MOLECULAR BASIS OF THE PLATELET STORAGE LESION

采集和体外保存血小板的结果是 磷脂酰丝氨酸(PS)的进行性运动和 磷脂酰乙醇胺(PE)从内到外的小叶 血小板质膜。这种正常质膜的丧失 这些氨基磷脂暴露时的磷脂不对称性 在血小板表面与凝血酶的形成有关， 补体活化与肝脾隔离症 输血后加速了血小板的清除。本项目 旨在查明造成这一异常的机制(S) 贮藏过程中质膜磷脂的跨双层运动 并推导出保存正常的保存条件 将PS和PE隔离到内侧小叶。具体目标 包括：(1)确定PS的进行性运动是否向 自体血浆保存过程中的血小板表面反射 通过机械剪切诱导的膜重组，减少了 血小板膜氨基磷脂转位酶活性， 和/或不适当地激活血小板质膜 磷脂加扰酶；(2)测定 细胞内钙离子、三磷酸腺苷和pH值改变为加速的跨双层 血小板膜磷脂的运动；(3)确定如何运动 磷脂酶加扰酶和氨基磷脂的氧化变化 细胞储存过程中的转位酶影响细胞的跨双层分布 质膜磷脂；(4)测定血浆的作用 浓缩血小板中所含的成分对加速的 氨基磷脂向血小板表面的运动。特别的 感兴趣的是凝血酶、纤溶酶和C5b-9组分的作用 补充；(5)确定优化的存储条件，以保持 正常隔离的血小板膜氨基磷脂。 这些条件被认为是最优的，最大限度地提高了 氨基磷脂转位酶和最小化细胞内转位酶 Ca~(2+)激活PL加扰酶。

Collection and in vitro storage of blood platelets results in the progressive movement of phosphatidylserine (PS) and phosphatidylethanolamine (PE) from inner to outer leaflet of the platelet plasma membrane. This loss of normal plasma membrane phospholipid (PL) asymmetry with exposure of these aminophospholipids on the platelet surface is implicated in the formation of thrombin, in the activation of complement, and in hepato-splenic sequestration and accelerated clearance of platelets following transfusion. This Project aims to identify the mechanism(s) responsible for this abnormal transbilayer movement of plasma membrane phospholipids in stored platelets and to deduce conditions of storage that will preserve normal sequestration of PS and PE to the inner leaflet. The Specific Aims include: (1) To determine whether the progressive movement of PS to the surface of platelets during storage in autologous plasma reflects membrane reorganization induced through mechanical shear, a decrease in activity of the platelet plasma membrane aminophospholipid translocase, and/or inappropriate activation of the platelet plasma membrane phospholipid scramblase; (2) To determine the relative contributions of altered cytosolic Ca2+, ATP, and pH to the accelerated transbilayer movement of platelet plasma membrane phospholipids; (3) To determine how oxidative changes in either PL scramblase or aminophospholipid translocase during cell storage affect transbilayer distribution of plasma membrane phospholipids; (4) To determine the role of plasma components contained in platelet concentrates to the accelerated movement of aminophospholipids to the platelet surface. Of particular interest is the role of thrombin, plasmin and the C5b-9 components of complement; (5) To identify storage conditions optimized to maintain the normal sequestration of platelet plasma membrane aminophospholipids. Those conditions are considered optimal that maximize the activity of aminophospholipid traslocase and minimize that of the intracellular Ca2+-activated PL scramblase.