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DiNicolantonio JJ, Mehta V, O'Keefe JH. Is Salt a Culprit or an Innocent Bystander in Hypertension? A Hypothesis Challenging the Ancient Paradigm. Am J Med 2017; 130:893-899. [PMID: 28373112 DOI: 10.1016/j.amjmed.2017.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 12/21/2022]
Abstract
For decades the notion that an excessive consumption of salt (NaCl) leads to hypertension has persisted. However, this idea is based on opinion, not scientific proof. Despite this, every health organization, agency, and clinicians around the world have been advising salt restriction, especially to hypertensive patients. The present review article suggests that the consumption of a high-salt diet is not the cause of hypertension and that there are other factors, such as added sugars, which are causative for inducing hypertension and cardiovascular disease.
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Affiliation(s)
| | - Varshil Mehta
- Mount Sinai Hospital, New York, NY; MGM Medical College, Navi Mumbai, India
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2
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Moreira MCDS, Pinto ISDJ, Mourão AA, Fajemiroye JO, Colombari E, Reis ÂADS, Freiria-Oliveira AH, Ferreira-Neto ML, Pedrino GR. Does the sympathetic nervous system contribute to the pathophysiology of metabolic syndrome? Front Physiol 2015; 6:234. [PMID: 26379553 PMCID: PMC4548210 DOI: 10.3389/fphys.2015.00234] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/05/2015] [Indexed: 12/18/2022] Open
Abstract
The metabolic syndrome (MS), formally known as syndrome X, is a clustering of several risk factors such as obesity, hypertension, insulin resistance, and dislypidemia which could lead to the development of diabetes and cardiovascular diseases (CVD). The frequent changes in the definition and diagnostic criteria of MS are indications of the controversy and the challenges surrounding the understanding of this syndrome among researchers. Obesity and insulin resistance are leading risk factors of MS. Moreover, obesity and hypertension are closely associated to the increase and aggravation of oxidative stress. The recommended treatment of MS frequently involves change of lifestyles to prevent weight gain. MS is not only an important screening tool for the identification of individuals at high risk of CVD and diabetes but also an indicator of suitable treatment. As sympathetic disturbances and oxidative stress are often associated with obesity and hypertension, the present review summarizes the role of sympathetic nervous system and oxidative stress in the MS.
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Affiliation(s)
- Marina C Dos Santos Moreira
- Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Federal University of Goiás Goiânia, Brazil
| | - Izabella S de Jesus Pinto
- Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Federal University of Goiás Goiânia, Brazil
| | - Aline A Mourão
- Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Federal University of Goiás Goiânia, Brazil
| | - James O Fajemiroye
- Laboratory of Pharmacology of Natural Products, Federal University of Goiás Goiânia, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, Universidade Estadual Paulista Araraquara, Brazil
| | - Ângela A da Silva Reis
- Department of Biochemistry and Molecular Biology, Federal University of Goiás Goiânia, Brazil
| | - André H Freiria-Oliveira
- Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Federal University of Goiás Goiânia, Brazil
| | - Marcos L Ferreira-Neto
- Laboratory of Experimental Physiology, Faculty of Physical Education, Federal University of Uberlândia Uberlândia, Brazil
| | - Gustavo R Pedrino
- Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Federal University of Goiás Goiânia, Brazil
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Li F, Yang J, Jones JE, Villar VAM, Yu P, Armando I, Felder RA, Jose PA. Sorting nexin 5 and dopamine d1 receptor regulate the expression of the insulin receptor in human renal proximal tubule cells. Endocrinology 2015; 156:2211-21. [PMID: 25825816 PMCID: PMC4430625 DOI: 10.1210/en.2014-1638] [Citation(s) in RCA: 14] [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: 01/07/2023]
Abstract
Sorting nexin 5 (SNX5) belongs to the SNX family, which is composed of a diverse group of proteins that mediate trafficking of plasma membrane proteins, receptors, and transporters. SNX5 is important in the resensitization of the dopamine D1-like receptor (D1R). D1R is uncoupled from its effector proteins in hypertension and diabetes, and treatment of diabetes restores D1R function and insulin receptor (IR) expression. We tested the hypothesis that the D1R and SNX5 regulate IR by studying the expression, distribution, dynamics, and functional consequences of their interaction in human renal proximal tubule cells (hRPTCs). D1R, SNX5, and IR were expressed and colocalized in the brush border of RPTs. Insulin promoted the colocalization of SNX5 and IR at the perinuclear area of hRPTCs. Unlike SNX5, the D1R colocalized and coimmunoprecipitated with IR, and this interaction was enhanced by insulin. To evaluate the role of SNX5 and D1R on IR signaling, we silenced via RNA interference the endogenous expression of SNX5 or the D1R gene DRD1 in hRPTCs. We observed a decrease in IR expression and abundance of phosphorylated IR substrate and phosphorylated protein kinase B, which are crucial components of the IR signal transduction pathway. Our data indicate that SNX5 and D1R are necessary for normal IR expression and activity. It is conceivable that D1R and SNX5 may interact to increase the sensitivity to insulin via a positive regulation of IR and insulin signaling.
