scholarly journals Adenosine inhibits the basolateral Cl− ClC-K2/b channel in collecting duct intercalated cells

2020 ◽  
Vol 318 (4) ◽  
pp. F870-F877
Author(s):  
Oleg Zaika ◽  
Viktor N. Tomilin ◽  
Oleh Pochynyuk
Keyword(s):  
Salt Intake ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Inhibitory Effect ◽  
Intercalated Cells ◽  
Dietary Salt ◽  
Open Probability ◽  
Salt Loading ◽  
Principal Cells ◽  
High Salt Intake

Adenosine plays an important role in various aspects of kidney physiology, but the specific targets and mechanisms of actions are not completely understood. The collecting duct has the highest expression of adenosine receptors, particularly adenosine A1 receptors (A1Rs). Interstitial adenosine levels are greatly increased up to a micromolar range in response to dietary salt loading. We have previously shown that the basolateral membrane of principal cells has primarily K+ conductance mediated by Kir4.1/5.1 channels to mediate K+ recycling and to set up a favorable driving force for Na+/K+ exchange ( 47 ). Intercalated cells express the Cl− ClC-K2/b channel mediating transcellular Cl− reabsorption. Using patch-clamp electrophysiology in freshly isolated mouse collecting ducts, we found that acute application of adenosine reversely inhibits ClC-K2/b open probability from 0.31 ± 0.04 to 0.17 ± 0.06 and to 0.10 ± 0.05 for 1 and 10 µM, respectively. In contrast, adenosine (10 µM) had no measureable effect on Kir4.1/5.1 channel activity in principal cells. The inhibitory effect of adenosine on ClC-K2/b was abolished in the presence of the A1R blocker 8-cyclopentyl-1,3-dipropylxanthine (10 µM). Consistently, application of the A1R agonist N6-cyclohexyladenosine (1 µM) recapitulated the inhibitory action of adenosine on ClC-K2/b open probability. The effects of adenosine signaling in the collecting duct were independent from its purinergic counterpartner, ATP, having no measurable actions on ClC-K2/b and Kir4.1/5.1. Overall, we demonstrated that adenosine selectively inhibits ClC-K2/b activity in intercalated cells by targeting A1Rs. We propose that inhibition of transcellular Cl− reabsorption in the collecting duct by adenosine would aid in augmenting NaCl excretion during high salt intake.

Structural-functional relationships along the distal nephron

1986 ◽  
Vol 250 (1) ◽  
pp. F1-F15 ◽  
Author(s):  
K. M. Madsen ◽  
C. C. Tisher
Keyword(s):  
Atpase Activity ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Distal Tubule ◽  
Structural Heterogeneity ◽  
Apical Plasma Membrane ◽  
Thick Ascending Limb ◽  
Intercalated Cells ◽  
Principal Cells ◽  
Functional Relationships

The distal tubule, which includes the thick ascending limb (TAL), the macula densa, and the distal convoluted tubule (DCT), and the collecting duct are structurally heterogeneous, thus reflecting the functional heterogeneity that is also present. As the TAL ascends from medulla to cortex, the surface area of the apical plasma membrane increases while that of the basolateral membrane decreases. The structure of the DCT resembles that of the medullary TAL. An excellent correlation exists between structure, Na-K-ATPase activity, and NaCl reabsorptive capacity in the distal tubule. The collecting duct is subdivided into the initial collecting tubule (ICT), and cortical (CCD), outer medullary (OMCD), and inner medullary (IMCD) collecting ducts. Between the distal tubule and the collecting duct is a transition region termed the connecting segment or connecting tubule (CNT). Considerable structural heterogeneity exists along the collecting duct within the two major cell populations, the intercalated cells and the principal cells. In the CNT, the ICT, and the CCD, potassium loading and mineralocorticoids stimulate Na-K-ATPase activity and cause proliferation of the basolateral membrane of CNT cells and principal cells, thus identifying the cells responsible for mineralocorticoid-stimulated potassium secretion in these regions. Finally, at least two morphologically distinct populations of intercalated cells exist, types A and B. In the rat, type A predominates in the CNT and the OMCD and is believed to be responsible for H+ secretion, at least in the OMCD. Type B predominates in the CCD, where it may be involved in bicarbonate secretion.

