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Alexander RT, Dimke H. Molecular mechanisms underlying paracellular calcium and magnesium reabsorption in the proximal tubule and thick ascending limb. Ann N Y Acad Sci 2022; 1518:69-83. [PMID: 36200584 DOI: 10.1111/nyas.14909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Calcium and magnesium are the most abundant divalent cations in the body. The plasma level is controlled by coordinated interaction between intestinal absorption, reabsorption in the kidney, and, for calcium at least, bone storage and exchange. The kidney adjusts urinary excretion of these ions in response to alterations in their systemic concentration. Free ionized and anion-complexed calcium and magnesium are filtered at the glomerulus. The majority (i.e., >85%) of filtered divalent cations are reabsorbed via paracellular pathways from the proximal tubule and thick ascending limb (TAL) of the loop of Henle. Interestingly, the largest fraction of filtered calcium is reabsorbed from the proximal tubule (65%), while the largest fraction of filtered magnesium is reclaimed from the TAL (60%). The paracellular pathways mediating these fluxes are composed of tight junctional pores formed by claudins. In the proximal tubule, claudin-2 and claudin-12 confer calcium permeability, while the exact identity of the magnesium pore remains to be determined. Claudin-16 and claudin-19 contribute to the calcium and magnesium permeable pathway in the TAL. In this review, we discuss the data supporting these conclusions and speculate as to why there is greater fractional calcium reabsorption from the proximal tubule and greater fractional magnesium reabsorption from the TAL.
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Affiliation(s)
- R Todd Alexander
- Departments of Physiology & Pediatrics, University of Alberta, Edmonton, Alberta, Canada.,Women's and Children's Health Institute, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
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2
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Garneau AP, Marcoux AA, Slimani S, Tremblay LE, Frenette-Cotton R, Mac-Way F, Isenring P. Physiological roles and molecular mechanisms of K + -Cl - cotransport in the mammalian kidney and cardiovascular system: where are we? J Physiol 2019; 597:1451-1465. [PMID: 30659612 DOI: 10.1113/jp276807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/07/2018] [Indexed: 11/08/2022] Open
Abstract
In the early 80s, renal microperfusion studies led to the identification of a basolateral K+ -Cl- cotransport mechanism in the proximal tubule, thick ascending limb of Henle and collecting duct. More than ten years later, this mechanism was found to be accounted for by three different K+ -Cl- cotransporters (KCC1, KCC3 and KCC4) that are differentially distributed along the renal epithelium. Two of these isoforms (KCC1 and KCC3) were also found to be expressed in arterial walls, the myocardium and a variety of neurons. Subsequently, valuable insights have been gained into the molecular and physiological properties of the KCCs in both the mammalian kidney and cardiovascular system. There is now robust evidence indicating that KCC4 sustains distal renal acidification and that KCC3 regulates myogenic tone in resistance vessels. However, progress in understanding the functional significance of these transporters has been slow, probably because each of the KCC isoforms is not identically distributed among species and some of them share common subcellular localizations with other KCC isoforms or sizeable conductive Cl- pathways. In addition, the mechanisms underlying the process of K+ -Cl- cotransport are still ill defined. The present review focuses on the knowledge gained regarding the roles and properties of KCCs in renal and cardiovascular tissues.
