Roles of cellular signal transduction in the defensive mechanism of rabbit stomach

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We investigated the roles of cellular signal transduction system in the defensive mechanism of rabbit somach using primary culture gastric mucous cells. Rabbit gastric epithelial cells were isolated by enzyme digestion and cultured in F-12 medium with 10% FBS. Cultured cells were mainly composed of mucous cells, as assessed by electronmicroscopy and PAS staining. These cells produced prostaglandin (PG)E_2. Influx of extracellular Ca^<2+> and activation of protein kinase C induced stimulation of PGE_2 release, while modulation of cAMP had no effect. Acid secretagogues such as histamine, carhachol, or gastrin did not alter PGE_2 release, while deoxycholic acid markedly increased PGE_2 release mainly through the influx of extracellular Ca^<2+>. Mucus secretion was also stimulated by the increase of intracellular Ca^<2+>, but not by cAMP. ATP, purinergic P2 receptor agonist increased cellular Ca^- and stimulated mucus secretion and PGE_2 release.In conclusion, intracellular Ca^<2+> might be an important factor in the activation of rabbit gastric defensive mechanism.