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Affiliation(s)
- Fengmin Li
- Department of Physiology and Biophysics (F.L., P.A.J.), Georgetown University Medical Center, Washington, DC 20057; Liver Disease Branch (F.L.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892; Department of Nutrition (J.Y.), Daping Hospital, The Third Military Medical University, Chongqing 400042, People's Republic of China; Division of Nephrology (J.Y.J.E.J., V.A.M.V., P.Y., I.A., P.A.J.), Department of Medicine, and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore, Maryland 21201; and University of Virginia Health Sciences Center (R.A.F.), Charlottesville, Virginia 22908
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Banerjee A, Udin S, Krishna A. Regulation of leptin synthesis in white adipose tissue of the female fruit bat,Cynopterus sphinx: role of melatonin with or without insulin. Exp Physiol 2010; 96:216-25. [DOI: 10.1113/expphysiol.2010.055129] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ferreira DN, Katayama IA, Oliveira IB, Rosa KT, Furukawa LNS, Coelho MS, Casarini DE, Heimann JC. Salt-induced cardiac hypertrophy and interstitial fibrosis are due to a blood pressure-independent mechanism in Wistar rats. J Nutr 2010; 140:1742-51. [PMID: 20724490 DOI: 10.3945/jn.109.117473] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High salt intake is a known cardiovascular risk factor and is associated with cardiac alterations. To better understand this effect, male Wistar rats were fed a normal (NSD: 1.3% NaCl), high 4 (HSD4: 4%), or high 8 (HSD8: 8%) salt diet from weaning until 18 wk of age. The HSD8 group was subdivided into HSD8, HSD8+HZ (15 mg . kg(-1) . d(-1) hydralazine in the drinking water), and HSD8+LOS (20 mg . kg(-1) . d(-1) losartan in the drinking water) groups. The cardiomyocyte diameter was greater in the HSD4 and HSD8 groups than in the HSD8+LOS and NSD groups. Interstitial fibrosis was greater in the HSD4 and HSD8 groups than in the HSD8+HZ and NSD groups. Hydralazine prevented high blood pressure (BP) and fibrosis, but not cardiomyocyte hypertrophy. Losartan prevented high BP and cardiomyocyte hypertrophy, but not fibrosis. Angiotensin II type 1 receptor (AT(1)) protein expression in both ventricles was greater in the HSD8 group than in the NSD group. Losartan, but not hydralazine, prevented this effect. Compared with the NSD group, the binding of an AT(1) conformation-specific antibody that recognizes the activated form of the receptor was lower in both ventricles in all other groups. Losartan further lowered the binding of the anti-AT(1) antibody in both ventricles compared with all other experimental groups. Angiotensin II was greater in both ventricles in all groups compared with the NSD group. Myocardial structural alterations in response to HSD are independent of the effect on BP. Salt-induced cardiomyocyte hypertrophy and interstitial fibrosis possibly are due to different mechanisms. Evidence from the present study suggests that salt-induced AT(1) receptor internalization is probably due to angiotensin II binding.
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Affiliation(s)
- Daniele N Ferreira
- Laboratory of Experimental Hypertension, University of São Paulo, São Paulo 01246-903, Brazil
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6
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Lima N, Tozetto D, Lima L, Nobre F, Moriguti J, Ferriolli E, Foss M. Salt and insulin sensitivity after short and prolonged high salt intake in elderly subjects. Braz J Med Biol Res 2009; 42:738-43. [DOI: 10.1590/s0100-879x2009000800008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 05/13/2009] [Indexed: 02/05/2023] Open
Affiliation(s)
| | | | | | - F. Nobre
- Universidade de São Paulo, Brasil
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7
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Chadwick M, Vercoe P, Williams I, Revell D. Dietary exposure of pregnant ewes to salt dictates how their offspring respond to salt. Physiol Behav 2009; 97:437-45. [DOI: 10.1016/j.physbeh.2009.03.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 03/17/2009] [Accepted: 03/17/2009] [Indexed: 11/29/2022]
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Fonseca-Alaniz MH, Takada J, Andreotti S, de Campos TBF, Campaña AB, Borges-Silva CN, Lima FB. High sodium intake enhances insulin-stimulated glucose uptake in rat epididymal adipose tissue. Obesity (Silver Spring) 2008; 16:1186-92. [PMID: 18369340 DOI: 10.1038/oby.2008.69] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE This study investigated the effect of different sodium content diets on rat adipose tissue carbohydrate metabolism and insulin sensitivity. METHODS AND PROCEDURES Male Wistar rats were fed on normal- (0.5% Na(+); NS), high- (3.12% Na(+); HS),or low-sodium (0.06% Na(+); LS) diets for 3, 6, and 9 weeks after weaning. Blood pressure (BP) was measured using a computerized tail-cuff system. An intravenous insulin tolerance test (ivITT) was performed in fasted animals. At the end of each period, rats were killed and blood samples were collected for glucose and insulin determinations. The white adipose tissue (WAT) from abdominal and inguinal subcutaneous (SC) and periepididymal (PE) depots were weighed and processed for adipocyte isolation and measurement of in vitro rates of insulin-stimulated 2-deoxy-D-[(3)H]-glucose uptake (2DGU) and conversion of -[U-(14)C]-glucose into (14)CO(2). RESULTS After 6 weeks, HS diet significantly increased the BP, SC and PE WAT masses, PE adipocyte size, and plasma insulin concentration. The sodium dietary content did not influence the whole-body insulin sensitivity. A higher half-maximal effective insulin concentration (EC(50)) from the dose-response curve of 2DGU and an increase in the insulin-stimulated glucose oxidation rate were observed in the isolated PE adipocytes from HS rats. DISCUSSION The chronic salt overload enhanced the adipocyte insulin sensitivity for glucose uptake and the insulin-induced glucose metabolization, contributing to promote adipocyte hypertrophy and increase the mass of several adipose depots, particularly the PE fat pad.
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MESH Headings
- Adipocytes, White/drug effects
- Adipocytes, White/metabolism
- Adipocytes, White/pathology
- Adipose Tissue/pathology
- Adipose Tissue, White/drug effects
- Adipose Tissue, White/metabolism
- Adipose Tissue, White/pathology
- Animals
- Biological Transport/drug effects
- Blood Glucose/metabolism
- Blood Pressure/drug effects
- Body Weight/physiology
- Cells, Cultured
- Dose-Response Relationship, Drug
- Epididymis/drug effects
- Epididymis/metabolism
- Epididymis/pathology
- Glucose/metabolism
- Glucose/pharmacokinetics
- Heart Rate/drug effects
- Hypertrophy
- Insulin/blood
- Insulin/pharmacology
- Male
- Rats
- Rats, Wistar
- Sodium, Dietary/pharmacology
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Affiliation(s)
- Miriam H Fonseca-Alaniz
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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9
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Fonseca-Alaniz MH, Brito LC, Borges-Silva CN, Takada J, Andreotti S, Lima FB. High dietary sodium intake increases white adipose tissue mass and plasma leptin in rats. Obesity (Silver Spring) 2007; 15:2200-8. [PMID: 17890487 DOI: 10.1038/oby.2007.261] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Salt restriction has been reported to increase white adipose tissue (WAT) mass in rodents. The objective of this study was to investigate the effect of different sodium content diets on the lipogenic and lipolytic activities of WAT. RESEARCH METHODS AND PROCEDURES Male Wistar rats were fed on normal-sodium (NS; 0.5% Na(+)), high-sodium (HS; 3.12% Na(+)), or low-sodium (LS; 0.06% Na(+)) diets for 3, 6, and 9 weeks after weaning. Blood pressure (BP) was measured using a computerized tail-cuff system. At the end of each period, rats were killed and blood samples were collected for leptin determinations. The WAT from abdominal and inguinal subcutaneous (SC), periepididymal (PE) and retroperitoneal (RP) depots was weighed and processed for adipocyte isolation, rate measurement of lipolysis and d-[U-(14)C]-glucose incorporation into lipids, glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme activity evaluation, and determination of G6PDH and leptin mRNA expression. RESULTS After 6 weeks, HS diet significantly increased BP; SC, PE, and RP WAT masses; PE adipocyte size; plasma leptin concentration; G6PDH activity in SC WAT; and PE depots and malic activity only in SC WAT. The leptin levels correlated positively with WAT masses and adipocyte size. An increase in the basal and isoproterenol-stimulated lipolysis and in the ability to incorporate glucose into lipids was observed in isolated adipocytes from HS rats. DISCUSSION HS diet induced higher adiposity characterized by high plasma leptin concentration and adipocyte hypertrophy, probably due to an increased lipogenic capacity of WAT.