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Affiliation(s)
- A P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6.,Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, Montreal University, 900, rue Saint-Denis, Montréal, (Qc) H2X 0A9
| | - A A Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - S Slimani
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - L E Tremblay
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - R Frenette-Cotton
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - F Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - P Isenring
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Dimke H, Schnermann J. Axial and cellular heterogeneity in electrolyte transport pathways along the thick ascending limb. Acta Physiol (Oxf) 2018; 223:e13057. [PMID: 29476644 DOI: 10.1111/apha.13057] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 01/27/2018] [Accepted: 02/17/2018] [Indexed: 12/21/2022]
Abstract
The thick ascending limb (TAL) extends from the border of the inner medulla to the renal cortex, thus ascending through regions with wide differences in tissue solute and electrolyte concentrations. Structural and functional differences between TAL cells in the medulla (mTAL) and the cortex (cTAL) would therefore be useful to adapt TAL transport function to a changing external fluid composition. While mechanisms common to all TAL cells play a central role in the reclamation of about 25% of the NaCl filtered by the kidney, morphological features, Na+ / K+ -ATPase activity, NKCC2 splicing and phosphorylation do vary between segments and cells. The TAL contributes to K+ homeostasis and TAL cells with high or low basolateral K+ conductances have been identified which may be involved in K+ reabsorption and secretion respectively. Although transport rates for HCO3- do not differ between mTAL and cTAL, divergent axial and cellular expression of H+ transport proteins in TAL have been documented. The reabsorption of the divalent cations Ca2+ and Mg2+ is highest in cTAL and paralleled by differences in divalent cation permeability and the expression of select claudins. Morphologically, two cell types with different cell surface phenotypes have been described that still need to be linked to specific functional characteristics. The unique external environment and its change along the longitudinal axis require an axial functional heterogeneity for the TAL to optimally participate in conserving electrolyte homeostasis. Despite substantial progress in understanding TAL function, there are still considerable knowledge gaps that are just beginning to become bridged.
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Affiliation(s)
- H. Dimke
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - J. Schnermann
- National Institute of Diabetes and Digestive and Kidney Diseases; Bethesda MD USA
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Grill A, Schießl IM, Gess B, Fremter K, Hammer A, Castrop H. Salt-losing nephropathy in mice with a null mutation of the Clcnk2 gene. Acta Physiol (Oxf) 2016; 218:198-211. [PMID: 27421685 DOI: 10.1111/apha.12755] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/03/2016] [Accepted: 07/11/2016] [Indexed: 12/19/2022]
Abstract
AIM The basolateral chloride channel ClC-Kb facilitates Cl reabsorption in the distal nephron of the human kidney. Functional mutations in CLCNKB are associated with Bartter's syndrome type 3, a hereditary salt-losing nephropathy. To address the function of ClC-K2 in vivo, we generated ClC-K2-deficient mice. METHODS ClC-K2-deficient mice were generated using TALEN technology. RESULTS ClC-K2-deficient mice were viable and born in a Mendelian ratio. ClC-K2-/- mice showed no gross anatomical abnormalities, but they were growth retarded. The 24-h urine volume was increased in ClC-K2-/- mice (4.4 ± 0.6 compared with 0.9 ± 0.2 mL per 24 h in wild-type littermates; P = 0.001). Accordingly, ambient urine osmolarity was markedly reduced (590 ± 39 vs. 2216 ± 132 mosmol L-1 in wild types; P < 0.0001). During water restriction (24 h), urinary osmolarity increased to 1633 ± 153 and 3769 ± 129 mosmol L-1 in ClC-K2-/- and wild-type mice (n = 12; P < 0.0001), accompanied by a loss of body weight of 12 ± 0.4 and 8 ± 0.2% respectively (P < 0.0001). ClC-K2-/- mice showed an increased renal sodium excretion and compromised salt conservation during a salt-restricted diet. The salt-losing phenotype of ClC-K2-/- mice was associated with a reduced plasma volume, hypotension, a slightly reduced glomerular filtration rate, an increased renal prostaglandin E2 generation and a massively stimulated renin-angiotensin system. Clckb-/- mice showed a reduced sensitivity to furosemide and were completely resistant to thiazides. CONCLUSION Loss of ClC-K2 compromises TAL function and abolishes salt reabsorption in the distal convoluted tubule. Our data suggest that ClC-K2 is crucial for renal salt reabsorption and concentrating ability. ClC-K2-deficient mice in most aspects mimic patients with Bartter's syndrome type 3.
