Low-NaCl diet increases H-K-ATPase in intercalated cells from rat cortical collecting duct.
Extracellular K+-dependent H+ extrusion after an acute acid load, an index of H/K exchange, was monitored in intercalated cells (ICs) from rat cortical collecting tubule (CCT) using ratiometric fluorescence imaging of the intracellular pH (pHi) indicator, 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). The hypothesis tested was that 12- to 14-day NaCl deprivation increases H-K-ATPase in rat ICs. The rate of H/K exchange in the low-NaCl ICs was double that of controls. In control ICs, H/K exchange was inhibited by Sch-28080 (10 microM). In the low-NaCl ICs, it was partially blocked by Sch-28080 or ouabain (1 mM). Simultaneous addition of both inhibitors abolished K-dependent pHi recovery. The induced H/K exchange observed with NaCl restriction was not due to elevated plasma aldosterone as evidenced by experiments on ICs from rats implanted with osmotic minipumps administering aldosterone such that plasma levels were comparable to those of NaCl-deficient rats. The results suggest that NaCl deficiency induces two isoforms of H-K-ATPase in ICs and that this effect is not mediated by elevated plasma aldosterone.
Department of Physiology, Cornell University Medical College, New York, New York 10021, USA.
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D000450:Aldosterone / Q000097:blood / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004039:Diet, Sodium-Restricted; D004573:Electrolytes / Q000097:blood / Q000652:urine; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017506:H(+)-K(+)-Exchanging ATPase / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000494:pharmacology; D007672:Kidney Cortex / Q000166:cytology* / Q000201:enzymology* / Q000502:physiology; D007685:Kidney Tubules, Collecting / Q000166:cytology* / Q000201:enzymology* / Q000502:physiology; D007700:Kinetics; D018942:Macrolides; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D054328:Proton Pump Inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D013997:Time Factors
D000900:Anti-Bacterial Agents; D004573:Electrolytes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D018942:Macrolides; D054328:Proton Pump Inhibitors; C035235:Sch 28080; D000450:Aldosterone; D010042:Ouabain; C040929:bafilomycin A1; D017506:H(+)-K(+)-Exchanging ATPase