scholarly journals Insulin and IGF-1 activate Kir4.1/5.1 channels in cortical collecting duct principal cells to control basolateral membrane voltage

2016 ◽  
Vol 310 (4) ◽  
pp. F311-F321 ◽  
Author(s):  
Oleg Zaika ◽  
Oleg Palygin ◽  
Viktor Tomilin ◽  
Mykola Mamenko ◽  
Alexander Staruschenko ◽  
...  
Keyword(s):  
Single Channel ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Sodium Reabsorption ◽  
Cortical Collecting Duct ◽  
Open Probability ◽  
Whole Cell ◽  
Principal Cells ◽  
Basolateral Side ◽  
Kinase Cascade

Potassium Kir4.1/5.1 channels are abundantly expressed at the basolateral membrane of principal cells in the cortical collecting duct (CCD), where they are thought to modulate transport rates by controlling transepithelial voltage. Insulin and insulin-like growth factor-1 (IGF-1) stimulate apically localized epithelial sodium channels (ENaC) to augment sodium reabsorption in the CCD. However, little is known about their actions on potassium channels localized at the basolateral membrane. In this study, we implemented patch-clamp analysis in freshly isolated murine CCD to assess the effect of these hormones on Kir4.1/5.1 at both single channel and cellular levels. We demonstrated that K+-selective conductance via Kir4.1/5.1 is the major contributor to the macroscopic current recorded from the basolateral side in principal cells. Acute treatment with 10 μM amiloride (ENaC blocker), 100 nM tertiapin-Q (TPNQ; ROMK inhibitor), and 100 μM ouabain (Na+-K+-ATPase blocker) failed to produce a measurable effect on the macroscopic current. In contrast, Kir4.1 inhibitor nortriptyline (100 μM), but not fluoxetine (100 μM), virtually abolished whole cell K+-selective conductance. Insulin (100 nM) markedly increased the open probability of Kir4.1/5.1 and nortriptyline-sensitive whole cell current, leading to significant hyperpolarization of the basolateral membrane. Inhibition of the phosphatidylinositol 3-kinase cascade with LY294002 (20 μM) abolished action of insulin on Kir4.1/5.1. IGF-1 had similar stimulatory actions on Kir4.1/5.1-mediated conductance only when applied at a higher (500 nM) concentration and was ineffective at 100 nM. We concluded that both insulin and, to a lesser extent, IGF-1 activate Kir4.1/5.1 channel activity and open probability to hyperpolarize the basolateral membrane, thereby facilitating Na+ reabsorption in the CCD.

scholarly journals Dietary salt induces transcription of the prostaglandin transporter gene in renal collecting ducts

2008 ◽  
Vol 295 (3) ◽  
pp. F765-F771 ◽  
Author(s):  
Yuling Chi ◽  
Michael L. Pucci ◽  
Victor L. Schuster
Keyword(s):  
Salt Intake ◽  
Collecting Duct ◽  
Prostaglandin E ◽  
Mrna Levels ◽  
Dietary Salt ◽  
Water Excretion ◽  
Salt Loading ◽  
Dietary Salt Intake ◽  
High Sodium ◽  
Transgenic Mouse Line

Prostaglandin E2 (PGE2) plays an important role in maintaining body fluid homeostasis by activating its receptors on the renal collecting duct (CD) to stimulate renal Na+ and water excretion. The PG carrier prostaglandin transporter (PGT) is expressed on the CD apical membrane, where it mediates PG reuptake as part of the termination of autocrine PG signaling. Here we tested the hypothesis that dietary salt loading regulates PGT gene transcription in renal CDs. We placed green fluorescence protein (GFP) under control of 3.3 kb of the mouse PGT promoter and injected this construct into the pronuclei of fertilized FVB mouse eggs. Four of thirty-eight offspring were GFP positive by genotyping. We extensively characterized one (no. 29) PGT-GFP transgenic mouse line. On microscopic examination, GFP was expressed in CDs as determined by their expression of aquaporin-2. We fed mice a low (0.03% NaCl)-, normal (0.3% NaCl)-, or high-salt (3% NaCl) diet for 2 wk and quantified CD GFP expression. The average number of GFP-positive CD cells per microscopic section varied directly with dietary salt intake. Compared with mice on the control (0.3% sodium) diet, mice on a low-sodium (0.03%) diet had reduced numbers of GFP-positive cells (71% of control, P < 0.001), whereas mice on a high-sodium (3%) diet had increased numbers of GFP-positive cells (139% of control, P < 0.001). This increase in apparent CD PGT transcription resulted in a 51–55% increase ( P < 0.001) in whole kidney PGT mRNA levels as determined by real-time PCR. The regulation of PG signal termination via reuptake represents a new pathway for controlling renal Na+ balance.

Renal potassium transport: morphological and functional adaptations

1989 ◽  
Vol 257 (5) ◽  
pp. R989-R997 ◽  
Author(s):  
B. A. Stanton
Keyword(s):  
Collecting Duct ◽  
Cell Structure ◽  
Basolateral Membrane ◽  
Distal Tubule ◽  
Morphological Evidence ◽  
Intercalated Cells ◽  
Principal Cells ◽  
K Secretion ◽  
K Concentration ◽  
And Function

Maintenance of K+ homeostasis in mammals and amphibians depends primarily on the kidneys which excrete 95% of K+ ingested in the diet. The amount of K+ in the urine is determined by the rate of K+ secretion or absorption by the distal tubule and the collecting duct. When K+ intake is increased, K+ secretion rises. The mechanisms of K+ secretion by the distal tubule and collecting duct are so efficient that K+ intake can increase 20-fold with little or no increase in body K+ content or in plasma K+ concentration. Elevated K+ secretion by the distal tubule and collecting duct occurs in part because of an increase in the quantity of Na+-K+-adenosinetriphosphatase (Na+-K+-ATPase) and amplification of the basolateral membrane of principal cells. When dietary K+ intake is reduced, urinary K+ excretion falls, because K+ secretory mechanisms are suppressed and K+ absorptive mechanisms, residing in the distal tubule and collecting duct, are activated. Because a low-K+ diet is associated with hypertrophy of intercalated cells, it has been suggested that this cell type absorbs K+, possibly by an H+-K+-ATPase. In this review, I discuss the functional and morphological evidence that supports the view that principal cells secrete K+ and that intercalated cells absorb K+. In addition, some of the hormones and factors that are responsible for these changes in cell structure and function are discussed.

Functional activity of H-K-ATPase in individual cells of OMCD: localization and effect of K+ depletion

1996 ◽  
Vol 270 (1) ◽  
pp. F116-F122 ◽  
Author(s):  
M. Kuwahara ◽  
W. J. Fu ◽  
F. Marumo
Keyword(s):  
Functional Activity ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Cell Types ◽  
Intercalated Cells ◽  
Principal Cells ◽  
Before And After ◽  
The Difference ◽  
K Depletion

