Takeuchi T, Shimizu M, Okuda M, Yagasaki O
Department of Veterinary Pharmacology, Faculty of Agriculture, University of Osaka Prefecture, Sakai, Japan.
Jpn J Pharmacol. 1989 Apr;49(4):455-61. doi: 10.1254/jjp.49.455.
The effects of external concentration of Ca2+ [( Ca2+]o) 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+]o 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+]o tested. The nicotine-induced release of ACh was significantly inhibited by IND with no relation to [Ca2+]o, and these inhibitory effects of IND were prevented by PGE2. At 0.45 mM [Ca2+]o, the extent of the recovery by PGE2 was less potent than those at other [Ca2+]o. IND inhibited the spontaneous release of ACh at lower [Ca2+]o, 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+]o.
在豚鼠回肠肌间神经丛中，研究了细胞外钙离子浓度（[Ca2+]o）对吲哚美辛（IND）或前列腺素E2（PGE2）调节乙酰胆碱（ACh）诱发释放的影响。将[Ca2+]o从0.45 mM增加到3.6 mM会抑制ACh的自发释放和尼古丁诱导的释放，而电场刺激（EFS）或高钾诱导的ACh释放则增强。在任何给定的测试[Ca2+]o下，IND和PGE2均未改变EFS和高钾诱导的ACh释放。IND对尼古丁诱导的ACh释放有显著抑制作用，且与[Ca2+]o无关，PGE2可阻止IND的这些抑制作用。在[Ca2+]o为0.45 mM时，PGE2的恢复程度比在其他[Ca2+]o时弱。IND在较低的[Ca2+]o时抑制ACh的自发释放，而在PGE2存在时未观察到这种抑制作用。因此，PGE2对ACh自发释放和尼古丁诱导释放的调节作用可能部分取决于[Ca2+]o。
