Effect of K+ channel-blockers on sugar uptake by isolated chicken enterocytes.

The effects of Ba2+, quinine, verapamil, and Ca2(+)-free saline solutions on sugar active transport have been investigated in isolated chicken enterocytes. Ba2+, quinine, and verapamil, which have been shown to inhibit Ca2(+)-activated K+ channels, decreased basal and theophylline-dependent 3-O-methylglucose (3-O-MG) accumulation. Ca2(+)-free conditions reduced 3-O-MG uptake in theophylline-treated enterocytes, but it had no effect in control cells. On the other hand, the uptake of a non-actively transported sugar, 2-deoxyglucose (2-DOG), by control or theophylline-treated cells was not modified by the presence of verapamil or by Ca2(+)-removal. 3-O-MG increased ouabain-sensitive Na(+)-efflux, but had no effect on either K+ efflux or K+ uptake. However, in the presence of Ba2+, K+ uptake was stimulated by 3-O-MG, and this increase was prevented by ouabain. All these findings are discussed in terms of the role that K+ permeability may play in cellular homeostasis during sugar active transport.