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Hermidorff MM, de Assis LVM, Isoldi MC. Genomic and rapid effects of aldosterone: what we know and do not know thus far. Heart Fail Rev 2018; 22:65-89. [PMID: 27942913 DOI: 10.1007/s10741-016-9591-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Aldosterone is the most known mineralocorticoid hormone synthesized by the adrenal cortex. The genomic pathway displayed by aldosterone is attributed to the mineralocorticoid receptor (MR) signaling. Even though the rapid effects displayed by aldosterone are long known, our knowledge regarding the receptor responsible for such event is still poor. It is intense that the debate whether the MR or another receptor-the "unknown receptor"-is the receptor responsible for the rapid effects of aldosterone. Recently, G protein-coupled estrogen receptor-1 (GPER-1) was elegantly shown to mediate some aldosterone-induced rapid effects in several tissues, a fact that strongly places GPER-1 as the unknown receptor. It has also been suggested that angiotensin receptor type 1 (AT1) also participates in the aldosterone-induced rapid effects. Despite this open question, the relevance of the beneficial effects of aldosterone is clear in the kidneys, colon, and CNS as aldosterone controls the important water reabsorption process; on the other hand, detrimental effects displayed by aldosterone have been reported in the cardiovascular system and in the kidneys. In this line, the MR antagonists are well-known drugs that display beneficial effects in patients with heart failure and hypertension; it has been proposed that MR antagonists could also play an important role in vascular disease, obesity, obesity-related hypertension, and metabolic syndrome. Taken altogether, our goal here was to (1) bring a historical perspective of both genomic and rapid effects of aldosterone in several tissues, and the receptors and signaling pathways involved in such processes; and (2) critically address the controversial points within the literature as regarding which receptor participates in the rapid pathway display by aldosterone.
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Affiliation(s)
- Milla Marques Hermidorff
- Laboratory of Hypertension, Research Center in Biological Science, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35400-000, Brazil
| | - Leonardo Vinícius Monteiro de Assis
- Laboratory of Comparative Physiology of Pigmentation, Department of Physiology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Mauro César Isoldi
- Laboratory of Hypertension, Research Center in Biological Science, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35400-000, Brazil.
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Cui Y, Li H, Wu S, Zhao R, Du D, Ding Y, Nie H, Ji HL. Formaldehyde impairs transepithelial sodium transport. Sci Rep 2016; 6:35857. [PMID: 27762337 PMCID: PMC5071906 DOI: 10.1038/srep35857] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/06/2016] [Indexed: 01/26/2023] Open
Abstract
Unsaturated oxidative formaldehyde is a noxious aldehyde in cigarette smoke that causes edematous acute lung injury. However, the mechanistic effects of formaldehyde on lung fluid transport are still poorly understood. We examined how formaldehyde regulates human epithelial sodium channels (ENaC) in H441 and expressed in Xenopus oocytes and exposed mice in vivo. Our results showed that formaldehyde reduced mouse transalveolar fluid clearance in vivo. Formaldehyde caused a dose-dependent inhibition of amiloride-sensitive short-circuit Na+ currents in H441 monolayers and of αβγ-ENaC channel activity in oocytes. α-ENaC protein was reduced, whereas phosphorylation of the extracellular regulated protein kinases 1 and 2 (ERK1/2) increased significantly post exposure. Moreover, both α- and γ-ENaC transcripts were down-regulated. Reactive oxygen species (ROS) was elevated significantly by formaldehyde in addition to markedly augmented membrane permeability of oocytes. These data suggest that formaldehyde contributes to edematous acute lung injury by reducing transalveolar Na+ transport, through decreased ENaC activity and enhanced membrane depolarization, and by elevating ROS production over long-term exposure.
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Affiliation(s)
- Yong Cui
- Department of Anesthesiology, First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China
| | - Huiming Li
- Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, Liaoning, China
| | - Sihui Wu
- Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, Liaoning, China
| | - Runzhen Zhao
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Deyi Du
- Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, Liaoning, China
| | - Yan Ding
- Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, Liaoning, China
| | - Hongguang Nie
- Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, Liaoning, China
| | - Hong-Long Ji
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
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Chen C, Chen RP, Lin HH, Zhang WY, Huang XL, Huang ZM. Tolvaptan regulates aquaporin-2 and fecal water in cirrhotic rats with ascites. World J Gastroenterol 2016; 22:3363-3371. [PMID: 27022218 PMCID: PMC4806194 DOI: 10.3748/wjg.v22.i12.3363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/19/2015] [Accepted: 12/08/2015] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the role of tolvaptan in regulating aquaporin (AQP)-2 expression and fecal water content in cirrhotic rats with ascites.
