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

The effects of Ba 2+ , quinine, verapamil, and Ca 2+ ‐free saline solutions on sugar active transport have been investigated in isolated chicken enterocytes. Ba 2+ , quinine, and verapamil, which have been shown to inhibit Ca 2+ ‐activated K + channels, decreased basal and theophylline‐dependent 3‐O‐methylglucose (3‐O‐MG) accumulation. Ca 2+ ‐free conditions reduced 3‐O‐MG uptake in the‐ophylline‐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 Ca 2+ ‐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 Ba 2+ , 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.