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Slattery P, Frölich S, Goren I, Nüsing RM. Salt supplementation ameliorates developmental kidney defects in COX-2 −/− mice. Am J Physiol Renal Physiol 2017; 312:F1044-F1055. [DOI: 10.1152/ajprenal.00565.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/15/2017] [Accepted: 02/27/2017] [Indexed: 11/22/2022] Open
Abstract
Deficiency of cyclooxygenase-2 (COX-2) activity in the early postnatal period causes impairment of kidney development leading to kidney insufficiency. We hypothesize that impaired NaCl reabsorption during the first days of life is a substantial cause for nephrogenic defects observed in COX-2−/− mice and that salt supplementation corrects these defects. Daily injections of NaCl (0.8 mg·g−1·day−1) for the first 10 days after birth ameliorated impaired kidney development in COX-2−/− pups resulting in an increase in glomerular size and fewer immature superficial glomeruli. However, impaired renal subcortical growth was not corrected. Increasing renal tubular flow by volume load or injections of KCl did not relieve the renal histomorphological damage. Administration of torsemide and spironolactone also affected nephrogenesis resulting in diminished glomeruli and cortical thinning. Treatment of COX-2−/− pups with NaCl/DOCA caused a stronger mitigation of glomerular size and induced a slight but significant growth of cortical tissue mass. After birth, renal mRNA expression of NHE3, NKCC2, ROMK, NCCT, ENaC, and Na+/K+-ATPase increased relative to postnatal day 2 in wild-type mice. However, in COX-2−/− mice, a significantly lower expression was observed for NCCT, whereas NaCl/DOCA treatment significantly increased NHE3 and ROMK expression. Long-term effects of postnatal NaCl/DOCA injections indicate improved kidney function with normalization of pathologically enhanced creatinine and urea plasma levels; also, albumin excretion was observed. In summary, we present evidence that salt supplementation during the COX-2-dependent time frame of nephrogenesis partly reverses renal morphological defects in COX-2−/− mice and improves kidney function.
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Affiliation(s)
- Patrick Slattery
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt, Germany; and
| | - Stefanie Frölich
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt, Germany; and
| | - Itamar Goren
- Institute of Pharmacology and Toxicology, Goethe-University, Frankfurt, Germany
| | - Rolf M. Nüsing
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt, Germany; and
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Jesse NM, McCartney J, Feng X, Richards EM, Wood CE, Keller-Wood M. Expression of ENaC subunits, chloride channels, and aquaporins in ovine fetal lung: ontogeny of expression and effects of altered fetal cortisol concentrations. Am J Physiol Regul Integr Comp Physiol 2009; 297:R453-61. [PMID: 19515987 DOI: 10.1152/ajpregu.00127.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transition of the epithelium of the fetal lung from fluid secretion to fluid reabsorption requires changes in the expression of ion channels. Corticosteroids regulate expression of several of these channels, including the epithelium sodium channel (ENaC) subunits and aquaporins (AQP). We investigated the ontogenetic changes in these ion channels in the ovine fetal lung during the last half of gestation, a time of increasing adrenal maturation. Expression of the mRNAs for the chloride channels, cystic fibrosis transmembrane conductance regulator (CFTR), and chloride channel 2 (CLCN2) decreased with age. Expression of mRNAs for AQP1, AQP5, and for subunits of ENaC (alpha, beta, gamma) increased with age. In the fetal sheep the expression of ENaCbeta mRNA was dramatically higher than the expression of ENaCalpha or ENaCgamma, but expression of ENaCbeta protein decreased with maturation, although the ratio of the mature (112 kDa) to immature (102 kDa) ENaCbeta protein increased with age, particularly in the membrane fraction. In contrast, ENaCalpha mRNA and protein both increase with maturation, and the mature form of ENaCalpha (68 kDa) predominates at all ages. A modest increase in fetal cortisol, within the range expected to occur naturally in late gestation but prior to active labor, increased ENaCalpha mRNA but not ENaCbeta, ENaCgamma, or AQP mRNAs. We conclude that in the ovine fetal lung, appearance of functional sodium channels is associated with induction of ENACalpha and ENaCgamma, and that ENaCalpha expression may be induced by even small, preterm increases in fetal cortisol.
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Affiliation(s)
- Nathan M Jesse
- Department of Pediatrics, College of Medicine, University of Florida, Gainesville, Florida, USA
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Yeh J, Kim BS, Gaines L, Peresie J, Page C, Arroyo A. The expression of hyperpolarization activated cyclic nucleotide gated (HCN) channels in the rat ovary are dependent on the type of cell and the reproductive age of the animal: a laboratory investigation. Reprod Biol Endocrinol 2008; 6:35. [PMID: 18710573 PMCID: PMC2533335 DOI: 10.1186/1477-7827-6-35] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 08/18/2008] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Aim of this study was to test the hypothesis that levels of hyperpolarization activated cyclic nucleotide gated channels 1 to 4 (HCN1-4) are linked to the reproductive age of the ovary. METHODS Young, adult, and reproductively aged ovaries were collected from Sprague-Dawley rats. RT-PCR and western blot analysis of ovaries was performed to investigate the presence of mRNA and total protein for HCN1-4. Immunohistochemistry with semiquantitative H score analysis was performed using whole ovarian histologic sections. RESULTS RT-PCR analysis showed the presence of mRNA for HCN1-4. Western blot analysis revealed HCN1-3 proteins in all ages of ovarian tissues. Immunohistochemistry with H score analysis demonstrated distinct age-related changes in patterns of HCN1-3 in the oocytes, granulosa cells, theca cells, and corpora lutea. HCN4 was present only in the oocytes, with declining levels during the reproduction lifespan. CONCLUSION The evidence presented here demonstrates cell-type and developmental age patterns of HCN1-4 channel expression in rat ovaries. Based on this, we hypothesize that HCN channels have functional significance in rat ovaries and may have changing roles in reproductive aging.
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Affiliation(s)
- John Yeh
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
| | - Beom Su Kim
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
| | - Larry Gaines
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
| | - Jennifer Peresie
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
| | - Carly Page
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
| | - Armando Arroyo
- Department of Gynecology-Obstetrics, University at Buffalo, The State University of New York, Buffalo, New York, 14222, USA
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Abstract
PURPOSE OF REVIEW This review examines the maturational changes that occur in renal tubules during postnatal development. RECENT FINDINGS The ability to study transport in neonatal tubules and the use of molecular techniques have allowed studies that not only examine the mechanism of solute and water transport in neonates but also what causes the maturational changes in transport at a molecular and cellular level. SUMMARY This review demonstrates that there are significant quantitative and qualitative differences in transport during postnatal maturation in every nephron segment. In some segments the maturational changes involve simply a change in abundance of transporters, while in others the difference in transport is due to changes in transporter isoforms, changes in paracellular permeability or changes in intracellular signaling that regulate the transporter. This review focuses on these changes and what is known about what causes the maturational changes in transport.
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Affiliation(s)
- Michel Baum
- Departments of Pediatrics and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9063, USA.
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Nakamura K, Stokes JB, McCray PB. Endogenous and exogenous glucocorticoid regulation of ENaC mRNA expression in developing kidney and lung. Am J Physiol Cell Physiol 2002; 283:C762-72. [PMID: 12176733 DOI: 10.1152/ajpcell.00029.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lung liquid absorption at birth is crucial for the successful onset of respiration. Na absorption by the renal collecting duct plays an important role in renal fluid and electrolyte homeostasis during the early postnatal period. The epithelial Na channel (ENaC) plays a central role in mediating these functions, and its subunit expression is developmentally regulated in a temporal and tissue specific pattern. Several lines of evidence suggest that the prenatal increase in circulating glucocorticoids may play an important role in increasing ENaC expression during maturation. We tested the role of the prenatal surge using corticotropin-releasing hormone (CRH) knockout (KO) mice. Relative ENaC expression in lungs of KO mice increased at the same rate as in wild-type (WT) mice, but absolute expression was only 20-30% of WT. In contrast, relative and absolute expression of all three subunits in kidneys was not different between KO and WT mice. Dexamethasone (Dex) increased alpha-ENaC mRNA in fetal lung and kidney explants within 24 h but had different effects on beta- or gamma-ENaC. Dex increased beta- and gamma-ENaC in lung, but only after >48 h of exposure, and had no effect on kidney. The results suggest that the kidney metabolizes endogenous glucocorticoids, but the lung does not. Furthermore, the marked difference between lung and kidney responsiveness to glucocorticoids in beta- and gamma-ENaC expression suggests that factors other than steroids may be important in regulating functional ENaC expression during development.
