EP1 and EP4 Receptors Mediate Exocytosis Evoked by Prostaglandin E sub(2) in Guinea-Pig Antral Mucous Cells

• Published in: Experimental physiology Vol. 86; no. 4; pp. 451 - 460
• Main Authors: Ohnishi, Atsuko, Shimamoto, Chikao, Katsu, Ken-ichi, Ito, Sigenori, Imai, Yusuke, Nakahari, Takashi
• Format: Journal Article
• Language: English
• Published: 01.07.2001
• ISSN: 0958-0670; 1469-445X
• DOI: 10.1113/eph8602160

Effects of prostaglandin E sub(2) (PGE sub(2)) on exocytosis of mucin were studied in mucous cells isolated from guinea-pig antrum using video-microscopy. Stimulation with PGE sub(2) elicited a sustained increase in the frequency of exocytotic events in a dose-dependent manner, which was under regulation by both Ca super(2+) and cAMP. Stimulation with a selective prostanoid EP4 receptor agonist (ONO-AEI-329, 10 mu M), which activates cAMP signals, elicited a sustained increase in the frequency of exocytotic events (30% of that evoked by 1 mu M PGE sub(2)). Stimulation with an EP1 agonist (17-P-T-PGE sub(2), 1 mu M), which activates Ca super(2+) signals, increased the frequency of exocytotic events to a lesser extent (5% of that evoked by 1 mu M PGE sub(2)), while addition of an EP1 antagonist (ONO-8713, 10 mu M) decreased the frequency of exocytotic events (approximately 40% of that evoked by 1 mu M PGE sub(2)). However, addition of the EP1 agonist potentiated the frequency of exocytotic events evoked by the EP4 agonist or forskolin (which elevates cAMP levels) and increased the sensitivity of the exocytotic events to forskolin. These results suggest that the Ca super(2+) signal activated via the EP1 receptor potentiates the cAMP-regulated exocytotic events activated via the EP4 receptor during PGE sub(2) stimulation, by increasing the sensitivity of the exocytotic response to cAMP. In conclusion, exocytotic events in PGE sub(2)-stimulated antral mucous cells were regulated by interactions between EP1 and EP4 receptors.