Potassium conductance in rabbit esophageal epithelium.
K+ conductance in apical and basolateral cell membranes of rabbit esophageal epithelial cells was investigated within intact epithelium by impalement with conventional microelectrodes from luminal or serosal sides. Under steady-state conditions, K+ conductance was demonstrated in basolateral, but not apical, membranes by showing 1) membrane depolarization upon exposure to either solutions high in K+ (20-65 mM) or containing Ba2+, tetraethylammonium, or quinine, and 2) a resistance ratio that increased on exposure to high K+ solution and decreased on exposure to Ba2+, quinine, and tetraethylammonium. From exposures to high K+, the apparent K+ transference number and electromotive force generated at the basolateral membrane were calculated and found to be 0.42 +/- 0.01 and -83 +/- 3 mV, respectively. Furthermore, basolateral K+ conductance was shown to be important for maintaining resting net transepithelial Na+ absorption in that high K+ or barium inhibited the transepithelial potential difference and short-circuit current of Ussing-chambered epithelia. We conclude that under steady-state conditions the basolateral, but not apical, membranes of esophageal epithelial cells contain a K(+)-conductive pathway and that this pathway is important for active sodium absorption.
Khalbuss
W E
WE
Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
Alkiek
R
R
Marousis
C G
CG
Orlando
R C
RC
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004553:Electric Conductivity; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D004947:Esophagus / Q000166:cytology / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D011188:Potassium / Q000037:antagonists & inhibitors / Q000502:physiology*; D011817:Rabbits; D012964:Sodium / Q000493:pharmacokinetics
D012964:Sodium; D011188:Potassium