Potassium conductances in tracheal epithelium activated by secretion and cell swelling.
Increased basolateral membrane K conductance accompanies stimulation of Cl secretion across canine trachea. To assess the K conductance properties, we permeabilized the apical membranes with amphotericin B and monitored the current and conductance caused by K flow across the basolateral membranes. Under basal unstimulated conditions, two K conductances could be distinguished by blockers. One was inhibited only by barium; the other was sensitive also to quinidine and lidocaine. The permeabilities of the basal conductance pathways to K and Rb were similar (PK/PRb approximately equal to 1.5). The secretory agonist, epinephrine, selectively increased the quinidine-insensitive conductance, implicating it in the Cl secretory response. Cell swelling induced a third conductance with a low permeability to Rb (PK/PRb approximately equal to 10) that was quinidine sensitive. In tissues not treated with amphotericin, neither quinidine nor Rb-for-K replacement inhibited transepithelial Cl secretion. Thus neither of the quinidine-sensitive K conductances (basal or swelling induced) contribute to the increase in basolateral K conductance during Cl secretion. Cell shrinkage inhibited all three conductances and secretion, suggesting that the initial priority of the cell is volume regulation.
Butt
A G
AG
Department of Physiology, University of Alabama, Birmingham 35294.
Clapp
W L
WL
Frizzell
R A
RA
D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D004285:Dogs; D004553:Electric Conductivity; D004837:Epinephrine / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D009092:Mucous Membrane / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011802:Quinidine / Q000494:pharmacology; D012413:Rubidium / Q000378:metabolism; D014132:Trachea / Q000502:physiology*
D002712:Chlorides; D015221:Potassium Channels; D002034:Bumetanide; D001464:Barium; D010042:Ouabain; D000666:Amphotericin B; D011802:Quinidine; D012413:Rubidium; D011188:Potassium; D004837:Epinephrine