Leukotriene-evoked cyclic chloride secretion is mediated by enteric neuronal modulation in guinea-pig colon

Short term exposure to leukotrienes evoked a well known nerve mediated increase in short circuit current. It is unknown whether leukotrienes evoke in addition oscillations in chloride secretion, as has been reported for some of the other mediators released during inflammation. Therefore, the aim of this study was to characterize the effects of a long time exposure of leukotrienes on mucosal functions. Conventional Ussing chamber, and intracellular recording techniques were used to investigate the actions of leukotriene D4 and C4 on short-circuit current and excitability of submucosal neurons in guinea-pig distal colon. In Ussing chambers, long term exposure to leukotriene D4 or C4 evoked rhythmic oscillations in short-circuit current in 35% and 50% of tissues, respectively. These current bursts were blocked by tetrodotoxin, atropine, hexamethonium and piroxicam. Secretory response to short term exposure of leukotrienes was significantly higher in tissues exhibiting current bursts. Likewise, the potentiating effects of leukotrienes on the response to field stimulation was only observed in tissues exhibiting current bursts. In intracellular recording experiments, leukotriene C4 evoked activation of submucosal neurons that was partly sensitive to indomethacin; no oscillations in neuronal excitability could be demonstrated. Results suggested that long term exposure to leukotrienes evoked current bursts that were mediated by neural, cholinergic mechanisms as well as endogeneous prostaglandins.