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Affiliation(s)
- Miriam H Fonseca-Alaniz
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, 1524 Prof Lineu Prestes Ave., 05508-900, Sao Paulo, SP, Brazil
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10
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Lima NKC, Lima FB, dos Santos EA, Okamoto MM, Sumida DH, Hell NS, Furukawa LNS, Heimann JC. Effect of Lifelong High- or Low-Salt Intake on Blood Pressure, Left Ventricular Mass and Plasma Insulin in Wistar Rats. Am J Med Sci 2006; 331:309-14. [PMID: 16775437 DOI: 10.1097/00000441-200606000-00003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Salt restriction is recommended for hypertension treatment to reduce blood pressure, but its effect on some risk factors is still a matter of discussion. The aim of this study was to observe the effect of a long period of salt restriction or overload on blood pressure, left ventricular mass (LVM), kidney mass (KM), glucose tolerance, and plasma insulin. METHODS Male Wistar rats were fed from weaning with a low-salt diet (LSD) or a high-salt diet (HSD) until 72 weeks of age. After 48 weeks, the diets were changed in half of the rats: HSD until 48 weeks and then LSD (LHSD) and LSD until 48 weeks and then HSD (HLSD). Body weight, blood pressure, electrolyte excretion, creatinine clearance, plasma renin activity, LVM, KM, and intravenous glucose tolerance test with insulin determinations were evaluated. RESULTS Blood pressure, LVM and KM were higher on the HSD than on the LSD. Blood pressure was lower on the LHSD than on the HLSD. There were no differences in LVM and KM on the LHSD compared with the HLSD. The relationship between area under the curve (AUC) of insulin and glucose during the intravenous glucose tolerance test was higher on the LSD. No differences were detected in AUC between the two groups of rats whose diet were inverted with 48 weeks of age. CONCLUSIONS A chronic HSD increases blood pressure, LVM, and KM and a chronic LSD increases plasma insulin in response to a glucose challenge in aging rats. The hypotensive effect of salt restriction is not modified by a previous long period on a HSD.
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Affiliation(s)
- Nereida K C Lima
- Division of General Internal and Geriatric Medicine, Department of Internal Medicine, Ribeirão Preto Medical School, São Paulo, Brazil
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Abstract
A regulação da homeostasia intra e extra-celular da glicose está diretamente relacionada ao controle preciso da expressão dos genes que codificam as diferentes isoformas de proteínas transportadoras de glicose, as quais se expressam de maneira tecido-específica, em conseqüência do padrão de ativação dos fatores transcricionais reguladores de cada gene, em cada tipo celular. A síndrome metabólica (SM) abrange uma grande variedade de alterações fisiopatológicas, todas de repercussões sistêmicas, acometendo os mais distintos territórios do organismo, nos quais alterações nos transportadores de glicose presentes são observadas em maior ou menor grau. A presente revisão abordará as alterações na expressão de transportadores de glicose claramente demonstradas na literatura, cujas repercussões nos fluxos territoriais de glicose auxiliam na compreensão de mecanismos fisiopatológicos da SM, assim como dos tratamentos propostos para esta entidade.
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Affiliation(s)
- Ubiratan Fabres Machado
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP.
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Coelho MS, Passadore MD, Gasparetti AL, Bibancos T, Prada PO, Furukawa LL, Furukawa LNS, Fukui RT, Casarini DE, Saad MJA, Luz J, Chiavegatto S, Dolnikoff MS, Heimann JC. High- or low-salt diet from weaning to adulthood: effect on body weight, food intake and energy balance in rats. Nutr Metab Cardiovasc Dis 2006; 16:148-155. [PMID: 16487915 DOI: 10.1016/j.numecd.2005.09.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 04/22/2005] [Accepted: 05/24/2005] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To get some additional insight on the mechanisms of the effect of salt intake on body weight. DESIGN AND METHODS Rats were fed a low (LSD), normal (NSD), or high (HSD) salt diet. In a first set, body weight, tail-cuff blood pressure, fasting plasma thyroid-stimulating hormone, triiodothyronine, L-thyroxine, glucose, insulin, and angiotensin II were measured. Angiotensin II content was determined in white and brown adipose tissues. Uncoupling protein 1 expression was measured in brown adipose tissue. In a second set, body weight, food intake, energy balance, and plasma leptin were determined. In a third set of rats, motor activity and body weight were evaluated. RESULTS Blood pressure increased on HSD. Body weight was similar among groups at weaning, but during adulthood it was lower on HSD and higher on LSD. Food intake, L-thyroxine concentration, uncoupling protein 1 expression and energy expenditure were higher in HSD rats, while non-fasting leptin concentration was lower in these groups compared to NSD and LSD animals. Plasma thyroid-stimulating hormone decreased on both HSD and LSD while plasma glucose and insulin were elevated only on LSD. A decrease in plasma angiotensin II was observed in HSD rats. On LSD, an increase in brown adipose tissue angiotensin II content was associated to decreased uncoupling protein 1 expression and energy expenditure. In this group, a low angiotensin II content in white adipose tissue was also found. Motor activity was not influenced by the dietary salt content. CONCLUSIONS Chronic alteration in salt intake is associated with changes in body weight, food intake, hormonal profile, and energy expenditure and tissue angiotensin II content.
