ISSN:
1432-1424
Keywords:
A6 cells
;
Chloride
;
Sodium
;
Cell volume
;
Epithelium
;
MQAE
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract To assess the role of chloride in cell volume and sodium transport regulation, we measured cell height changes (CH), transepithelial chloride and sodium fluxes, and intracellular chloride content during challenge with hyposmotic solutions under open circuit (OC) conditions. CH maximally increased following hyposmotic challenge within ∼5 minutes. The change in CH was smaller under short circuit (SC) conditions or following replacement of chloride in the mucosal solution by gluconate or cyclamate (Cl−-free m ). When corrected for the osmotically inactive cell volume (30 ± 2%), ΔCH for controls (OC) were greater than predicted for an ideal osmometer. In contrast, ACH for Cl−-free m or SC conditions were similar to that predicted for an ideal osmometer. Na+ and Cl− mucosa-to-serosa fluxes increased following hyposmotic challenge. Chloride fluxes increased maximally within 5 min, then decreased. In contrast, the Na+ flux increased slowly and reached a steady state after ∼25 min. Under isosmotic conditions, exposure to Cl−-free m solutions led to decreases in the transepithelial conductance, Na+ flux, and CH. Chloride permeabilities in the apical and basolateral membranes were detected using the fluorescent intracellular chloride indicator MQAE. The results indicate that during osmotic swelling, the entry of both sodium and chloride is increased. The time courses of these increases differ, suggesting distinct mechanisms for the osmotic regulation of these apical membrane transport processes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00238419
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