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Chang HF, Cheng JY. Glioblastoma U-87 cell electrotaxis is hindered by doxycycline with a concomitant reduction in the matrix metallopeptidase-9 expression. Biochem Biophys Rep 2024; 38:101690. [PMID: 38571555 PMCID: PMC10987802 DOI: 10.1016/j.bbrep.2024.101690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024] Open
Abstract
Electric fields (EF) play an essential role in cancer cell migration. Numerous cancer cell types exhibit electrotaxis under direct current electric fields (dcEF) of physiological electric field strength (EFs). This study investigated the effects of doxycycline on the electrotactic responses of U87 cells. After EF stimulation, U87 cells migrated toward the cathode, whereas doxycycline-treated U87 cells exhibited enhanced cell mobility but hindered cathodal migration. We further investigated the expression of the metastasis-correlated proteins matrix metallopeptidase-2 (MMP-2) and MMP-9 in U87 cells. The levels of MMP-2 in the cells were not altered under EF or doxycycline stimulation. In contrast, the EF stimulation greatly enhanced the levels of MMP-9 and then repressed in doxycycline-cotreated cells, accompanied by reduced cathodal migration. Our results demonstrated that an antibiotic at a non-toxic concentration could suppress the enhanced cell migration accelerated by EF of physiological strength. This finding may be applied as an anti-metastatic treatment for cancers.
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Affiliation(s)
- Hui-Fang Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
| | - Ji-Yen Cheng
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Institute of Biophotonics, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung, Taiwan
- College of Engineering, Chang Gung University, Taoyuan, Taiwan
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2
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Hibberd TJ, Ramsay S, Spencer-Merris P, Dinning PG, Zagorodnyuk VP, Spencer NJ. Circadian rhythms in colonic function. Front Physiol 2023; 14:1239278. [PMID: 37711458 PMCID: PMC10498548 DOI: 10.3389/fphys.2023.1239278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/17/2023] [Indexed: 09/16/2023] Open
Abstract
A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are subject to entrainment by a multitude of factors, many of which are directly or indirectly controlled by the light-entrainable clock located in the suprachiasmatic nucleus of the hypothalamus. Peripheral clocks occur in the gastrointestinal tract, notably the epithelia whose functions include regulation of absorption, permeability, and secretion of hormones; and in the myenteric plexus, which is the intrinsic neural network principally responsible for the coordination of muscular activity in the gut. This review focuses on the physiological circadian variation of major colonic functions and their entraining mechanisms, including colonic motility, absorption, hormone secretion, permeability, and pain signalling. Pathophysiological states such as irritable bowel syndrome and ulcerative colitis and their interactions with circadian rhythmicity are also described. Finally, the classic circadian hormone melatonin is discussed, which is expressed in the gut in greater quantities than the pineal gland, and whose exogenous use has been of therapeutic interest in treating colonic pathophysiological states, including those exacerbated by chronic circadian disruption.
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Affiliation(s)
- Timothy J. Hibberd
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Stewart Ramsay
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | | | - Phil G. Dinning
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
- Colorectal Surgical Unit, Division of Surgery, Flinders Medical Centre, Adelaide, SA, Australia
| | | | - Nick J. Spencer
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
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Spradling-Reeves KD, Shade RE, Haywood JR, Cox LA. Primate response to angiotensin infusion and high sodium intake differ by sodium lithium countertransport phenotype. ACTA ACUST UNITED AC 2017; 11:178-184. [PMID: 28238630 DOI: 10.1016/j.jash.2017.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/05/2017] [Accepted: 01/24/2017] [Indexed: 11/18/2022]
Abstract
An increased level of sodium-lithium countertransport (SLC) activity has been associated with salt-sensitive hypertension. Previous findings have suggested that dysregulation of the renin-angiotensin-aldosterone system (RAAS) may be involved in the mechanism linking elevated SLC activity and hypertension. Therefore, baboons with different levels of SLC activity were given two diets differing in sodium content, with and without an angiotensin II (ANG II) infusion, to investigate the relationship between SLC activity, the RAAS, and physiological regulation by sodium. Although we anticipated that high SLC activity would be associated with inappropriate function of the RAAS and greater arterial pressure sensitivity to dietary sodium and ANG II and that low SLC activity would be associated with the least BP sensitivity, we found that the low SLC phenotype correlated with BP sensitivity similar to the high SLC phenotype, and the normal SLC phenotype showed the least BP sensitivity to dietary sodium and ANG II.
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Affiliation(s)
| | - Robert E Shade
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Joseph R Haywood
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - Laura A Cox
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX, USA; Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
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4
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Keppner A, Andreasen D, Mérillat AM, Bapst J, Ansermet C, Wang Q, Maillard M, Malsure S, Nobile A, Hummler E. Epithelial Sodium Channel-Mediated Sodium Transport Is Not Dependent on the Membrane-Bound Serine Protease CAP2/Tmprss4. PLoS One 2015; 10:e0135224. [PMID: 26309024 PMCID: PMC4550455 DOI: 10.1371/journal.pone.0135224] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 07/20/2015] [Indexed: 01/27/2023] Open
Abstract
The membrane-bound serine protease CAP2/Tmprss4 has been previously identified in vitro as a positive regulator of the epithelial sodium channel (ENaC). To study its in vivo implication in ENaC-mediated sodium absorption, we generated a knockout mouse model for CAP2/Tmprss4. Mice deficient in CAP2/Tmprss4 were viable, fertile, and did not show any obvious histological abnormalities. Unexpectedly, when challenged with sodium-deficient diet, these mice did not develop any impairment in renal sodium handling as evidenced by normal plasma and urinary sodium and potassium electrolytes, as well as normal aldosterone levels. Despite minor alterations in ENaC mRNA expression, we found no evidence for altered proteolytic cleavage of ENaC subunits. In consequence, ENaC activity, as monitored by the amiloride-sensitive rectal potential difference (ΔPD), was not altered even under dietary sodium restriction. In summary, ENaC-mediated sodium balance is not affected by lack of CAP2/Tmprss4 expression and thus, does not seem to directly control ENaC expression and activity in vivo.
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Affiliation(s)
- Anna Keppner
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Ditte Andreasen
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Anne-Marie Mérillat
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Julie Bapst
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Camille Ansermet
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Qing Wang
- Department of Medicine/Division of Nephrology and Hypertension, Lausanne University Hospital (CHUV), Lausanne, Switzerland
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland
| | - Marc Maillard
- Department of Medicine/Division of Nephrology and Hypertension, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Sumedha Malsure
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Antoine Nobile
- Institut Universitaire de Pathologie, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology & Toxicology, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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5
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Frindt G, Palmer LG. Acute effects of aldosterone on the epithelial Na channel in rat kidney. Am J Physiol Renal Physiol 2014; 308:F572-8. [PMID: 25520012 DOI: 10.1152/ajprenal.00585.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The acute effects of aldosterone administration on epithelial Na channels (ENaC) in rat kidney were examined using electrophysiology and immunodetection. Animals received a single injection of aldosterone (20 μg/kg body wt), which reduced Na excretion over the next 3 h. Channel activity was assessed in principal cells of cortical collecting ducts as amiloride-sensitive whole cell clamp current (INa). INa averaged 100 pA/cell, 20-30% of that reported for the same preparation under conditions of chronic stimulation. INa was negligible in control animals that did not receive hormone. The acute physiological response correlated with changes in ENaC processing and trafficking. These effects included increases in the cleaved forms of α-ENaC and γ-ENaC, assessed by Western blot, and increases in the surface expression of β-ENaC and γ-ENaC measured after surface protein biotinylation. These changes were qualitatively and quantitatively similar to those of chronic stimulation. This suggests that altered trafficking to or from the apical membrane is an early response to the hormone and that later increases in channel activity require stimulation of channels residing at the surface.
