Detection of a Na+-H+ antiporter in cultured rat renal papillary collecting duct cells.
To examine whether Na+-dependent H+ transport is present in the papillary collecting duct, changes in intracellular pH (pHi) were evaluated in cultured papillary collecting duct cells acidified to a pHi of 6.3 and then placed into Na+-free or Na+-containing solutions. pHi was determined from changes in the fluorescent signal of the pH-sensitive dye BCECF. pHi did not change significantly when cells were placed in tetramethylammonium chloride- or KCl-containing solutions; however, a significant rise in pHi occurred when acid-loaded cells were placed in solutions containing 140 mM NaCl. The Na+-dependent rise in pHi was blocked by high concentrations of amiloride, but was not affected by alterations in membrane potential across the cell. The rate of rise in pHi was a function of extracellular sodium concentration with a Km for Na+ of 30 +/- 12 mM (n = 6). The properties of this Na+-dependent H+ efflux supports the presence of a Na+-H+ antiporter in the papillary collecting duct.
Wall
S M
SM
Medical Service, Veterans Administration Medical Center, West Los Angeles, California 90073.
Muallem
S
S
Kraut
J A
JA
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007684:Kidney Tubules / Q000032:analysis*; D007685:Kidney Tubules, Collecting / Q000032:analysis*; D008297:Male; D008564:Membrane Potentials; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D000644:Quaternary Ammonium Compounds; D017923:Sodium-Hydrogen Exchangers; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000584:Amiloride; C027917:tetramethylammonium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid