TY - JOUR
T1 - Basolateral regulation of pH(i) in proximal tubules of avian loopless and long-looped nephrons in bicarbonate
AU - Brokl, Olga H.
AU - Martinez, Christina L.
AU - Kim, Yung Kyu
AU - Abbott, Diane E.
AU - Dantzler, William H.
PY - 1999/7/1
Y1 - 1999/7/1
N2 - In isolated, nonperfused chicken proximal tubules from both loopless reptilian-type and long-looped mammalian-type nephrons, resting intracellular pH (pH(i)), measured with pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF), was ~7.1 under control HCO3- conditions [20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)/5 mM HCO3-buffered medium with pH 7.4 at 37°C] and was reduced to ~6.8 in response to NH4Cl pulse. The rate of recovery of pH(i) (dpH(i)/dt) from this level to the resting level in proximal tubules from both nephron types was (1) significantly reduced by the removal of Na+ or both Na+ and Cl- from the bath, and (2) unaffected by the removal of Cl- from the bath or the presence of a high K+ concentration or Ba2+ in the bath. In proximal tubules from long-looped mammalian-type, but not loopless reptilian-type, nephrons, dpH(i)/dt was significantly reduced by the addition of either 5-(N-ethyl-N-isopropyl) amiloride (EIPA) or 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) to the bath. These data suggest that a Na+/H+ exchanger and most likely a Na+-dependent Cl-/HCO3- exchanger are involved in basolateral regulation of pH(i) in mammalian-type nephrons whereas none of the commonly identified basolateral acid-base transporters appear to be involved in regulation of pH(i) in reptilian-type nephrons.
AB - In isolated, nonperfused chicken proximal tubules from both loopless reptilian-type and long-looped mammalian-type nephrons, resting intracellular pH (pH(i)), measured with pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF), was ~7.1 under control HCO3- conditions [20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)/5 mM HCO3-buffered medium with pH 7.4 at 37°C] and was reduced to ~6.8 in response to NH4Cl pulse. The rate of recovery of pH(i) (dpH(i)/dt) from this level to the resting level in proximal tubules from both nephron types was (1) significantly reduced by the removal of Na+ or both Na+ and Cl- from the bath, and (2) unaffected by the removal of Cl- from the bath or the presence of a high K+ concentration or Ba2+ in the bath. In proximal tubules from long-looped mammalian-type, but not loopless reptilian-type, nephrons, dpH(i)/dt was significantly reduced by the addition of either 5-(N-ethyl-N-isopropyl) amiloride (EIPA) or 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) to the bath. These data suggest that a Na+/H+ exchanger and most likely a Na+-dependent Cl-/HCO3- exchanger are involved in basolateral regulation of pH(i) in mammalian-type nephrons whereas none of the commonly identified basolateral acid-base transporters appear to be involved in regulation of pH(i) in reptilian-type nephrons.
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U2 - 10.1002/(SICI)1097-010X(19990701)284:2<174::AID-JEZ7>3.0.CO;2-W
DO - 10.1002/(SICI)1097-010X(19990701)284:2<174::AID-JEZ7>3.0.CO;2-W
M3 - Article
C2 - 10404646
AN - SCOPUS:0033153768
SN - 0022-104X
VL - 284
SP - 174
EP - 187
JO - Journal of Experimental Zoology
JF - Journal of Experimental Zoology
IS - 2
ER -