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Affiliation(s)
- Gustavo Frindt
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
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Kim MS, Lee MH, Kwon BJ, Seo HJ, Koo MA, You KE, Kim D, Park JC. Effects of direct current electric-field using ITO plate on breast cancer cell migration. Biomater Res 2014; 18:10. [PMID: 26331061 PMCID: PMC4549139 DOI: 10.1186/2055-7124-18-10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 07/09/2014] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Cell migration is an essential activity of the cells in various biological phenomena. The evidence that electrotaxis plays important roles in many physiological phenomena is accumulating. In electrotaxis, cells move with a directional tendency toward the anode or cathode under direct-current electric fields. Indium tin oxide, commonly referred to as ITO has high luminous transmittance, high infrared reflectance, good electrical conductivity, excellent substrate adherence, hardness and chemical inertness and hence, have been widely and intensively studied for many years. Because of these properties of ITO films, the electrotaxis using ITO plate was evaluated. RESULTS Under the 0 V/cm condition, MDA-MB-231 migrated randomly in all directions. When 1 V/cm of dc EF was applied, cells moved toward anode. The y forward migration index was -0.046 ± 0.357 under the 0 V/cm and was 0.273 ± 0.231 under direct-current electric field of 1 V/cm. However, the migration speed of breast cancer cell was not affected by direct-current electric field using ITO plate. CONCLUSIONS In this study, we designed a new electrotaxis system using an ITO coated glass and observed the migration of MDA-MB-231 on direct current electric-field of the ITO glass.
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Affiliation(s)
- Min Sung Kim
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Mi Hee Lee
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Byeong-Ju Kwon
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Hyok Jin Seo
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Min-Ah Koo
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Kyung Eun You
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Dohyun Kim
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
| | - Jong-Chul Park
- Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea ; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 Korea
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7
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Rossier BC. Epithelial sodium channel (ENaC) and the control of blood pressure. Curr Opin Pharmacol 2014; 15:33-46. [DOI: 10.1016/j.coph.2013.11.010] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 11/29/2022]
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8
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Malsure S, Wang Q, Charles RP, Sergi C, Perrier R, Christensen BM, Maillard M, Rossier BC, Hummler E. Colon-specific deletion of epithelial sodium channel causes sodium loss and aldosterone resistance. J Am Soc Nephrol 2014; 25:1453-64. [PMID: 24480829 DOI: 10.1681/asn.2013090936] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Aldosterone promotes electrogenic sodium reabsorption through the amiloride-sensitive epithelial sodium channel (ENaC). Here, we investigated the importance of ENaC and its positive regulator channel-activating protease 1 (CAP1/Prss8) in colon. Mice lacking the αENaC subunit in colonic superficial cells (Scnn1a(KO)) were viable, without fetal or perinatal lethality. Control mice fed a regular or low-salt diet had a significantly higher amiloride-sensitive rectal potential difference (∆PDamil) than control mice fed a high-salt diet. In Scnn1a(KO) mice, however, this salt restriction-induced increase in ∆PDamil did not occur, and the circadian rhythm of ∆PDamil was blunted. Plasma and urinary sodium and potassium did not change with regular or high-salt diets or potassium loading in control or Scnn1a(KO) mice. However, Scnn1a(KO) mice fed a low-salt diet lost significant amounts of sodium in their feces and exhibited high plasma aldosterone and increased urinary sodium retention. Mice lacking the CAP1/Prss8 in colonic superficial cells (Prss8(KO)) were viable, without fetal or perinatal lethality. Compared with controls, Prss8(KO) mice fed regular or low-salt diets exhibited significantly reduced ∆PDamil in the afternoon, but the circadian rhythm was maintained. Prss8(KO) mice fed a low-salt diet also exhibited sodium loss through feces and higher plasma aldosterone levels. Thus, we identified CAP1/Prss8 as an in vivo regulator of ENaC in colon. We conclude that, under salt restriction, activation of the renin-angiotensin-aldosterone system in the kidney compensated for the absence of ENaC in colonic surface epithelium, leading to colon-specific pseudohypoaldosteronism type 1 with mineralocorticoid resistance without evidence of impaired potassium balance.
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Affiliation(s)
- Sumedha Malsure
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Qing Wang
- Service of Nephrology, University Hospital of Lausanne (CHUV), Lausanne, Switzerland; and Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Roch-Philippe Charles
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Chloe Sergi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Romain Perrier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | | | - Marc Maillard
- Service of Nephrology, University Hospital of Lausanne (CHUV), Lausanne, Switzerland; and
| | - Bernard C Rossier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland;
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Pácha J, Sumová A. Circadian regulation of epithelial functions in the intestine. Acta Physiol (Oxf) 2013; 208:11-24. [PMID: 23461998 DOI: 10.1111/apha.12090] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/21/2013] [Accepted: 02/21/2013] [Indexed: 12/24/2022]
Abstract
Many physiological functions exhibit a diurnal rhythmicity that is influenced by biological clocks and feeding rhythms. In this review, we discuss the growing evidence showing the important role of circadian rhythms in regulating intestinal mucosa. First, we introduce the molecular timing system and the interrelationship between the master biological clock in the suprachiasmatic nuclei of the brain and the peripheral intestinal clock and provide evidence that the intestinal clock is entrained with the external environment. Second, we review the circadian rhythmicity of enterocyte proliferation and the largely unknown regulatory mechanisms behind these rhythms. Finally, we focus on the circadian clock control of food processing that functions by regulating the expression of digestive enzymes and intestinal nutrient and salt transporters. The concepts to be discussed highlight the ability of the intestinal epithelium to utilize self-sustained clock signals together with signals associated with changes in the cellular environment and to use endogenous temporal control of the gastrointestinal functions to meet varying physiological and pathophysiological demands. The fact that internal de-synchronizations within the body, such as those that occur in shift workers or with changes in food intake behaviour, are often associated with malfunctions of the gastrointestinal tract indicates that more information about the connections between the circadian clock and intestinal mucosa/transporting enterocytes could provide clues for future therapies.
