Inhibition by diethylcarbamazine of acetylcholine-induced endothelium-dependent relaxation of rabbit aorta: are leukotrienes involved?

Acetylcholine caused relaxations of preconstricted rabbit aortic strips if the endothelium was intact. These relaxations were reversed in a concentration-dependent manner by diethylcarbamazine, an inhibitor of slow-reacting substance and leukotriene formation. However, when exogenous leukotrienes (LTA4, LTB4, LTC4 and LTD4) were added to the precontracted arterial strips none of them caused relaxation, showing that they are unlikely to be involved as mediators in the acetylcholine-induced relaxation of rabbit aorta.