An outwardly rectifying chloride channel in BeWo choriocarcinoma cell line

The open probability (Po) of the channel exhibited dependence with the applied membrane potential with greater activity at positive pulses. The channel activity was inhibited by the sulphonylurea hypoglycemic agent glibenclamide (50 μM) or by diphenylamine-2-carboxylate (DPC, 500 μM) added to the cytoplasmic side of the patch whereas conductances remained unchanged. The blockade with glibenclamide and DPC was independent of the applied membrane potential. All these results are characteristic of the outwardly rectifying Cl channel (ORCC) found in other types of cells. Neither Po, conductances nor reversal potential (Er) values were affected by the absence of intracellular Ca2+, suggesting that the channel is not sensitive to Ca2+.