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Affiliation(s)
- J. Pácha
- Institute of Physiology; Academy of Sciences of the Czech Republic; Prague; Czech Republic
| | - A. Sumová
- Institute of Physiology; Academy of Sciences of the Czech Republic; Prague; Czech Republic
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10
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The effect of endogenous angiotensin II on alveolar fluid clearance in rats with acute lung injury. Can Respir J 2013; 19:311-8. [PMID: 23061076 DOI: 10.1155/2012/951025] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND In acute lung injury (ALI), angiotensin II (Ang II) plays a vital role in the stimulation of pulmonary permeability edema formation through the angiotensin type 1 (AT1) receptor. The effect of Ang II on alveolar fluid clearance (AFC) in ALI remains unknown. METHODS Sprague Dawley rats were anesthetized and intratracheally injected with 1 mg⁄kg lipopolysaccharide (LPS), while control rats received saline. The AT1 receptor antagonist ZD7155 was injected intraperitoneally (10 mg⁄kg) 30 min before LPS administration. The lungs were isolated for AFC measurement, and alpha-epithelial sodium channel (ENaC) messenger RNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot. RESULTS LPS-induced ALI caused an increase in Ang II levels in plasma and lung tissue but a decrease in AFC. The time course of Ang II levels paralleled that of AFC. Pretreatment with ZD7155 prevented ALI-induced reduction of AFC. ZD7155 also reversed the ALI-induced reduction of beta-ENaC and gamma-ENaC levels, and further decreased alpha-ENaC levels. CONCLUSIONS These findings suggest that endogenous Ang II inhibits AFC and dysregulates ENaC expression via AT1 receptors, which contribute to alveolar filling and pulmonary edema in LPS-induced ALI.
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11
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Frateschi S, Keppner A, Malsure S, Iwaszkiewicz J, Sergi C, Merillat AM, Fowler-Jaeger N, Randrianarison N, Planès C, Hummler E. Mutations of the serine protease CAP1/Prss8 lead to reduced embryonic viability, skin defects, and decreased ENaC activity. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:605-15. [PMID: 22705055 DOI: 10.1016/j.ajpath.2012.05.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 04/23/2012] [Accepted: 05/02/2012] [Indexed: 11/17/2022]
Abstract
CAP1/Prss8 is a membrane-bound serine protease involved in the regulation of several different effectors, such as the epithelial sodium channel ENaC, the protease-activated receptor PAR2, the tight junction proteins, and the profilaggrin polypeptide. Recently, the V170D and the G54-P57 deletion mutations within the CAP1/Prss8 gene, identified in mouse frizzy (fr) and rat hairless (fr(CR)) animals, respectively, have been proposed to be responsible for their skin phenotypes. In the present study, we analyzed those mutations, revealing a change in the protein structure, a modification of the glycosylation state, and an overall reduction in the activation of ENaC of the two mutant proteins. In vivo analyses demonstrated that both fr and fr(CR) mutant animals present analogous reduction of embryonic viability, similar histologic aberrations at the level of the skin, and a significant decrease in the activity of ENaC in the distal colon compared with their control littermates. Hairless rats additionally had dehydration defects in skin and intestine and significant reduction in the body weight. In conclusion, we provided molecular and functional evidence that CAP1/Prss8 mutations are accountable for the defects in fr and fr(CR) animals, and we furthermore demonstrate a decreased function of the CAP1/Prss8 mutant proteins. Therefore, fr and fr(CR) animals are suitable models to investigate the consequences of CAP1/Prss8 action on its target proteins in the whole organism.
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Affiliation(s)
- Simona Frateschi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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12
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Wang Q, Domenighetti AA, Schäfer SC, Weber J, Simon A, Maillard MP, Pedrazzini T, Chen J, Lehr HA, Burnier M. Impact of salt on cardiac differential gene expression and coronary lesion in normotensive mineralocorticoid-treated mice. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1025-33. [DOI: 10.1152/ajpregu.00387.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We previously reported that excess of deoxycorticosterone-acetate (DOCA)/salt-induced cardiac hypertrophy in the absence of hypertension in one-renin gene mice. This model allows us to study molecular mechanisms of high-salt intake in the development of cardiovascular remodeling, independently of blood pressure in a high mineralocorticoid state. In this study, we compared the effect of 5-wk low- and high-salt intake on cardiovascular remodeling and cardiac differential gene expression in mice receiving the same amount of DOCA. Differential gene and protein expression was measured by high-density cDNA microarray assays, real-time PCR and Western blot analysis in DOCA-high salt (HS) vs. DOCA-low salt (LS) mice. DOCA-HS mice developed cardiac hypertrophy, coronary perivascular fibrosis, and left ventricular dysfunction. Differential gene and protein expression demonstrated that high-salt intake upregulated a subset of genes encoding for proteins involved in inflammation and extracellular matrix remodeling (e.g., Col3a1, Col1a2, Hmox1, and Lcn2). A major subset of downregulated genes encoded for transcription factors, including myeloid differentiation primary response (MyD) genes. Our data provide some evidence that vascular remodeling, fibrosis, and inflammation are important consequences of a high-salt intake in DOCA mice. Our study suggests that among the different pathogenic factors of cardiac and vascular remodeling, such as hypertension and mineralocorticoid excess and sodium intake, the latter is critical for the development of the profibrotic and proinflammatory phenotype observed in the heart of normotensive DOCA-treated mice.
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Affiliation(s)
- Qing Wang
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
- Huazhong University of Science and Technology, Wuhan, China
| | | | | | - Johanns Weber
- The Lausanne DNA Array Facility, University of Lausanne, Switzerland
| | - Alexandra Simon
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Marc P. Maillard
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | | | - Ju Chen
- Department of Medicine, University of California, San Diego, La Jolla, California
| | | | - Michel Burnier
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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Firsov D, Tokonami N, Bonny O. Role of the renal circadian timing system in maintaining water and electrolytes homeostasis. Mol Cell Endocrinol 2012; 349:51-5. [PMID: 21763748 DOI: 10.1016/j.mce.2011.06.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 06/29/2011] [Accepted: 06/29/2011] [Indexed: 11/24/2022]
Abstract
Many basic physiological functions exhibit circadian rhythmicity. These functional rhythms are driven, in part, by the circadian clock, an ubiquitous molecular mechanism allowing cells and tissues to anticipate regular environmental events and to prepare for them. This mechanism has been shown to play a particularly important role in maintaining stability (homeostasis) of internal conditions. Because the homeostatic equilibrium is continuously challenged by environmental changes, the role of the circadian clock is thought to consist in the anticipative adjustment of homeostatic pathways in relation with the 24h environmental cycle. The kidney is the principal organ responsible for the regulation of the composition and volume of extracellular fluids (ECF). Several major parameters of kidney function, including renal plasma flow (RPF), glomerular filtration rate (GFR) and tubular reabsorption and secretion have been shown to exhibit strong circadian oscillations. Recent evidence suggest that the circadian clock can be involved in generation of these rhythms through external circadian time cues (e.g. humoral factors, activity and body temperature rhythms) or, trough the intrinsic renal circadian clock. Here, we discuss the role of renal circadian mechanisms in maintaining homeostasis of water and three major ions, namely, Na(+), K(+) and Cl(-).
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Affiliation(s)
- Dmitri Firsov
- Department of Pharmacology and Toxicology, University of Lausanne, 1005 Lausanne, Switzerland.
