A. Jarry et al., CYCLIC AMP-INDUCED MUCIN EXOCYTOSIS IS INDEPENDENT OF CL- MOVEMENTS IN HUMAN COLONIC EPITHELIAL-CELLS (HT29-CL.16E), Biochemical journal, 304, 1994, pp. 675-678
The human colonic epithelial goblet cell line HT29-CL16E was used to t
est whether stimulated Cl- transport is involved in the mucin exocytot
ic response to an increase in intracellular cyclic AMP by measuring in
parallel the short-circuit current (Isc) and mucin exocytosis. Additi
on of 50 mu M forskolin to HT29-Cl.16E cells resulted in a 2-fold stim
ulation of mucin release and an increase in Isc by 20 mu A/cm(2). To e
valuate the requirement for cosecretion of Cl-, the Cl- flux was alter
ed by three different manipulations: (1) Cl- in the medium was replace
d by the poorly transported anion gluconate; (2) basolateral Cl- influ
x through the Na+-K+-2Cl(-) cotransporter was inhibited by bumetanide;
and (3) an inward Cl- flux through the apical plasma membrane was gen
erated by reversing the Cl- gradient. These manipulations did not chan
ge the forskolin-stimulated mucin release and thereby provide evidence
that Cl- movements are not required for fusion of mucin granules with
the plasma membrane.