Effects of prostaglandin E2 and cholera toxin on apical sodium uptake in thyroid epithelial cells: role of cAMP.

When cultured in tissue culture polystyrene dishes, porcine thyroid cells formed polarized monolayers. Their apical pole was oriented towards the culture medium. Influx of sodium 22 (5 min) through the apical surface was partially inhibited by amiloride. Amiloride-sensitive Na uptake was increased about 3-fold by prostaglandin E2 (1 microM, 30 min) and by cholera toxin (0.01 micrograms/ml, 1 h). This increase, which was also obtained with forskolin and 8-(4-chlorophenylthio)adenosine-3':5'-monophosphate, cyclic (8-chloro-cAMP), is probably a consequence of the increase of the intracellular cAMP level by prostaglandin and cholera toxin.