We investigated the effect of isoprostanes (IsoPs) on potassium (K +)-depolarization-evoked release of [3H]dopamine from isolated bovine retinae. Isolated retinae were preloaded with [ 3H]dopamine and then prepared for studies of [3H]dopamine release using the superfusion method. 8-iso(15R)PGF2α, 8-isoPGE2, 8-isoPGE1 and 8-isoPGF2α attenuated [3H]dopamine release from isolated bovine retinae. At a concentration of 1 μM, the rank order of activity displayed by IsoP agonists was: 8-iso(15R)PGF2α > 8-isoPGE2 > 8-isoPGE1 > 8-isoPGF2α. Inhibition of cyclooxygenase (COX) with flurbiprofen reversed the effects caused by 8-isoPGE2 (10 nM and 10 μM), 8-iso(15R)PGF2α (1 μM) and 8-isoPGE1 (1 μM). Although the EP1/EP2 antagonist, AH 6809 (10 μM) had no significant effect on K+-induced [ 3H]dopamine release, it blocked the inhibitory effect of both 8-isoPGE1 (10 μM) and 8-isoPGE2 (10 μM). In conclusion, IsoPs attenuate K+-induced [3H]dopamine release in isolated bovine retinae, presumably via an indirect action on COX pathway leading to the production of prostanoids, which in turn, activates EP receptors.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience