scholarly journals Cloning, renal distribution, and regulation of the rat Na+- HCO 3 − cotransporter

1998 ◽  
Vol 274 (6) ◽  
pp. F1119-F1126 ◽  
Author(s):  
Charles E. Burnham ◽  
Michael Flagella ◽  
Zhaohui Wang ◽  
Hassane Amlal ◽  
Gary E. Shull ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Rat Kidney ◽  
Human Kidney ◽  
Cloning And Expression ◽  
Thick Ascending Limb ◽  
Mrna Levels ◽  
Reading Frame ◽  
Medullary Thick Ascending Limb ◽  
Nephron Segment

We recently reported the cloning and expression of a human kidney Na+-[Formula: see text]cotransporter (NBC-1) (C. E. Burnham, H. Amlal, Z. Wang, G. E. Shull, and M. Soleimani. J. Biol. Chem. 272: 19111–19114, 1997). To expedite in vivo experimentation, we now report the cDNA sequence of rat kidney NBC-1. In addition, we describe both the organ and nephron segment distributions and the regulation of NBC-1 mRNA under three models of pH stress: chloride-depletion alkalosis (CDA), metabolic acidosis, and bicarbonate loading. Rat NBC-1 cDNA encodes an open reading frame of 1,035 amino acids, with 96 and 87% identity to human and salamander NBC-1, respectively. Rat NBC-1 mRNA is expressed at high levels in kidney and brain, with lower levels in colon, stomach, and heart. None appears in liver. In the kidney, NBC-1 is expressed mainly in the proximal tubule, with traces found in medullary thick ascending limb and papilla. [Formula: see text] loading decreased NBC-1 mRNA levels, which were unchanged either by metabolic acidosis or by CDA.

Regional and segmental localization of AE2 anion exchanger mRNA and protein in rat kidney

1995 ◽  
Vol 269 (4) ◽  
pp. F461-F468 ◽  
Author(s):  
F. C. Brosius ◽  
K. Nguyen ◽  
A. K. Stuart-Tilley ◽  
C. Haller ◽  
J. P. Briggs ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Chloride Concentration ◽  
Transepithelial Transport ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Base Exchange ◽  
Medullary Thick Ascending Limb ◽  
Nephron Segment ◽  
Medullary Collecting Duct

Chloride/base exchange activity has been detected in every mammalian nephron segment in which it has been sought. However, in contrast to the Cl-/HCO3- exchanger AE1 in type A intercalated cells, localization of AE2 within the kidney has not been reported. We therefore studied AE2 expression in rat kidney. AE2 mRNA was present in cortex, outer medulla, and inner medulla. Semiquantitative polymerase chain reaction of cDNA from microdissected tubules revealed AE2 cDNA levels as follows [copies of cDNA derived per mm tubule (+/- SE)]: proximal convoluted tubule, 688 +/- 161; proximal straight tubule, 652 +/- 189; medullary thick ascending limb, 1,378 +/- 226; cortical thick ascending limb, 741 +/- 24; cortical collecting duct, 909 +/- 71; and outer medullary collecting duct, 579 +/- 132. AE2 cDNA was also amplified in thin limbs and in inner medullary collecting duct. AE2 polypeptide was detected in all kidney regions. AE2 mRNA and protein were also detected in several renal cell lines. The data are compatible with the postulated roles of AE2 in maintenance of intracellular pH and chloride concentration and with its possible participation in transepithelial transport.

scholarly journals Kidney outer medulla mitochondria are more efficient compared with cortex mitochondria as a strategy to sustain ATP production in a suboptimal environment

2018 ◽  
Vol 315 (3) ◽  
pp. F677-F681 ◽  
Author(s):  
Tomas A. Schiffer ◽  
Håkan Gustafsson ◽  
Fredrik Palm
Keyword(s):  
Oxygen Affinity ◽  
Kidney Cortex ◽  
Thick Ascending Limb ◽  
Kidney Medulla ◽  
Atp Production ◽  
Medullary Thick Ascending Limb ◽  
Functional Problem ◽  
Nephron Segment ◽  
Regional Renal Blood Flow

The kidneys receive ~25% of cardiac output, which is a prerequisite to maintain sufficient glomerular filtration rate. However, both intrarenal regional renal blood flow and tissue oxygen levels are heterogeneous with decreasing levels in the inner part of the medulla. These differences, in combination with the heterogeneous metabolic activity of the different nephron segment located in the different parts of the kidney, may constitute a functional problem when challenged. The proximal tubule and the medullary thick ascending limb of Henle are considered to have the highest metabolic rate, which is related to the high mitochondria content needed to sustain sufficient ATP production from oxidative phosphorylation to support high electrolyte transport activity in these nephron segments. Interestingly, the cells located in kidney medulla function at the verge of hypoxia, and the mitochondria may have adapted to the surrounding environment. However, little is known about intrarenal differences in mitochondria function. We therefore investigated functional differences between mitochondria isolated from kidney cortex and medulla of healthy normoglycemic rats by using high-resolution respirometry. The results demonstrate that medullary mitochondria had a higher degree of coupling, are more efficient, and have higher oxygen affinity, which would make them more suitable to function in an environment with limited oxygen supply. Furthermore, these results support the hypothesis that mitochondria of medullary cells have adapted to the normal hypoxic in vivo situation as a strategy of sustaining ATP production in a suboptimal environment.

Effect of metabolic acidosis and alkalosis on NEM-sensitive ATPase in rat nephron segments

1992 ◽  
Vol 262 (4) ◽  
pp. F583-F590 ◽  
Author(s):  
C. Khadouri ◽  
S. Marsy ◽  
C. Barlet-Bas ◽  
L. Cheval ◽  
A. Doucet
Keyword(s):  
Metabolic Acidosis ◽  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Nephron Segments ◽  
Medullary Thick Ascending Limb ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Nephron Segment ◽  
Electrogenic Proton Pump ◽  
Chloride Treatment

An N-ethylmaleimide (NEM)-sensitive adenosinetriphosphatase (ATPase) displaying the kinetic and pharmacological properties of an electrogenic proton pump has been described in the different segments of rat nephron, where it mediates part of the active tubular proton secretion. This study was therefore designed to evaluate whether changes in urinary acidification observed during metabolic acidosis or alkalosis were associated with alterations of the activity of tubular NEM-sensitive ATPase, and if so, to localize the nephron segments responsible for these changes. Within 1 wk after the onset of ammonium chloride treatment, rats developed a metabolic acidosis, and NEM-sensitive ATPase activity was markedly increased in the medullary thick ascending limb of Henle's loop and outer medullary collecting tubule, and slightly increased in the cortical collecting tubule. Conversely, treatment with sodium bicarbonate induced a metabolic alkalosis that was accompanied by decreased NEM-sensitive ATPase activity in medullary thick ascending limb and outer medullary collecting tubule. NEM-sensitive ATPase activity was not altered in any other nephron segment tested in alkalotic and acidotic rats, i.e., the proximal tubule and the cortical thick ascending limb of Henle's loop. Changes qualitatively similar were observed as soon as 3 h after the onset of NaHCO3 or NH4Cl-loading. In the medullary collecting tubule, alterations of NEM-sensitive ATPase activity are in part due to hyperaldosteronism observed in both acidotic and alkalotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiation of Na+-K+ pump in rat proximal tubule is modulated by Na+-H+ exchanger

1988 ◽  
Vol 255 (3) ◽  
pp. F552-F557 ◽  
Author(s):  
Y. Fukuda ◽  
A. Aperia
Keyword(s):  
Atpase Activity ◽  
Rat Kidney ◽  
Thick Ascending Limb ◽  
Adult Rats ◽  
Entry Pathway ◽  
Medullary Thick Ascending Limb ◽  
Weanling Rats ◽  
Rat Proximal Tubule ◽  
Exchange Activity