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Soták M, Polidarová L, Musílková J, Hock M, Sumová A, Pácha J. Circadian regulation of electrolyte absorption in the rat colon. Am J Physiol Gastrointest Liver Physiol 2011; 301:G1066-74. [PMID: 21903759 DOI: 10.1152/ajpgi.00256.2011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal transport of nutrients exhibits distinct diurnal rhythmicity, and the enterocytes harbor a circadian clock. However, temporal regulation of the genes involved in colonic ion transport, i.e., ion transporters and channels operating in absorption and secretion, remains poorly understood. To address this issue, we assessed the 24-h profiles of expression of genes encoding the sodium pump (subunits Atp1a1 and Atp1b1), channels (α-, β-, and γ-subunits of Enac and Cftr), transporters (Dra, Ae1, Nkcc1, Kcc1, and Nhe3), and the Na(+)/H(+) exchanger (NHE) regulatory factor (Nherf1) in rat colonic mucosa. Furthermore, we investigated temporal changes in the spatial localization of the clock genes Per1, Per2, and Bmal1 and the genes encoding ion transporters and channels along the crypt axis. In rats fed ad libitum, the expression of Atp1a1, γEnac, Dra, Ae1, Nhe3, and Nherf1 showed circadian variation with maximal expression at circadian time 12, i.e., at the beginning of the subjective night. The peak γEnac expression coincided with the rise in plasma aldosterone. Restricted feeding phase advanced the expression of Dra, Ae1, Nherf, and γEnac and decreased expression of Atp1a1. The genes Atp1b1, Cftr, αEnac, βEnac, Nkcc1, and Kcc1 did not show any diurnal variations in mRNA levels. A low-salt diet upregulated the expression of βEnac and γEnac during the subjective night but did not affect expression of αEnac. Similarly, colonic electrogenic Na(+) transport was much higher during the subjective night than the subjective day. These findings indicate that the transporters and channels operating in NaCl absorption undergo diurnal regulation and suggest a role of an intestinal clock in the coordination of colonic NaCl absorption.
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Affiliation(s)
- M Soták
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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15
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Deng J, Wang DX, Deng W, Li CY, Tong J, Ma H. Regulation of alveolar fluid clearance and ENaC expression in lung by exogenous angiotensin II. Respir Physiol Neurobiol 2011; 181:53-61. [PMID: 22138610 DOI: 10.1016/j.resp.2011.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Revised: 11/17/2011] [Accepted: 11/18/2011] [Indexed: 01/11/2023]
Abstract
Angiotensin II (Ang II) has been demonstrated as a pro-inflammatory effect in acute lung injury, but studies of the effect of Ang II on the formation of pulmonary edema and alveolar filling remains unclear. Therefore, in this study the regulation of alveolar fluid clearance (AFC) and the expression of epithelial sodium channel (ENaC) by exogenous Ang II was verified. SD rats were anesthetized and were given Ang II with increasing doses (1, 10 and 100 μg/kg per min) via osmotic minipumps, whereas control rats received only saline vehicle. AT1 receptor antagonist ZD7155 (10 mg/kg) and inhibitor of cAMP degeneration rolipram (1 mg/kg) were injected intraperitoneally 30 min before administration of Ang II. The lungs were isolated for measurement of alveolar fluid clearance. The mRNA and protein expression of ENaC were detected by RT-PCR and Western blot. Exposure to higher doses of Ang II reduced AFC in a dose-dependent manner and resulted in a non-coordinate regulation of α-ENaC vs. the regulation of β- and γ-ENaC, however Ang II type 1 (AT1) receptor antagonist ZD7155 prevented the Ang II-induced inhibition of fluid clearance and dysregulation of ENaC expression. In addition, exposure to inhibitor of cAMP degradation rolipram blunted the Ang II-induced inhibition of fluid clearance. These results indicate that through activation of AT(1) receptor, exogenous Ang II promotes pulmonary edema and alveolar filling by inhibition of alveolar fluid clearance via downregulation of cAMP level and dysregulation of ENaC expression.
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Affiliation(s)
- Jia Deng
- Department of Respiratory Medicine, Second Affiliated of Chongqing Medical University, Chongqing, China
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16
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Brown MB, Haack KKV, Pollack BP, Millard-Stafford M, McCarty NA. Low abundance of sweat duct Cl- channel CFTR in both healthy and cystic fibrosis athletes with exceptionally salty sweat during exercise. Am J Physiol Regul Integr Comp Physiol 2011; 300:R605-15. [PMID: 21228336 PMCID: PMC3064278 DOI: 10.1152/ajpregu.00660.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 01/06/2011] [Indexed: 11/22/2022]
Abstract
To understand potential mechanisms explaining interindividual variability observed in human sweat sodium concentration ([Na(+)]), we investigated the relationship among [Na(+)] of thermoregulatory sweat, plasma membrane expression of Na(+) and Cl(-) transport proteins in biopsied human eccrine sweat ducts, and basal levels of vasopressin (AVP) and aldosterone. Lower ductal luminal membrane expression of the Cl(-) channel cystic fibrosis transmembrane conductance regulator (CFTR) was observed in immunofluorescent staining of sweat glands from healthy young adults identified as exceptionally "salty sweaters" (SS) (n = 6, P < 0.05) and from patients with cystic fibrosis (CF) (n = 6, P < 0.005) compared with ducts from healthy young adults with "typical" sweat [Na(+)] (control, n = 6). Genetic testing of healthy subjects did not reveal any heterozygotes ("carriers") for any of the 39 most common disease-causing CFTR mutations in the United States. SS had higher baseline plasma [AVP] compared with control (P = 0.029). Immunostaining to investigate a potential relationship between higher plasma [AVP] (and sweat [Na(+)]) and ductal membrane aquaporin-5 revealed for all groups a relatively sparse and location-dependent ductal expression of the water channel with localization primarily to the secretory coil. Availability of CFTR for NaCl transport across the ductal membrane appears related to the significant physiological variability observed in sweat salt concentration in apparently healthy humans. At present, a heritable link between healthy salty sweaters and the most prevalent disease-causing CFTR mutations cannot be established.
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Affiliation(s)
- Mary Beth Brown
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, USA.
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Wang Q, Maillard M, Schibler U, Burnier M, Gachon F. Cardiac hypertrophy, low blood pressure, and low aldosterone levels in mice devoid of the three circadian PAR bZip transcription factors DBP, HLF, and TEF. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1013-9. [DOI: 10.1152/ajpregu.00241.2010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cardiovascular system is under the control of the circadian clock, and disturbed circadian rhythms can induce cardiovascular pathologies. This cyclic regulation is probably brought about by the circadian expression of genes encoding enzymes and regulators involved in cardiovascular functions. We have previously shown that the rhythmic transcription of output genes is, in part, regulated by the clock-controlled PAR bZip transcription factors DBP (albumin D-site binding protein), HLF (hepatic leukemia factor), and TEF (thyrotroph embryonic factor). The simultaneous deletion of all three PAR bZip transcription factors leads to increased morbidity and shortened life span. In the present study, we demonstrate that Dbp/ Tef/ Hlf triple knockout mice develop cardiac hypertrophy and left ventricular dysfunction associated with a low blood pressure. These dysfunctions are exacerbated by an abnormal response to this low blood pressure characterized by low aldosterone levels. The phenotype of PAR bZip knockout mice highlights the importance of circadian regulators in the modulation of cardiovascular functions.