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Affiliation(s)
- A. Grill
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - I. M. Schießl
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - B. Gess
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - K. Fremter
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - A. Hammer
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - H. Castrop
- Institute of Physiology; University of Regensburg; Regensburg Germany
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Limmer F, Schinner E, Castrop H, Vitzthum H, Hofmann F, Schlossmann J. Regulation of the Na(+)-K(+)-2Cl(-) cotransporter by cGMP/cGMP-dependent protein kinase I after furosemide administration. FEBS J 2015; 282:3786-98. [PMID: 26183401 DOI: 10.1111/febs.13376] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 07/09/2015] [Accepted: 07/10/2015] [Indexed: 12/01/2022]
Abstract
Sodium chloride reabsorption in the thick ascending limb of the loop of Henle is mediated by the Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). The loop diuretic furosemide is a potent inhibitor of NKCC2. However, less is known about the mechanism regulating the electrolyte transporter. Considering the well-established effects of nitric oxide on NKCC2 activity, cGMP is likely involved in this regulation. cGMP-dependent protein kinase I (cGKI; PKGI) is a cGMP target protein that phosphorylates different substrates after activation through cGMP. We investigated the potential correlation between the cGMP/cGKI pathway and NKCC2 regulation. We treated wild-type (wt) and cGKIα-rescue mice with furosemide. cGKIα-rescue mice expressed cGKIα only under the control of the smooth muscle-specific transgelin (SM22) promoter in a cGKI deficient background. Furosemide treatment increased the urine excretion of sodium and chloride in cGKIα-rescue mice compared to that in wt mice. We analyzed the phosphorylation of NKCC2 by western blotting and immunostaining using the phosphospecific antibody R5. The administration of furosemide significantly increased the phosphorylated NKCC2 signal in wt but not in cGKIα-rescue mice. NKCC2 activation led to its phosphorylation and membrane translocation. To examine whether cGKI was involved in this process, we analyzed vasodilator-stimulated phosphoprotein, which is phosphorylated by cGKI. Furosemide injection resulted in increased vasodilator-stimulated phosphoprotein phosphorylation in wt mice. We hypothesize that furosemide administration activated cGKI, leading to NKCC2 phosphorylation and membrane translocation. This cGKI-mediated pathway could be a mechanism to compensate for the inhibitory effect of furosemide on NKCC2.
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Affiliation(s)
- Franziska Limmer
- Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, Germany
| | - Elisabeth Schinner
- Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, Germany
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Germany
| | - Helga Vitzthum
- Department of Cellular and Integrative Physiology, University Medical Centre Hamburg-Eppendorf, Germany
| | - Franz Hofmann
- Pharmakologisches Institut, Technische Universität München, Germany
| | - Jens Schlossmann
- Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, Germany
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Glaudemans B, Terryn S, Gölz N, Brunati M, Cattaneo A, Bachi A, Al-Qusairi L, Ziegler U, Staub O, Rampoldi L, Devuyst O. A primary culture system of mouse thick ascending limb cells with preserved function and uromodulin processing. Pflugers Arch 2013; 466:343-56. [DOI: 10.1007/s00424-013-1321-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/23/2013] [Accepted: 06/23/2013] [Indexed: 11/28/2022]
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Wu P, Wang M, Luan H, Li L, Wang L, Wang W, Gu R. Angiotensin II stimulates basolateral 10-pS Cl channels in the thick ascending limb. Hypertension 2013; 61:1211-7. [PMID: 23569086 PMCID: PMC3686115 DOI: 10.1161/hypertensionaha.111.01069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 03/09/2013] [Indexed: 02/07/2023]
Abstract