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Affiliation(s)
- Kenzo Nakamura
- Department of Internal Medicine, University of Iowa College of Medicine and Veterans Affairs Medical Center, Iowa City 52242, USA
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Thomas CP, Loftus RW, Liu KZ, Itani OA. Genomic organization of the 5' end of human beta-ENaC and preliminary characterization of its promoter. Am J Physiol Renal Physiol 2002; 282:F898-909. [PMID: 11934701 DOI: 10.1152/ajprenal.00268.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mRNA for the beta-subunit of the epithelial Na(+) channel (beta-ENaC) is regulated developmentally and, in some tissues, in response to corticosteroids. To understand the mechanisms of transcriptional regulation of the human beta-ENaC gene, we characterized the 5' end of the gene and its 5'-flanking regions. Adaptor-ligated human kidney and lung cDNA were amplified by 5' rapid amplification of cDNA ends, and transcription start sites of two 5' variant transcripts were determined by nuclease protection or primer extension assays. Cosmid clones that contain the 5' end of the gene were isolated, and analysis of these clones indicated that alternate first exons approximately 1.5 kb apart and approximately 45 kb upstream of a common second exon formed the basis of these transcripts. Genomic fragments that included the proximal 5'-flanking region of either transcript were able to direct expression of a reporter gene in lung epithelia and to bind Sp1 in nuclear extracts, confirming the presence of separate promoters that regulate beta-ENaC expression.
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Affiliation(s)
- Christie P Thomas
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242-1081, USA.
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Velázquez H, Silva T, Andújar E, Desir GV, Ellison DH, Greger R. The distal convoluted tubule of rabbit kidney does not express a functional sodium channel. Am J Physiol Renal Physiol 2001; 280:F530-9. [PMID: 11181416 DOI: 10.1152/ajprenal.2001.280.3.f530] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We sought to assess whether the distal convoluted tubule (DCT) segment of the rabbit nephron expresses a functional epithelial sodium channel. First, the transepithelial voltage (V(te), lumen vs. bath) was measured in isolated perfused DCT segments (assessed separately in the upstream half and the downstream half of the DCT). V(te) was zero and not affected by amiloride or barium in the upstream DCT. V(te) was sometimes negative in the downstream DCT and depolarized by amiloride and hyperpolarized by barium, suggesting inclusion of connecting tubule (CNT) cells. To determine expression of epithelial sodium channel (ENaC) mRNA subunits by the upstream DCT, rabbit alpha-, beta-, and gamma-ENaC cDNA fragments were cloned and primers were selected for single-nephron RT-PCR analysis. Although alpha-ENaC was expressed by the DCT, beta- and gamma-ENaC were not detected in the DCT. In contrast, the CNT, CCD, and outer medullary collecting duct (OMCD) expressed all three subunits. Nedd4 was also not detected in the DCT but was expressed by the CNT, CCD, and OMCD. When upstream DCT fragments were grown to confluent monolayers in primary culture, the epithelia exhibited negative voltages and high transepithelial resistances and expressed mRNA for all three ENaC subunits as well as for Nedd4. The absence of a negative voltage and failure to detect transcript for beta- and gamma-ENaC and Nedd4 in the native rabbit DCT suggest that the sodium channel is not a significant pathway for sodium absorption by this segment. The phenotype conversion observed when DCT cells are grown in culture does not rule out the possibility that there may be conditions in which the DCT in the intact kidney expresses sodium channel activity. The results are consistent with the notion that DCT sodium transport is predominantly, if not exclusively, electroneutral.
