ISSN:
1432-1424
Keywords:
Na+ and Cl− conductance
;
Amiloride
;
Intralobular ducts
;
Mouse mandibular glands
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Our previously published whole-cell patch-clamp studies on the cells of the intralobular (granular) ducts of the mandibular glands of male mice revealed the presence of an amiloride-sensitive Na+ conductance in the plasma membrane. In this study we demonstrate the presence also of a Cl− conductance and we show that the sizes of both conductances vary with the Cl− concentration of the fluid bathing the cytosolic surface of the plasma membrane. As the cytosolic Cl− concentration rises from 5 to 150 mmol/liter, the size of the inward Na+ current declines, the decline being half-maximal when the Cl− concentration is approximately 50 mmol/liter. In contrast, as cytosolic Cl− concentration increases, the inward Cl− current remains at a constant low level until the Cl− concentration exceeds 80 mmol/liter, when it begins to increase. Studies in which Cl− in the pipette solution was replaced by other anions indicate that the Na+ current is suppressed by intracellular Br-, Cl− and NO 3 - but not by intracellular I-, glutamate or gluconate. Our studies also show that the Cl− conductance allows passage of Cl− and Br- equally well, I-less well, and NO 3 - , glutamate and gluconate poorly, if at all. The findings with NO 3 - are of particular interest because they show that suppression of the Na+ current by a high intracellular concentration of a particular anion does not depend on actual passage of that anion through the Cl− conductance. In mouse granular duct cells there is, thus, a reciprocal regulation of Na+ and Cl− conductances by the cytosolic Cl− concentration. Since the cytosolic Cl− concentration is closely correlated with cell volume in many epithelia, this reciprocal regulation of Na+ and Cl− conductances may provide a mechanism by which ductal Na+ and Cl transport rates are adjusted so as to maintain a stable cell volume.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00211100
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