This study examines the effect of in vivo modulation of Na+-H+ exchange activity on the development of Na+-K+-ATPase in rat kidney proximal convoluted tubule (PCT) segments. To stimulate Na+-H+ exchanger (major entry pathway for Na in PCT), weanling rats were fed NH4Cl for 4 days to induce metabolic acidosis (MA). In vehicle (Vh)-fed rats PCT Na+-K+-ATPase activity (pmol Pi.mm tubule-1.h-1 +/- SE) increased from 481 +/- 78 at 16 days to 1,122 +/- 119 at 20 days. In 20-day-old chronic MA rats, PCT Na+-K+-ATPase activity was 1,717 +/- 109, i.e., significantly higher (P less than 0.01) relative to controls. Chronic MA had no effect on PCT Mg ATPase activity and on Na+-K+-ATPase in the medullary thick ascending limb (MTAL). To inhibit the Na+-H+ exchanger, weanling rats received amiloride (30 micrograms.100 g body wt-1.day-1) via osmotic minipump for 4 days. In Vh-treated rats PCT Na+-K+-ATPase increased from 481 +/- 78 at 16 days to 1,428 +/- 81 at 20 days. In rats given chronic amiloride, PCT Na+-K+-ATPase was significantly lower (858 +/- 75) at 20 days relative to controls but PCT Mg ATPase and MTAL Na+-K+-ATPase activity was the same as in controls. Chronic MA and amiloride had no significant effect on PCT Na+-K+-ATPase activity in adult rats. Acute MA and acute amiloride injection had no significant effect on PCT Na+-K+-ATPase in weanling rats.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Expression of the polymeric immunoglobulin receptor and excretion of secretory IgA in the postischemic kidney

1999 ◽  
Vol 276 (5) ◽  
pp. F666-F673 ◽  
Author(s):  
James C. Rice ◽  
Jeff S. Spence ◽  
Judit Megyesi ◽  
Randall M. Goldblum ◽  
Robert L. Safirstein
Keyword(s):  
Mucosal Immune Response ◽  
Secretory Component ◽  
Secretory Iga ◽  
Polymeric Immunoglobulin Receptor ◽  
Thick Ascending Limb ◽  
Mrna Levels ◽  
Immunoglobulin Receptor ◽  
Medullary Thick Ascending Limb ◽  
Tract Infections

The humoral mucosal immune response of the kidney involves the transport of secretory IgA (S-IgA) through renal epithelial cells by the polymeric immunoglobulin receptor (pIgR). The pIgR is cleaved and released as free secretory component (FSC) or attached to IgA (S-IgA). We examined the effects of an ischemic model of acute renal failure (ARF) on the expression of pIgR and the secretion of FSC and S-IgA in the urine. Kidney pIgR mRNA levels decreased in ischemic animals by 55% at 4 h and by 85% at 72 h compared with controls. pIgR protein expression in the medullary thick ascending limb (TAL) decreased within 24 h and was nearly undetectable by 72 h. Urinary S-IgA and FSC concentrations decreased by 60% between days 3 and 6. pIgR mRNA and pIgR protein in the kidney returned to ∼90% of control levels and urinary FSC and S-IgA concentrations returned to ∼55% of control levels by day 7. We demonstrate that ischemic ARF decreases renal mucosal S-IgA transport in vivo and may contribute to the increased incidence of urinary tract infections.

11 beta-hydroxysteroid dehydrogenase and corticosteroid hormone receptors in the rat colon

1993 ◽  
Vol 264 (6) ◽  
pp. E951-E957 ◽  
Author(s):  
C. B. Whorwood ◽  
P. C. Barber ◽  
J. Gregory ◽  
M. C. Sheppard ◽  
P. M. Stewart
Keyword(s):  
Epithelial Cells ◽  
Lamina Propria ◽  
Hormone Receptors ◽  
Rat Kidney ◽  
Distal Colon ◽  
Hydroxysteroid Dehydrogenase ◽  
Neuroendocrine Cells ◽  
Rat Colon ◽  
Mrna Levels

In the rat kidney 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) maintains normal in vivo specificity for mineralocorticoid receptor (MR) by converting the active steroid corticosterone to inactive 11-dehydrocorticosterone, leaving aldosterone to occupy the MR. Clinical observations support the hypothesis that 11 beta-HSD also protects the distal colonic MR from glucocorticoid excess. We have measured 11 beta-HSD mRNA and activity along the rat colon and have analyzed the distribution of 11 beta-HSD, MR, and glucocorticoid receptor (GR) mRNA within rat distal colon using in situ hybridization. Levels of 11 beta-HSD mRNA (1.7 and 3.4 kb) and activity were higher in distal vs. proximal colon, paralleling reported MR mRNA levels. Within the distal colon mucosa both 11 beta-HSD immunoreactivity and mRNA was observed in cells in the lamina propria but not in epithelial cells. MR mRNA was present in surface epithelial cells, but was also colocalized with the same 11 beta-HSD-expressing cells in the lamina propria. In contrast GR mRNA was more uniformly distributed. The localization of MR mRNA to nonepithelial cells in the lamina propria, possibly neuroendocrine cells, suggests that mineralocorticoid-regulated sodium transport across colonic epithelial cells may also involve a paracrine mechanism. As with the kidney, exposure of active mineralocorticoid to the MR in these cells in the lamina propria is dictated by 11 beta-HSD in an autocrine fashion.

