AJP - Renal Physiology, Vol 244, Issue 6 639-F645, Copyright © 1983 by American Physiological Society
Barium inhibition of basolateral membrane potassium conductance in tracheal epithelium
M. J. Welsh
Addition of barium ion, Ba2+, to the submucosal bathing solution of canine
tracheal epithelium reversibly decreased the short-circuit current and
increased transepithelial resistance. The decrease in short-circuit current
represented a decrease in the net rate of Cl secretion with no change in
the rate of Na absorption. Intracellular microelectrode techniques and an
equivalent electrical circuit analysis were used to localize the effect of
Ba2+ to an inhibition of the permeability of the basolateral membrane to K.
Ba2+ (2 mM) doubled basolateral membrane resistance, decreased the
equivalent electromotive force at the basolateral membrane, and decreased
the magnitude of the depolarization of basolateral membrane voltage
produced by increasing the submucosal K concentration. The inhibition of
the basolateral K permeability depolarized the negative intracellular
voltage, resulting in both a decrease in the driving force for Cl exit and
an estimated increase in intracellular Cl concentration. These studies
indicate that there is a Ba2+-inhibitable K conductance at the basolateral
membrane of tracheal epithelial cells and that the K permeability plays an
important role in the generation of the negative intracellular electrical
potential that provides the driving force for Cl exit from the cell.