Recent studies have indicated the presence of hydrogen-potassium-adenosinetriphosphatase (H-K-ATPase) in the collecting duct. We examined the localization of functional H-K-ATPase activity in individual cells of the outer and inner stripes of outer medullary collecting ducts (OMCDo and OMCDi). Tubules were isolated from control and K(+)-depleted rabbits and perfused in vitro. Intracellular pH (pHi) of principal cells, intercalated cells, and OMCDi cells was monitored by fluorescence ratio imaging using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). An intracellular acid load was induced by NH3/NH4 prepulse in extracellular Na(+)-, K(+)-, and HCO3(-)-free condition, and then 5 mM K+ was added to the lumen or the bath in the presence of Ba2+. Functional activity of H-K-ATPase was estimated by the difference in the rates of pHi recovery before and after K+ addition. In the control condition, luminal addition of K+ significantly increased the pHi recovery rate by 1.6 +/- 0.4 and 1.9 +/- 0.4 x 10(-3) pH units/s in intercalated calls and OMCDi cells, respectively, but not in principal cells. This K(+)-dependent pHi recovery was inhibited by 63% in intercalated cells and 74% in OMCDi cells in the presence of luminal Sch-28080 (10 microM) but was not affected in the presence of luminal bafilomycin-A1 (10 nM). K+ depletion increased the K(+)-dependent pHi recovery to 2.3-fold in intercalated cells and 2.6-fold in OMCDi cells. By contrast, K(+)-dependent pHi recovery was not detected in the basolateral membrane of any cell types in either the control or the K(+)-depleted condition. These results provide functional evidence that H-K-ATPase is distributed in the luminal membrane of intercalated cells and OMCDi cells and that this ATPase is activated by K+ depletion, suggesting the contribution of intercalated cells and OMCDi cells to K+ conservation in rabbit OMCD.

Kir4.1/Kir5.1 channel forms the major K+ channel in the basolateral membrane of mouse renal collecting duct principal cells

2008 ◽  
Vol 294 (6) ◽  
pp. F1398-F1407 ◽  
Author(s):  
Sahran Lachheb ◽  
Françoise Cluzeaud ◽  
Marcelle Bens ◽  
Mathieu Genete ◽  
Hiroshi Hibino ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Hill Coefficient ◽  
Specific Marker ◽  
Patch Clamp Technique ◽  
Open Probability ◽  
Principal Cells ◽  
Inside Out

K+ channels in the basolateral membrane of mouse cortical collecting duct (CCD) principal cells were identified with patch-clamp technique, real-time PCR, and immunohistochemistry. In cell-attached membrane patches, three K+ channels with conductances of ∼75, 40, and 20 pS were observed, but the K+ channel with the intermediate conductance (40 pS) predominated. In inside-out membrane patches exposed to an Mg2+-free medium, the current-voltage relationship of the intermediate-conductance channel was linear with a conductance of 38 pS. Addition of 1.3 mM internal Mg2+ had no influence on the inward conductance ( Gin = 35 pS) but reduced outward conductance ( Gout) to 13 pS, yielding a Gin/ Gout of 3.2. The polycation spermine (6 × 10−7 M) reduced its activity on inside-out membrane patches by 50% at a clamp potential of 60 mV. Channel activity was also dependent on intracellular pH (pHi): a sigmoid relationship between pHi and channel normalized current ( NPo) was observed with a p K of 7.24 and a Hill coefficient of 1.7. By real-time PCR on CCD extracts, inwardly rectifying K+ (Kir)4.1 and Kir5.1, but not Kir4.2, mRNAs were detected. Kir4.1 and Kir5.1 proteins cellularly colocalized with aquaporin 2 (AQP2), a specific marker of CCD principal cells, while AQP2-negative cells (i.e., intercalated cells) showed no staining. Dietary K+ had no influence on the properties of the intermediate-conductance channel, but a Na+-depleted diet increased its open probability by ∼25%. We conclude that the Kir4.1/Kir5.1 channel is a major component of the K+ conductance in the basolateral membrane of mouse CCD principal cells.

