Abstract
Collumnar cells in epithelial crypts are responsible for secretion of chloride and water in the intestine but the terminal cellular effectors of the secretory mechanism remain unknown. We comparatively assessed VIP-induced chloride channel activity and protein phosphorylation in crypts, freshly isolated from the rat colon, and in the human tumor cell-line Caco-2. Chloride channel function was determined by measuring fluxes of 125I-, a halide tracer well suited for probing chloride secretion, since it enters and leaves polar epithelial cells exclusively via apical membrane chloride channels. Basal and VIP-stimulated (200 nM) uptake showed similar kinetic behaviour in both cell types with VIP decreasing uptake by 70%. In crypts, the chloride channel blocker 4,4'-diIsothiocyano-2,2'-stillbenedisulfonate (DIDS) completely inhibited iodite uptake at 50 uM concentration whereas in Caco–2 cells DIDS of 16, 42 and 55 kDa proteins in both cell types, and several other proteins, that differed between the two cell types. The data suggest that 1.VIP-induced chloride channel activation may be dependent on phosphorylation of specific proteins, and 2. chloride channel types activated by VIP may be different in crypts and caco–2.
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Heinz-Erian, P., Dorka, B., Huber, S. et al. 157 COMPARISON OF VIP-STIMULATED CHILORIDE SECRETION AND PROTEIN PHOSPHORYLATION IN ISOLATED RAT COLONIC CRYPTS AND CACO-2 CELLS. Pediatr Res 30, 654 (1991). https://doi.org/10.1203/00006450-199112000-00187
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DOI: https://doi.org/10.1203/00006450-199112000-00187