METHODS: Cirrhosis with ascites was induced in rats by repetitive dorsal injection of CCl4 for 14 wk. In total, 84 cirrhotic rats with ascites divided into three groups (vehicle, 3 mg/kg and 5 mg/kg tolvaptan), and then further divided into five subgroups (days 1, 2, 3, 4, and 5). Blood samples were obtained to measure vasopressin and sodium concentrations. Rats were killed and colonic mucosa was scraped for analysis of protein expression and AQP-2 transcriptional level. The whole layer was fixed for hematoxylin&eosin (HE) staining and feces were collected for determination of fecal water content.
CONCLUSION: Compared with vehicle, vasopressin decreased significantly in the tolvaptan groups from day 2 to a similar level in each treatment group. AQP-2 showed significant upregulation in cirrhotic rats with ascites compared with an untreated control group (100% ± 22.9% vs 22.2% ± 10.23%, P < 0.01). After administration of tolvaptan, AQP-2 expression began to decrease significantly from day 2 in each treatment group, but no significant difference was finally found between the treatment groups. Fecal water content in the distal colon was increased by 5 mg/kg tolvaptan on day 1 (66.8% ± 9.3% vs 41.4% ± 6.3%, in the vehicle group, P < 0.05). Fecal water content returned to baseline at day 4 at the latest in both treatment groups, and did not correspond to the change in AQP-2 expression. HE staining of the colonic mucosa showed no mucosal damage related to tolvaptan.
CONCLUSION: Upregulation of AQP-2 in the distal colon is found in cirrhotic rats with ascites. Tolvaptan inhibits its expression and may decrease water reabsorption and induce diarrhea.
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Pérez-Bosque A, Miró L, Maijó M, Polo J, Campbell J, Russell L, Crenshaw J, Weaver E, Moretó M. Dietary intervention with serum-derived bovine immunoglobulins protects barrier function in a mouse model of colitis. Am J Physiol Gastrointest Liver Physiol 2015; 308:G1012-8. [PMID: 25882614 DOI: 10.1152/ajpgi.00378.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Dietary supplementation with immunoglobulins from animal plasma has anti-inflammatory effects on intestinal and lung models of acute inflammation. Here, we aimed to establish whether dietary intervention with serum-derived bovine immunoglobulin (SBI) can prevent alterations in intestinal barrier function in a mouse model with a genetic predisposition to inflammatory bowel disease (IBD). Wild-type (WT) mice and mice lacking the mdr1a gene (KO) were fed diets supplemented with either SBI (2% wt/wt) or milk proteins (control diet), from day 21 (weaning) until day 56. The epithelial permeability of distal colon crypts was measured by confocal microscopy using a fluorescent marker. The expression of junctional epithelial E-cadherin and β-catenin proteins were determined by Western blot and zonula occludens-1 (ZO-1) by immunofluorescence. Mucins (MUC1, MUC2, MUC4), TFF3, cytokines (TNF-α, IFN-γ), and inducible nitric oxide synthase RNA expression were quantified by real-time PCR. SBI blocked the increase in colon crypt permeability and partially prevented the reduction in E-cadherin and ZO-1 expression that characterize the KO mouse model (both P < 0.05). SBI inclusion also reduced the mucosal expression of the inflammatory markers TNF-α, IFN-γ, and inducible nitric oxide synthase (all P < 0.005). The number of goblet cells in the colon of KO mice was low and correlated well with MUC2 and TFF3 expression (P < 0.001), whereas dietary supplementation with SBI attenuated these effects (all P < 0.05). In short, dietary SBI ameliorated colonic barrier alterations and reduced the expression of mucosal inflammatory markers in a genetic model of IBD.
