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.
McCann
J D
JD
Howard Hughes Medical Institute, Department of Physiology, University of Iowa College of Medicine, Iowa City 52242.
Welsh
M J
MJ
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