Effect of cholera toxin on secretion of mucin by explants of guinea pig trachea.
Cholera toxin (CT) elicits a dosage-dependent increase in mucin secretion by explants of guinea pig trachea. Concomitantly, the mucin in goblet cells of the mucosa and submucosal glands is depleted. This effect is realized in the absence of cell injury, as assessed morphologically and by the assay of culture medium for the release of acid phosphatase. Mucosal concentrations of cyclic AMP increase after exposure to CT. However, the stimulatory effects on secretion appear to be independent of the cyclic nucleotide, as exogenous dibutyryl cyclic AMP and cyclic GMP fail to increase secretion, and theophylline, a phosphodiesterase inhibitor, also is ineffective. The stimulatory effect of CT is decreased by preincubation of the explants with inhibitors of microtubules (nocodazole) and microfilaments (cytochalasin D) in a dosage-dependent manner. Addition of the calcium chelator, ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid, with CT also inhibits the secretory response. CT appears to stimulate mucin secretion by tracheal epithelial cells by a mechanism independent of cyclic nucleotide activation but requires intact microtubules, microfilaments, and exogenous calcium ions.
D000818:Animals; D002118:Calcium / Q000502:physiology; D002772:Cholera Toxin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008297:Male; D009077:Mucins / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology
D009077:Mucins; D002772:Cholera Toxin; D013806:Theophylline; D000242:Cyclic AMP; D002118:Calcium