Ouabain-sensitive and -insensitive K-ATPases in rat nephron: effect of K depletion

1995 ◽  
Vol 268 (6) ◽  
pp. F1141-F1147 ◽  
Author(s):  
M. Younes-Ibrahim ◽  
C. Barlet-Bas ◽  
B. Buffin-Meyer ◽  
L. Cheval ◽  
R. Rajerison ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Collecting Duct ◽  
Proximal Tubules ◽  
Lower Sensitivity ◽  
Mammalian Kidney ◽  
Henle's Loop ◽  
Collecting Ducts ◽  
Straight Tubules ◽  
K Depletion ◽  
Higher Sensitivity

Because a ouabain-sensitive H-K-adenosinetriphosphatase (H-K-ATPase) has been identified recently in the amphibian bladder, we evaluated whether such an ATPase might exist also in the mammalian kidney, along with the ouabain-insensitive H-K-ATPase previously described in the collecting duct. For this purpose, we searched for an Na-independent, K-stimulated, ouabain- and Sch-28080-inhibitable ATPase activity in single segments of rat nephron. Ouabain-sensitive K-stimulated ATPase activity was detected in the absence of Na+ in rat proximal convoluted and straight tubules and in medullary and cortical thick ascending limbs of Henle's loop but not in collecting ducts. This K-ATPase differs from Na-K-ATPase by 1) its absence of requirement for Na, 2) its sensitivity to Sch-28080, 3) its higher sensitivity to ouabain, and 4) its absence in the collecting duct. It differs from the collecting duct H-K-ATPase by 1) its distribution along the nephron, 2) its sensitivity to ouabain, and 3) its lower sensitivity to Sch-28080. Furthermore, in rats fed a K-depleted diet for 2 wk, ouabain-sensitive K-ATPase activity was markedly reduced in both proximal tubules and thick ascending limbs, whereas collecting duct H-K-ATPase was upregulated.

K depletion modifies the properties of Sch-28080-sensitive K-ATPase in rat collecting duct

1997 ◽  
Vol 272 (1) ◽  
pp. F124-F131 ◽  
Author(s):  
B. Buffin-Meyer ◽  
M. Younes-Ibrahim ◽  
C. Barlet-Bas ◽  
L. Cheval ◽  
S. Marsy ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Lower Sensitivity ◽  
Kinetic Properties ◽  
Type I ◽  
Type Ii ◽  
Distribution Profile ◽  
Adenosine Triphosphatases ◽  
Collecting Ducts ◽  
K Depletion

Two distinct Sch-28080-sensitive K-adenosine triphosphatases (K-ATPases) were previously described in the rat nephron: a ouabain-resistant K-ATPase (type I) present in collecting ducts (CD) and a ouabain-sensitive from (type II) located in proximal tubules (PT) and thick ascending limbs (TAL). In K-depleted rats, K-ATPase activity is increased in CD, whereas it is reduced in PT and TAL. Because expression of colonic H-K-ATPase is restricted to the CD of K-depleted rats, we hypothesized that K-ATPase from the CD of K-depleted rats might be different from types I and II. Indeed, type III K-ATPase displays higher sensitivities to ouabain and to Sch-28080 than type II, a lower sensitivity to Sch-28080 than type I, and, conversely to types I and II, it can be stimulated by Na+. Pharmacological differences between types II and III K-ATPases were confirmed by [3H]ouabain binding experiments. Thus the rat kidney expresses three K-ATPases that differ by their pharmacological and kinetic properties, their distribution profile along the nephron and their behavior during K depletion.

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

2000 ◽  
Vol 279 (1) ◽  
pp. F195-F202 ◽  
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.

Carbonic anhydrase XII mRNA encodes a hydratase that is differentially expressed along the rabbit nephron

2003 ◽  
Vol 284 (2) ◽  
pp. F399-F410 ◽  
Author(s):  
George J. Schwartz ◽  
Anne M. Kittelberger ◽  
Richard H. Watkins ◽  
Michael A. O'Reilly
Keyword(s):  
Carbonic Anhydrase ◽  
Transmembrane Protein ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Thick Ascending Limb ◽  
Basolateral Membranes ◽  
Collecting Ducts ◽  
Straight Tubules ◽  
Hydratase Activity

