The human colonic epithelial goblet cell line HT29-Cl.16E was used to test whether stimulated Cl- transport is involved in the mucin exocytotic response to an increase in intracellular cyclic AMP by measuring in parallel the short-circuit current (Isc) and mucin exocytosis. Addition of 50 microM forskolin to HT29-Cl.16E cells resulted in a 2-fold stimulation of mucin release and an increase in Isc by 20 microA/cm2. To evaluate the requirement for cosecretion of Cl-, the Cl- flux was altered by three different manipulations: (1) Cl- in the medium was replaced by the poorly transported anion gluconate; (2) basolateral Cl- influx through the Na(+)-K(+)-2Cl- cotransporter was inhibited by bumetanide; and (3) an inward Cl- flux through the apical plasma membrane was generated by reversing the Cl- gradient. These manipulations did not change the forskolin-stimulated mucin release and thereby provide evidence that Cl- movements are not required for fusion of mucin granules with the plasma membrane.
Cyclic AMP-induced mucin exocytosis is independent of Cl− movements in human colonic epithelial cells (HT29-Cl.16E)
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A Jarry, D Merlin, U Hopfer, C L Laboisse; Cyclic AMP-induced mucin exocytosis is independent of Cl− movements in human colonic epithelial cells (HT29-Cl.16E). Biochem J 15 December 1994; 304 (3): 675–678. doi: https://doi.org/10.1042/bj3040675
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