EFFECT OF OXITROPIUM BROMIDE ON HISTAMINE-INDUCED AIRWAY GOBLET CELL SECRETION

To determine whether histamine affects airway goblet cell secretion an d, if so, whether cholinergic mechanism is involved, we studied guinea pig airways by a semiquantitative morphometric method. The goblet cel l secretion was assessed in histologic sections of the tracheal mucosa stained with Alcian blue and periodic acid-Schiff (PAS) by determinin g the mucus score, which is inversely related to the magnitude of mucu s discharge. Inhaled or intravenously administrated histamine dose dep endently decreased the mucus score, an effect that was similarly obser ved in cartilaginous and muscular portions. Inhalation of the antichol inergic agent oxitropium bromide at doses of 1.5 mu g and higher great ly attenuated the decrease in mucus score produced by intravenous hist amine but not by inhaled histamine. Likewise, cutting of bilateral vag us nerves or atropine abolished intravenous histamine-induced goblet c ell secretion. The response of the mucus score to inhaled histamine wa s abolished by cimetidine, whereas the response to intravenous histami ne was reduced by mepyramine but not by cimetidine or thioperamide. Th ese results suggest that inhaled histamine increases airway goblet sec retion, probably by stimulating histamine H-2-receptors on goblet cell s, and that intravenous histamine produces a similar effect through a stimulation of histamine H-1-receptor-mediated release of acetylcholin e from cholinergic nerve terminals, presumably involving vagal reflex.