Modulation of acetylcholine release from the myenteric plexus of guinea-pig ileum by 5-lipoxygenase metabolites of arachidonic acid.

Eicosatetraenoic acid, an inhibitor of 5- and 12-lipoxygenase, and AA861, a selective inhibitor of 5-lipoxygenase, dose dependently inhibited acetylcholine release from the myenteric plexus of guinea-pig ileum induced by electrical field stimulation. Metabolites of arachidonic acid produced by the 5-lipoxygenase pathway, such as 5-hydroxyeicosatetraenoic acid (5-HETE), leukotriene C4, D4 and E4, reversed the inhibitory effect of AA861. Among them, leukotriene D4 was the most potent, having an EC50 value of about 3 nM. The present study shows for the first time that 5-lipoxygenase metabolites may have a modulatory effect on acetylcholine release in the myenteric plexus of guinea-pig ileum.