Defective Platelet Adhesion and Aggregation on Subendothelium Exposed in Vivo or in Vitro to Flowing Blood of Fawn-Hooded Rats with Storage Pool Disease

Abstract

SummaryCitrated rat blood was exposed to either subendothelium or the fibrillar collagen of enzymatically modified subendothelium of rabbit aorta in a perfusion system under laminar blood flow conditions at a wall shear rate of 830 s−1. The resulting platelet surface interaction was estimated by a morphometric method.With blood of fawn-hooded (FH) rats, which suffer from hereditary platelet “storage pool disease”, platelet spreading was slower on both exposed surfaces and resulted in a lower rate of surface coverage with platelets on subendothelium if compared with controls.The rate of adhesion of FH-platelets to the fibrillar collagen, however, was slightly higher as compared to controls despite reduced platelet spreading. This was probably due to the absence of platelet thrombus formation observed with FH-rat blood, whereas massive platelet thrombus formation took place in the controls. It is suggested that platelets of controls which arrive near the surface are preferentially incorporated into the rapidly forming platelet thrombi rather than reaching the surface, and hence do not increase surface-coverage with adhering platelets.The defective platelet adhesion and aggregation in the FH-rat was also apparent after desendothelialization of the aorta in vivo, although to a lesser extent, probably due to the extremely low thrombogenicity of rat aorta subendothelium.