Mucin Secretion Evoked by Prostaglandin E2 in Guinea Pig Antral Mucous Cells: Role of EP1/EP4 Receptors

Inhibition of ACh-stimulated exocytosis by NSAIDs in guinea pig antral mucous cells: autocrine regulation of mucin secretion by PGE2

“…Isolated antral mucous cells were mounted on a coverslip precoated with neutralized Cell-Tak (Becton Dickinson Labware, Bedford, MA) for the firm attachment of cells. The coverslip with cells was set in a perfusion chamber that was mounted on the stage of a differential interference contrast microscope (BX50Wi; Olympus, Tokyo, Japan) connected to a videoenhanced contrast system (model ARGUS-10; Hamamatsu Photonics, Hamamatsu, Japan) (1,8,10,(13)(14)(15)(16)(17). Images were recorded continuously with a video recorder.…”

“…The volume of the perfusion chamber was ϳ20 l, and the rate of perfusion was 200 l/min. Exocytotic events, which were detected as rapid changes in the light intensity of granules (1,3,10,11,13,14,16,17), were counted in five to six cells every 30 s and were normalized to the cell number (events per cell per 30 s). The frequencies of exocytotic events in three to seven experiments were expressed as means Ϯ SE.…”

“…MUCIN EXOCYTOSIS IN guinea pig antral mucous cells is regulated by two mechanisms: Ca 2ϩ -regulated exocytosis and cAMPregulated exocytosis (8,13,(15)(16)(17). The Ca 2ϩ -regulated exocytosis is the major mechanism operating in antral mucous cells, because the frequency of exocytosis induced by cAMP accumulation was Ͻ10% of that induced by the increase in intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) (8,13,16,17).…”

“…PGE 2 , which induces the accumulation of cAMP in antral mucous cells via the EP4 prostaglandin receptor (16,17), protects the gastric mucosa from lesions. In contrast, the inhibition of PGE 2 production by NSAIDs, such as indomethacin (IDM) or aspirin [acetylsalicylic acid (ASA)], induces gastric lesions.…”

“…The Ca 2ϩ -regulated exocytosis is the major mechanism operating in antral mucous cells, because the frequency of exocytosis induced by cAMP accumulation was Ͻ10% of that induced by the increase in intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) (8,13,16,17). The Ca 2ϩ -regulated exocytosis in pancreatic acinar cells consists of two biochemically distinct steps: ATP-dependent priming and Ca 2ϩ -dependent fusion (19,32).…”