Effect of sulphinpyrazone and aspirin on platelet adhesion to subendothelium following oral administration to rabbits

Sulphinpyrazone 20mg/kg, aspirin 15mg/kg or placebo were given orally to rabbits for five days. Platelets and samples of aorta were then prepared from treated animals. Adhesion of radiolabelled platelets to everted aorta was measured in a perfusion device. By using different combinations of placebo or drugtreated material effects of sulphinpyrazone or aspirin on platelets, vascular cells, or both in combination were studied separately. Residual PGI 2-like activity of vascular samples was assessed by inhibition of ADP-induced aggregation. Sulphinpyrazone treatment of aorta enhanced adhesion of normal platelets, though PGI 2-like activity was only minimally reduced. Exposure of both aorta and platelets to the drug resulted in significant reduction of platelet adherence. Treatment with aspirin almost totally abolished PGI 2-like activity. There was a statistically insignificant trend towards increased platelet adhesion to treated aorta, but exposure of both tissues to aspirin did not affect adhesion. The results indicate that sulphinpyrazone and aspirin differ in their effects on platelet adhesion to vascular surfaces.