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Affiliation(s)
- Qing Wang
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois, Lausanne
- Huazhong University of Science and Technology, Wuhan, China
| | - Marc Maillard
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois, Lausanne
| | - Ueli Schibler
- Department of Molecular Biology and National Center of Competence Research Frontiers in Genetics, University of Geneva, Geneva
| | - Michel Burnier
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois, Lausanne
| | - Frédéric Gachon
- Department of Molecular Biology and National Center of Competence Research Frontiers in Genetics, University of Geneva, Geneva
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; and
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Musch MW, Li YC, Chang EB. Angiotensin II directly regulates intestinal epithelial NHE3 in Caco2BBE cells. BMC PHYSIOLOGY 2009; 9:5. [PMID: 19338654 PMCID: PMC2669048 DOI: 10.1186/1472-6793-9-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 04/01/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Angiotensin II (AII) effects on intestinal Na+ transport may be multifactorial. To determine if AII might have a direct effect on intestinal epithelial Na+ transport, we investigated its actions on Na+ transport in human intestinal epithelial Caco2BBE cells. RESULTS AII increased apical (brush border) sodium-hydrogen exchanger (NHE)-3, but not NHE2, activity within one hour. Similarly, only apical membrane NHE3 abundance increased at 1-2 hours without any change in total NHE3 protein abundance. From 4-48 hours, AII stimulated progressively larger increases in apical NHE3 activity and surface abundance, which was associated with increases in NHE3 protein expression. At 4-24 hours, NHE3 mRNA increases over baseline expression, suggesting increased gene transcription. This was supported by AII induced increases in rat NHE3 gene promoter-reporter activity. AII induction of NHE3 was blocked by the AII type I receptor antagonist losartan. Acute changes in AII-induced increases in NHE3 exocytosis were blocked by a phospholipase C inhibitor, an arachidonic acid cytochrome P450 epoxygenase inhibitor, as well as phosphatidylinositol 3 kinase (PI3K) inhibitors and Akt inhibitor, partially blocked by a metalloproteinase inhibitor and an EGF (epidermal growth factor) receptor kinase inhibitor, but not affected by an inhibitor of MEK-1 (MAPKK-1, mitogen activated protein kinase kinase-1). CONCLUSION We conclude that angiotensin II has a direct role in regulating intestinal fluid and electrolyte absorption which may contribute to its overall effects in regulation systemic volume and blood pressure. AII activates several key signaling pathways that induce acute and chronic changes in NHE3 membrane trafficking and gene transcription.
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Affiliation(s)
- Mark W Musch
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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Cincunegui LM, Ituarte LMI, Viera TB, Ibañez JE, Carra GE, Saldeña TA, Saravi FD. Effects of chronic hypoxia on electrogenic transport and transport-related oxygen consumption in rat distal colon. Dig Dis Sci 2008; 53:1593-600. [PMID: 17939049 DOI: 10.1007/s10620-007-0042-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Accepted: 09/26/2007] [Indexed: 12/09/2022]
Abstract
The distal colon epithelium of rats submitted to chronic hypoxia shows higher short-circuit current (Isc) which, unlike non-hypoxic rat epithelium, has an amiloride-sensitive component despite low serum aldosterone levels. Isc and oxygen consumption (QO2) were simultaneously measured in mucosae from rats submitted to 0.5 atm for 10 days and from control rats in a modified Ussing chamber. Hypoxia increased Isc but not QO2. The slope of the regression line between Isc and QO2 reduction after ouabain addition was decreased in epithelia from hypoxic rats (P = 0.03). Chloride secretion blockade reduced Isc and QO2 in both groups, while sodium channel blockade did so only in the hypoxic group. Dual blockade in hypoxic rat epithelia caused correlated (P = 0.0025) additive decreases in Isc and QO2. Presented results suggest that chronic hypoxia induces an improved coupling between QO2 and electrogenic ion transport, and electrogenic sodium absorption despite low aldosterone levels.
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Affiliation(s)
- Liliana M Cincunegui
- Area de Física Biológica, Departamento de Morfología y Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 33, Mendoza 5500, Argentina
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20
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Fejes-Tóth G, Frindt G, Náray-Fejes-Tóth A, Palmer LG. Epithelial Na+channel activation and processing in mice lacking SGK1. Am J Physiol Renal Physiol 2008; 294:F1298-305. [DOI: 10.1152/ajprenal.00579.2007] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Amiloride-sensitive Na+channel activity was examined in the cortical collecting ducts of a mouse line (SGK1−/−) deficient in the serum- and glucocorticoid-dependent protein kinase SGK1. This activity was correlated with changes in renal Na handling and in the maturation of epithelial Na+channel (ENaC) protein. Neither SGK1−/−mice nor paired SGK1+/+animals expressed detectable channel activity, measured as amiloride-sensitive whole-cell current ( INa), under control conditions with standard chow. Administration of aldosterone (0.5 μg/h via osmotic minipump for 7 days) increased INato a similar extent in SGK1+/+(378 ± 61 pA/cell at −100 mV) and in SGK1−/−(350 ± 57 pA/cell) animals. However, the maturation of ENaC, assessed as the ratio of cleaved to full-length forms of γ-ENaC, was more pronounced in SGK+/+mice. The SGK1−/−animals exhibited a salt-wasting phenotype when kept on a low-Na diet for up to 2 days, losing significantly more Na in the urine than wild-type mice. Under these conditions, INawas enhanced more in SGK1−/−(94 ± 14 pA/cell) than in SGK+/+(23 ± 5 pA/cell) genotypes. Despite the larger currents, the ratio of cleaved to full-length γ-ENaC was lower in the knockout animals. The mice also expressed a smaller amount of Na+-Cl−cotransporter protein under Na-depleted conditions. These results indicated that SGK1 is essential for optimal processing of ENaC but is not required for activation of the channel by aldosterone.
