Control of the amiloride-sensitive Na+ current in mouse salivary ducts by intracellular anions is mediated by a G protein.
1. We have previously reported that the Na+ conductance in mouse intralobular salivary duct cells is controlled by cytosolic anions, being inhibited by high cytosolic concentrations of Cl- and NO3- but not of glutamate. In the present paper, we use whole-cell patch-clamp methods to investigate whether this anion effect is mediated by a G protein. 2. Inclusion of 100 mumol l-1 GTP-gamma-S, a non-hydrolysable GTP analogue, in the glutamate-containing pipette solution, i.e. when the Na+ conductance is active, reduced the size of the Na+ conductance whereas inclusion of 100 mumol l-1 GDP-beta-S, a non-hydrolysable GDP analogue, had no effect. 3. Inclusion of 100 mumol l-1 GDP-beta-S in the NO3(-)-containing pipette solution, i.e. when the Na+ conductance is inhibited, reactivated the conductance. Inclusion of 500 ng ml-1 activated pertussis toxin in the NO3(-)-containing pipette solution had a similar effect on the Na+ conductance. 4. We conclude that the inhibitory effect of intracellular anions such as NO3- and Cl- on the amiloride-sensitive Na+ conductance in mouse mandibular intralobular duct cells is mediated by a G protein sensitive to pertussis toxin.
Department of Physiology, University of Sydney, NSW, Australia.
A
A
Dinudom
P
P
Komwatana
J A
JA
Young
D I
DI
Cook
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001369:Axons / Q000502:physiology; D001711:Biotransformation / Q000187:drug effects; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D051379:Mice; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin; D018987:Salivary Ducts / Q000187:drug effects / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D018118:Chloride Channels; D004232:Diuretics; D015222:Sodium Channels; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C023427:guanosine 5'-O-(2-thiodiphosphate); D000584:Amiloride; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins