Effect of mast cell degranulation on chicken ileal ion transport in vitro

Histamine is a primary mediator of the inflammatory response in mammals. Degranulation of intestinal mast cells results in the release of mast cell mediators such as histamine. Histamine stimulates epithelial ion transport in a range of mammalian tissues via specific histamine receptors. The aim of this study was to assess a potential role of tissue mast cells and of exogenous histamine in the regulation of ion transport in avian mucosa. Broiler chicken ileal histamine release and secretory responses to mast cell degranulation were determined in vitro with the use of ELISA and Ussing chamber techniques. Pharmacological degranulation of mucosal mast cells using compound 48/80 (15 mu g/mL) resulted in histamine release and an immediate-onset transient increase in transmural short-circuit current, The response to compound 48/80 was subject to tachyphylaxis and was significantly reduced in the presence of the histamine H, antagonist mepyramine, but was unaffected by the cyclooxygenase inhibitor piroxicam. Prior incubation with the mast cell stabilizer ketotifen prevented compound 48/80-induced increase in transmural short-circuit current. In conclusion, degranulation of avian intestinal mast cells would appear to result in histamine release that stimulates epithelial ion transport via histamine H, receptor activation. Although prostaglandin E-2 is a potent secretagogue in the avian small intestine epithelium, prostanoid production appears to have little role to play in mast cell-mediated epithelial ion transport.