Chloride channels in the basolateral membrane play a key role in Cl absorption in the thick ascending limb (TAL). The patch-clamp experiments were performed to test whether angiotensin II (AngII) increases Cl absorption in the TAL by stimulating the basolateral 10-pS Cl channels. AngII (1-100 nmol/L) stimulated the 10-pS Cl channel in the TAL, an effect that was blocked by losartan (angiotension AT1 receptor [AT1R] antagonist) but not by PD123319 (angiotension AT2 receptor [AT2R] antagonist). Inhibition of phospholipase C or protein kinase C also abolished the stimulatory effect of AngII on Cl channels. Moreover, stimulation of protein kinase C with phorbol-12-myristate-13-acetate mimicked the effect of AngII and increased Cl channel activity. However, the stimulatory effect of AngII on Cl channels was absent in the TAL pretreated with diphenyleneiodonium sulfate, an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Moreover, treatment of the TAL with diphenyleneiodonium sulfate also blocked the effect of phorbol-12-myristate-13-acetate on the 10-pS Cl channel. Western blotting demonstrated that incubation of isolated TAL with AngII increased phosphorylation of p47(phox) at Ser(304), suggesting that AngII stimulates the basolateral Cl channels by increasing NADPH oxidase-dependent superoxide generation. This notion was also supported by the observation that H2O2 significantly increased 10-pS Cl channel activity in the TAL. We conclude that stimulation of AT1R increased the basolateral Cl channels by activating the protein kinase C-dependent NADPH oxidase pathway. The stimulatory effect of AngII on the basolateral Cl channel may contribute to AngII-induced increases in NaCl reabsorption in the TAL and AngII-infuse-induced hypertension.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Mingxiao Wang
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Haiyan Luan
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Lili Li
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Lijun Wang
- Department of Physiology, Harbin Medical University, Harbin, China
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Wenhui Wang
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Ruimin Gu
- Department of Pharmacology, Harbin Medical University, Harbin, China
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9
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Azroyan A, Morla L, Crambert G, Laghmani K, Ramakrishnan S, Edwards A, Doucet A. Regulation of pendrin by cAMP: possible involvement in β-adrenergic-dependent NaCl retention. Am J Physiol Renal Physiol 2012; 302:F1180-7. [PMID: 22262479 DOI: 10.1152/ajprenal.00403.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The sodium-independent anion exchanger pendrin is expressed in several tissues including the kidney cortical collecting duct (CCD), where it acts as a chloride/bicarbonate exchanger and has been shown to participate in the regulation of acid-base homeostasis and blood pressure. The renal sympathetic nervous system is known to play a key role in the development of salt-induced hypertension. This study aimed to determine whether pendrin may partly mediate the effects of β adrenergic receptors (β-AR) on renal salt handling. We investigated the regulation of pendrin activity by the cAMP/protein kinase A (PKA) signaling pathway, both in vitro in opossum kidney proximal (OKP) cells stably transfected with pendrin cDNA and ex vivo in isolated microperfused CCDs stimulated by isoproterenol, a β-AR agonist. We found that stimulation of the cAMP/PKA pathway in OKP cells increased the amount of pendrin at the cell surface as well as its transport activity. These effects stemmed from increased exocytosis of pendrin and were associated with its phosphorylation. Furthermore, cAMP effects on the membrane expression and activity of pendrin were abolished by mutating the serine 49 located in the intracellular N-terminal domain of pendrin. Finally, we showed that isoproterenol increases pendrin trafficking to the apical membrane as well as the reabsorption of both Cl(-) and Na(+) in microperfused CCDs. All together, our results strongly suggest that pendrin activation by the cAMP/PKA pathway underlies isoproterenol-induced stimulation of NaCl reabsorption in the kidney collecting duct, a mechanism likely involved in the sodium-retaining effect of β-adrenergic agonists.
