Immunoelectron microscopic localization of NBC3 sodium-bicarbonate cotransporter in rat kidney

2000 ◽  
Vol 278 (2) ◽  
pp. F327-F336 ◽  
Author(s):  
Tae-Hwan Kwon ◽  
Alexander Pushkin ◽  
Natalia Abuladze ◽  
Søren Nielsen ◽  
Ira Kurtz

In the present study, we produced a rabbit peptide-derived polyclonal COOH-terminal antibody that selectively recognizes NBC3, to determine the cellular and subcellular localization of NBC3 in rat kidney, using immunocytochemistry and immunoelectron microscopy. Immunocytochemistry with cryostat sections and semithin cryosections revealed specific staining of intercalated cells (ICs) in the connecting tubule and in cortical, outer medullary, and initial inner medullary collecting ducts. In the connecting tubule and in the cortical and medullary collecting duct, the labeling was associated with both type A and type B ICs. In type A ICs, labeling was confined to the apical and subapical domains, whereas in type B ICs, basal domains were exclusively labeled. In contrast, collecting duct principal cells were consistently unlabeled, and this was confirmed using anti-aquaporin-2 antibodies, which labeled principal cells in parallel semithin cryosections. Glomeruli, proximal tubules, descending thin limbs, ascending thin limbs, thick ascending limbs, distal convoluted tubules, and vascular structures were unlabeled. For immunoelectron microscopy, tissue samples were freeze-substituted, and immunolabeling was performed on ultrathin Lowicryl HM20 sections. Immunoelectron microscopy demonstrated that NBC3 labeling was very abundant in the apical plasma membrane, in intracellular vesicles, and in tubulocisternal profiles in the subapical domains of type A ICs. In type B ICs, NBC3 was mainly present in the basolateral plasma membrane. Immunolabeling controls using peptide-absorbed antibody were consistently negative. In conclusion, NBC3 is highly abundant in the apical plasma membrane of type A ICs and in the basolateral plasma membrane of type B ICs. This suggests that NBC3 plays an important role in modulating bicarbonate transport in the connecting tubule and collecting duct.

1992 ◽  
Vol 262 (2) ◽  
pp. F309-F319 ◽  
Author(s):  
J. W. Verlander ◽  
K. M. Madsen ◽  
J. H. Galla ◽  
R. G. Luke ◽  
C. C. Tisher

We examined the effect of Cl- depletion metabolic alkalosis (CDA) on H(+)-ATPase and band 3 protein localization in intercalated cells (IC) of the rat cortical collecting duct (CCD) and the outer medullary collecting duct (OMCD). After 30 min of peritoneal dialysis against 0.15 M NaHCO3 to produce CDA, or Ringer bicarbonate to serve as controls (CON), both groups were infused intravenously with an 80 mM Cl- solution for 90 min. For CDA vs. CON, physiological parameters were as follows: plasma total CO2, 38.0 +/- 1.1 vs. 27.8 +/- 0.6 meq/l (P less than 0.001); urinary total CO2 excretion, 141 +/- 89 vs. 20 +/- 3 neq.min-1.100 g body wt-1; and urinary Cl- excretion, 20 +/- 10 vs. 486 +/- 144 neq.min-1.100 g body wt-1 (P less than 0.001). H(+)-ATPase was localized in thin sections using a rabbit polyclonal antibody against the 70-kDa subunit of bovine brain H(+)-ATPase. Band 3 protein was localized using a polyclonal antibody against the 43-kDa subunit of the cytoplasmic domain of human erythrocyte band 3 protein. In CON rats, H(+)-ATPase localized along the apical plasma membrane and over the apical cytoplasmic vesicles of type A ICs in the CCD and ICs of the OMCD. H(+)-ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout type B ICs. In CDA rats, H(+)-ATPase was only observed over apical cytoplasmic vesicles in type A ICs and in the majority of OMCD ICs. In type B ICs, H(+)-ATPase staining was intensified along the basal plasma membrane in CDA. Band 3 protein was consistently localized in the basolateral plasma membrane of all type A cells in the CCD and ICs of the OMCD in both CON and CDA. In summary, stimulation of HCO3- secretion in rats caused withdrawal of H(+)-ATPase from the apical plasma membrane and storage in apical cytoplasmic vesicles of ICs of the OMCD and type A ICs of the CCD. H(+)-ATPase appeared to be inserted into the basal plasma membrane of type B ICs. These findings suggest that, during correction of CDA, proton secretion by type A and OMCD ICs is suppressed and proton transport across the basolateral plasma membrane of type B ICs is stimulated.


2002 ◽  
Vol 283 (4) ◽  
pp. F744-F754 ◽  
Author(s):  
Young-Hee Kim ◽  
Tae-Hwan Kwon ◽  
Sebastian Frische ◽  
Jin Kim ◽  
C. Craig Tisher ◽  
...  

Recent studies have demonstrated that a novel anion exchanger, pendrin, is expressed in the apical domain of type B intercalated cells in the mammalian collecting duct. The purpose of this study was 1) to determine the expression and distribution of pendrin along the collecting duct and connecting tubule of mouse and rat kidney and establish whether pendrin is expressed in the non-A-non-B intercalated cells and 2) to determine the intracellular localization of pendrin in the different populations of intercalated cells by immunoelectron microscopy. A peptide-derived affinity-purified antibody was generated that specifically recognized pendrin in immunoblots of rat and mouse kidney. Immunohistochemistry and confocal laser scanning microscopy demonstrated the presence of pendrin in apical domains of all type B intercalated cells in mouse and rat connecting tubule and collecting duct. In addition, strong pendrin immunostaining was observed in non-A-non-B intercalated cells. There was no labeling of type A intercalated cells. Immunoelectron microscopy demonstrated that pendrin was located in the apical plasma membrane and intracellular vesicles of both type B intercalated cells and non-A-non-B cells; the latter was identified by the presence of H+-ATPase in the apical plasma membrane. The results of this study demonstrate that both pendrin and H+-ATPase are expressed in the apical plasma membrane of non-A-non-B intercalated cells, suggesting that these cells are capable of both HCO[Formula: see text] and proton secretion. Furthermore, the presence of pendrin in both the apical plasma membrane and the apical intracellular vesicles of type B and non-A-non-B intercalated cells suggests that HCO[Formula: see text] secretion may be regulated by trafficking of pendrin between the two membrane compartments.


2000 ◽  
Vol 278 (1) ◽  
pp. F29-F42 ◽  
Author(s):  
Birgitte Mønster Christensen ◽  
Marina Zelenina ◽  
Anita Aperia ◽  
Søren Nielsen

Phosphorylation of Ser256, in a PKA consensus site, in AQP2 (p-AQP2) appears to be critically involved in the vasopressin-induced trafficking of AQP2. In the present study, affinity-purified antibodies that selectively recognize AQP2 phosphorylated at Ser256 were developed. These antibodies were used to determine 1) the subcellular localization of p-AQP2 in rat kidney and 2) changes in distribution and/or levels of p-AQP2 in response to [desamino-Cys1,d-Arg8]vasopressin (DDAVP) treatment or V2-receptor blockade. Immunoelectron microscopy revealed that p-AQP2 was localized in both the apical plasma membrane and in intracellular vesicles of collecting duct principal cells. Treatment of rats with V2-receptor antagonist for 30 min resulted in almost complete disappearance of p-AQP2 labeling of the apical plasma membrane with only marginal labeling of intracellular vesicles remaining. Immunoblotting confirmed a marked decrease in p-AQP2 levels. In control Brattleboro rats (BB), lacking vasopressin secretion, p-AQP2 labeling was almost exclusively present in intracellular vesicles. Treatment of BB rats with DDAVP for 2 h induced a 10-fold increase in p-AQP2 labeling of the apical plasma membrane. The overall abundance of p-AQP2, however, was not increased, as determined both by immunoelectron microscopy and immunoblotting. Consistent with this, 2 h of DDAVP treatment of normal rats also resulted in unchanged p-AQP2 levels. Thus the results demonstrate that AQP2 phosphorylated in Ser256 is present in the apical plasma membrane and in intracellular vesicles and that both the intracellular distribution/trafficking, as well as the abundance of p-AQP2, are regulated via V2 receptors by altering phosphorylation and/or dephosphorylation of Ser256in AQP2.


1989 ◽  
Vol 256 (2) ◽  
pp. F366-F369 ◽  
Author(s):  
D. Brown ◽  
E. J. Sorscher ◽  
D. A. Ausiello ◽  
D. J. Benos

Amiloride-sensitive Na+ channels were localized in semithin frozen sections of rat renal medullary collecting ducts, using polyclonal antibodies directed against purified bovine kidney Na+ channel protein. The apical plasma membrane of collecting duct principal cells was heavily stained by indirect immunofluorescence, whereas intercalated cells were negative. Basolateral plasma membranes of both cell types were unstained, as were subapical vesicles in the cytoplasm of these cells. In the thick ascending limb of Henle, some scattered granular fluorescence was seen in the cytoplasm and close to the apical pole of epithelial cells, suggesting the presence of antigenic sites associated with some membrane domains in these cells. No staining was detected in thin limbs of Henle, or in proximal tubules in the outer medulla. These results show that amiloride-sensitive sodium channels are located predominantly on the apical plasma membrane of medullary collecting duct principal cells, the cells that are involved in Na+ homeostasis in this region of the kidney.


1999 ◽  
Vol 10 (1) ◽  
pp. 1-12 ◽  
Author(s):  
JIN KIM ◽  
YOUNG-HEE KIM ◽  
JUNG-HO CHA ◽  
C. CRAIG TISHER ◽  
KIRSTEN M. MADSEN

Abstract. At least two populations of intercalated cells, type A and type B, exist in the connecting tubule (CNT), initial collecting tubule (ICT), and cortical collecting duct (CCD). Type A intercalated cells secrete protons via an apical H+ - ATPase and reabsorb bicarbonate by a band 3-like Cl-/HCO3- exchanger, AE1, located in the basolateral plasma membrane. Type B intercalated cells secrete bicarbonate by an apical Cl-/HCO3- exchanger that is distinct from AE1 and remains to be identified. They express H+ -ATPase in the basolateral plasma membrane and in vesicles throughout the cytoplasm. A third type of intercalated cell with apical H+ -ATPase, but no AE1, has been described in the CNT and CCD of both rat and mouse. The prevalence of the third cell type is not known. The aim of this study was to characterize and quantify intercalated cell subtypes, including the newly described third non A-non B cell, in the CNT, ICT, and CCD of the rat and mouse. A triple immunolabeling procedure was developed in which antibodies to H+ -ATPase and band 3 protein were used to identify subpopulations of intercalated cells, and segment-specific antibodies were used to identify distal tubule and collecting duct segments. In both rat and mouse, intercalated cells constituted approximately 40% of the cells in the CNT, ICT, and CCD. Type A, type B, and non A-non B intercalated cells were observed in all of the three segments, with type A cells being the most prevalent in both species. In the mouse, however, non A-non B cells constituted more than half of the intercalated cells in the CNT, 39% in the ICT, and 22% in the CCD, compared with 14, 7, and 5%, respectively, in the rat. In contrast, type B intercalated cells accounted for only 8 to 16% of the intercalated cells in the three segments in the mouse compared with 26 to 39% in the rat. It is concluded that striking differences exist in the prevalence and distribution of the different types of intercalated cells in the CNT, ICT, and CCD of rat and mouse. In the rat, the non A-non B cells are fairly rare, whereas in the mouse, they constitute a major fraction of the intercalated cells, primarily at the expense of the type B intercalated cells.


2001 ◽  
Vol 280 (6) ◽  
pp. F1093-F1106 ◽  
Author(s):  
Henrik Hager ◽  
Tae-Hwan Kwon ◽  
Anna K. Vinnikova ◽  
Shyama Masilamani ◽  
Heddwen L. Brooks ◽  
...  