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Affiliation(s)
- Anna Pérez-Bosque
- Departament de Fisiologia, Facultat de Farmàcia and Institut de Recerca en Nutrició i Seguretat Alimentària, Universitat de Barcelona, Barcelona, Spain
| | - Lluïsa Miró
- Departament de Fisiologia, Facultat de Farmàcia and Institut de Recerca en Nutrició i Seguretat Alimentària, Universitat de Barcelona, Barcelona, Spain
| | - Mònica Maijó
- Departament de Fisiologia, Facultat de Farmàcia and Institut de Recerca en Nutrició i Seguretat Alimentària, Universitat de Barcelona, Barcelona, Spain
| | | | | | | | | | | | - Miquel Moretó
- Departament de Fisiologia, Facultat de Farmàcia and Institut de Recerca en Nutrició i Seguretat Alimentària, Universitat de Barcelona, Barcelona, Spain
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Miró L, Pérez-Bosque A, Maijó M, Naftalin RJ, Moretó M. Vasopressin regulation of epithelial colonic proliferation and permeability is mediated by pericryptal platelet-derived growth factor A. Exp Physiol 2014; 99:1325-34. [PMID: 25085844 DOI: 10.1113/expphysiol.2014.080952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Arginine vasopressin (AVP) has trophic effects on the rat distal colon, increasing the growth of pericryptal myofibroblasts and reducing the colonic crypt wall permeability. This study aimed to reproduce in vitro the effects of AVP observed in vivo using cultures of human CCD-18Co myofibroblasts and T84 colonic epithelial cells. Proliferation of myofibroblasts was quantified by bromodeoxyuridine incorporation; the expression of platelet-derived growth factor A (PDGFA), platelet-derived growth factor B, epidermal growth factor, transforming growth factor-β and vascular endothelial growth factor was measured by PCR and the expression of epithelial junction proteins by Western blot. Arginine vasopressin stimulated myofibroblast proliferation and the expression of PDGFA without affecting the expression of platelet-derived growth factor B, epidermal growth factor, transforming growth factor-β or vascular endothelial growth factor. These effects were prevented when AVP receptor inhibitors were present in the medium. Pre-incubation of CCD-18Co cells with anti-PDGF antibody or with an inhibitor of the PDGF receptor abolished the effects of AVP. When colonocytes were incubated with medium obtained from myofibroblasts incubated with AVP, both cell proliferation and the expression of epithelial junction proteins increased; however, direct incubation of colonocytes with AVP did not modify these variables. These results demonstrate that AVP stimulates myofibroblast proliferation and induces PDGFA secretion, implying that PDGFA mediates local myofibroblast proliferation by an autocrine feedback loop and regulates epithelial proliferation and permeability by a paracrine mechanism.
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Affiliation(s)
- Lluïsa Miró
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Anna Pérez-Bosque
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona (UB), Barcelona, Spain
| | - Mònica Maijó
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona (UB), Barcelona, Spain
| | | | - Miquel Moretó
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona (UB), Barcelona, Spain
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Miró L, Pérez-Bosque A, Maijó M, Amat C, Naftalin RJ, Moretó M. Aldosterone induces myofibroblast EGF secretion to regulate epithelial colonic permeability. Am J Physiol Cell Physiol 2013; 304:C918-26. [DOI: 10.1152/ajpcell.00292.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In vivo studies show that raised aldosterone (Aldo) during low-Na adaptation regulates the growth of pericryptal myofibroblasts and reduces the permeability of the colonic epithelium. The aim of this study was to reproduce in vitro the in vivo condition of increased Aldo using human CCD-18Co myofibroblasts and T84 colonic epithelial cells to measure myofibroblast and epithelial proliferation and the expression of intercellular junction proteins. Proliferation was quantified by measuring 5-bromo-2′-deoxyuridine incorporation. The myofibroblast expression of EGF, VEGFa, and transforming growth factor-β1 (TGF-β1) was measured by real-time PCR and the expression of junctional complex proteins by Western blot. Aldo stimulated the proliferation of myofibroblasts by 70% ( P < 0.05) and increased EGF mRNA expression by 30% ( P < 0.05) without affecting VEGFa and TGF-β1. EGF concentration in the incubation medium increased by 30% ( P < 0.05) 24 h after Aldo addition, and these effects were prevented by the addition of spironolactone. Myofibroblast proliferation in response to Aldo was mediated by EGF receptor (EGFR) and involved both MAPKK and phosphatidylinositol 3-kinase pathways. When T84 cells were incubated with medium from myofibroblasts stimulated with Aldo (conditioned medium), the expression of β-catenin and claudin IV was increased by 30% ( P < 0.05) and proliferation by 40% ( P < 0.05). T84 proliferation decreased when α-EGF, or the EGFR antagonist AG1478, was present. Results in vivo indicate that rats fed a low-salt diet showed an increased expression of EGF and EGFR in the colonic mucosa. These results support the view that changes in colonic permeability during low-Na adaptation are mediated by the EGF secreted by myofibroblasts in response to raised Aldo.
