The effects of dazoxiben, an inhibitor of thromboxane synthetase, on cold‐induced forearm vasoconstriction and platelet behaviour in different individuals.

Abstract

1 The effect of dazoxiben, a thromboxane synthetase inhibitor, on cold-induced forearm vasoconstriction was determined in two groups of human volunteers, those in whom dazoxiben abolished the platelet aggregation and release reaction induced by sodium arachidonate (group I) and those in whom it did not (group II). Dazoxiben abolished cold-induced forearm vasoconstriction in group I volunteers but not in those of group II. These results imply a correlation between platelet behaviour and cold-induced changes in vascular tone. 2 In the group I volunteers the effect of dazoxiben on cold-induced vasoconstriction was abolished by 1800 mg of aspirin, but not by 40 mg. Since the lower dose of aspirin inhibits platelet cyclo-oxygenase but has no effect on cyclo-oxygenase in blood vessel walls, it is possible that platelets play no part in the modulation of vascular tone by dazoxiben. It is more likely that the effects of dazoxiben are confined to the vessel wall.

Role of cyclooxygenase in the vascular responses to extremity cooling in Caucasian and African males

“…Using forearm and finger venous occlusion plethysmography, previous research has demonstrated that the reflex vascular responses to arm or foot cooling are not altered by COX inhibition (Cowley et al 1983(Cowley et al , 1985Gresele et al 1985;Hechtman & Jageneau, 1985), with one study demonstrating an increase in vascular resistance during foot cooling (Serneri et al 1981). As the skin temperature (in degrees Celsius; B) during hand cooling and subsequent spontaneous rewarming after placebo and COX inhibition * Significant difference (P < 0.05) between CAU and AFD after placebo.…”