Epithelial sodium channel (ENaC) subunit (α, β, and γ) mRNA and protein have been localized to the principal cells of the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD) in rat kidney. However, the subcellular localization of ENaC subunits in the principal cells of these cells is undefined. The cellular and subcellular localization of ENaC subunits in rat kidney was therefore examined. Immunocytochemistry demonstrated the presence of all three subunits in principal cells of the CNT, CCD, OMCD, and IMCD. In cortex and outer medulla, confocal microscopy demonstrated a difference in the subcellular localization of subunits. α-ENaC was localized mainly in a zone in the apical domains, whereas β- and γ-ENaC were found throughout the cytoplasm. Immunoelectron microscopy confirmed the presence of ENaC subunits in both the apical plasma membrane and intracellular vesicles. In contrast to the labeling pattern seen in cortex, α-ENaC labeling in IMCD cells was distributed throughout the cytoplasm. In the urothelium covering pelvis, ureters, and bladder, immunoperoxidase and confocal microscopy revealed differences the presence of all ENaC subunits. As seen in CCD, α-ENaC was present in a narrow zone near the apical plasma membrane, whereas β- and γ-ENaC were dispersed throughout the cytoplasm. In conclusion, all three subunits of ENaC are expressed throughout the collecting duct (CD), including the IMCD as well as in the urothelium. The intracellular vesicular pool in CD principal cells suggests ENaC trafficking as a potential mechanism for the regulation of Na+ reabsorption.


2002 ◽  
Vol 283 (5) ◽  
pp. F1160-F1166 ◽  
Author(s):  
Stephen Shaw ◽  
David Marples

AVP increases the osmotic water permeability of renal collecting ducts by inducing the translocation of specific aquaporin-2 (AQP2) water channels from cytoplasmic vesicles to the apical plasma membrane of the principal cells. Here, we report a novel inner medullary tubule suspension for the study of this phenomenon that overcomes some of the drawbacks faced by present techniques; both primary cultures of inner medullary collecting duct cells and cell lines expressing AQP2 show aberrant trafficking and/or signaling pathways. The tubule suspensions were prepared by proteolytic digestion of inner medullas dissected from freshly isolated rat kidneys. After drug treatment, cellular distribution of AQP2 was determined by membrane fractionation and Western blotting or by immunocytochemistry. Treatment of suspensions with 1 nM AVP caused redistribution of AQP2 to the apical plasma membrane of the principal cells, a process inhibited by microtubule disruption or PKA inhibition. We conclude that this method provides a valuable new approach to the study of the cellular mechanisms involved in the response of the collecting duct to AVP.


1996 ◽  
Vol 7 (12) ◽  
pp. 2533-2542 ◽  
Author(s):  
S M Ginns ◽  
M A Knepper ◽  
C A Ecelbarger ◽  
J Terris ◽  
X He ◽  
...  

Two bumetanide-sensitive ion cotransporters that carry Na+, K+, and Cl- in a coupled fashion have been identified. One type, the "absorptive" isoform, carries these ions across the apical plasma membrane of the thick ascending limb of Henle's loop. Another isoform, the "secretory" cotransporter, has been identified in a number of epithelial tissues by physiological means, but its sites of expression in the kidney have not been fully characterized. Complementary DNA believed to code for the secretory isoform (called "BSC2" or "NKCC1") have recently been cloned. This study used a specific affinity-purified antipeptide antibody to this protein for immunolocalization in the rat kidney. Immunoblot studies using this antibody show abundant immunoreactivity against bands of 140-190 and 120 kd in the parotid gland, colon, and stomach, sites where the secretory form of the cotransporter has been identified by physiological techniques. This distribution supports the hypothesis that this isoform represents the secretory form of the cotransporter. Studies in the kidney revealed that the same bands are associated with membrane fractions chiefly in the outer medulla. Immunolocalizations show that immunoreactivity is selectively and intensely localized to the basolateral plasma membrane of a subfraction of outer medullary collecting duct cells. An independently produced monoclonal antibody (T4) specific for Na-K-Cl cotransporter displays the same localization. Dual localizations of cotransporter antibody with respect to antibody specific for principal cells (aquaporin-2) and intercalated cells (band 3 and H(+)-ATPase) show that cotransporter immunoreactivity is localized to alpha-intercalated cells of the outer medullary collecting duct in the rat. This distinctive localization suggests that the secretory form of the cotransporter may play a role in renal NH4+ and/or acid secretion by this cell type.