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21
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Torp M, Brønd L, Hadrup N, Nielsen JB, Praetorius J, Nielsen S, Christensen S, Jonassen TEN. Losartan decreases vasopressin-mediated cAMP accumulation in the thick ascending limb of the loop of Henle in rats with congestive heart failure. Acta Physiol (Oxf) 2007; 190:339-50. [PMID: 17635349 DOI: 10.1111/j.1748-1716.2007.01722.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Vasopressin (AVP) stimulates sodium reabsorption and Na,K,2Cl-cotransporter (NKCC2) protein level in the thick ascending limb (TAL) of Henle's loop in rats. Rats with congestive heart failure (CHF) have increased protein level of NKCC2, which can be normalized by angiotensin II receptor type-1 (AT(1)) blockade with losartan. AIM In this study, we investigated whether CHF rats displayed changes in AVP stimulated cAMP formation in the TAL and examined the role of AT(1) receptor blockade on this system. METHOD CHF was induced by ligation of the left anterior descending coronary artery (LAD). SHAM-operated rats were used as controls. Half of the rats were treated with losartan (10 mg kg day(-1) i.p.). RESULTS CHF rats were characterized by increased left ventricular end diastolic pressure. Measurement of cAMP in isolated outer medullary TAL showed that both basal and AVP (10(-6) m) stimulated cAMP levels were significantly increased in CHF rats (25.52 +/- 4.49 pmol cAMP microg(-1) protein, P < 0.05) compared to Sham rats (8.13 +/- 1.14 pmol cAMP microg(-1) protein), P < 0.05). Losartan significantly reduced the basal level of cAMP in CHF rats (CHF: 12.56 +/- 1.93 fmol microg(-1) protein vs. Los-CHF: 7.49 +/- 1.08, P < 0.05), but not in Sham rats (SHAM: 4.66 +/- 0.59 vs. Los-SHAM: 4.75 +/- 0.71). AVP-mediated cAMP accumulation was absent in both groups treated with losartan (Los-SHAM: 4.75 +/- 0.71 and Los-CHF: 7.49 +/- 1.08). CONCLUSION The results indicate that the increased NKCC2 protein level in the mTAL from CHF rats is associated with increased cAMP accumulation in this segment. Furthermore, the finding that AT(1) receptor blockade prevents AVP-mediated cAMP accumulation in both SHAM and CHF rats suggests an interaction between angiotensin II and AVP in regulation of mTAL Na reabsorption.
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Affiliation(s)
- M Torp
- Department of Pharmacology, University of Copenhagen, Copenhagen N, Denmark
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22
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Fakitsas P, Adam G, Daidié D, van Bemmelen MX, Fouladkou F, Patrignani A, Wagner U, Warth R, Camargo SMR, Staub O, Verrey F. Early aldosterone-induced gene product regulates the epithelial sodium channel by deubiquitylation. J Am Soc Nephrol 2007; 18:1084-92. [PMID: 17344426 DOI: 10.1681/asn.2006080902] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The mineralocorticoid hormone aldosterone controls sodium reabsorption and BP largely by regulating the cell-surface expression and function of the epithelial sodium channel (ENaC) in target kidney tubules. Part of the stimulatory effect of aldosterone on ENaC is mediated by the induction of serum- and glucocorticoid-regulated kinase 1 (Sgk1), a kinase that interferes with the ubiquitylation of ENaC by ubiquitin-protein ligase Nedd4-2. In vivo early aldosterone-regulated mRNA now has been identified in microselected mouse distal nephron by microarray. From 22 mRNA that displayed a two-fold or more change, 13 were downregulated and nine were upregulated. Besides Sgk1, the induced mRNA include Grem2 (protein related to DAN and cerebrus [PRDC]), activating transcription factor 3, cAMP responsive element modulator, and the ubiquitin-specific protease Usp2-45. The induction of this last enzyme isoform was verified in mouse distal nephron tubule at the protein level. With the use of Hek293 cells, Xenopus oocytes, and mpkCCD(c14) cells as expression systems, it was shown that Usp2-45 deubiquitylates ENaC and stimulates ENaC-mediated sodium transport, an effect that is not additive to that of Sgk1. A deubiquitylating enzyme that targets ENaC in vitro and thus may play a role in sodium transport regulation was identified within a series of new in vivo early aldosterone-regulated gene products.
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Affiliation(s)
- Panagiotis Fakitsas
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Cao XR, Shi PP, Sigmund RD, Husted RF, Sigmund CD, Williamson RA, Stokes JB, Yang B. Mice heterozygous for beta-ENaC deletion have defective potassium excretion. Am J Physiol Renal Physiol 2006; 291:F107-15. [PMID: 16571596 PMCID: PMC2818793 DOI: 10.1152/ajprenal.00159.2005] [Citation(s) in RCA: 10] [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 present studies were designed to determine whether mice heterozygous for deletion of beta-ENaC exhibited defects in Na+/K+ transport and blood pressure regulation. In response to an acute KCl infusion, +/-mice developed higher serum [K+] and excreted only 40% of the K+ excreted by +/+mice. After 6 days on a low (0.01%)-Na+ diet, the cumulative Na+ excretion from days 3-6 was greater for +/-mice. This low-Na+ diet caused higher serum [K+] and lower K+ excretion rates in +/-mice than in +/+mice, but the rectal potential differences were not different. Analyses of mRNA from mice on this diet showed the expected approximately 50% reduction of beta-ENaC in kidney and colon of +/-mice. Unexpectedly, the level of gamma-ENaC mRNA was similarly reduced. NHE3 mRNA was approximately 30% higher in +/-mice whereas mRNA of the Na-K-2Cl cotransporter was not different. Also unexpectedly, the amount of beta-ENaC proteins was similar in both groups of mice but there was a reduction of one form of gamma-ENaC in +/-mice. These experiments demonstrate that mice heterozygous for beta-ENaC have a small but detectable defect in their ability to conserve Na+ and a more readily apparent defect in the ability to secrete K+.
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Affiliation(s)
- X Renee Cao
- Department of Obstetrics and Gynecology, Carver College of Medicine, 463 MRF, University of Iowa, and Veterans Affairs Medical Center, Iowa City, IA 52242, USA
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24
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Gaeggeler HP, Gonzalez-Rodriguez E, Jaeger NF, Loffing-Cueni D, Norregaard R, Loffing J, Horisberger JD, Rossier BC. MineralocorticoidversusGlucocorticoid Receptor Occupancy Mediating Aldosterone-Stimulated Sodium Transport in a Novel Renal Cell Line. J Am Soc Nephrol 2005; 16:878-91. [PMID: 15743993 DOI: 10.1681/asn.2004121110] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Aldosterone controls sodium balance by regulating an epithelial sodium channel (ENaC)-mediated sodium transport along the aldosterone-sensitive distal nephron, which expresses both mineralocorticoid (MR) and glucocorticoid receptors (GR). Mineralocorticoid specificity is ensured by 11beta-hydroxysteroid dehydrogenase type 2, which metabolizes cortisol or corticosterone into inactive metabolites that are unable to bind MR and/or GR. The fractional occupancy of MR and GR by aldosterone mediating the sodium transport response in the aldosterone-sensitive distal nephron cannot be studied in vivo. For answering this question, a novel mouse cortical collecting duct cell line (mCCD(cl1)), which expresses significant levels of MR and GR and a robust aldosterone sodium transport response, was used. Aldosterone elicited a biphasic response: Low doses (K(1/2) = approximately 0.5 nM) induced a transient and early increase of sodium transport (peaking at 3 h), whereas high doses (K(1/2) = approximately 90 nM) entailed an approximately threefold larger, long-lasting response. At 3 h, the corticosterone dose-response curve was shifted to the right compared with that of aldosterone by more than two log concentrations, an effect that was fully reverted in the presence of the 11beta-hydroxysteroid dehydrogenase type 2 inhibitor carbenoxolone. Low doses of dexamethasone (0.1 to 1 nM) failed to induce an early response, but high doses elicited a long-lasting response (K(1/2) = approximately 8 nM), similar to that observed for high aldosterone concentrations. Equilibrium binding assays showed that both aldosterone and corticosterone bind to a high-affinity, low-capacity site, whereas dexamethasone binds to one site. Within the physiologic range of aldosterone concentrations, sodium transport is predicted to be controlled by MR occupancy during circadian cycles and by MR and GR occupancy during salt restriction or acute stress.
