Pretreatment with aspirin does not influence the pressor response to alpha 2-adrenoceptor agonists in conscious...

It has proved relatively easy to demonstrate pressor responses mediated via alpha 2-adrenoceptors in-vivo and in whole blood perfused vascular beds, but not in in-vitro work. The possibility that platelet alpha 2-adrenoceptor activation, with subsequent release of vasoactive prostanoids, contributes to the pressor response to alpha 2-adrenoceptor agonists was investigated. The pressor response to the alpha 2-adrenoceptor agonist BHT 920 (Alefexole) was compared in rabbits pretreated with distilled water or aspirin (3 X 200 mg kg-1 by gavage). Aspirin pretreatment had no significant effect on responses to BHT 920; thus, prostanoid formation does not appear to be an important mechanism contributing to postsynaptic alpha 2-adrenoceptor activation.