Adaptation of Cortical Collecting Duct (CCD) Beta Intercalated Cells(β-ICCs) to Metabolic Acidosis • 1824

The ammonia transporter family member, Rh B Glycoprotein (Rhbg), is an ammonia-specific transporter heavily expressed in the kidney and is necessary for the normal increase in ammonia excretion in response to metabolic acidosis. Hypokalemia is a common clinical condition in which there is increased renal ammonia excretion despite the absence of metabolic acidosis. The purpose of this study was to examine Rhbg's role in this response through the use of mice with intercalated cell-specific Rhbg deletion (IC-Rhbg-KO). Hypokalemia induced by feeding a K+-free diet increased urinary ammonia excretion significantly. In mice with intact Rhbg expression, hypokalemia increased Rhbg protein expression in intercalated cells in the cortical collecting duct (CCD) and in the outer medullary collecting duct (OMCD). Deletion of Rhbg from intercalated cells inhibited hypokalemia-induced changes in urinary total ammonia excretion significantly and completely prevented hypokalemia-induced increases in urinary ammonia concentration, but did not alter urinary pH. We conclude that hypokalemia increases Rhbg expression in intercalated cells in the cortex and outer medulla and that intercalated cell Rhbg expression is necessary for the normal increase in renal ammonia excretion in response to hypokalemia.

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Galectin-3 expression is induced in renal β-intercalated cells during metabolic acidosis

AJP Renal Physiology ◽

10.1152/ajprenal.00244.2005 ◽

2006 ◽

Vol 290 (1) ◽

pp. F148-F158 ◽

Cited By ~ 24

Author(s):

Andrew L. Schwaderer ◽

Soundarapandian Vijayakumar ◽

Qais Al-Awqati ◽

George J. Schwartz

Keyword(s):

Extracellular Matrix ◽

Metabolic Acidosis ◽

Collecting Duct ◽

Rabbit Kidney ◽

Cell Phenotype ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Outer Cortex ◽

Galectin 3 ◽

Inner Cortex

The adaptation of the cortical collecting duct (CCD) to metabolic acidosis requires the polymerization and deposition in the extracellular matrix of the novel protein hensin. HCO3−-secreting β-intercalated cells remove apical Cl−:HCO3− exchangers and may reverse functional polarity to secrete protons. Using intercalated cells in culture, we found that galectin-3 facilitated hensin polymerization, thereby causing their differentiation into the H+-secreting cell phenotype. We examined the expression of galectin-3 in the rabbit kidney and its relationship to hensin during metabolic acidosis. In control kidneys, galectin-3 was expressed in the cortical and medullary collecting ducts. In the outer cortex 26 ± 3% of CCD cells expressed galectin-3 compared with 64 ± 3% of the cells of the inner cortex. In the CCD, galectin-3 was rarely expressed in β-intercalated cells, being primarily present in α-intercalated and principal cells. During metabolic acidosis, the intensity of cellular staining for galectin-3 increased and more cells began to express it; the percentage of CCD cells expressing galectin-3 increased from 26 ± 3 to 66 ± 3% in the outer cortex and from 64 ± 3 to 78 ± 4% in the inner cortex. This was particularly evident in β-intercalated cells where expression was found in only 8 ± 2% in control animals but in 75 ± 2% during metabolic acidosis in the outer cortex and similarly for the inner cortex (26 ± 6 to 90 ± 7%). Importantly, both galectin-3 and hensin were found in the extracellular matrix of microdissected CCDs; and during metabolic acidosis, many more cells exhibited this extracellular colocalization. Thus galectin-3 may play several important roles in the CCD, including mediating the adaptation of β-intercalated cells during metabolic acidosis.

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Stimulation of apical H-K-ATPase in intercalated cells of cortical collecting duct with chronic metabolic acidosis

AJP Renal Physiology ◽

10.1152/ajprenal.1996.270.3.f539 ◽

1996 ◽

Vol 270 (3) ◽

pp. F539-F547 ◽

Cited By ~ 14

Author(s):

R. B. Silver ◽

P. A. Mennitt ◽

L. M. Satlin

Keyword(s):

Metabolic Acidosis ◽

Recovery Rate ◽

Collecting Duct ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Atpase Inhibitor ◽

Chronic Metabolic Acidosis ◽

Ethanesulfonic Acid ◽

And Control

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.

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Potassium depletion increases proton pump (H+-ATPase) activity in intercalated cells of cortical collecting duct

AJP Renal Physiology ◽

10.1152/ajprenal.2000.279.1.f195 ◽

2000 ◽

Vol 279 (1) ◽

pp. F195-F202 ◽

Cited By ~ 21

Author(s):

Randi B. Silver ◽

Sylvie Breton ◽

Dennis Brown

Keyword(s):

Plasma Membrane ◽

Atpase Activity ◽

Collecting Duct ◽

Proton Pumps ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Collecting Ducts ◽

Acid Load ◽

Collecting Tubules ◽

Atpase Staining

Intercalated cells (ICs) from kidney collecting ducts contain proton-transporting ATPases (H+-ATPases) whose plasma membrane expression is regulated under a variety of conditions. It has been shown that net proton secretion occurs in the distal nephron from chronically K+-depleted rats and that upregulation of tubular H+- ATPase is involved in this process. However, regulation of this protein at the level of individual cells has not so far been examined. In the present study, H+-ATPase activity was determined in individually identified ICs from control and chronically K+-depleted rats (9–14 days on a low-K+ diet) by monitoring K+- and Na+-independent H+ extrusion rates after an acute acid load. Split-open rat cortical collecting tubules were loaded with the intracellular pH (pHi) indicator 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, and pHiwas determined by using ratiometric fluorescence imaging. The rate of pHi recovery in ICs in response to an acute acid load, a measure of plasma membrane H+-ATPase activity, was increased after K+ depletion to almost three times that of controls. Furthermore, the lag time before the start of pHirecovery after the cells were maximally acidified fell from 93.5 ± 13.7 s in controls to 24.5 ± 2.1 s in K+-depleted rats. In all ICs tested, Na+- and K+-independent pHi recovery was abolished in the presence of bafilomycin (100 nM), an inhibitor of the H+-ATPase. Analysis of the cell-to-cell variability in the rate of pHi recovery reveals a change in the distribution of membrane-bound proton pumps in the IC population of cortical collecting duct from K+-depleted rats. Immunocytochemical analysis of collecting ducts from control and K+-depleted rats showed that K+-depletion increased the number of ICs with tight apical H+ATPase staining and decreased the number of cells with diffuse or basolateral H+-ATPase staining. Taken together, these data indicate that chronic K+ depletion induces a marked increase in plasma membrane H+ATPase activity in individual ICs.

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Pendrin immunoreactivity in the gill epithelium of a euryhaline elasmobranch

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00178.2002 ◽

2002 ◽

Vol 283 (4) ◽

pp. R983-R992 ◽

Cited By ~ 51

Author(s):

Peter M. Piermarini ◽

Jill W. Verlander ◽

Ines E. Royaux ◽

David H. Evans

Keyword(s):

Collecting Duct ◽

Apical Region ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Gill Epithelium ◽

Dasyatis Sabina ◽

Proton Atpase ◽

Atlantic Stingray ◽

Freshwater Stingray ◽

Gill Lamellae

Pendrin is an anion exchanger in the cortical collecting duct of the mammalian nephron that appears to mediate apical Cl−/HCO[Formula: see text]exchange in bicarbonate-secreting intercalated cells. The goals of this study were to determine 1) if pendrin immunoreactivity was present in the gills of a euryhaline elasmobranch (Atlantic stingray, Dasyatis sabina), and 2) if branchial pendrin immunoreactivity was influenced by environmental salinity. Immunoblots detected pendrin immunoreactivity in Atlantic stingray gills; pendrin immunoreactivity was greatest in freshwater stingrays compared with freshwater stingrays acclimated to seawater (seawater acclimated) and marine stingrays. Using immunohistochemistry, pendrin-positive cells were detected on both gill lamellae and interlamellar regions of freshwater stingrays but were more restricted to interlamellar regions in seawater-acclimated and marine stingray gills. Pendrin immunolabeling in freshwater stingray gills was more apical, discrete, and intense compared with seawater-acclimated and marine stingrays. Regardless of salinity, pendrin immunoreactivity occurred on the apical region of cells rich with basolateral vacuolar-proton-ATPase, and not in Na+-K+-ATPase-rich cells. We suggest that a pendrin-like transporter may contribute to apical Cl−/HCO[Formula: see text] exchange in gills of Atlantic stingrays from both freshwater and marine environments.

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ANP-stimulated Na+ secretion in the collecting duct prevents Na+ retention in the renal adaptation to acid load

AJP Renal Physiology ◽

10.1152/ajprenal.00059.2019 ◽

2019 ◽

Vol 317 (2) ◽

pp. F435-F443

Author(s):

Lydie Cheval ◽

Naziha Bakouh ◽

Christine Walter ◽

Dignê Tembely ◽

Luciana Morla ◽

...

Keyword(s):

Metabolic Acidosis ◽

Urinary Excretion ◽

Secretory Pathway ◽

Collecting Duct ◽

Type A ◽

Intercalated Cells ◽

Membrane Expression ◽

Acid Load ◽

Anp Receptors ◽

Stimulation Of

We have recently reported that type A intercalated cells of the collecting duct secrete Na+ by a mechanism coupling the basolateral type 1 Na+-K+-2Cl− cotransporter with apical type 2 H+-K+-ATPase (HKA2) functioning under its Na+/K+ exchange mode. The first aim of the present study was to evaluate whether this secretory pathway is a target of atrial natriuretic peptide (ANP). Despite hyperaldosteronemia, metabolic acidosis is not associated with Na+ retention. The second aim of the present study was to evaluate whether ANP-induced stimulation of Na+ secretion by type A intercalated cells might account for mineralocorticoid escape during metabolic acidosis. In Xenopus oocytes expressing HKA2, cGMP, the second messenger of ANP, increased the membrane expression, activity, and Na+-transporting rate of HKA2. Feeding mice with a NH4Cl-enriched diet increased urinary excretion of aldosterone and induced a transient Na+ retention that reversed within 3 days. At that time, expression of ANP mRNA in the collecting duct and urinary excretion of cGMP were increased. Reversion of Na+ retention was prevented by treatment with an inhibitor of ANP receptors and was absent in HKA2-null mice. In conclusion, paracrine stimulation of HKA2 by ANP is responsible for the escape of the Na+-retaining effect of aldosterone during metabolic acidosis.

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Regulation of AE2 mRNA expression in the cortical collecting duct by acid/base balance

AJP Renal Physiology ◽

10.1152/ajprenal.1998.274.3.f596 ◽

1998 ◽

Vol 274 (3) ◽

pp. F596-F601 ◽

Cited By ~ 2

Author(s):

Géza Fejes-Tóth ◽

Erzsébet Rusvai ◽

Emily S. Cleaveland ◽

Anikó Náray-Fejes-Tóth

Keyword(s):

Mrna Expression ◽

Collecting Duct ◽

Cell Types ◽

Alkaline Media ◽

Mrna Levels ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Acid Base Balance ◽

Acid Base ◽

Base Balance

AE2 mRNA and protein is expressed in several nephron segments, one of which is the cortical collecting duct (CCD). However, the distribution of AE2 among the different cell types of the CCD and the function of AE2 in the kidney are not known. The purpose of this study was to determine the distribution of AE2 mRNA among the three CCD cell types and to examine the effects of changes in acid/base balance on its expression. Following NH4Cl (acid) or NaHCO3 (base) loading of rabbits for ∼18 h, CCD cells were isolated by immunodissection. AE2 mRNA levels were determined by RT-PCR and were normalized for β-actin levels. We found that CCD cells express high levels of AE2 mRNA (∼500 copies/cell). AE2 mRNA levels were significantly higher in CCD cells originating from base-loaded than acid-loaded rabbits, with an average increase of 3.7 ± 1.07-fold. The effect of pH on AE2 mRNA levels was also tested directly using primary cultures of CCD cells. CCD cells incubated in acidic media expressed significantly lower levels of AE2 mRNA than those in normal or alkaline media. Experiments with isolated principal cells, α-intercalated cells, and β-intercalated cells (separated by fluorescence-activated cell sorting) demonstrated that AE2 mRNA levels are comparable in the three collecting duct cell subtypes and are similarly regulated by changes in acid/base balance. Based on these results, we conclude that adaptation to changes in extracellular H+ concentration is accompanied by opposite changes in AE2 mRNA expression. The observations that AE2 mRNA is not expressed in a cell-type-specific manner and that changes in acid/base balance have similar effects on each CCD cell subtype suggest that AE2 might serve a housekeeping function rather than being the apical anion exchanger of β-intercalated cells.

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Immunolocalization of the Na+/Ca2+ exchanger in rabbit kidney

AJP Renal Physiology ◽

10.1152/ajprenal.1993.265.2.f327 ◽

1993 ◽

Vol 265 (2) ◽

pp. F327-F332 ◽

Cited By ~ 19

Author(s):

R. F. Reilly ◽

C. A. Shugrue ◽

D. Lattanzi ◽

D. Biemesderfer

Keyword(s):

Collecting Duct ◽

Membrane Vesicle ◽

Immunoblot Analysis ◽

Rabbit Kidney ◽

Kidney Cortex ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Intracellular Loop ◽

Nephron Segments ◽

Vesicle Preparation

We recently isolated a cDNA encoding a Na+/Ca2+ exchanger from rabbit kidney that was highly similar to the canine cardiac sarcolemmal Na+/Ca2+ exchanger. In the present study, we used two different antibodies to the exchanger to identify the protein and establish its cellular and subcellular localization in the kidney. The first antibody was prepared against a fusion protein consisting of 190 amino acids of the large, presumably intracellular loop of the rabbit renal exchanger fused to the maltose-binding protein. The second was a monoclonal antibody generated against the isolated purified canine cardiac sarcolemmal exchanger. To identify the Na+/Ca2+ exchanger protein, we performed immunoblot analysis against a membrane vesicle preparation from rabbit kidney cortex. Both antibodies immunoblotted proteins of 120 and 70 kDa that are known to be associated with the exchanger. Indirect immunofluorescence revealed that both antisera labeled the basolateral surface of the majority of cells in the connecting tubule (CNT). Since the phase-dense (intercalated) cells in the CNT were not stained, this suggested that the labeled cells were CNT cells. No labeling was detected in other nephron segments with the exception of occasional faint staining of the majority cell population of the cortical collecting duct. The fact that we did not detect labeling in other nephron segments is consistent with either 1) the absence of expression of the Na+/Ca2+ exchanger in these segments, 2) the expression of the exchanger in levels below the threshold of detection of the two antibodies used in this study, or 3) the exchanger in these segments is represented by a different isoform.(ABSTRACT TRUNCATED AT 250 WORDS)

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Minealocorticoid receptors and 11 beta-steroid dehydrogenase activity in renal principal and intercalated cells

AJP Renal Physiology ◽

10.1152/ajprenal.1994.266.1.f76 ◽

1994 ◽

Vol 266 (1) ◽

pp. F76-F80 ◽

Cited By ~ 8

Author(s):

A. Naray-Fejes-Toth ◽

E. Rusvai ◽

G. Fejes-Toth

Keyword(s):

Cell Sorting ◽

Direct Action ◽

Collecting Duct ◽

Cell Types ◽

Target Cells ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Specific Receptors ◽

Principal And Intercalated Cells ◽

Steroid Dehydrogenase

Aldosterone exerts complex effects on the cortical collecting duct (CCD): it increases Na+ and K+ transport, and it also influences H+ and HCO3 transport. Whether these latter effects represent direct action of aldosterone on intercalated cells (ICC) or are secondary to changes in the transport of other electrolytes is unclear. Because the presence of specific receptors is the prerequisite of a direct steroid action, and mineralocorticoid receptors (MR) have not yet been demonstrated in ICC, in this study we determined the density of MR directly in isolated principal cells (PC) and beta-ICC. Purified populations of these two cell types were obtained from rabbit renal cortex by immunodissection and fluorescence-activated cell sorting. We found that both PC and beta-ICC contained a significant number of MR, although receptor density was higher in PC than in beta-ICC (6,704 +/- 912 vs. 2,181 +/- 388 MR sites/cell; P < 0.001). 11 beta-Hydroxysteroid dehydrogenase (11 beta-OHSD), an enzyme that is present predominantly in mineralocorticoid target cells, exhibited a distribution similar to that of MR in the two cell types. 11 beta-OHSD activity, determined by measuring the rate of conversion of [3H]corticosterone to 11-dehydrocorticosterone, was 1.08 +/- 0.14 and 0.34 +/- 0.08 fmol.min-1 x 1,000 cells-1 (P < 0.001) in intact PC and beta-ICC, respectively. 11 beta-OHSD in both cell types utilized NAD as cofactor. These results suggest that beta-ICC are potential direct targets of aldosterone and that MR in both PC and beta-ICC are protected by 11 beta-OHSD.

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Cortical distal nephron Cl− transport in volume homeostasis and blood pressure regulation

AJP Renal Physiology ◽

10.1152/ajprenal.00022.2013 ◽

2013 ◽

Vol 305 (4) ◽

pp. F427-F438 ◽

Cited By ~ 39

Author(s):

Susan M. Wall ◽

Alan M. Weinstein

Keyword(s):

Blood Pressure ◽

Pressor Response ◽

Collecting Duct ◽

Basolateral Membrane ◽

Extracellular Volume ◽

Intercalated Cells ◽

Cortical Collecting Duct ◽

Acid Base Balance ◽

Relative Contribution ◽

And Function

Renal intercalated cells mediate the secretion or absorption of Cl− and OH−/H+ equivalents in the connecting segment (CNT) and cortical collecting duct (CCD). In so doing, they regulate acid-base balance, vascular volume, and blood pressure. Cl− absorption is either electrogenic and amiloride-sensitive or electroneutral and thiazide-sensitive. However, which Cl− transporter(s) are targeted by these diuretics is debated. While epithelial Na+ channel (ENaC) does not transport Cl−, it modulates Cl− transport probably by generating a lumen-negative voltage, which drives Cl− flux across tight junctions. In addition, recent evidence indicates that ENaC inhibition increases electrogenic Cl− secretion via a type A intercalated cells. During ENaC blockade, Cl− is taken up across the basolateral membrane through the Na+-K+−2Cl− cotransporter (NKCC1) and then secreted across the apical membrane through a conductive pathway (a Cl− channel or an electrogenic exchanger). The mechanism of this apical Cl− secretion is unresolved. In contrast, thiazide diuretics inhibit electroneutral Cl− absorption mediated by a Na+-dependent Cl−/HCO3− exchanger. The relative contribution of the thiazide and the amiloride-sensitive components of Cl− absorption varies between studies and probably depends on the treatment model employed. Cl− absorption increases markedly with angiotensin and aldosterone administration, largely by upregulating the Na+-independent Cl−/HCO3− exchanger pendrin. In the absence of pendrin [ Slc26a4 (−/−) or pendrin null mice], aldosterone-stimulated Cl− absorption is significantly reduced, which attenuates the pressor response to this steroid hormone. Pendrin also modulates aldosterone-induced changes in ENaC abundance and function through a kidney-specific mechanism that does not involve changes in the concentration of a circulating hormone. Instead, pendrin changes ENaC abundance and function, at least in part, by altering luminal HCO3−. This review summarizes mechanisms of Cl− transport in CNT and CCD and how these transporters contribute to the regulation of extracellular volume and blood pressure.

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