Localization and regulation of the rat renal Na(+)-K(+)-2Cl- cotransporter, BSC-1

1996 ◽  
Vol 271 (3) ◽  
pp. F619-F628 ◽  
Author(s):  
C. A. Ecelbarger ◽  
J. Terris ◽  
J. R. Hoyer ◽  
S. Nielsen ◽  
J. B. Wade ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Rat Colon ◽  
Thick Ascending Limb ◽  
Outer Medulla ◽  
Water Excretion ◽  
Saline Loading ◽  
Cloned Cdna ◽  
Urinary Concentrating Ability

To investigate the role of the thick ascending limb (TAL) Na(+)-K(+)-2Cl- cotransporter in regulation of water excretion, we have prepared a peptide-derived polyclonal antibody based on the cloned cDNA sequence of the rat type 1 bumetanide-sensitive cotransporter, BSC-1 (also termed "NKCC-2"). Immunoblots revealed a single broad 161-kDa band in membrane fractions of rat renal outer medulla and cortex but not from rat colon or parotid gland. A similar protein was labeled in mouse kidney. Immunoperoxidase immunohistochemistry in rat kidney revealed labeling restricted to the medullary and cortical TAL segments. Because long-term regulation of urinary concentrating ability may depend on regulation of Na(+)-K(+)-2Cl- cotransporter abundance, we used immunoblotting to evaluate the effects of several in vivo factors on expression levels of BSC-1 protein in rat kidney outer medulla. Chronic oral saline loading with 0.16 M NaCl markedly increased BSC-1 abundance. However, long-term vasopressin infusion or thirsting of rats did not affect BSC-1 abundance. Chronic furosemide infusion caused a 9-kDa upward shift in apparent molecular mass and an apparent increase in expression level. These results support the previous identification of BSC-1 as the TAL Na(+)-K(+)-2Cl- transporter and demonstrate that the expression of this transporter is regulated.

scholarly journals Angiotensin II inhibits NaCl absorption in the rat medullary thick ascending limb

2004 ◽  
Vol 287 (3) ◽  
pp. F404-F410 ◽  
Author(s):  
Nicolas Lerolle ◽  
Soline Bourgeois ◽  
Françoise Leviel ◽  
Gaëtan Lebrun ◽  
Michel Paillard ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Plasma Membranes ◽  
Inhibitory Effect ◽  
Thick Ascending Limb ◽  
Sprague Dawley ◽  
Experimental Conditions ◽  
Nacl Absorption ◽  
Medullary Thick Ascending Limb

NaCl reabsorption in the medullary thick ascending limb of Henle (MTALH) contributes to NaCl balance and is also responsible for the creation of medullary interstitial hypertonicity. Despite the presence of angiotensin II subtype 1 (AT1) receptors in both the luminal and the basolateral plasma membranes of MTALH cells, no information is available on the effect of angiotensin II on NaCl reabsorption in MTALH and, furthermore, on angiotensin II-dependent medullary interstitial osmolality. MTALHs from male Sprague-Dawley rats were isolated and microperfused in vitro; transepithelial net chloride absorption ( JCl) as well as transepithelial voltage ( Vte) were measured. Luminal or peritubular 10−11 and 10−10 M angiotensin II had no effect on JCl or Vte. However, 10−8 M luminal or peritubular angiotensin II reversibly decreased both JCl and Vte. The effect of both luminal and peritubular angiotensin II was prevented by the presence of losartan (10−6 M). By contrast, PD-23319, an AT2-receptor antagonist, did not alter the inhibitory effect of 10−8 M angiotensin II. Finally, no additive effect of luminal and peritubular angiotensin II was observed. We conclude that both luminal and peritubular angiotensin II inhibit NaCl absorption in the MTALH via AT1 receptors. Because of intrarenal angiotensin II synthesis, angiotensin II concentration in medullary tubular and interstitial fluids may be similar in vivo to the concentration that displays an inhibitory effect on NaCl reabsorption under the present experimental conditions.

