Sodium- and chloride-conductive pathways in cultured mouse tracheal epithelium.
The utility of a transgenic murine model of cystic fibrosis (CF) lung disease will likely depend on whether the mouse's proximal airway epithelium is characterized by Na(+)- and Cl(-)-conductive pathways comparable to those found in human airways. Therefore, the electrophysiological properties of primary cultures of mouse tracheal epithelium (MTE) were investigated using double-barreled, Cl(-)-selective microelectrodes. Epithelial cells isolated from freshly excised mouse tracheae formed confluent polarized monolayers on permeable collagen supports and developed significant transepithelial potential differences (approximately -10 mV) within 5-6 days postseeding. Under basal conditions, the MTE monolayers had an equivalent short-circuit current (Ieq) of -21.1 +/- 2.1 microA/cm2 and a transepithelial resistance of 424 +/- 49 omega.cm2. Intracellular measurements indicated that the apical (Va) and basolateral (Vb) membrane potential differences were -16.9 +/- 1.5 and -25.4 +/- 1.5 mV, respectively; apical membrane fractional resistance was 0.36 +/- 0.03; and intracellular Cl- activity was 56.1 +/- 2.3 mM. The presence of an apical Na+ conductance was demonstrated by luminal amiloride application (10(-4)M), which decreased Ieq, hyperpolarized Va, and increased the fractional resistance of the apical membrane. The presence of an apical Cl- conductance was demonstrated by substitution of Cl- with gluconate in the luminal bath, which decreased intracellular Cl- activity and increased the fractional resistance of the apical membrane. Luminal application of ATP (10(-4) M was also found to increase the rate of Cl- secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
Clarke
L L
LL
Department of Medicine, University of North Carolina, Chapel Hill 27599-7020.
Burns
K A
KA
Bayle
J Y
JY
Boucher
R C
RC
Van Scott
M R
MR
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000502:physiology*; D004553:Electric Conductivity; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D012964:Sodium / Q000502:physiology*; D014132:Trachea / Q000166:cytology / Q000502:physiology*
D002712:Chlorides; D000584:Amiloride; D000255:Adenosine Triphosphate; D012964:Sodium; D007545:Isoproterenol