Characterization of K+ channels in the basolateral membrane of rat tracheal epithelia.
To study K+ channels in the basolateral membrane of chloride-secreting epithelia, rat tracheal epithelial monolayers were cultured on permeable filters and mounted into an Ussing chamber system. The mucosal membrane was permeabilized with nystatin (180 microg/ml) in the symmetrical high K+ (145 mm) Ringer solution. During measurement of the macroscopic K+ conductance properties of the basolateral membrane under a transepithelial voltage clamp, we detected at least two types of K+ currents: one is an inwardly rectifying K+ current and the other is a slowly activating outwardly rectifying K+ current. The inwardly rectifying K+ current is inhibited by Ba2+. The slowly activating K+ current was potentiated by cAMP and inhibited by clofilium, phorbol 12-myristate 13-acetate (PMA) and lowering temperature. This is consistent with the biophysical characteristics of ISK channel. RT-PCR analysis revealed the presence of ISK cDNA in the rat trachea epithelia. Although 0.1 mM Ba2+ only had minimal affect on short-circuit current (Isc) induced by cAMP in intact epithelia, 0.1 mM clofilium strongly inhibited it. These results indicate that ISK might be important for maintaining cAMP-induced chloride secretion in the rat trachea epithelia.
Hwang
T
T
Department of Physiology, College of Dentistry, Pusan National University, Pusan, Korea.
Suh
D
D
Bae
H
H
Lee
S
S
Jung
J
J
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D002478:Cells, Cultured; D018118:Chloride Channels / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D015640:Ion Channel Gating / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials; D009761:Nystatin / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014132:Trachea / Q000166:cytology / Q000378:metabolism*
D018118:Chloride Channels; D002712:Chlorides; D018076:DNA, Complementary; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D000644:Quaternary Ammonium Compounds; C059983:potassium channel protein I(sk); D009761:Nystatin; D001464:Barium; C022799:clofilium; D013755:Tetradecanoylphorbol Acetate