Alteration in the modulatory role of respiratory epithelium after exposure of guinea pigs to respirable cotton dust.
Smith-JA; Frazer-DG; Fedan-JS
J Pharmacol Exp Ther 1993 Feb; 264(2):683-688
The effect of exposure to cotton dust on airway reactivity was studied in-vitro. Guinea-pigs were exposed to cotton dust for 6 hours and the tracheae removed immediately or 18 hours after exposure. Each dissected trachea was mounted on a stainless steel perfusion apparatus and placed in a perfusion bath (the serosal extraluminal (EL) compartment) while the lumen of the tracheae (the mucosal intraluminal (IL) compartment) was perfused from a separate reservoir. Contractile responses were measured after the addition of methacholine (MCh) to the solutions in each compartment. MCh treatment in the EL compartment was more potent than in the IL compartment in animals that had been exposed to room air. Alterations in IL reactivity were seen following the inhalation of 30mg/m3 cotton dust, and the direction of these alterations was dependent upon the time after exposure. Dramatic increases in the mucosal maximum responses were seen immediately after the exposure, but they were decreased 18 hours post exposure. Moderate increases in the mucosal maximum responses were seen both immediately after, as well as 18 hours after exposure to 10mg/m3 cotton dust, raising them to the magnitude of the EL maximum response. The potency of MCh administered to the EL compartment was unaffected by any cotton dust exposure. Removal of the epithelium prior to perfusion increased the mucosal reactivity to the EL level in both cotton dust exposed, as well as unexposed controls, and eliminated the effects of the cotton dust on the mucosal reactivity to MCh. The authors suggest that the balance between the inhibitory and excitatory modulatory effects of the epithelium may be altered by inhaled cotton dust.
NIOSH-Author; Cotton-dust; Byssinosis; In-vitro-study; Muscle-tissue; Laboratory-animals; Exposure-levels; Inhalation-studies; Air-contamination
Journal of Pharmacology and Experimental Therapeutics