Effects of Zaldaride Maleate, an Antidiarrheal Compound, on Intracellular Ca²⁺-Mediated Short-Circuit Current Response in the Rat Colonic Mucosa

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The effect of zaldaride maleate(ZAL)on intracellular Ca²⁺−mediated short−curcuit current(Isc)response in rat colonic mucosa was investigated.The Isc response to acetylcholine was partially reduced by the neuronal blocker tetrodotoxin.The tetrodotoxin−sensitive Isc response to acetylcholine was inhibited by ZAL.The tetrodotoxin−insensitive effect, which indicates direct stimulation of acetylcholine in colonic mucosa, was not affected by ZAL.The Isc response to the Ca²⁺ ionophore A23187 was reduced by ZAL in the presence of tetrodotoxin.These results suggest that ZAL reduces colonic ion secretion by inhibiting a tetrodotoxin−sensitive neuronal pathway and an intracellular Ca²⁺ pathway in epithelium.