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Affiliation(s)
- Anie Azroyan
- UPMC Université Paris 06, Université Paris 05, INSERM, UMRS872, and CNRS ERL7226, Laboratoire de Génomique, Physiologie et Physiopathologie Rénales, Centre de Recherche des Cordeliers, Paris, France
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Leviel F, Hübner CA, Houillier P, Morla L, El Moghrabi S, Brideau G, Hassan H, Hatim H, Parker MD, Kurth I, Kougioumtzes A, Sinning A, Pech V, Riemondy KA, Miller RL, Hummler E, Shull GE, Aronson PS, Doucet A, Wall SM, Chambrey R, Eladari D. The Na+-dependent chloride-bicarbonate exchanger SLC4A8 mediates an electroneutral Na+ reabsorption process in the renal cortical collecting ducts of mice. J Clin Invest 2010; 120:1627-35. [PMID: 20389022 DOI: 10.1172/jci40145] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 02/03/2010] [Indexed: 12/11/2022] Open
Abstract
Regulation of sodium balance is a critical factor in the maintenance of euvolemia, and dysregulation of renal sodium excretion results in disorders of altered intravascular volume, such as hypertension. The amiloride-sensitive epithelial sodium channel (ENaC) is thought to be the only mechanism for sodium transport in the cortical collecting duct (CCD) of the kidney. However, it has been found that much of the sodium absorption in the CCD is actually amiloride insensitive and sensitive to thiazide diuretics, which also block the Na-Cl cotransporter (NCC) located in the distal convoluted tubule. In this study, we have demonstrated the presence of electroneutral, amiloride-resistant, thiazide-sensitive, transepithelial NaCl absorption in mouse CCDs, which persists even with genetic disruption of ENaC. Furthermore, hydrochlorothiazide (HCTZ) increased excretion of Na+ and Cl- in mice devoid of the thiazide target NCC, suggesting that an additional mechanism might account for this effect. Studies on isolated CCDs suggested that the parallel action of the Na+-driven Cl-/HCO3- exchanger (NDCBE/SLC4A8) and the Na+-independent Cl-/HCO3- exchanger (pendrin/SLC26A4) accounted for the electroneutral thiazide-sensitive sodium transport. Furthermore, genetic ablation of SLC4A8 abolished thiazide-sensitive NaCl transport in the CCD. These studies establish what we believe to be a novel role for NDCBE in mediating substantial Na+ reabsorption in the CCD and suggest a role for this transporter in the regulation of fluid homeostasis in mice.
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Affiliation(s)
- Françoise Leviel
- Centre de recherche des Cordeliers, Université Pierre et Marie Curie, ERL CNRS 7226, INSERM UMRS 872 Equipe 3, Paris, France
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Gu RM, Yang L, Zhang Y, Wang L, Kong S, Zhang C, Zhai Y, Wang M, Wu P, Liu L, Gu F, Zhang J, Wang WH. CYP-omega-hydroxylation-dependent metabolites of arachidonic acid inhibit the basolateral 10 pS chloride channel in the rat thick ascending limb. Kidney Int 2009; 76:849-56. [PMID: 19641481 PMCID: PMC2861852 DOI: 10.1038/ki.2009.287] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Metabolites of arachidonic acid influence sodium chloride (NaCl) transport in the thick ascending limb. Because a 10 pS Cl channel is the major type of chloride channel in the basolateral membrane of this nephron segment, we explored the effect of arachidonic acid on this channel in cell-attached patches. Addition of 5 micromol arachidonic acid significantly decreased channel activity (a product of channel number and open probability) while linoleic acid had no effect. To determine if this was mediated by acachidonic acid per se or by its metabolites, we measured channel activity in the presence of the cyclooxygenase inhibitor indomethacin, the selective lipoxygenase inhibitor nordihydroguaiaretic acid, and the cytochrome P-450 (CYP)-omega-hydroxylation inhibitor 17-octadecynoic acid. Neither cyclooxygenase nor lipoxygenase inhibition had an effect on basal chloride channel activity; further they failed to abolish the inhibitory effect of arachidonate on the 10 pS channel. However, inhibition of CYP-omega-hydroxylation completely abolished the effect of arachidonic acid. The similarity of the effects of 20-hydroxyeicosatetraenoic acid (20-HETE) and arachidonic acid suggests that the effect of arachidonic acid was mediated by CYP-omega-hydroxylation-dependent metabolites. We conclude that arachidonic acid inhibits the 10 pS chloride channel in the basolateral membrane of the medullary thick ascending limb, an effect mediated by the CYP-omega-hydroxylation-dependent metabolite 20-HETE.