Membrane-bound carbonic anhydrase (CA) facilitates acidification in the kidney. Although most hydratase activity is considered due to CA IV, some in the basolateral membranes could be attributed to CA XII. Indeed, CA IV is glycosylphosphatidylinositol anchored, connoting apical polarization, but CA IV immunoreactivity has been detected on basolateral membranes of proximal tubules. Herein, we determined whether CA XII mRNA was expressed in acidifying segments of the rabbit nephron. The open reading frame of CA XII was sequenced from a rabbit kidney cortex cDNA library; it was 83% identical to human CA XII and coded for a 355-amino acid single-pass transmembrane protein. Northern blot analysis revealed an abundant 4.5-kb message in kidney cortex, medulla, and colon. By in situ hybridization, CA XII mRNA was expressed by proximal convoluted and straight tubules, cortical and medullary collecting ducts, and papillary epithelium. By RT-PCR, CA XII mRNA was abundantly expressed in cortical and medullary collecting ducts and thick ascending limb of Henle's loop; it was also expressed in proximal convoluted and straight tubules but not in glomeruli or S3 segments. FLAG-CA XII of ∼40 kDa expressed in Escherichia coli showed hydratase activity that was inhibited by 0.1 mM acetazolamide. Unlike CA IV, expressed CA XII activity was inhibited by 1% SDS, suggesting insufficient disulfide linkages to stabilize the molecule. Western blotting of expressed CA XII with two anti-rabbit CA IV peptide antibodies showed no cross-reactivity. Our findings indicate that CA XII may contribute to the membrane CA activity of proximal tubules and collecting ducts.

scholarly journals Intracellular Na+ Controls Cell Surface Expression of Na,K-ATPase via a cAMP-independent PKA Pathway in Mammalian Kidney Collecting Duct Cells

2003 ◽  
Vol 14 (7) ◽  
pp. 2677-2688 ◽  
Author(s):  
Manlio Vinciguerra ◽  
Georges Deschênes ◽  
Udo Hasler ◽  
David Mordasini ◽  
Martine Rousselot ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Cell Surface ◽  
Atpase Activity ◽  
Collecting Duct ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Cortical Collecting Duct ◽  
Mammalian Kidney ◽  
Duct Cells ◽  
Collecting Duct Cells

In the mammalian kidney the fine control of Na+ reabsorption takes place in collecting duct principal cells where basolateral Na,K-ATPase provides the driving force for vectorial Na+ transport. In the cortical collecting duct (CCD), a rise in intracellular Na+ concentration ([Na+]i) was shown to increase Na,K-ATPase activity and the number of ouabain binding sites, but the mechanism responsible for this event has not yet been elucidated. A rise in [Na+]i caused by incubation with the Na+ ionophore nystatin, increased Na,K-ATPase activity and cell surface expression to the same extent in isolated rat CCD. In cultured mouse mpkCCDcl4 collecting duct cells, increasing [Na+]i either by cell membrane permeabilization with amphotericin B or nystatin, or by incubating cells in a K+-free medium, also increased Na,K-ATPase cell surface expression. The [Na+]i-dependent increase in Na,K-ATPase cell-surface expression was prevented by PKA inhibitors H89 and PKI. Moreover, the effects of [Na+]i and cAMP were not additive. However, [Na+]i-dependent activation of PKA was not associated with an increase in cellular cAMP but was prevented by inhibiting the proteasome. These findings suggest that Na,K-ATPase may be recruited to the cell membrane following an increase in [Na+]i through cAMP-independent PKA activation that is itself dependent on proteasomal activity.

Expression of calcineurin activity and alpha-subunit isoforms in specific segments of the rat nephron

1995 ◽  
Vol 269 (4) ◽  
pp. F558-F563 ◽  
Author(s):  
J. A. Tumlin ◽  
J. T. Someren ◽  
C. E. Swanson ◽  
J. P. Lea
Keyword(s):  
Atpase Activity ◽  
Proximal Tubule ◽  
Proximal Tubules ◽  
Alpha Subunit ◽  
Specific Substrate ◽  
Fk 506 ◽  
Collecting Ducts ◽  
Subunit Isoforms ◽  
Proximal Tubule Segments ◽  
Calcineurin Activity

Calcineurin activity and alpha-subunit expression were studied in microdissected proximal tubules (S2), medullary thick ascending limbs (MTAL), cortical collecting ducts (CCD), connecting tubules (CNT), and outer medullary collecting ducts (OMCD). We have shown that cyclosporin A (CsA) and FK-506 inhibit sodium-potassium-adenosinetriphosphatase (Na-K-ATPase) activity in CCD, OMCD, and MTAL but did not uncover the mechanism for resistance of proximal tubule segments to these drugs. Because cells expressing high calcineurin activity are relatively resistant to the biological effects of CsA and FK-506, we hypothesized that the resistance of proximal tubules may be linked to increased calcineurin expression. Consequently, we measured calcineurin activity in microdissected tubules using a calcineurin-specific substrate. Calcineurin activity in S2 proximal tubule segments was 10-fold higher than in CCD, CNT, OMCD, or MTAL. FK-506 (6.0 ng/ml) inhibited calcineurin activity in CCD, CNT, and MTAL but not S2; 250 ng/ml FK-506 inhibited S2 calcineurin activity by 50%. Likewise, high concentrations of CsA (25 micrograms/ml) and FK-506 (250 ng/ml) inhibited S2 Na-K-ATPase activity by 77 and 73%, respectively. To investigate whether the resistance of S2 segments might be due to differential expression of calcineurin alpha-subunit isoforms, we determined the isoform expression by Western blot analysis using isoform-specific antibodies against the alpha 1-, alpha 2-, and alpha 3-isoforms. We found that alpha 1 expression in S2 was significantly greater than in the CCD and MTAL, whereas alpha 2 expression in the S2 was significantly less than in CCD and MTAL. No alpha 3 was detected in any nephron segment tested.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Decreased Sensitivity of Distal Nephron and Collecting Duct to Parathyroid Hormone in Pseudohypoparathyroidism Type I