Salt-resistant blood pressure and salt-sensitive renal autoregulation in chronic streptozotocin diabetes

2009 ◽  
Vol 296 (6) ◽  
pp. R1761-R1770 ◽  
Author(s):  
Catherine Lau ◽  
Ian Sudbury ◽  
Michael Thomson ◽  
Perry L. Howard ◽  
Alex B. Magil ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Salt Intake ◽  
Collecting Duct ◽  
Periodic Acid ◽  
Systolic Pressure ◽  
Diabetic Rats ◽  
Tubuloglomerular Feedback ◽  
Dietary Salt ◽  
Periodic Acid Schiff ◽  
High Salt Intake

Hyperfiltration occurs in early type 1 diabetes mellitus in both rats and humans. It results from afferent vasodilation and thus may impair stabilization of glomerular capillary pressure by autoregulation. It is inversely related to dietary salt intake, the “salt paradox.” Restoration of normal glomerular filtration rate (GFR) involves increased preglomerular resistance, probably mediated by tubuloglomerular feedback (TGF). To begin to test whether the salt paradox has pathogenic significance, we compared intact vs. diabetic (streptozotocin) Long-Evans rats with normal and increased salt intake, 1 and ∼3% by weight of food eaten, respectively. Weekly 24-h blood pressure records were acquired by telemetry before and during diabetes. Blood glucose was maintained at ∼20 mmol/l by insulin implants. GFR was significantly elevated only in diabetic rats on normal salt intake, confirming diabetic hyperfiltration and the salt paradox. Renal blood flow dynamics show strong contributions to autoregulation by both TGF and the myogenic mechanism and were not impaired by diabetes or by increased salt intake. Separately, systolic pressure was not elevated in diabetic rats at any time during 12 wk with normal or high salt intake. Autoregulation was effective in all groups, and the diabetic-normal salt group showed significantly improved autoregulation at low perfusion pressures. Histological examination revealed very minor glomerulosclerosis and modest mesangial expansion, although neither was diagnostic of diabetes. Periodic acid-Schiff-positive droplets found in distal tubules and collecting duct segments were diagnostic of diabetic kidneys. Biologically significant effects attributable to increased salt intake were abrogation of hyperfiltration and of the left shift in autoregulation in diabetic rats.

scholarly journals Regulation of the epithelial Na+ channel by endothelin-1 in rat collecting duct

2008 ◽  
Vol 295 (4) ◽  
pp. F1063-F1070 ◽  
Author(s):  
Vladislav Bugaj ◽  
Oleh Pochynyuk ◽  
Elena Mironova ◽  
Alain Vandewalle ◽  
Jorge L. Medina ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Na Channel ◽  
Open Probability ◽  
Endothelin 1 ◽  
Principal Cells ◽  
Patch Clamp Electrophysiology ◽  
Src Family Tyrosine Kinases

We used patch-clamp electrophysiology to investigate regulation of the epithelial Na+ channel (ENaC) by endothelin-1 (ET-1) in isolated, split-open rat collecting ducts. ET-1 significantly decreases ENaC open probability by about threefold within 5 min. ET-1 decreases ENaC activity through basolateral membrane ETB but not ETA receptors. In rat collecting duct, we find no role for phospholipase C or protein kinase C in the rapid response of ENaC to ET-1. ET-1, although, does activate src family tyrosine kinases and their downstream MAPK1/2 effector cascade in renal principal cells. Both src kinases and MAPK1/2 signaling are necessary for ET-1-dependent decreases in ENaC open probability in the split-open collecting duct. We conclude that ET-1 in a physiologically relevant manner rapidly suppresses ENaC activity in native, mammalian principal cells. These findings may provide a potential mechanism for the natriuresis observed in vivo in response to ET-1, as well as a potential cause for the salt-sensitive hypertension found in animals with impaired endothelin signaling.

scholarly journals The sodium-activated sodium channel is expressed in the rat kidney thick ascending limb and collecting duct cells and is upregulated during high salt intake

2012 ◽  
Vol 303 (1) ◽  
pp. F105-F109 ◽  
Author(s):  
Lucienne S. Lara ◽  
Ryousuke Satou ◽  
Camille R. T. Bourgeois ◽  
Alexis A. Gonzalez ◽  
Andrea Zsombok ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Salt Intake ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Extracellular Fluid ◽  
High Salt ◽  
Thick Ascending Limb ◽  
Principal Cells ◽  
High Salt Intake

