Contribution of External Ca2+ to the Modulation by Prostaglandin E2 of the Release of Acetylcholine from the Myenteric Plexus of Guinea Pig Ileum

摘要

References(27) Cited-By(3) The effects of external concentration of [Ca2+] ([Ca2+]0) on the modulation by indomethacin (IND) or prostaglandin E2 (PGE2) of the evoked release of acetylcholine (ACh) were investigated in the myenteric plexus of guinea pig ileum. An increase in the [Ca2+]0 from 0.45 to 3.6 mM depressed both the spontaneous and the nicotine-induced release of ACh, while the releases of ACh induced by electrical-field stimulation (EFS) or by high K+ were augmented. IND and PGE2 did not modify the release of ACh induced by EFS and high K+, at any given [Ca2+]0 tested. The nicotine-induced release of ACh was significantly inhibited by IND with no relation to [Ca2+]0, and these inhibitory effects of IND were prevented by PGE2. At 0.45 mM [Ca2+]0, the extent of the recovery by PGE2 was less potent than those at other [Ca2+]0. IND inhibited the spontaneous release of ACh at lower [Ca2+]0, and such inhibition was not observed in the presence of PGE2. Thus, the modulatory actions of PGE2 on the spontaneous and the nicotine-induced release of ACh may depend partially on [Ca2+]0.