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Affiliation(s)
- Lluïsa Miró
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, and Institut de Recerca en Nutrició i Seguretat Alimentària, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain; and
| | - Anna Pérez-Bosque
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, and Institut de Recerca en Nutrició i Seguretat Alimentària, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain; and
| | - Mònica Maijó
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, and Institut de Recerca en Nutrició i Seguretat Alimentària, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain; and
| | - Concepció Amat
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, and Institut de Recerca en Nutrició i Seguretat Alimentària, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain; and
| | - Richard J. Naftalin
- Physiology Department, King's College London, Franklin-Wilkins Building, Waterloo Campus, London, United Kingdom
| | - Miquel Moretó
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, and Institut de Recerca en Nutrició i Seguretat Alimentària, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain; and
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Xenon/Remifentanil Anesthesia Protects Against Adverse Effects of Losartan on Hemodynamic Challenges Induced by Anesthesia and Acute Blood Loss. Shock 2010; 34:628-35. [DOI: 10.1097/shk.0b013e3181e682f9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Francis RCE, Höhne C, Klein A, Kaisers UX, Pickerodt PA, Boemke W. Endothelin receptor subtype A blockade does not affect the haemodynamic recovery from haemorrhage during xenon/remifentanil or isoflurane/remifentanil anaesthesia in dogs. Vet Anaesth Analg 2010; 37:258-68. [PMID: 20230551 DOI: 10.1111/j.1467-2995.2010.00530.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To test the compensatory role of endothelin-1 when acute blood loss is superimposed on anaesthesia, by characterizing the effect of systemic endothelin receptor subtype A (ET(A)) blockade on the haemodynamic and hormonal responses to haemorrhage in dogs anaesthetized with xenon/remifentanil (X/R) or isoflurane/remifentanil (I/R). STUDY DESIGN Prospective experimental randomized controlled study. ANIMALS Six female Beagle dogs, 13.4 +/- 1.3 kg. METHODS Animals were anaesthetized with remifentanil 0.5 microg kg(-1) minute(-1) plus either 0.8% isoflurane (I/R) or 63% xenon (X/R), with and without (Control) the systemic intravenous endothelin receptor subtype A antagonist atrasentan (four groups, n = 6 each). After 60 minutes of baseline anaesthesia, the dogs were bled (20 mL kg(-1)) over 5 minutes and hypovolemia was maintained for 1 hour. Continuous haemodynamic monitoring was performed via femoral and pulmonary artery catheters; vasoactive hormones were measured before and after haemorrhage. RESULTS In Controls, systemic vascular resistance (SVR), vasopressin and catecholamine plasma concentrations were higher with X/R than with I/R anaesthesia at pre-haemorrhage baseline. The peak increase after haemorrhage was higher during X/R than during I/R anaesthesia (SVR 7420 +/- 867 versus 5423 +/- 547 dyne seconds cm(-5); vasopressin 104 +/- 23 versus 44 +/- 6 pg mL(-1); epinephrine 2956 +/- 310 versus 177 +/- 99 pg mL(-1); norepinephrine 862 +/- 117 versus 195 +/- 33 pg mL(-1), p < 0.05). Haemorrhage reduced central venous pressure from 3 +/- 1 to 1 +/- 1 cm H(2)O (I/R, ns) and from 8 +/- 1 to 5 +/- 1 cm H(2)O (X/R, p < 0.05), but did not reduce mean arterial pressure, nor cardiac output. Atrasentan did not alter the haemodynamic and hormonal response to haemorrhage during either anaesthetic protocol. CONCLUSIONS AND CLINICAL RELEVANCE Selective ET(A) receptor blockade with atrasentan did not impair the haemodynamic and hormonal compensation of acute haemorrhage during X/R or I/R anaesthesia in dogs.
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Affiliation(s)
- Roland C E Francis
- Department of Anesthesiology and Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.