Interactions of external and internal K+ with K(+)-HCO3- cotransporter of rat medullary thick ascending limb

1996 ◽  
Vol 271 (1) ◽  
pp. C218-C225 ◽  
Author(s):  
A. Blanchard ◽  
F. leviel ◽  
M. Bichara ◽  
R. A. Podevin ◽  
M. Paillard
Keyword(s):  
Maximum Velocity ◽  
Hill Coefficient ◽  
Kinetic Properties ◽  
Thick Ascending Limb ◽  
Medullary Thick Ascending Limb ◽  
Sigmoidal Curve ◽  
K Concentration ◽  
Physiological Variations ◽  
Allosteric Activator

We studied [K+]i and [K+]o, where subscripts i and o refer to intracellular and extracellular, respectively, concentration dependency of the kinetic properties of the electroneutral K(+)-HCO3-cotransport, using suspensions of rat medullary thick ascending limb (mTAL). With the use of nigericin and monensin, [K+]i was clamped at various values, while maintaining [Na+]i = [Na+]o = 37 mM, [HCO3-]i = [HCO3-]o = 23 mM, and pHi = pHo = 7.4. As indicated by 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein HCO3(-)-dependent rates of change in pHi, at constant [K+]i, increasing the magnitude of the outward K+ gradient by varying [K+]o saturated HCO3-efflux with a Michaelis-Menten curve (apparent Michaelis constant for [K+]o = 2 mM, Hill coefficient = 1). On the other hand, increasing [K+]i from 30 to 140 mM, while either [K+]o or the magnitude of the K+ concentration gradient was fixed, saturated HCO3- efflux with a sigmoidal curve and yielded a Hill coefficient of 3.4 and 50% of maximum velocity at 70 mM [K+]i. These results indicate that [K+]i, independent of its role as a transportable substrate for the cotransport with HCO3-, has a role as an allosteric activator of the K(+)-HCO3- cotransporter. Such an allosteric modulation may contribute to the maintenance of net HCO3- absorption despite large in vivo physiological variations of K+ concentration in the medullary interstitium.

scholarly journals Water and solute permeabilities of medullary thick ascending limb apical and basolateral membranes

1998 ◽  
Vol 274 (3) ◽  
pp. F453-F462 ◽  
Author(s):  
Rickey Rivers ◽  
Anne Blanchard ◽  
Dominique Eladari ◽  
Francois Leviel ◽  
Michel Paillard ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Basolateral Membrane ◽  
Thick Ascending Limb ◽  
Membrane Structures ◽  
Membrane Unit ◽  
Small Surface ◽  
Basolateral Membranes ◽  
Medullary Thick Ascending Limb ◽  
Osmotic Water

The medullary thick ascending limb (MTAL) reabsorbs solute without water and concentrates [Formula: see text] in the interstitium without a favorable pH gradient, activities which require low water and NH3 permeabilities. The contributions of different apical and basolateral membrane structures to these low permeabilities are unclear. We isolated highly purified apical and basolateral MTAL plasma membranes and measured, by stopped-flow fluorometry, their permeabilities to water, urea, glycerol, protons, and NH3. Osmotic water permeability at 20°C averaged 9.4 ± 0.8 × 10−4 cm/s for apical and 11.9 ± 0.5 × 10−4cm/s for basolateral membranes. NH3 permeabilities at 20°C averaged 0.0023 ± 0.00035 and 0.0035 ± 0.00080 cm/s for apical and basolateral membranes, respectively. These values are consistent with those obtained in isolated perfused tubules and can account for known aspects of MTAL function in vivo. Because the apical and basolateral membrane unit permeabilities are similar, the ability of the apical membrane to function as the site of barrier function arises from its very small surface area when compared with the highly redundant basolateral membrane.

Sign in / Sign up

Export Citation Format

Share Document