[Role of platelets in arterial hypotension induced by arachidonic acid and in carrageenan induced edema in the rat].

When rat platelets are incubated in vitro in the presence of aspirin, the formation of malonaldehyde from arachidonic acid is inhibited. The production of malonaldehyde reflects the synthesis of prostaglandins and associated compounds. The same inhibition is found when the platelets originate from rats pretreated with aspirin. Small doses of aspirin are active in vitro and 10-20 mg/kg in vivo. This dosage of aspirin does not affect the hypotensive activity of arachidonic acid nor the oedematous properties of carrageenan in the rat. These two effects are thus independent from the prostaglandins formed in the platelets.