2001 ◽  
Vol 12 (9) ◽  
pp. 1965-1970
Author(s):  
MASAKO GOTO ◽  
KAZUTOSHI MIZUNASHI ◽  
NORIKO KIMURA ◽  
YOHTARO FURUKAWA
Keyword(s):  
Parathyroid Hormone ◽  
Cathepsin D ◽  
Collecting Duct ◽  
Distal Tubule ◽  
Type I ◽  
Distal Nephron ◽  
Henle's Loop ◽  
Collecting Ducts ◽  
Calcium Resorption ◽  
Convoluted Tubules

Abstract. Parathyroid hormone (PTH) transiently increases urinary excretion of the lysosomal enzyme, N-acetyl-β-D-glucosaminidase, which is distributed mainly in proximal tubules. The response is reduced in pseudohypoparathyroidism (PHP) type I, which is characterized by target-organ resistance to PTH. Evidenced by normal calcium resorption, distal tubule sensitivity to PTH has been believed to be normal in this disorder. This hypothesis was tested through a search for another marker of distal nephron sensitivity to PTH. In the human kidney, cathepsin D was expressed predominantly in distal segments of the nephron, cortical and medullary thick ascending limbs of Henle's loop, distal convoluted tubules, and connecting tubules and in cortical collecting ducts and medullary collecting ducts. PTH infusion transiently increased cathepsin D excretion in normal subjects. The cathepsin D response to PTH was reduced in the patients with PHP type I. The decrease in cathepsin D response in PHP type I indicates a resistance to PTH in the distal nephron (cortical thick ascending limbs of Henle's loop, distal convoluted tubules, and connecting tubules) and cortical collecting ducts. These observations suggest that the preservation of renal tubular sensitivity to PTH in this disorder may be confined to PTH-dependent calcium resorption in distal tubules.

Electrophysiological study of renal papilla of golden hamsters

1964 ◽  
Vol 206 (4) ◽  
pp. 694-700 ◽  
Author(s):  
Erich E. Windhager
Keyword(s):  
Collecting Duct ◽  
Electrophysiological Study ◽  
Electrical Potential ◽  
Cross Sectional ◽  
Henle's Loop ◽  
Collecting Ducts ◽  
Series Of Experiments ◽  
Collecting Duct Epithelium ◽  
Terminal Nephron ◽  
Microelectrode Techniques

Electrical potential differences across the tubular epithelium of loops of Henle and of collecting ducts were measured by microelectrode techniques. In a separate series of experiments concentrations of Na22 and of chloride were estimated in fluid collected from Henle's loop and in vas rectum plasma at corresponding cross-sectional levels of the papilla. The lumen of thin ascending limbs of Henle's loop was found electrically more negative (mean: –11 mv), with respect to interstitial fluid, than the lumen of thin descending limbs (–3 mv). No chemical driving force for reabsorptive net diffusion of sodium chloride was found across the wall of thin limbs of Henle's loop. The magnitude of the electrical potential differences observed across the collecting duct epithelium (mean: –14 mv) indicates the existence of active transport of both sodium and chloride across this part of the terminal nephron.

Regulation of colonic H-K-ATPase in large intestine and kidney by dietary Na depletion and dietary K depletion

1997 ◽  
Vol 272 (2) ◽  
pp. C685-C696 ◽  
Author(s):  
P. Sangan ◽  
V. M. Rajendran ◽  
A. S. Mann ◽  
M. Kashgarian ◽  
H. J. Binder
Keyword(s):  
Atpase Activity ◽  
Large Intestine ◽  
Collecting Duct ◽  
Cdna Probe ◽  
Distal Colon ◽  
Specific Protein ◽  
Proximal Colon ◽  
Rat Colon ◽  
Na Depletion ◽  
K Depletion

