in normal plasma, and the unusually large vWF multimers produced and secreted by human endothelial cells.