Regulation of intracellular pH in avian renal proximal tubules.
In proximal tubules isolated from chicken transitional nephrons, intracellular pH (pHi), measured with the pH-sensitive fluorescent dye 2'.7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF), was approximately 7.3-7.4 under control conditions [N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered medium with pH 7.4 at 39 degrees C] and was reduced to approximately 6.8 in response to NH4Cl pulse. The rate of recovery of pHi (dpHi/dt) from this acid level to the resting level and the resting pHi were 1) significantly reduced by the removal of Na+ from the bath, 2) significantly increased by the removal of Cl from the bath, and 3) unchanged by the removal of both Na+ and Cl from the bath. The addition of either amiloride or 4,4'-diisothiocyanostilbene-2,2'-disulfonate to the bath reduced dpHi/dt to about the same extent as the removal of Na+. These data suggest that both Na(+)-coupled and Cl-coupled acid-base fluxes at the basolateral membrane are involved in determining the resting pHi and the rate of recovery of pHi after acidification. The most likely possibilities appear to be a basolateral Na+/Hi exchanger, a basolateral Na(+)-coupled Cl/HCO3 exchanger, a basolateral Na(+)-HCO3(-)CO(3)2 cotransporter, and a basolateral Na(+)-independent Cl-/HCO3 exchanger.
Kim
Y K
YK
Department of Physiology, College of Medicine, University of Arizona, Tucson 85724-5051, USA.
Brokl
O H
OH
Dantzler
W H
WH
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000641:Ammonia / Q000493:pharmacokinetics; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002021:Buffers; D002645:Chickens / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008954:Models, Biological; D010539:Permeability; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
D002021:Buffers; D002712:Chlorides; D000643:Ammonium Chloride; D000641:Ammonia; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium