scholarly journals Thyroid hormone deficiency alters expression of acid-base transporters in rat kidney

2007 ◽  
Vol 293 (1) ◽  
pp. F416-F427 ◽  
Author(s):  
Nilufar Mohebbi ◽  
Jana Kovacikova ◽  
Marta Nowik ◽  
Carsten A. Wagner
Keyword(s):  
Metabolic Acidosis ◽  
Proximal Tubule ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Type A ◽  
Hormone Deficiency ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Mild Defect ◽  
Acid Challenge

Hypothyroidism in humans is associated with incomplete distal renal tubular acidosis, presenting as the inability to respond appropriately to an acid challenge by excreting less acid. Here, we induced hypothyroidism in rats with methimazole (HYPO) and in one group substituted with l-thyroxine (EU). After 4 wk, acid-base status was similar in both groups. However, after 24 h acid loading with NH4Cl HYPO rats displayed a more pronounced metabolic acidosis. The expression of the Na+/H+ exchanger NHE3, the Na+-phosphate cotransporter NaPi-IIa, and the B2 subunit of the vacuolar H+-ATPase was reduced in the brush-border membrane of the proximal tubule of the HYPO group, paralleled by a lower abundance of the Na+/HCO3− cotransporter NBCe1 and a higher expression of the acid-secretory type A intercalated cell-specific Cl−/HCO3− exchanger AE1. In contrast to control conditions, the expression of NBCe1 was increased in the HYPO group during metabolic acidosis. In addition, net acid excretion was similar in both groups. The relative number of type A intercalated cells was increased in the connecting tubule and cortical collecting duct of the HYPO group during acidosis. Thus thyroid hormones modulate the renal response to an acid challenge and alter the expression of several key acid-base transporters. Mild hypothyroidism is associated only with a very mild defect in renal acid handling, which appears to be mainly located in the proximal tubule and is compensated by the distal nephron.

Cellular and subcellular immunolocalization of ClC-5 channel in mouse kidney: colocalization with H+-ATPase

1999 ◽  
Vol 277 (6) ◽  
pp. F957-F965 ◽  
Author(s):  
Hisato Sakamoto ◽  
Yoshikazu Sado ◽  
Ichiro Naito ◽  
Tae-Hwan Kwon ◽  
Shinichi Inoue ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Type A ◽  
Mouse Kidney ◽  
Thick Ascending Limb ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Double Labeling ◽  
Cytoplasmic Staining ◽  
Confocal Images

To determine the immunolocalization of ClC-5 in the mouse kidney, we developed a ClC-5-specific rat monoclonal antibody. Immunoblotting demonstrated an 85-kDa band of ClC-5 in the kidney and ClC-5 transfected cells. Immunocytochemistry revealed significant labeling of ClC-5 in brush-border membrane and subapical intracellular vesicles of the proximal tubule. In addition, apical and cytoplasmic staining was observed in the type A intercalated cells in the cortical collecting duct. In contrast, the staining was minimal in the outer and inner medullary collecting ducts and the thick ascending limb. Western blotting of vesicles immunoisolated by the ClC-5 antibody showed the presence of H+-ATPase, strongly indicating that these two proteins were present in the same membranes. Double labeling with antibodies against ClC-5 and H+-ATPase and analysis by confocal images showed that ClC-5 and H+-ATPase colocalized in these ClC-5-positive cells. These findings suggest that ClC-5 might be involved in the endocytosis and/or the H+ secretion in the proximal tubule cells and the cortical collecting duct type A intercalated cells in mouse kidney.

scholarly journals Regulation of the apical Cl−/HCO 3 − exchanger pendrin in rat cortical collecting duct in metabolic acidosis

2003 ◽  
Vol 284 (1) ◽  
pp. F103-F112 ◽  
Author(s):  
Snezana Petrovic ◽  
Zhaohui Wang ◽  
Liyun Ma ◽  
Manoocher Soleimani
Keyword(s):  
Metabolic Acidosis ◽  
Mrna Expression ◽  
Intracellular Ph ◽  
Northern Blot ◽  
Collecting Duct ◽  
Kidney Cortex ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Ph Change ◽  
Immunofluorescence Labeling

Pendrin is an apical Cl−/OH−/HCO[Formula: see text] exchanger in β-intercalated cells (β-ICs) of rat and mouse cortical collecting duct (CCD). However, little is known about its regulation in acid-base disorders. Here, we examined the regulation of pendrin in metabolic acidosis, a condition known to decrease HCO[Formula: see text]secretion in CCD. Rats were subjected to NH4Cl loading for 4 days, which resulted in metabolic acidosis. Apical Cl−/HCO[Formula: see text] exchanger activity in β-ICs was determined as amplitude and rate of intracellular pH change when Cl was removed in isolated, microperfused CCDs. Intracellular pH was measured by single-cell digital ratiometric imaging using fluorescent pH-sensitive dye 2′,7′-bis-(3-carboxypropyl)-5-(and-6)-carboxyfluorescein-AM. Pendrin mRNA expression in kidney cortex was examined by Northern blot hybridizations. Expression of pendrin protein was assessed by indirect immunofluorescence. Microperfused CCDs isolated from acidotic rats demonstrated ∼60% reduction in apical Cl−/HCO[Formula: see text] exchanger activity in β-ICs ( P < 0.001 vs. control). Northern blot hybridizations indicated that the mRNA expression of pendrin in kidney cortex decreased by 68% in acidotic animals ( P < 0.02 vs. control). Immunofluorescence labeling demonstrated significant reduction in pendrin expression in CCDs of acidotic rats. We conclude that metabolic acidosis decreases the activity of the apical Cl−/HCO[Formula: see text] exchanger in β-ICs of the rat CCD by reducing the expression of pendrin. Adaptive downregulation of pendrin in metabolic acidosis indicates the important role of this exchanger in acid-base regulation in the CCD.

Versatility of NaCl transport mechanisms in the cortical collecting duct

2017 ◽  
Vol 313 (6) ◽  
pp. F1254-F1263 ◽  
Author(s):  
Aurélie Edwards ◽  
Gilles Crambert
Keyword(s):  
Collecting Duct ◽  
Type A ◽  
Transport Systems ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Type B ◽  
Cell Type ◽  
Acid Base ◽  
Nacl Transport ◽  
Principal Cells

The cortical collecting duct (CCD) forms part of the aldosterone-sensitive distal nephron and plays an essential role in maintaining the NaCl balance and acid-base status. The CCD epithelium comprises principal cells as well as different types of intercalated cells. Until recently, transcellular Na+ transport was thought to be restricted to principal cells, whereas (acid-secreting) type A and (bicarbonate-secreting) type B intercalated cells were associated with the regulation of acid-base homeostasis. This review describes how this traditional view has been upended by several discoveries in the past decade. A series of studies has shown that type B intercalated cells can mediate electroneutral NaCl reabsorption by a mechanism involving Na+-dependent and Na+-independent Cl−/[Formula: see text] exchange, and that is energetically driven by basolateral vacuolar H+-ATPase pumps. Other research indicates that type A intercalated cells can mediate NaCl secretion, through a bumetanide-sensitive pathway that is energized by apical H+,K+-ATPase type 2 pumps operating as Na+/K+ exchangers. We also review recent findings on the contribution of the paracellular route to NaCl transport in the CCD. Last, we describe cross-talk processes, by which one CCD cell type impacts Na+/Cl− transport in another cell type. The mechanisms that have been identified to date demonstrate clearly the interdependence of NaCl and acid-base transport systems in the CCD. They also highlight the remarkable versatility of this nephron segment.

Ureter obstruction alters expression of renal acid-base transport proteins in rat kidney

2008 ◽  
Vol 295 (2) ◽  
pp. F497-F506 ◽  
Author(s):  
Guixian Wang ◽  
Chunling Li ◽  
Soo Wan Kim ◽  
Troels Ring ◽  
Jianguo Wen ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Molecular Mechanisms ◽  
Urinary Tract Obstruction ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Acid Base ◽  
Ureter Obstruction ◽  
Urinary Acidification ◽  
Medullary Collecting Duct ◽  
Type 3

Urinary tract obstruction impairs renal function and is often associated with a urinary acidification defect caused by diminished net H+ secretion and/or HCO3− reabsorption. To identify the molecular mechanisms of these defects, protein expression of key acid-base transporters were examined along the renal nephron and collecting duct of kidneys from rats subjected to 24-h bilateral ureteral obstruction (BUO), 4 days after release of BUO (BUO-R), or BUO-R rats with experimentally induced metabolic acidosis (BUO-A). Semiquantitative immunoblotting revealed that BUO caused a significant reduction in the expression of the type 3 Na+/H+ exchanger (NHE3) in the cortex (21 ± 4%), electrogenic Na+/HCO3− cotransporter (NBC1; 71 ± 5%), type 1 bumetanide-sensitive Na+-K+-2Cl− cotransporter (NKCC2; 3 ± 1%), electroneutral Na+/HCO3− cotransporter (NBCn1; 46 ± 7%), and anion exchanger (pendrin; 87 ± 2%). The expression of H+-ATPase increased in the inner medullary collecting duct (152 ± 13%). These changes were confirmed by immunocytochemistry. In BUO-R rats, there was a persistent downregulation of all the acid-base transporters including H+-ATPase. Two days of NH4Cl loading reduced plasma pH and HCO3− levels in BUO-A rats. The results demonstrate that the expression of multiple renal acid-base transporters are markedly altered in response to BUO, which may be responsible for development of metabolic acidosis and contribute to the urinary acidification defect after release of the obstruction.

Pendrin: an apical Cl−/OH−/HCO3 −exchanger in the kidney cortex

2001 ◽  
Vol 280 (2) ◽  
pp. F356-F364 ◽  
Author(s):  
Manoocher Soleimani ◽  
Tracey Greeley ◽  
Snezana Petrovic ◽  
Zhaohui Wang ◽  
Hassane Amlal ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Immunoblot Analysis ◽  
Kidney Cortex ◽  
Cortical Collecting Duct ◽  
Hek 293 ◽  
Kidney Proximal Tubule ◽  
293 Cells ◽  
Nephron Segment

The identities of the apical Cl−/base exchangers in kidney proximal tubule and cortical collecting duct (CCD) cells remain unknown. Pendrin (PDS), which is expressed at high levels in the thyroid and its mutation causes Pendred's syndrome, is shown to be an anion exchanger. We investigated the renal distribution of PDS and its function. Our results demonstrate that pendrin mRNA expression in the rat kidney is abundant and limited to the cortex. Proximal tubule suspensions isolated from kidney cortex were highly enriched in pendrin mRNA. Immunoblot analysis studies localized pendrin to cortical brush-border membranes. Nephron segment RT-PCR localized pendrin mRNA to proximal tubule and CCD. Expression studies in HEK-293 cells demonstrated that pendrin functions in the Cl−/OH−, Cl−/HCO3 −, and Cl−/formate exchange modes. The conclusion is that pendrin is an apical Cl−/base exchanger in the kidney proximal tubule and CCD and mediates Cl−/OH−, Cl−/HCO3 −, and Cl−/formate exchange.

Regulated expression of pendrin in rat kidney in response to chronic NH4Cl or NaHCO3 loading

2003 ◽  
Vol 284 (3) ◽  
pp. F584-F593 ◽  
Author(s):  
Sebastian Frische ◽  
Tae-Hwan Kwon ◽  
Jørgen Frøkiær ◽  
Kirsten M. Madsen ◽  
Søren Nielsen
Keyword(s):  
Plasma Membrane ◽  
Sodium Intake ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Apical Plasma Membrane ◽  
Cortical Collecting Duct ◽  
Acid Base Balance ◽  
Acid Base ◽  
Control Value ◽  
Base Balance

The anion exchanger pendrin is present in the apical plasma membrane of type B and non-A-non-B intercalated cells of the cortical collecting duct (CCD) and connecting tubule and is involved in HCO[Formula: see text]secretion. In this study, we investigated whether the abundance and subcellular localization of pendrin are regulated in response to experimental metabolic acidosis and alkalosis with maintained water and sodium intake. NH4Cl loading (0.033 mmol NH4Cl/g body wt for 7 days) dramatically reduced pendrin abundance to 22 ± 4% of control values ( n = 6, P < 0.005). Immunoperoxidase labeling for pendrin showed reduced intensity in NH4Cl-loaded animals compared with control animals. Moreover, double-label laser confocal microscopy revealed a reduction in the fraction of cells in the CCD exhibiting pendrin labeling to 65% of the control value ( n = 6, P < 0.005). Conversely, NaHCO3 loading (0.033 mmol NaHCO3/g body wt for 7 days) induced a significant increase in pendrin expression to 153 ± 11% of control values ( n = 6, P < 0.01) with no change in the fraction of cells expressing pendrin. Immunoelectron microscopy revealed no major changes in the subcellular distribution, with abundant labeling in both the apical plasma membrane and the intracellular vesicles in all conditions. These results indicate that changes in pendrin protein expression play a key role in the well-established regulation of HCO[Formula: see text] secretion in the CCD in response to chronic changes in acid-base balance and suggest that regulation of pendrin expression may be clinically important in the correction of acid-base disturbances.

Decrease in N-ethylmaleimide-sensitive ATPase activity in collecting duct by metabolic alkalosis

1990 ◽  
Vol 68 (8) ◽  
pp. 1119-1123 ◽  
Author(s):  
Lal C. Garg ◽  
Neelam Narang
Keyword(s):  
Atpase Activity ◽  
Metabolic Alkalosis ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Control Group ◽  
Cortical Collecting Duct ◽  
Acid Base Balance ◽  
Acid Base ◽  
Significant Difference ◽  
Base Balance

Changes in systemic acid – base balance are known to influence acidification in the collecting duct. The H+ secretion in the collecting duct has been shown to be an electrogenic process and it has been suggested that an H-ATPase sensitive to inhibition by N-ethylmaleimide (NEM) is responsible for H+ secretion. This study was designed to determine the effect of metabolic alkalosis on NEM-sensitive ATPase activity in the microdissected segments of the distal nephron. Metabolic alkalosis was produced by giving NaHCO3 to normal rats for 7 days. The plasma total CO2 concentration in the experimental group was 31.5 ± 1.8 mM compared with 23.4 ± 1.0 mM in the control group. NEM-sensitive ATPase activity was significantly lower in the cortical collecting duct and in the outer and inner medullary collecting ducts of alkali-loaded rats than those of control rats. There was no significant difference in the enzyme activity between the two groups of animals in the other nephron segments examined. Our results suggest that NEM-sensitive H-APTase activity in all three segments of the collecting duct is modulated by the acid – base status of the animal.Key words: collecting duct, H-ATPase, electrogenic H-pump, metabolic alkalosis, rat kidney.

Distribution of mineralocorticoid and glucocorticoid receptor mRNA along the nephron

1993 ◽  
Vol 264 (5) ◽  
pp. F781-F791 ◽  
Author(s):  
K. M. Todd-Turla ◽  
J. Schnermann ◽  
G. Fejes-Toth ◽  
A. Naray-Fejes-Toth ◽  
A. Smart ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Proximal Tubule ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Rna Extraction ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Nephron Segment ◽  
Medullary Collecting Duct ◽  
Glucocorticoid Receptor Mrna

In the present study, a competitive polymerase chain reaction (PCR) technique was used to quantitate the relative levels of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) mRNA in microdissected nephron segments from the rat kidney and of MR mRNA from isolated principal and intercalated collecting duct cells from rabbit. RNA was isolated from cells and isolated tubules, cDNA was synthesized, and receptor cDNA was coamplified by PCR with a competitive control template. beta-Actin PCR products were also obtained from each nephron segment studied, to assess variations in RNA extraction and cDNA synthesis. MR mRNA, as determined by this competitive PCR technique, was 10-fold more abundant in cortical collecting duct (CCD), outer medullary collecting duct, and inner medullary collecting duct segments than in the proximal tubule and thick ascending limb segments (P < 0.05). Both principal and beta-intercalated cells of the CCD contained detectable levels of MR mRNA, although the levels in the principal cells were threefold higher (P < 0.01). GR mRNA was twofold more abundant in glomeruli, proximal tubule, and thick ascending limb segments than in the collecting duct segments (P < 0.05). In general, the distribution pattern of MR and GR mRNA is consistent with the distribution of adrenal corticosteroid function along the nephron.

The calcineurin inhibitor FK506 (tacrolimus) is associated with transient metabolic acidosis and altered expression of renal acid-base transport proteins

2009 ◽  
Vol 297 (2) ◽  
pp. F499-F509 ◽  
Author(s):  
Nilufar Mohebbi ◽  
Marija Mihailova ◽  
Carsten A. Wagner
Keyword(s):  
Metabolic Acidosis ◽  
Collecting Duct ◽  
Transport Proteins ◽  
Protein Abundance ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Urine Ph ◽  
Altered Expression ◽  
Connecting Tubule ◽  
Baseline Conditions

Calcineurin inhibitors like FK506 (tacrolimus) are routinely used for immunosuppression following transplantation. Its use is limited by many side effects, including renal tubular acidosis (RTA), mainly of the distal type. In this study, rats were treated with FK506 and at baseline (after 9 days) systemic acid-base status was similar to that in control animals. However, FK506-treated rats given NH4Cl in the drinking water for 2 days developed a more severe metabolic acidosis than control animals. Urine pH was more alkaline, but net acid excretion was normal. After 7 days of acid load, all differences related to acid-base homeostasis were equalized in both groups. Protein abundance of type IIa Na-Pi cotransporter, type 3 Na+/H+ exchanger, and electrogenic Na+-bicarbonate cotransporter, and both a4 and B2 subunits of the vacuolar H+-ATPase were reduced under baseline conditions, while induction of metabolic acidosis enhanced protein abundance of these transporters in FK506-treated animals. In parallel, protein expression of AE1 was reduced at baseline and increased together with pendrin during NH4Cl loading in FK506 rats. Protein abundance of the Na+-bicarbonate cotransporter NBCn1 was reduced under baseline conditions but remained downregulated during metabolic acidosis. Morphological analysis revealed an increase in the relative number of non-type A intercalated cells in the connecting tubule and cortical collecting duct at the expense of principal cells. Additionally, subcellular distribution of the a4 subunit of the vacuolar H+-ATPase was affected by FK506 with less luminal localization in the connecting tubule and outer medullary collecting duct. These data suggest that FK506 impacts on several major acid-base transport proteins in the kidney, and its use is associated with transient metabolic acidosis and altered expression of key renal acid-base transport proteins.

scholarly journals Intercalated cell-specific Rh B glycoprotein deletion diminishes renal ammonia excretion response to hypokalemia

2013 ◽  
Vol 304 (4) ◽  
pp. F422-F431 ◽  
Author(s):  
Jesse M. Bishop ◽  
Hyun-Wook Lee ◽  
Mary E. Handlogten ◽  
Ki-Hwan Han ◽  
Jill W. Verlander ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Collecting Duct ◽  
Ammonia Excretion ◽  
Ammonia Concentration ◽  
Intercalated Cells ◽  
Cortical Collecting Duct ◽  
Intercalated Cell ◽  
Transporter Family ◽  
Total Ammonia ◽  
Normal Increase

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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