Prostaglandins and intracellular cyclic AMP in respiratory secretory cells

Prostaglandins are known to affect ion transport and mucus secretion in the trachea, and at least part of their effect is thought to be mediated by cyclic AMP. Because no prostaglandin receptor assay is currently available, we have used an immunocytochemical probe for the intracellular localization of cyclic AMP to identify those specific cell types in dog and cat trachea that respond to prostaglandins. Using tracheal explants similar to those used by other investigators for in vitro studies of ion transport and glycoprotein secretion, we examined the effect of endogenous and exogenous prostaglandins on immunoreactive cyclic AMP. Endogenous prostaglandins, which may be secreted in response to minor distortion of tissue membranes, stimulated immunoreactive cyclic AMP in ciliated epithelial cells and in both serous and mucous submucosal gland cells. This was not observed in tissues assayed 60 min after dissection, or dissected in the presence of indomethacin or of BW755C. Exogenous prostaglandin E1 increased cyclic AMP in these same cell types. We conclude that prostaglandins stimulate cyclic AMP in specific cell types in the trachea, and that endogenous prostaglandins play a major role in many in vitro preparations.