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Affiliation(s)
- Hans-Peter Gaeggeler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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25
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Wang Q, Clement S, Gabbiani G, Horisberger JD, Burnier M, Rossier BC, Hummler E. Chronic hyperaldosteronism in a transgenic mouse model fails to induce cardiac remodeling and fibrosis under a normal-salt diet. Am J Physiol Renal Physiol 2004; 286:F1178-84. [PMID: 14761862 DOI: 10.1152/ajprenal.00386.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primary aldosteronism causes severe hypertension in humans (Conn's syndrome) with cardiac hypertrophy, characterized by a fibrosis more severe than the one observed in patients with essential hypertension. This suggests that aldosterone by itself may have specific and direct effects on cardiac remodeling through the activation of the cardiac mineralocorticoid receptor. Experimental evidence obtained in studying uninephrectomized rats treated with aldosterone or deoxycorticosterone (DOC) together with salt loading has led to similar conclusions. To examine the direct consequences of chronically elevated aldosterone levels on cardiac pathophysiology, we analyzed a mouse model (α-epithelial Na channel −/−Tg) that is normotensive under normal-salt diet but exhibits chronic hyperaldosteronism. Sixteen-month-old transgenic rescue mice that were kept under a regular salt diet that contains a small amount of sodium (0.3% Na+) displayed a compensated PHA-1 phenotype with normal body weight, normal kidney index, normal blood pressure, but 6.3-fold elevated plasma aldosterone levels compared with the age-matched control group. Peripheral resistance of distal colon to aldosterone was shown by a significant decrease of the amiloride-sensitive rectal potential difference, and its diurnal cyclicity was blunted. Despite chronically high plasma aldosterone levels, these animals do not show any evidence of cardiac hypertrophy, remodeling, or fibrosis, using collagen staining and anti-α-skeletal and α-smooth actin immunochemical labeling of heart sections. Cardiac fibrosis as seen in DOC- or aldosterone/salt-treated animal models is therefore likely to be due to the synergistic effect of salt, aldosterone, and other confounding factors rather than to the elevated circulating aldosterone levels alone.
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Affiliation(s)
- Qing Wang
- Dept. of Pharmacology and Toxicology, Rue du Bugnon 27, CH-1005 Lausanne, Switzerland.
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26
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Mycielska ME, Djamgoz MBA. Cellular mechanisms of direct-current electric field effects: galvanotaxis and metastatic disease. J Cell Sci 2004; 117:1631-9. [PMID: 15075225 DOI: 10.1242/jcs.01125] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endogenous direct-current electric fields (dcEFs) occur in vivo in the form of epithelial transcellular potentials or neuronal field potentials, and a variety of cells respond to dcEFs in vitro by directional movement. This is termed galvanotaxis. The passive influx of Ca2+ on the anodal side should increase the local intracellular Ca2+ concentration, whereas passive efflux and/or intracellular redistribution decrease the local intracellular Ca2+ concentration on the cathodal side. These changes could give rise to `push-pull' effects, causing net movement of cells towards the cathode. However, such effects would be complicated in cells that possess voltage-gated Ca2+ channels and/or intracellular Ca2+ stores. Moreover, voltage-gated Na+ channels, protein kinases, growth factors, surface charge and electrophoresis of proteins have been found to be involved in galvanotaxis. Galvanotactic mechanisms might operate in both the short term (seconds to minutes) and the long term (minutes to hours), and recent work has shown that they might be involved in metastatic disease. The galvanotactic responses of strongly metastatic prostate and breast cancer cells are much more prominent, and the cells move in the opposite direction compared with corresponding weakly metastatic cells. This could have important implications for the metastatic process and has clinical implications. Galvanotaxis could thus play a significant role in both cellular physiology and pathophysiology.
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Affiliation(s)
- Maria E Mycielska
- Department of Biological Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London, SW7 2AZ, UK
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27
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Inagaki A, Yamaguchi S, Ishikawa T. Amiloride-sensitive epithelial Na+channel currents in surface cells of rat rectal colon. Am J Physiol Cell Physiol 2004; 286:C380-90. [PMID: 14576089 DOI: 10.1152/ajpcell.00373.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Surface cells of the mammalian distal colon are shown to molecularly express the amiloride-sensitive epithelial Na+channel composed of three homologous subunits (α-, β-, and γ-ENaC). However, because basic electrophysiological properties of amiloride-sensitive Na+channels expressed in these cells are largely unknown at the cellular level, functional evidence for the involvement of the subunits in the native channels is incomplete. Using electrophysiological techniques, we have now characterized functional properties of native ENaC in surface cells of rectal colon (RC) of rats fed a normal Na+diet. Ussing chamber experiments showed that apical amiloride inhibited a basal short-circuit current in mucosal preparation of RC with an apparent half-inhibition constant ( Ki) value of 0.20 μM. RT-PCR analysis confirmed the presence of transcripts of α-, β-, and γ-rENaC in rectal mucosa. Whole cell patch-clamp experiments in surface cells of intact crypts acutely isolated from rectal mucosa identified an inward cationic current, which was inhibited by amiloride with a Kivalue of 0.12 μM at a membrane potential of –64 mV, the inhibition being weakly voltage dependent. Conductance ratios of the currents were Li+(1.8) > Na+(1) >> K+(≈0), respectively. Amiloride-sensitive current amplitude was almost the same at 15 or 150 mM extracellular Na+, suggesting a high Na+affinity for current activation. These results are consistent with the hypothesis that a heterooligomer composed of α-, β-, and γ-ENaC may be the molecular basis of the native channels, which are responsible for amiloride-sensitive electrogenic Na+absorption in rat rectal colon.
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Affiliation(s)
- A Inagaki
- Laboratory of Physiology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
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Frindt G, McNair T, Dahlmann A, Jacobs-Palmer E, Palmer LG. Epithelial Na channels and short-term renal response to salt deprivation. Am J Physiol Renal Physiol 2002; 283:F717-26. [PMID: 12217863 DOI: 10.1152/ajprenal.00379.2001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To test the role of epithelial Na channels in the day-to-day regulation of renal Na excretion, rats were infused via osmotic minipumps with the Na channel blocker amiloride at rates that achieved drug concentrations of 2-5 microM in the lumen of the distal nephron. Daily Na excretion rates were unchanged, although amiloride-treated animals tended to excrete more Na in the afternoon and less in the late evening than controls. When the rats were given a low-Na diet, Na excretion rates were elevated in the amiloride-treated group within 4 h and remained higher than controls for at least 48 h. Adrenalectomized animals responded similarly to the low-Na diet. In contrast, rats infused with polythiazide at rates designed to inhibit NaCl transport in the distal tubule were able to conserve Na as well as did the controls. Injection of aldosterone (2 microg/100 g body wt) decreased Na excretion in control animals after a 1-h delay. This effect was largely abolished in amiloride-treated rats. On the basis of quantitative analysis of the results, we conclude that activation of amiloride-sensitive channels by mineralocorticoids accounts for 50-80% of the immediate natriuretic response of the kidney to a reduction in Na intake. Furthermore, the channels are necessary to achieve minimal rates of Na excretion during more chronic Na deprivation.