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Luo X, Yin P, Reierstad S, Ishikawa H, Lin Z, Pavone ME, Zhao H, Marsh EE, Bulun SE. Progesterone and mifepristone regulate L-type amino acid transporter 2 and 4F2 heavy chain expression in uterine leiomyoma cells. J Clin Endocrinol Metab 2009; 94:4533-9. [PMID: 19808856 PMCID: PMC2775649 DOI: 10.1210/jc.2009-1286] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
CONTEXT Progesterone and its receptor (PR) play key roles in uterine leiomyoma growth. Previously, using chromatin immunoprecipitation-based cloning, we uncovered L-type amino acid transporter 2 (LAT2) as a novel PR target gene. LAT2 forms heterodimeric complexes with 4F2 heavy chain (4F2hc), a single transmembrane domain protein essential for LAT2 to exert its function in the plasma membrane. Until now, little is known about the roles of LAT2/4F2hc in the regulation of the growth of human uterine leiomyoma. OBJECTIVE The aim of the study is to investigate the regulation of LAT2 and 4F2hc by progesterone and the antiprogestin mifepristone and their functions in primary human uterine leiomyoma smooth muscle (LSM) cells and tissues from 39 premenopausal women. RESULTS In primary LSM cells, progesterone significantly induced LAT2 mRNA levels, and this was blocked by cotreatment with mifepristone. Progesterone did not alter 4F2hc mRNA levels, whereas mifepristone significantly induced 4F2hc mRNA expression. Small interfering RNA knockdown of LAT2 or 4F2hc markedly increased LSM cell proliferation. LAT2, PR-B, and PR-A levels were significantly higher in freshly isolated LSM cells vs. adjacent myometrial cells. In vivo, mRNA levels of LAT2 and PR but not 4F2hc were significantly higher in leiomyoma tissues compared with matched myometrial tissues. CONCLUSION We present evidence that progesterone and its antagonist mifepristone regulate the amino acid transporter system LAT2/4F2hc in leiomyoma tissues and cells. Our findings suggest that products of the LAT2/4F2hc genes may play important roles in leiomyoma cell proliferation. We speculate that critical ratios of LAT2 to 4F2hc regulate leiomyoma growth.
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Affiliation(s)
- Xia Luo
- Division of Reproductive Biology Research, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
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Ruiz-Ederra J, Levin MH, Verkman AS. In situ fluorescence measurement of tear film [Na+], [K+], [Cl-], and pH in mice shows marked hypertonicity in aquaporin-5 deficiency. Invest Ophthalmol Vis Sci 2009; 50:2132-8. [PMID: 19136711 PMCID: PMC2904304 DOI: 10.1167/iovs.08-3033] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Tear film composition depends on water and ion transport across ocular surface epithelia and on fluid secretion by lacrimal glands. The purpose of this study was to establish in situ fluorescence methods to measure tear film ionic concentrations and pH in mice and to determine whether tear film composition is sensitive to deficiency of the major ocular surface aquaporin water channels. METHODS Tear film ionic concentrations and pH were measured in anesthetized mice by ratio imaging fluorescence microscopy after topical application of ion/pH-sensing, dual-wavelength fluorescent indicators. [Na(+)], [K(+)], and [Cl(-)] were measured with membrane-impermeant indicators developed by our laboratory, and pH was measured with bis(carboxyethyl)-carboxyfluorescein fluorescence-conjugated dextran. Measurements were performed on wild-type mice and on knockout mice lacking aquaporins AQP1, AQP3, and AQP5. RESULTS In wild-type mice, tear film [Na(+)] was 139 +/- 8 mM, [K(+)] was 48 +/- 1 mM, [Cl(-)] was 127 +/- 4 mM, and pH was 7.59 +/- 0.2 (SE; n = 5-8). pH did not differ significantly in the AQP knockout mice. [Na(+)] was increased by approximately twofold in AQP5 null mice (230 +/- 20 mM) and was greatly reduced after exposure of the ocular surface to a humidified atmosphere. [K(+)] was mildly reduced in AQP1 null mice. CONCLUSIONS These results establish an in situ optical methodology to measure tear film [Na(+)], [K(+)], [Cl(-)], and pH in living mice, without the need for fluid sampling. Tear film hypertonicity in AQP5 deficiency is likely caused by reduced transcorneal water secretion in response to evaporative water loss.
