Carbachol potentiates cholera toxin-induced secretion in a colonic epithelial cell line (HT29-19A) and rat real mucosa in vitro

Recent studies show that enteric nerves are involved in the action of chole ra toxin, both in vivo and in vitro. The aim of this study was to investiga te in vitro the influence of carbachol, a cholinergic agonist, on the actio n of cholera toxin, Cultured HT29-19A cell lines and rat ileal mucosa were used in an Ussing chamber for the measurement of short-circuit current indu ced by cholera toxin, Cyclic AMP was measured from HT29-19A cell lines by s tandard radioimmunoassay, Pre-treatment of the HT29-19A cell lines with car bachol potentiated cholera toxin-induced secretory response, and enhanced a ccumulation of cAMP. Carbachol also potentiated the cholera toxin-secretory response in the rat heal mucosa, but only following pretreatment with the prostaglandin synthesis inhibitor, indomethacin, There was synergistic inte raction between cholera toxin and cholinergic neurotransmitter carbachol on the intestinal epithelium, Cholinergic agonists may play a role in regulat ing the secretory response to the toxin. Such interaction is masked in the intact tissues in vitro due to the release of prostaglandins during isolati on.