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Affiliation(s)
- H Velázquez
- Renal Research, Veterans Affairs Connecticut Healthcare System, Research Office 151, West Haven, CT 06516, USA.
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Abstract
Embryonic epithelial membrane transporters are organized into transporter families that are functional in several epithelial organs, namely, in kidney, lung, pancreas, intestine, and salivary gland. Family members (subtypes) are developmentally expressed in plasma membranes in temporospatial patterns that are 1) similar for one subtype within different organs, like aquaporin-1 (AQP1) in lung and kidney; 2) different between subtypes within the same organ, like the amiloride-sensitive epithelial sodium channel (ENaC) in lung; and 3) apparently matched among members of different transporter families, as alpha-ENaC with AQP1 and -4 in lung and with AQP2 in kidney. Finally, comparison of temporal expression patterns in early embryonic development of transporters from different families [e.g., cystic fibrosis transmembrane conductance regulator (CFTR), ENaC, and outer medullary potassium channel] suggests regulatory activating or inactivating interactions in defined morphogenic periods. This review focuses on embryonic patterns, at the mRNA and immunoprotein level, of the following transporter entities expressed in epithelial cell plasma membranes: ENaC; the chloride transporters CFTR, ClC-2, bumetanide-sensitive Na-K-Cl cotransporter, Cl/OH, and Cl/HCO(3); the sodium glucose transporter-glucose transporter; the sodium/hydrogen exchanger; the sodium-phosphate cotransporter; the ATPases; and AQP. The purpose of this article is to relate temporal and spatial expression patterns in embryonic and in early postnatal epithelia to developmental changes in organ structure and function.
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Affiliation(s)
- M Horster
- Ludwig-Maximilians-Universität München, D-80336 Munich, Germany.
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Husted RF, Sigmund RD, Stokes JB. Mechanisms of inactivation of the action of aldosterone on collecting duct by TGF-beta. Am J Physiol Renal Physiol 2000; 278:F425-33. [PMID: 10710547 DOI: 10.1152/ajprenal.2000.278.3.f425] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of these experiments was to investigate the mechanisms whereby transforming growth factor-beta (TGF-beta) antagonizes the action of adrenocorticoid hormones on Na(+) transport by the rat inner medullary collecting duct in primary culture. Steroid hormones 1) increased Na(+) transport by three- to fourfold, 2) increased the maximum capacity of the Na(+)-K(+) pump by 30-50%, 3) increased the steady-state levels of the alpha(1)-subunit of the Na(+)-K(+)-ATPase by approximately 30%, and 4) increased the steady-state levels of the alpha-subunit of the rat epithelial Na(+) channel (alpha-rENaC) by nearly fourfold. TGF-beta blocked the effects of steroids on the increase in Na(+) transport and the stimulation of the Na(+)-K(+)-ATPase and pump capacity. However, there was no effect of TGF-beta on the steroid-induced increase in mRNA levels of alpha-rENaC. The effects of TGF-beta were not secondary to the decrease in Na(+) transport per se, inasmuch as benzamil inhibited the increase in Na(+) transport but did not block the increase in pump capacity or Na(+)-K(+)-ATPase mRNA. The results indicate that TGF-beta does not inactivate the steroid receptor or its translocation to the nucleus. Rather, they indicate complex pathways involving interruption of the enhancement of pump activity and activation/inactivation of pathways distal to the steroid-induced increase in the transcription of alpha-rENaC.
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Affiliation(s)
- R F Husted
- Department of Internal Medicine, University of Iowa, and Department of Veterans Affairs Medical Center, Iowa City, Iowa 52242, USA
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Horisberger JD. Chapter 11 Electrogenic transepithelial Na+ transport in the colon. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50013-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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