2003 ◽  
Vol 284 (4) ◽  
pp. F701-F717 ◽  
Author(s):  
Birgitte Mønster Christensen ◽  
Weidong Wang ◽  
Jørgen Frøkiær ◽  
Søren Nielsen

The purpose of the present study was to examine whether there is axial heterogeneity in the basolateral plasma membrane (BLM) localization of AQP2 and whether altered vasopressin action or medullary tonicity affects the BLM localization of AQP2. Immunocytochemistry and immunoelectron microscopy revealed AQP2 labeling of the BLM in connecting tubule (CNT) cells and inner medullary collecting duct (IMCD) principal cells in normal rats and vasopressin-deficient Brattleboro rats. In contrast there was little basolateral AQP2 labeling in cortical (CCD) and outer medullary collecting duct principal cells. Short-term desamino-Cys1, D-Arg8 vasopressin (dDAVP) treatment (2 h) of Brattleboro rats caused no increase in AQP2 labeling of the BLM. In contrast, long-term dDAVP treatment (6 days) of Brattleboro rats caused an increased BLM labeling in CNT, CCD, and IMCD. Treatment of normal rats with V2-receptor antagonist for 60 min caused retrieval of AQP2 from the apical plasma membrane. Moreover, AQP2 labeling of the BLM was unchanged in CNT and IMCD but increased in CCD. In conclusion, there is an axial heterogeneity in the subcellular localization of AQP2 with prominent AQP2 labeling of the BLM in CNT and IMCD. There was no increase in AQP2 labeling of the BLM in response to short-term dDAVP. Moreover, acute V2-receptor antagonist treatment did not cause retrieval of AQP2 from the BLM. In contrast, long-term dDAVP treatment caused a major increase in AQP2 expression in the BLM in CCD.


2000 ◽  
Vol 11 (12) ◽  
pp. 2179-2189
Author(s):  
ARVID B. MAUNSBACH ◽  
HENRIK VORUM ◽  
TAE-HWAN KWON ◽  
SØREN NIELSEN ◽  
BRIAN SIMONSEN ◽  
...  

Abstract. Immunofluorescence analysis has revealed that electrogenic Na+/HCO3- (NBC1) is expressed in the proximal tubule of rat kidney and in the proximal and distal tubules of the salamander Ambystoma tigrinum kidney. The present study was undertaken to define the detailed subcellular localization of the NBC1 in rat and Ambystoma kidney using high-resolution immunoelectron microscopy. For this purpose, two rabbit polyclonal antibodies raised against amino acids 928 to 1035 and amino acids 1021 to 1035 of the C-terminus of rat kidney (rkNBC1) were developed. The affinity-purified antibodies revealed a strong band of approximately 140 kD in immunoblots of membranes from rat kidney cortex but no signal in membranes isolated from outer and inner medulla. Deglycosylation reduced the apparent molecular weight to approximately 120 kD, corresponding to the predicted molecular weight. A similar but weaker band was also present in membranes isolated from the lateral part of Ambystoma kidney. In rat kidney, immunohistochemistry confirmed the presence of rkNBC1 in convoluted segments of the proximal tubules. In ultrathin cryosections or Lowicryl HM20 sections from rat kidney cortex, distinct immunogold labeling was associated with the basolateral plasma membrane of segments S1 and S2 of proximal tubules, whereas in S3 no labeling was observed. The labeling density was similar at the basal and lateral plasma membrane and was specifically associated with the inner surface of the membrane consistent with the internal position of the C-terminus of the transporter. In contrast, rkNBC1 was absent from the apical plasma membrane and not observed in intracellular vesicles, including those closely associated with basolateral plasma membrane. In Ambystoma kidney, a weak labeling was present in the basolateral membrane of the proximal tubule and stronger labeling was observed in the late distal segment. The results demonstrate that rkNBC1 is expressed only in segment S1 and segment S2 of rat proximal tubule as well as Ambystoma proximal and late distal tubule and that rkNBC1 is present in both basal and lateral plasma membranes and absent in intracellular vesicles of the apical plasma membrane.


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