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Affiliation(s)
- Rui-Min Gu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Lei Yang
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Yunhong Zhang
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Lijun Wang
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Shumin Kong
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Chengbiao Zhang
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Yuanyuan Zhai
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Mingxiao Wang
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Peng Wu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Liping Liu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Feng Gu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Jiye Zhang
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
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Nishimura M, Kakigi A, Takeda T, Takeda S, Doi K. Expression of aquaporins, vasopressin type 2 receptor, and Na+₋K+₋Cl⁻ cotransporters in the rat endolymphatic sac. Acta Otolaryngol 2009; 129:812-8. [PMID: 18841505 DOI: 10.1080/00016480802441754] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
CONCLUSION Since many water channels and pumps, such as aquaporin (AQP) 1-4, AQP6-9, vasopressin type 2 receptor (V(2)-R), Na(+)-K(+)-Cl(-) cotransporter (NKCC) 1, and NKCC2 were expressed in the rat endolymphatic sac, it should play an important role in the physiological function of acid-based metabolism and water balance in endolymphatic fluid homeostasis. OBJECTIVE To evaluate the expression and immunolocalization of AQP1-9, V(2)-R, NKCC1, and NKCC2 in the rat endolymphatic sac. MATERIALS AND METHODS Wistar rats were used. Expression of AQP1-9, V(2)-R, NKCC1, and NKCC2 mRNA in the rat endolymphatic sac was investigated using the reverse transcription-polymerase chain reaction (RT-PCR) method, and detailed immunolocalization of AQP1-9, V(2)-R, NKCC1, and NKCC2 was investigated using immunohistochemical methods, including immunofluorescence microscopy. RESULTS mRNAs and proteins of AQP1-4, AQP6-9, V(2)-R, NKCC1, and NKCC2 were expressed, but AQP5 was not expressed in the rat endolymphatic sac.
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Kakigi A, Nishimura M, Takeda T, Taguchi D, Nishioka R. Expression of aquaporin1, 3, and 4, NKCC1, and NKCC2 in the human endolymphatic sac. Auris Nasus Larynx 2008; 36:135-9. [PMID: 18606512 DOI: 10.1016/j.anl.2008.04.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 03/21/2008] [Accepted: 04/13/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To locate aquaporin (AQP) 1, 3, and 4, Na-K-2Cl cotransporter (NKCC) 1 and 2 in the human endolymphatic sac (ES). METHODS A sample of human ES was harvested during the removal of vestibular schwannoma via the translabyrinthine approach. The sample was immediately fixed in 4% paraformaldehyde and embedded in OCT compound. Immunohistochemistry was performed with AQP1, 3, and 4, NKCC1, and NKCC2 polyclonal antibodies. RESULTS AQP1, AQP3, and NKCC2 were strongly expressed in the epithelial layer of the ES. AQP4 and NKCC1 were weakly expressed in the epithelial layer of the ES. CONCLUSIONS As it is impossible to perform quantitative analysis based on the fluorescence intensity of each immunoreactivity, we have presented the existence of AQP1, 3, and 4, NKCC1, and NKCC2 in the ES. The expression of NKCC1 and 2 indicated that the ES may have both secretory and adsorptive functions to maintain the homeostasis of endolymph.
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Affiliation(s)
- Akinobu Kakigi
- Department of Otolaryngology, Kochi Medical School, Nankoku, Japan.