Increased dietary salt triggers oxidative stress and kidney injury in salt-sensitive hypertension; however, the mechanism for sensing increased extracellular Na+ concentration ([Na+]) remains unclear. A Na+-activated Na+ channel (Na sensor) described in the brain operates as a sensor of extracellular fluid [Na+]; nonetheless, its presence in the kidney has not been established. In the present study, we demonstrated the gene expression of the Na sensor by RT-PCR and Western blotting in the Sprague-Dawley rat kidney. Using immunofluorescence, the Na sensor was localized to the luminal side in tubular epithelial cells of collecting ducts colocalizing with aquaporin-2, a marker of principal cells, and in thick ascending limb, colocalizing with the glycoprotein Tamm-Horsfall. To determine the effect of a high-salt diet (HSD) on Na sensor gene expression, we quantified its transcript and protein levels primarily in renal medullas from control rats and rats subjected to 8% NaCl for 7 days ( n = 5). HSD increased Na sensor expression levels (mRNA: from 1.2 ± 0.2 to 5.1 ± 1.3 au; protein: from 0.98 ± 0.15 to 1.74 ± 0.28 au P < 0.05) in the kidney medulla, but not in the cortex. These data indicate that rat kidney epithelial cells of the thick ascending limb and principal cells of the collecting duct possess a Na sensor that is upregulated by HSD, suggesting an important role in monitoring changes in tubular fluid [Na+].

Macula densa basolateral ATP release is regulated by luminal [NaCl] and dietary salt intake

2004 ◽  
Vol 286 (6) ◽  
pp. F1054-F1058 ◽  
Author(s):  
Peter Komlosi ◽  
Janos Peti-Peterdi ◽  
Amanda L. Fuson ◽  
Attila Fintha ◽  
Laszlo Rosivall ◽  
...  
Keyword(s):  
Salt Intake ◽  
Mesangial Cells ◽  
Basolateral Membrane ◽  
Atp Release ◽  
Macula Densa ◽  
Tubuloglomerular Feedback ◽  
Thick Ascending Limb ◽  
Dietary Salt ◽  
Dietary Salt Intake ◽  
High Salt Intake

One component of the macula densa (MD) tubuloglomerular feedback (TGF) signaling pathway may involve basolateral release of ATP through a maxi-anion channel. Release of ATP has previously been studied during a maximal luminal NaCl concentration ([NaCl]L) stimulus (20–150 mmol/l). Whether MD ATP release occurs during changes in [NaCl]L within the physiological range (20–60 mmol/l) has not been examined. Also, because TGF is known to be enhanced by low dietary salt intake, we examined the pattern of MD ATP release from salt-restricted rabbits. Fluorescence microscopy, with fura 2-loaded cultured mouse mesangial cells as biosensors, was used to assess ATP release from the isolated, perfused thick ascending limb containing the MD segment. The mesangial biosensor cells, which contain purinergic receptors and elevate intracellular Ca2+ concentration ([Ca2+]i) on ATP binding, were placed adjacent to the MD basolateral membrane. Elevations in [NaCl]L between 0 and 80 mmol/l, in 20-mmol/l increments, caused stepwise increases in [Ca2+]i, with the highest increase at [NaCl]L of ∼60 mmol/l. Luminal furosemide at 10−4 mol/l blocked ATP release, which suggests that the efflux of ATP required MD Na-2Cl-K cotransport. A low-salt diet for 1 wk increased the magnitude of [NaCl]L-dependent elevations in biosensor [Ca2+]i by twofold, whereas high-salt intake had no effect. In summary, ATP release occurs over the same range of [NaCl]L (20–60 mmol/l) previously reported for TGF responses, and, similar to TGF, ATP release was enhanced by dietary salt restriction. Thus these two findings are consistent with the role of MD ATP release as a signaling component of the TGF pathway.

Sign in / Sign up

Export Citation Format

Share Document