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.
Montero
M C
MC
Department of Physiology, Pharmacy Faculty of the University of Seville, Spain.
Calonge
M L
ML
Bolufer
J
J
Ilundáin
A
A
D019325:3-O-Methylglucose; D000818:Animals; D001464:Barium / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002645:Chickens; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects*; D011803:Quinine / Q000494:pharmacology; D012964:Sodium / Q000502:physiology; D013806:Theophylline / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D008757:Methylglucosides; D008759:Methylglycosides; D015221:Potassium Channels; D019325:3-O-Methylglucose; D001464:Barium; D012964:Sodium; D011803:Quinine; D013806:Theophylline; D014700:Verapamil; D011188:Potassium; D002118:Calcium