Active K absorption in the rat distal colon is energized by an apical membrane H-K-ATPase, whereas K absorption in the distal collecting duct is generally believed to be modulated by a related renal H-K-ATPase. Experiments were performed to establish the mechanism(s) by which dietary Na depletion (with resulting elevated aldosterone levels) and K depletion stimulate K absorption. A colonic H-K-ATPase-specific cDNA probe and a polyclonal antibody were utilized to measure mRNA (Northern blot analyses) and protein (Western blot and immunofluorescence studies) abundance in the distal and proximal colon and renal collecting ducts and cortex of dietary Na- and K-depleted rats. Dietary Na depletion, but not K depletion, upregulated H-K-ATPase-specific mRNA and protein expression in the distal and proximal colon; Na depletion also stimulated H-K-ATPase activity in the distal colon. In contrast to the distal colon, H-K-ATPase-specific protein level in the outer medulla was enhanced by dietary K depletion, but not by Na depletion. This study establishes that 1) dietary Na depletion stimulates colonic H-K-ATPase activity most likely by a transcriptional process and 2) the regulation of colonic H-K-ATPase expression by dietary Na depletion and dietary K depletion is not identical in the large intestine and differs in the kidney from the colon, suggesting the presence of two (or more) H-K-ATPase isoforms in the rat colon.

Lactate production in isolated segments of the rat nephron

1985 ◽  
Vol 248 (4) ◽  
pp. F522-F526 ◽  
Author(s):  
S. Bagnasco ◽  
D. Good ◽  
R. Balaban ◽  
M. Burg
Keyword(s):  
Collecting Duct ◽  
Lactate Production ◽  
Proximal Tubules ◽  
Antimycin A ◽  
Anaerobic Glycolysis ◽  
Metabolic Substrate ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Convoluted Tubules

Lactate production was measured directly in individual segments of the rat nephron. Tubules were dissected and then incubated in vitro with glucose as the only metabolic substrate. Each segment was incubated with and without antimycin A, an inhibitor of oxidative metabolism. Proximal tubules produced no lactate with or without antimycin A. The distal segments all produced lactate. The rate of lactate production without antimycin A ranged from 0.4 to 0.9 pmol X min-1 X mm-1 in all distal segments except one, the inner medullary collecting duct, which produced lactate at the significantly higher rate of 2.8 pmol X min-1 X mm-1. Antimycin A increased lactate production significantly in all of the distal segments. The increase was largest in medullary thick ascending limbs (1,400%) and cortical (798%) and outer medullary collecting ducts (357%). Increments were smaller in cortical thick ascending limbs (98%) and distal convoluted tubules (98%) and least in the inner medullary collecting ducts (28%). We conclude that lactate production occurs only in distal segments of the nephron and that under anoxic conditions significant amounts of ATP are produced by anaerobic glycolysis in these segments.

Water channel expression in human ADPKD kidneys

1995 ◽  
Vol 268 (3) ◽  
pp. F398-F398 ◽  
Author(s):  
D. R. Bachinsky ◽  
I. Sabolic ◽  
D. S. Emmanouel ◽  
D. M. Jefferson ◽  
F. A. Carone ◽  
...  
Keyword(s):  
Gene Family ◽  
Western Blotting ◽  
Collecting Duct ◽  
Water Channel ◽  
Human Kidney ◽  
Proximal Tubules ◽  
Normal Human Kidney ◽  
Collecting Ducts ◽  
Normal Human ◽  
Autosomal Dominant Polycystic Kidney

Cyst enlargement in autosomal dominant polycystic kidney disease (ADPKD) results in part from the transport of solute and fluid into the lumen of the cyst. In proximal tubules and thin descending limbs of normal kidneys, the high transepithelial water permeability of these segments is due to the presence of the water channel protein, aquaporin-CHIP (AQP-CHIP, i.e., AQP-1). The collecting ducts of normal kidneys express another member of this gene family, the aquaporin collecting duct (AQP-CD, i.e., AQP-2). The expression and distribution of these two members of the aquaporin gene family were examined in ADPKD and normal human kidneys. In both tissues, Western blotting with the anti-AQP-CHIP antibody revealed a major 28-kDa band. By immunofluorescence, AQP-CHIP was present in proximal tubules and thin descending limbs of Henle of both normal and ADPKD kidneys. In the latter, AQP-CHIP was detected in the epithelia lining 71% of cysts. Many cysts were positive for the proximal tubule marker gp330 (44%). Some cysts expressing AQP-CHIP did not stain for gp330, suggesting a descending thin limb origin, and a few cysts were negative for both markers. In normal human kidney, Western blotting with the anti-AQP-CD antibody revealed a band at 28 kDa. AQP-CD was localized to collecting ducts and did not show colocalization with gp330 in normal human kidney. In ADPKD kidney, AQP-CD was expressed by only 8% of cysts. In summary, water channels, primarily AQP-CHIP, are expressed in epithelial cells lining cysts in approximately 80% of cysts in ADPKD kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

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