Regulation of intracellular pH in proximal tubules of avian loopless reptilian-type nephrons.
In proximal tubules isolated from chicken superficial loopless reptilian-type nephrons, intracellular pH (pHi), measured with pH-sensitive fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, was approximately 7.1-7.2 under control conditions (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered medium with pH 7.4 at 37 degrees C), and was reduced to approximately 6.9 in response to NH4Cl pulse. The rate of recovery of pHi (control value approximately equal to 5 x 10(-3) pH U/s) from this acid level was 1) significantly decreased by removal of Na+ or both Na+ and Cl- from the bath or addition of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.25 mM) to the bath, 2) significantly increased by high bath K+ (75 mM), and 3) unchanged by removal of Cl- alone from the bath or addition of ethylisopropylamiloride (1 mM) or Ba2+ (5 mM) to the bath. Resting pHi was 1) significantly decreased by Na+ or simultaneous Na+ and Cl- removal, 2) significantly increased by high K+, and 3) unchanged by Cl- removal alone or addition of Ba2+. The data do not fit the concept of pHi regulation by the most commonly suggested basolateral transporters (Na+/H+ exchanger, Na(+)-dependent and Na(+)-independent Cl-/HCO3- exchangers, or Na(+)-HCO3(-)-CO3(2-) cotransporter).
Martinez
C L
CL
Department of Physiology, College of Medicine, University of Arizona, Tucson 85724-5051, USA.
Brokl
O H
OH
Shuprisha
A
A
Abbott
D E
DE
Dantzler
W H
WH
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D017920:Antiporters / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D002645:Chickens; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007686:Kidney Tubules, Distal / Q000187:drug effects / Q000502:physiology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009399:Nephrons / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D012911:Snakes
D017920:Antiporters; D005452:Fluoresceins; D005456:Fluorescent Dyes; D000643:Ammonium Chloride; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; C039614:ethylisopropylamiloride