Stimulation of apical H-K-ATPase in intercalated cells of cortical collecting duct with chronic metabolic acidosis.
This study evaluated the role of H-K-adenosinetriphosphatase (H-K-ATPase) with chronic metabolic acidosis (CMA) in intercalated cells (ICs) of rabbit cortical collecting duct (CCD). CMA was induced by replacing drinking water with 75 mM NH4Cl in 5% sucrose for 10-14 days. CCDs isolated from CMA and control rabbits were split open and exposed to the intracellular pH (pHi) indicator 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. In N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered solutions, the resting pHi in ICs was similar for both groups. K-dependent pHi recovery (5 mM K, 140 mM N-methyl-D-glucamine) was monitored in response to a pulse of NH4Cl (10 mM). The K-dependent pHi recovery rate was threefold higher in CMAICs compared with controls and was abolished with the gastric H-K-ATPase inhibitor, Sch-28080 (10(-5) M). Polarity of the H-K-ATPase was studied in microperfused CMA and control CCDs. Luminal K-dependent pHi recovery was monitored in response to an acute pulse of NH4Cl in individual peanut lectin agglutinin (PNA)-binding ICs. The apical Sch-28080-inhibitable K-dependent pHi recovery rate was significantly greater in CMA ICs than control ICs. In summary, CMA enhances functional activity of an apical H-K-ATPase in PNA-binding ICs of rabbit CCD.
Silver
R B
RB
Department of Physiology, Cornell University Medical College, New York 10021, USA.
Mennitt
P A
PA
Satlin
L M
LM
D000141:Acidosis, Renal Tubular / Q000201:enzymology*; D000818:Animals; D002908:Chronic Disease; D005260:Female; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007685:Kidney Tubules, Collecting / Q000201:enzymology* / Q000503:physiopathology; D011817:Rabbits
D017506:H(+)-K(+)-Exchanging ATPase