Effect of dazoxiben on platelet-vessel wall interaction

1 Platelet monolayer adhesion to damaged rabbit aorta and to collagen-coated glass was quantified in a perfusion device. Addition of the thromboxane synthetase inhibitor dazoxiben (UK 37248) 1 and 10 microM reduced adhesion to damaged blood vessel by about 45% at both concentrations, but did not affect adhesion to collagen-coated glass. 2 Measurement by RIA indicated virtual abolition of thromboxane B2 production in the presence of the drug and a slight trend to an increase of 6-oxo-prostaglandin F1 alpha concentration in experiments using aorta. Inhibitory activity of dazoxiben was abolished by previous exposure of the aorta to 15-HPETE(?), an inhibitor of prostacyclin synthetase. 3 The results indicate that dazoxiben inhibits platelet adhesion to vascular subendothelium possibly by promoting synthesis of PGI2 from re-directed platelet endoperoxides.