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Affiliation(s)
- Gustavo Frindt
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York 10021, USA
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29
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Affiliation(s)
- Bernard C Rossier
- Institute of Pharmacology and Toxicology, University of Lausanne, Lausanne CH-1005, Switzerland
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30
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Wang Q, Hummler E, Nussberger J, Clément S, Gabbiani G, Brunner HR, Burnier M. Blood pressure, cardiac, and renal responses to salt and deoxycorticosterone acetate in mice: role of Renin genes. J Am Soc Nephrol 2002; 13:1509-16. [PMID: 12039980 DOI: 10.1097/01.asn.0000017902.77985.84] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Several studies have demonstrated that mice are polymorphic for the number of renin genes, with some inbred strains harboring one gene (Ren-1(c)) and other strains containing two genes (Ren-1(d) and Ren-2). In this study, the effects of 1% salt and deoxycorticosterone acetate (DOCA)/salt were investigated in one- and two-renin gene mice, for elucidation of the role of renin in the modulation of BP, cardiac, and renal responses to salt and DOCA. The results demonstrated that, under baseline conditions, mice with two renin genes exhibited 10-fold higher plasma renin activity, 100-fold higher plasma renin concentrations, elevated BP (which was angiotensin II-dependent), and an increased cardiac weight index, compared with one-renin gene mice (all P < 0.01). The presence of two renin genes markedly increased the BP, cardiac, and renal responses to salt. The number of renin genes also modulated the responses to DOCA/salt. In one-renin gene mice, DOCA/salt induced significant renal and cardiac hypertrophy (P < 0.01) even in the absence of any increase in BP. Treatment with losartan, an angiotensin II AT(1) receptor antagonist, decreased BP in two-renin gene mice but not in one-renin gene mice. However, losartan prevented the development of cardiac hypertrophy in both groups of mice. In conclusion, these data demonstrate that renin genes are important determinants of BP and of the responses to salt and DOCA in mice. The results confirm that the Ren-2 gene, which controls renin production mainly in the submaxillary gland, is physiologically active in mice and is not subject to the usual negative feedback control. Finally, these data provide further evidence that mineralocorticoids promote cardiac hypertrophy even in the absence of BP changes. This hypertrophic process is mediated in part by the activation of angiotensin II AT(1) receptors.
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Affiliation(s)
- Qing Wang
- Division of Hypertension and Vascular Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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31
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Wang Q, Hummler E, Maillard M, Nussberger J, Rossier BC, Brunner HR, Burnier M. Compensatory up-regulation of angiotensin II subtype 1 receptors in alpha ENaC knockout heterozygous mice. Kidney Int 2001; 59:2216-21. [PMID: 11380824 DOI: 10.1046/j.1523-1755.2001.00739.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND In mice, a partial loss of function of the epithelial sodium channel (ENaC), which regulates sodium excretion in the distal nephron, causes pseudohypoaldosteronism, a salt-wasting syndrome. The purpose of the present experiments was to examine how alpha ENaC knockout heterozygous (+/-) mice, which have only one allele of the gene encoding for the alpha subunit of ENaC, control their blood pressure (BP) and sodium balance. METHODS BP, urinary electrolyte excretion, plasma renin activity, and urinary adosterone were measured in wild-type (+/+) and heterozygous (+/-) mice on a low, regular, or high sodium diet. In addition, the BP response to angiotensin II (Ang II) and to Ang II receptor blockade, and the number and affinity of Ang II subtype 1 (AT1) receptors in renal tissue were analyzed in both mouse strains on the three diets. RESULTS In comparison with wild-type mice (+/+), alpha ENaC heterozygous mutant mice (+/-) showed an intact capacity to maintain BP and sodium balance when studied on different sodium diets. However, no change in plasma renin activity was found in response to changes in sodium intake in alpha ENaC +/- mice. On a normal salt diet, heterozygous mice had an increased vascular responsiveness to exogenous Ang II (P < 0.01). Moreover, on a normal and low sodium intake, these mice exhibited an increase in the number of AT1 receptors in renal tissues; their BP lowered markedly during the Ang II receptor blockade (P < 0.01) and there was a clear tendency for an increase in urinary aldosterone excretion. CONCLUSIONS alpha ENaC heterozygous mice have developed an unusual mechanism of compensation leading to an activation of the renin-angiotensin system, that is, the up-regulation of AT1 receptors. This up-regulation may be due to an increase in aldosterone production.
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MESH Headings
- Adaptation, Physiological/physiology
- Angiotensin II/pharmacology
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Body Weight/physiology
- Epithelial Sodium Channels
- Genotype
- Heart Rate/physiology
- Heterozygote
- Hypertension, Renal/genetics
- Hypertension, Renal/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/metabolism
- Renin/blood
- Renin-Angiotensin System/genetics
- Sodium Channels/genetics
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Q Wang
- Division of Hypertension and Vascular Medicine, CHUV, Lausanne, Switzerland
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32
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Verrey F. Sodium reabsorption in aldosterone-sensitive distal nephron: news and contributions from genetically engineered animals. Curr Opin Nephrol Hypertens 2001; 10:39-47. [PMID: 11195050 DOI: 10.1097/00041552-200101000-00007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The precise adaptation of renal sodium excretion to systemic needs is to a large extent achieved by the regulation of sodium re-absorption in the aldosterone-sensitive distal nephron. Transcellular sodium re-absorption by the segment-specific cells of the aldosterone-sensitive distal nephron (often called principal cells) is mainly controlled at the level of the expression and activity levels of the epithelial sodium channel, the apical amiloride-sensitive sodium influx pathway. Recent investigations have identified the first early aldosterone-induced proteins that act on epithelial sodium channel function in expression systems. Indirect evidence suggests that one of these aldosterone-induced proteins, the serum- and glucocorticoid-inducible protein kinase SGK1, plays a central integratory role in the control of epithelial sodium channel surface expression and activity, also in the mammalian kidney. Gene-modified animals lacking epithelial sodium channel subunits or expressing mutant subunits have substantiated the central role of the epithelial sodium channel in sodium re-absorption and blood pressure control, as well as for neonatal lung liquid clearance. Mice overexpressing or lacking specific hormones or their receptors have been used to study their role in sodium transport regulation, but the study of mouse physiology appears to lag behind the generation of gene-modified mice. Nonetheless, these new animal models have had a strong impact on research, by stimulating the integration of knowledge and techniques learned from reductionistic molecular approaches into tissue and animal studies, thus breaking down barriers and stimulating collaborations.
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Affiliation(s)
- F Verrey
- Institute of Physiology, University of Zürich, Switzerland.
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33
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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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