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14
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Garzón-Muvdi T, Pacheco-Alvarez D, Gagnon KBE, Vázquez N, Ponce-Coria J, Moreno E, Delpire E, Gamba G. WNK4 kinase is a negative regulator of K+-Cl- cotransporters. Am J Physiol Renal Physiol 2007; 292:F1197-207. [PMID: 17182532 DOI: 10.1152/ajprenal.00335.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
WNK kinases [with no lysine (K) kinase] are emerging as regulators of several membrane transport proteins in which WNKs act as molecular switches that coordinate the activity of several players. Members of the cation-coupled chloride cotransporters family (solute carrier family number 12) are one of the main targets. WNK3 activates the Na(+)-driven cotransporters NCC, NKCC1, and NKCC2 and inhibits the K(+)-driven cotransporters KCC1 to KCC4. WNK4 inhibits the activity of NCC and NKCC1, while in the presence of the STE20-related proline-alanine-rich kinase SPAK activates NKCC1. Nothing is known, however, regarding the effect of WNK4 on the K(+)-Cl(-) cotransporters. Using the heterologous expression system of Xenopus laevis oocytes, here we show that WNK4 inhibits the activity of the K(+)-Cl(-) cotransporters KCC1, KCC3, and KCC4 under cell swelling, a condition in which these cotransporters are maximally active. The effect of WNK4 requires its catalytic activity because it was lost by the substitution of aspartate 318 for alanine (WNK4-D318A) that renders WNK4 catalytically inactive. In contrast, three different WNK4 missense mutations that cause pseudohypoaldosteronism type II do not affect the WNK4-induced inhibition of KCC4. Finally, we observed that catalytically inactive WNK4-D318A is able to bypass the tonicity requirements for KCC2 and KCC3 activation in isotonic conditions. This effect is enhanced by the presence of catalytically inactive SPAK, was prevented by the presence of protein phosphatase inhibitors, and was not present in KCC1 and KCC4. Our results reveal that WNK4 regulates the activity of the K(+)-Cl(-) cotransporters expressed in the kidney.
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Affiliation(s)
- Tomas Garzón-Muvdi
- Molecular Physiology Unit, Vasco de Quiroga No. 15, Tlalpan 14000, México City, México
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15
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Ortiz PA. cAMP increases surface expression of NKCC2 in rat thick ascending limbs: role of VAMP. Am J Physiol Renal Physiol 2005; 290:F608-16. [PMID: 16144963 DOI: 10.1152/ajprenal.00248.2005] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
NaCl absorption by the thick ascending limb of Henle's loop (TAL) is mediated by the apical Na-K-2Cl cotransporter NKCC2. cAMP increases NaCl absorption in the TAL by stimulating NKCC2. In oocytes, cAMP increases NKCC2 activity by regulating its trafficking. However, the mechanism by which cAMP stimulates NKCC2 in TALs is not clear. We hypothesized that cAMP increases surface expression of NKCC2 and NaCl absorption in TALs and that vesicle-associated membrane protein (VAMP) is involved in this mechanism. We used surface biotinylation of rat medullary TALs (mTAL) to examine surface and total NKCC2 levels. When mTAL suspensions were treated with dibutyryl cAMP (db-cAMP) or forskolin plus IBMX for 20 min, surface NKCC2 expression increased by 126 +/- 23 and 92 +/- 17% above basal, respectively (P < 0.03). No changes in total NKCC2 expression were observed, suggesting that cAMP increased translocation of NKCC2. We studied the role of VAMP in NKCC2 translocation and found that incubating mTALs with tetanus toxin (30 nM), which inhibits vesicle trafficking by inactivating VAMP-2 and -3, completely blocked the stimulatory effect of db-cAMP on surface NKCC2 expression (tetanus toxin = 100% vs. tetanus toxin + db-cAMP = 102 +/- 21% of control; not significant). We studied VAMP-2 and -3 expression and localization in isolated perfused TALs by confocal microscopy and found that both of them were located in the subapical space of the TAL. Finally, in isolated perfused mTALs, db-cAMP increased net Cl absorption by 95.0 +/- 34.8% (P < 0.03), and pretreatment of TALs with tetanus toxin blocked the stimulation of Cl absorption (from 110.9 +/- 15.9 to 109.7 +/- 15.6 pmol.min(-1).mm(-1); not significant). We concluded that cAMP increases NKCC2 surface expression by a mechanism involving VAMP and that NKCC2 trafficking to the apical membrane is involved in the stimulation of TAL NaCl absorption by cAMP.
