title: Na+ and Cl- conductances are controlled by cytosolic Cl- concentration in the intralobular duct cells of mouse mandibular glands.
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 NO3- 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 NO3-, glutamate and gluconate poorly, if at all. The findings with NO3- 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.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology (F-13), University of Sydney, NSW, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Dinudom
authors.forename: J A
authors.initials: JA
authors.lastname: Young
authors.forename: D I
authors.initials: DI
authors.lastname: Cook
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001966:Bromine / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D018118:Chloride Channels / Q000032:analysis / Q000502:physiology*; D002712:Chlorides / Q000032:analysis* / Q000493:pharmacokinetics / Q000502:physiology*; D003600:Cytosol / Q000737:chemistry*; D005942:Gluconates / Q000494:pharmacology; D005971:Glutamates / Q000502:physiology; D008297:Male; D051379:Mice; D009566:Nitrates / Q000502:physiology; D012469:Salivary Glands / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D012964:Sodium / Q000493:pharmacokinetics / Q000502:physiology; D015222:Sodium Channels / Q000032:analysis / Q000502:physiology*
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D005942:Gluconates; D005971:Glutamates; D009566:Nitrates; D015222:Sodium Channels; D000584:Amiloride; D012964:Sodium; D001966:Bromine