PLATELET-HEPARIN INTERACTIONS IN CARDIOVASCULAR SURGERY

心血管手术中的血小板-肝素相互作用

• 批准号: 3356871
• 负责人: MICHAEL SOBEL
• 金额: $ 20.48万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3356871
• 关键词: affinity chromatography; affinity labeling; anticoagulants; binding proteins; calcium; calorimetry; carbohydrate structure; cardiovascular surgery; circular dichroism; conformation; crosslink; drug design /synthesis /production; extracorporeal circulation; fluorescent dye /probe; heparin; human tissue; immunocytochemistry; platelet activation; platelet aggregation; platelets; protein sequence; radiotracer; receptor binding; synthetic peptide; von Willebrand factor

Thrombosis and hemorrhage are two of the dominant problems associated with cardiovascular surgery, and platelets are central to both. The actions of heparin contribute to bleeding, including heparin's effects which lay beyond the inhibition of the classic plasma coagulation pathways. Paradoxically, while heparin may cause pathologic bleeding by impairment of critical platelet hemostatic function, heparin also has limited efficacy in preventing thrombosis in the arterial circulation, a process mediated in part by the interactions between platelets and von Willebrand Factor (vWF) at sites of vessel wall injury. Thus, there is a clear need for the development of antithrombotic agents with more specific and selective platelet effects, suited to the unique requirements of cardiovascular surgery, arterial injury, and blood contact with artificial surfaces. Data from our laboratories suggest that certain heparins bind more avidly to platelets, and we have identified platelet glycoproteins IIb and IIIa as binding sites (among others). Platelet-bound heparin may directly modulate platelet function via its effects on calcium. In contrast, heparin indirectly inhibits platelet hemostatic function, by interfering with vWF- platelet binding. Heparin's inhibition of vWF function is independent of its conventional anticoagulant activity. We have identified and characterized a 23 amino acid domain of vWF which binds heparin, and with this have isolated a heparin fraction with enhanced ability to inhibit vWF- dependent platelet function. We now propose to identify the mechanism(s) by which heparin directly alters platelet function by biochemical analysis of platelet binding sites and heparin structure, and physiologic studies of heparin-mediated platelet activation. We will map the heparin-binding domain(s) of vWF, determine the conformational changes induced by heparin binding, and isolate and characterize the structure of heparins with potent anti-vWF activity. These lines of investigation lead directly to our long term goals: the development of new antithrombotic glycosaminoglycans with unique, focussed biologic activity suited to the specific thrombotic and hemorrhage problems associated with cardiovascular surgery and extracorporeal circulation.

血栓形成和出血是与 心血管手术和血小板都是两者的核心。 行动 肝素有助于出血，包括肝素的作用 超越了经典血浆凝结途径的抑制。 矛盾的是，肝素可能会因损害而引起病理性出血 关键的血小板止血功能，肝素的功效也有限 防止动脉循环中的血栓形成，这是在 一部分是血小板与von Willebrand因子（VWF）之间的相互作用 在容器壁损伤的部位。 因此，显然需要 开发具有更具体和选择性的抗血栓形成剂 血小板效应，适合心血管的独特要求 手术，动脉损伤和人造表面的血接触。 来自我们实验室的数据表明，某些肝素更加热烈地结合 到血小板，我们已经确定血小板糖蛋白IIB和IIIA为 绑定站点（等）。 血小板结合的肝素可能直接调节 血小板功能通过其对钙的影响。 相反，肝素 通过干扰VWF-间接抑制血小板止血功能 血小板结合。 肝素对VWF功能的抑制与 它的常规抗凝活性。 我们已经确定了 表征了一个结合肝素的23个氨基酸结构域，并与 这已经隔离了肝素部分，具有抑制VWF-的能力增强 依赖性血小板功能。 我们现在建议识别肝素直接的机制 通过血小板结合位点的生化分析来改变血小板功能 肝素结构以及肝素介导的血小板的生理研究 激活。 我们将绘制VWF的肝素结合域，确定 肝素结合引起的构象变化，分离和分离和 表征具有有效的抗VWF活性的肝素结构。 这些调查直接导致我们的长期目标： 开发新的抗血栓性糖胺聚糖，具有独特的，集中的 适合特定血栓和出血问题的生物学活性 与心血管手术和体外循环有关。