Activation of Guinea Pig Alveolar Macrophages by Endothelin-1

SUMMARYEndothelin-1 (ET-1) induced a concentration-and time-dependent increase in arachidonic acid release from guinea pig alveolar macrophages, a maximum being reached at 1 n M ET-1. Regarding the time-course study, maximal release of arachidonic acid was observed after 30 s of incubation with ET-1 and then followed by a marked decrease, suggesting a reuptake of free arachidonic acid. ET-1 (0.1–10 n M) induced a concentration-and time-dependent release of TXB2, the stable metabolite of TXA2 evaluated by an ELISA technique. Maximum release was also obtained with 1 n M ET-1 but only after a 1-min incubation period. By contrast, ET-1 (1 p M-1μ) id not stimulate the release of superoxide anion at any time point of the kinetic study. These results suggest that ET-1 may activate guinea pig alveolar macrophages, probably through a mechanism involving the arachidonic acid pathway.