FIBRINOGEN RECEPTORS IN HEREDITARY THROMBOPATHIA

Basset Hound血栓病（BHT）是一种遗传性缺陷， 有严重出血素质的纯种狗。 在 初步研究，糖蛋白IIb-IIIa含量，125-标记 纤维蛋白原结合，金标记纤维蛋白原结合，电子 显微形态学、血小板计数和凝块收缩 都是正常的 BHT血小板的聚集不会 发生在对二磷酸腺苷（ADP）、血小板 活化因子（PAF），或A23187;是可逆的， 肾上腺素;并完全响应佛波醇肉豆蔻酸酯 醋酸盐（PMA）或凝血酶浓度大于0.1 U/ml。 由凝血酶或凝血酶引起的致密颗粒内容物的释放 PMA是正常的，但A23187或肾上腺素都不能诱导 重大释放。 ADP和PAF诱导正常细胞的释放 ATP的量，但释放速率增加。 这些 结果表明，BHT血小板聚集并仅释放 此时可以绕过磷酸肌醇水解途径。 工作假设提出，有一个缺陷，在 肌醇磷脂第二信使系统。 初步 研究，细胞质离子化Ca 2+（Cai 2+）通量在Quin 2加载 与ADP、PAF、凝血酶或A23187孵育的血小板， 正常 具体目标是系统地研究 包括进一步测量细胞质 Cai 2+通量，评估蛋白激酶C的作用 抑制剂H-7，测量血栓烷A2产生， 20和40-47 kDa蛋白磷酸化的评估，分离 蛋白激酶C，二酰基甘油产生的测量 以及磷脂酶A2的分离。 该计划的总体目标 是描述导致 BHT中的血小板聚集和分泌缺陷， 研究刺激-反应耦合现象， 血小板

Basset Hound thrombopathy (BHT) is a hereditary defect in linebred dogs in which there is a severe hemorrhagic diathesis. In initial studies, glycoprotein IIb-IIIa content, 125-labeled fibrinogen binding, gold-labeled fibrinogen binding, electron micrographic morphology, platelet counts and clot retraction were found to be normal. Aggregation of BHT platelets does not occur in response to adenosine diphosphate (ADP), platelet activating factor (PAF), or A23187; is reversible in response to epinephrine; and complete in response to phorbol myristate acetate (PMA) or concentrations of thrombin greater than 0.1 U/ml. Release of dense granule contents induced by thrombin or PMA is normal but neither A23187 or epinephrine is able to induce significant release. ADP and PAF induce release of a normal quantity of ATP, but the rate of release is increased. These results suggest that BHT platelets aggregate and release only when the phospho-inositide hydrolysis pathway can be bypassed. The working hypothesis proposes that there is a defect in the inositol phospholipid second messenger system. In preliminary studies, cytoplasmic ionized Ca2+ (Cai2+) fluxes in Quin 2-loaded platelets incubated with ADP, PAF, thrombin or A23187 are normal. Specific aims designed to methodically investigate the pathways of platelet activation include further measurement of cytoplasmic Cai2+ fluxes, assessment of the effects of the protein kinase C inhibitor H-7, measurement of thromboxane A2 production, assessment of 20 and 40-47 kDa protein phosphorylation, isolation of protein kinase C, measurement of diacylglycerol production and isolation of phospholipase A2. The overall aim of the program is to characterize the molecular abnormality responsible for the platelet aggregation and secretion defect in BHT and to investigate the stimulus-response coupling phenomena in the platelet.