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Affiliation(s)
- Javier Ruiz-Ederra
- Department of Medicine and Physiology, Cardiovascular Research Institute, University of California, San Francisco, California
| | - Marc H. Levin
- Department of Medicine and Physiology, Cardiovascular Research Institute, University of California, San Francisco, California
| | - A. S. Verkman
- Department of Medicine and Physiology, Cardiovascular Research Institute, University of California, San Francisco, California
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del Mónaco S, Assef Y, Kotsias BA. Epithelial sodium channel in a human trophoblast cell line (BeWo). J Membr Biol 2008; 223:127-39. [PMID: 18665318 DOI: 10.1007/s00232-008-9119-3] [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] [Received: 04/07/2008] [Accepted: 07/01/2008] [Indexed: 11/26/2022]
Abstract
The present study was performed to assay sodium currents in BeWo cells. These cells comprise a human trophoblast cell line which displays many of the biochemical and morphological properties similar to those reported for the in uterus proliferative cytotrophoblast. For whole-cell patch-clamp experiments, BeWo cells treated for 12 h with 100 nM aldosterone were exposed to 8Br-cAMP, a membrane-permeable cAMP analogue, to induce channel activity. Cells showed an amiloride-sensitive ion current (IC50 of 5.77 microM). Ion substitution experiments showed that the amiloride-sensitive current carried cations with a permeability rank order of Li+ > Na+ > K+ > NMDG (PLi/PNa = 1.3, PK/PNa = 0.6, PNMDG/PNa = 0.2). In cells pretreated with aldosterone, we observed that nearly half of successful patches had sodium channels with a linear conductance of 6.4 +/- 1.8 pS, a low voltage-independent Po and a PK/PNa of 0.19. Using RT-PCR, we determined that control cells express the alpha-, but not beta- and gamma-, epithelial sodium channel (ENaC) mRNA. When cells were treated with aldosterone (100 nM, 12 h), all alpha-, beta- and gamma-ENaC mRNAs were detected. The presence of ENaC subunit proteins in these cells was confirmed by Western blot analysis and immunolocalization with specific ENaC primary antibodies. In summary, our results suggest that BeWo cells express ENaC subunits and that aldosterone was able to modulate a selective response by generating amiloride-sensitive sodium currents similar to those observed in other human tissues.
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Affiliation(s)
- Silvana del Mónaco
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas A. Lanari, University of Buenos Aires, C. de Malvinas 3150, Buenos Aires 1427, Argentina
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Amaral JS, Pinho MJ, Soares-da-Silva P. Genomic regulation of intestinal amino acid transporters by aldosterone. Mol Cell Biochem 2008; 313:1-10. [PMID: 18347756 DOI: 10.1007/s11010-008-9735-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Accepted: 02/25/2008] [Indexed: 01/11/2023]
Abstract
Overexpression of renal LAT2, a Na+ -independent L-amino acid transporter, in spontaneous hypertensive rats (SHR) is organ specific and precedes the onset of hypertension (Pinho et al., Hypertension, 42:613-618, 2003). However, the expression of LAT2 correlates negatively with plasma aldosterone levels after high sodium intake (Pinho et al., Am J Physiol Ren Physiol 292:F1452-F1463, 2007). The present study evaluated the expression of Na+ -independent LAT1, LAT2, and 4F2hc and Na+ -dependent ASCT2 amino acid transporters in the intestine of normotensive Wistar rats chronically treated with aldosterone. In conditions of high salt intake, to keep endogenous aldosterone to a minimum, rats were implanted with aldosterone or spironolactone tablets. In aldosterone-treated and aldosterone + spironolactone-treated rats, aldosterone plasma levels were increased by fourfold. At the protein level, aldosterone treatment significantly increased LAT1 (62%), LAT2 (49%), 4F2hc (48%), and ASCT2 (65%) expression. The effect of aldosterone upon LAT1, LAT2, 4F2hc, and ASCT2 protein abundance was completely reversed by spironolactone. Aldosterone significantly increased intestinal LAT2 and 4F2hc mRNA levels (27% and 35% increase, respectively), with no changes in LAT1 and ASCT2 transcript levels. In conclusion, increases in intestinal Na+ -independent LAT1 and LAT2 and Na+ -dependent ASCT2 transcript and protein abundance during chronic treatment with aldosterone occur through a spironolactone-sensitive genomic mechanism.
