Basolateral K+ channels in airway epithelia. II. Role in Cl- secretion and evidence for two types of K+ channel.
We previously described a Ca2(+)-activated K+ channel (KCLIC) in airway epithelial cells [J. D. McCann, J. Matsuda, M. Garcia, G. Kaczorowski, and M. J. Welsh. Am. J. Physiol 258 (Lung Cell. Mol. Physiol. 2): L334-L342, 1990]. To determine whether the KCLIC channel is a basolateral membrane channel and to understand its role in Cl- secretion, we studied airway epithelial cells grown on permeable supports. When cells were stimulated with A23187, charybdotoxin (ChTX) inhibited Cl- secretion and 86Rb efflux at the same concentrations, indicating that the KCLIC channel is required for Ca2(+)-stimulated Cl- secretion. We also investigated the function of K+ channels in adenosine 3',5'-cyclic monophosphate-stimulated secretion. Addition of isoproterenol caused a biphasic increase in Cl- secretion; the time course of the transient component correlated with the time course of the isoproterenol-induced increase in Ca2+ concentration [( Ca2+]c). ChTX inhibited the transient component, but not the prolonged component of secretion; Ba2+ inhibited the sustained component. These results suggest that when cells are grown on permeable supports isoproterenol-induced secretion depends on activation of two types of K+ channel: the KCLIC channel that is stimulated initially and a ChTX-insensitive K+ channel that is stimulated during sustained secretion. This conclusion was supported by measurement of 86Rb efflux from cell monolayers.
Howard Hughes Medical Institute, Department of Physiology, University of Iowa College of Medicine, Iowa City 52242.
J D
JD
McCann
M J
MJ
Welsh
D000818:Animals; D001464:Barium / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018999:Charybdotoxin; D002712:Chlorides / Q000378:metabolism*; D004285:Dogs; D004553:Electric Conductivity; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D012413:Rubidium / Q000378:metabolism; D012414:Rubidium Radioisotopes; D012604:Scorpion Venoms / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014132:Trachea / Q000502:physiology
D002712:Chlorides; D015221:Potassium Channels; D012414:Rubidium Radioisotopes; D012604:Scorpion Venoms; D013757:Tetraethylammonium Compounds; D018999:Charybdotoxin; D001464:Barium; D000001:Calcimycin; D019789:Tetraethylammonium; D007545:Isoproterenol; D012413:Rubidium