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Affiliation(s)
- Pablo A Ortiz
- Hypertension and Vascular Research Division, Dept. of Internal Medicine, Henry Ford Hospital, 2799 W. Grand Blvd., Detroit, MI 48202, USA.
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Jeck N, Schlingmann KP, Reinalter SC, Kömhoff M, Peters M, Waldegger S, Seyberth HW. Salt handling in the distal nephron: lessons learned from inherited human disorders. Am J Physiol Regul Integr Comp Physiol 2005; 288:R782-95. [PMID: 15793031 DOI: 10.1152/ajpregu.00600.2004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The molecular basis of inherited salt-losing tubular disorders with secondary hypokalemia has become much clearer in the past two decades. Two distinct segments along the nephron turned out to be affected, the thick ascending limb of Henle's loop and the distal convoluted tubule, accounting for two major clinical phenotypes, hyperprostaglandin E syndrome and Bartter-Gitelman syndrome. To date, inactivating mutations have been detected in six different genes encoding for proteins involved in renal transepithelial salt transport. Careful examination of genetically defined patients (“human knockouts”) allowed us to determine the individual role of a specific protein and its contribution to the overall process of renal salt reabsorption. The recent generation of several genetically engineered mouse models that are deficient in orthologous genes further enabled us to compare the human phenotype with the animal models, revealing some unexpected interspecies differences. As the first line treatment in hyperprostaglandin E syndrome includes cyclooxygenase inhibitors, we propose some hypotheses about the mysterious role of PGE2in the etiology of renal salt-losing disorders.
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Affiliation(s)
- Nikola Jeck
- MD, Univ. Children's Hospital, Philipps-Univ., Deutschhausstrasse 12, D-35037 Marburg, Germany. )
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Garvin JL, Ortiz PA. The role of reactive oxygen species in the regulation of tubular function. ACTA ACUST UNITED AC 2004; 179:225-32. [PMID: 14616238 DOI: 10.1046/j.0001-6772.2003.01203.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UNLABELLED The phrase reactive oxygen species covers a number of molecules and atoms, including the quintessential member of the group, O2-; singlet oxygen; H2O2; organic peroxides; and OONO-. While nitric oxide (NO) is also technically a member of the reactive oxygen species family, it is generally considered with a different class of compounds and will not be considered here. To our knowledge, there are currently no published data reporting the effects of reactive oxygen species on net transepithelial flux in the proximal nephron. However, there is evidence that OONO- regulates Na+/K+ adenosine triphosphatase (ATPase) activity as well as paracellular permeability. While it is easy to speculate that such an effect on the pump would decrease net transepithelial solute and water reabsorption, one cannot do so without knowing how other transporters are affected. O2- stimulates NaCl absorption by the thick ascending limb by activating protein kinase C and blunting the effects of NO. The effects of O2- on thick ascending limb NaCl absorption may be important for the initiation of salt-sensitive hypertension. To our knowledge, there are no published data concerning the role of reactive oxygen species in the regulation of solute absorption in either the distal convoluted tubule or the collecting duct. However, OONO- inhibits basolateral K+ channels in the cortical collecting duct, although the net effect of such inhibition is unknown. CONCLUSION While the regulation of tubular transport by reactive oxygen species is important to overall salt and water balance, we know very little about where and how these regulators act along the nephron.
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Affiliation(s)
- J L Garvin
- Division of Hypertension and Vascular Research, Henry Ford Hospital, Detroit, MI, USA
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