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Affiliation(s)
- João S Amaral
- Faculty of Medicine, Institute of Pharmacology and Therapeutics, 4200-319 Porto, Portugal
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Key role of aldosterone and pericryptal myofibroblast growth in colonic permeability. J Pediatr Gastroenterol Nutr 2007; 45 Suppl 2:S127-30. [PMID: 18185073 DOI: 10.1097/mpg.0b013e31812e680b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
When sodium intake diminishes, both the kidney and distal colon contribute directly to sodium homeostasis. In response to a diet with low amounts of sodium, the body hormonal profile changes to produce different effects on crypt-colon permeability and absorption and in the pericryptal sheath surrounding distal colonic crypts. This adaptation produces an increase in Na absorption, a decreased crypt-wall permeability, and an activation of the growth of pericryptal myofibroblasts. The separate roles of the 2 main hormones implicated in the process, aldosterone and angiotensin II, until now have been unclear. Experiments conducted on adrenalectomized rats on low- and high-sodium diets, implanted with osmotic pumps perfusing either aldosterone or angiotensin II, allow us to discriminate between the effects of these hormones. In the distal colon, aldosterone acts as a trophic agent on the myofibroblasts layer and is the key hormone controlling colonic permeability, but angiotensin II alone has no discernable direct role in the process.
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Abstract
The specific role of vasopressin in colonic crypt function and its possible synergistic action with aldosterone were studied. Sprague-Dawley rats fed a high-Na+ (HS; 150 mM NaCl) or a low-Na+ (LS; 150 microM NaCl) diet were deprived of water or infused with vasopressin, and some animals were treated with specific vasopressin receptor subtype V1 and V2 antagonists. The expression of the epithelial Na+ channel (ENaC), alpha-smooth muscle actin (alpha-SMA) and aquaporin-2 (AQP-2) were determined by immunolocalization in distal colonic mucosa. The pericryptal Na+ concentration was determined by confocal microscopy, using a low-affinity Na+-sensitive fluorescent dye (sodium red) and crypt permeability was measured by the rate of escape of fluorescein isothiocyanate-labelled dextran (10 kDa) from the crypt lumen into the pericryptal space in isolated rat distal colonic mucosa. A high plasma concentration of vasopressin raised alpha-SMA expression in the pericryptal sheath (P < 0.05), increased the pericryptal Na+ accumulation in this space (P < 0.01) and caused a reduction of crypt wall permeability (P < 0.01). All these effects were reversed by selective blockade of V1 and V2 receptors. No synergistic effects with aldosterone were observed. Dehydration and vasopressin infusion increased AQP-2 expression in distal colonic mucosa (P < 0.05). This action of vasopressin was prevented by tolvaptan, a specific V2 receptor antagonist (P < 0.05). It is concluded that vasopressin has trophic effects in the rat distal colon, increasing pericryptal myofibroblast growth which affects crypt absorption, and these effects are independent of the presence of aldosterone.
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Affiliation(s)
- Esther Cristià
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
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Cristià E, Afzal-Ahmed I, Pérez-Bosque A, Amat C, Naftalin RJ, Moretó M. Pericryptal myofibroblast growth in rat descending colon induced by low-sodium diets is mediated by aldosterone and not by angiotensin II. J Membr Biol 2006; 206:53-9. [PMID: 16440181 DOI: 10.1007/s00232-005-0773-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Indexed: 10/25/2022]
Abstract
Pericryptal myofibroblast growth in descending colonic crypts correlates with the activation of the renin-angiotensin-aldosterone system. Earlier work showed that during the transition from a high-Na(+) (HS) to low-Na(+) (LS) diet there are changes in the colonic crypt wall and pericryptal sheath. As LS diet increases both aldosterone and angiotensin II, the aim here was to determine their individual contributions to the trophic changes in colonic crypts. Experiments were conducted on control and adrenalectomized Sprague-Dawley rats fed an HS diet and then switched to LS diet for 3 days and supplemented with aldosterone or angiotensin II. The actions of the angiotensin-converting enzyme inhibitor captopril, the angiotensin receptor antagonist losartan and the aldosterone antagonist spironolactone on extracellular matrix proteins, claudin 4 and E-cadherin myofibroblast proteins, alpha-smooth muscle actin (alpha-SMA) and OB-cadherin (cadherin 11), angiotensin type 1 and TGFbetar1 membrane receptors were determined by immunolocalization in fixed distal colonic mucosa. The LS diet or aldosterone supplementation following ADX in HS or LS increased extracellular matrix, membrane receptors and myofibroblast proteins, but angiotensin alone had no trophic effect on alpha-SMA. These results show that aldosterone stimulates myofibroblast growth in the distal colon independently of dietary Na(+) intake and of angiotensin levels. This stimulus could be a genomic response or secondary to stretch of the pericryptal sheath myofibroblasts accompanying enhanced rates of crypt fluid absorption.
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Affiliation(s)
- E Cristià
- Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
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