Oct 1, 1989

Localization of Cl- conductance in normal and Cl- impermeability in cystic fibrosis sweat duct epithelium

The American Journal of Physiology
M M Reddy, P M Quinton


We studied the Cl- permeability properties of apical and basolateral membranes of human reabsorptive sweat duct (RSD) from normal and cystic fibrosis (CF) subjects. In normal ducts, Cl- substitution by impermeant anion gluconate in the lumen increased the voltage divider ratio (VDR) from 4.8 +/- 0.9 to 7.0 +/- 1.1 (n = 8, P less than 0.05), whereas Cl- substitution in the contraluminal bath decreased the VDR from 3.2 +/- 0.7 to 1.9 +/- 0.4 (n = 7, P less than 0.05). These results are consistent with a significant Cl- permeability in both apical and basolateral membranes of normal ducts. Amiloride (10(-4) M) in the lumen of normal ducts resulted in a small increase in VDR from 4.2 +/- 0.6 to 5.0 +/- 0.8 (n = 10, P less than 0.05), whereas the current-induced basolateral membrane voltage deflections (delta Vb) increased from 6.9 +/- 1.3 to 7.7 +/- 1.2 mV, suggesting that inhibition of Na+ permeability decreased basolateral membrane Cl- permeability. In the absence of luminal Cl-, amiloride decreased delta Vb and induced much greater effect on VDR (from 5.2 +/- 1.1 to 10.8 +/- 2.3, n = 9, P less than 0.05) than in the presence of Cl-. Likewise, in the presence of amiloride, Cl- substitution in the lumen had greater effect on VDR (...Continue Reading

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Mentioned in this Paper

Establishment and Maintenance of Localization
Chloride Ion Level
Entire Duct
Tissue Membrane
Entire Lumen of Body System
Specimen Type - Sweat
Resting Potentials
Apical Membrane
Cystic Fibrosis

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