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Affiliation(s)
- Michella S Coelho
- Department of Internal Medicine, Nephrology Division, Laboratory of Experimental Hypertension of the University of São Paulo School of Medicine, São Paulo, Brazil
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13
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Vidonho AF, da Silva AA, Catanozi S, Rocha JC, Beutel A, Carillo BA, Furukawa LNS, Campos RR, de Toledo Bergamaschi CM, Carpinelli AR, Quintão ECR, Dolnikoff MS, Heimann JC. Perinatal salt restriction: a new pathway to programming insulin resistance and dyslipidemia in adult wistar rats. Pediatr Res 2004; 56:842-8. [PMID: 15470199 DOI: 10.1203/01.pdr.0000145258.75160.5b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Several studies support the hypothesis that chronic diseases in adulthood might be triggered by events that occur during fetal development. This study examined the consequences of perinatal salt intake on blood pressure (BP) and carbohydrate and lipid metabolism in adult offspring of dams on high-salt [HSD; 8% (HSD2) or 4% (HSD1)], normal-salt (NSD; 1.3%), or low-salt (LSD; 0.15% NaCl) diet during pregnancy and lactation. At 12 wk of age, female Wistar rats were matched with adult male rats that were fed NSD. Weekly tail-cuff BP measurements were performed before, during, and after pregnancy. After weaning, the offspring received only NSD and were housed in metabolic cages for 24-h urine collection for sodium and potassium and nitrate and nitrite excretion measurements. At 12 wk of age, intra-arterial mean BP was measured, a euglycemic-hyperinsulinemic clamp was performed, and plasma lipids and nitrate and nitrite concentrations were determined. Tail-cuff BP was higher during pregnancy in HSD2 and HSD1 than in NSD and LSD dams. Mean BP (mm Hg) was also higher in the offspring of HSD2 (110 +/- 5) and HSD1 (107 +/- 5) compared with NSD (100 +/- 2) and LSD (92 +/- 2). Lower glucose uptake and higher plasma cholesterol and triacylglycerols were observed in male offspring from LSD dams (glucose uptake: HSD2 17 +/- 4, HSD1 15 +/- 3, NSD 11 +/- 3, LSD 4 +/- 1 mg . kg(-1) . min(-1); cholesterol: HSD2 62 +/- 6, HSD1 82 +/- 11, NSD 68 +/- 10, LSD 98 +/- 17 mg/dL; triacylglycerols: HSD2 47 +/- 15, HSD1 49 +/- 12, NSD 56 +/- 19, LSD 83 +/- 11 mg/dL). In conclusion, maternal salt intake during pregnancy and lactation has long-term influences on arterial pressure, insulin sensitivity, and plasma lipids of the adult offspring.
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Affiliation(s)
- Armando F Vidonho
- Laboratory of Experimental Hypertension, Department of Internal Medicine, Nephrology Division, University of São Paulo School of Medicine, 01246-903 São Paulo SP, Brazil
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14
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Okamoto MM, Sumida DH, Carvalho CRO, Vargas AM, Heimann JC, Schaan BD, Machado UF. Changes in dietary sodium consumption modulate GLUT4 gene expression and early steps of insulin signaling. Am J Physiol Regul Integr Comp Physiol 2004; 286:R779-85. [PMID: 14670806 DOI: 10.1152/ajpregu.00396.2003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have shown that chronic salt overload increases insulin sensitivity, while chronic salt restriction decreases it. In the present study we investigated the influence of dietary sodium on 1) GLUT4 gene expression, by Northern and Western blotting analysis; 2) in vivo GLUT4 protein translocation, by measuring the GLUT4 protein in plasma membrane and microsome, before and after insulin injection; and 3) insulin signaling, by analyzing basal and insulin-stimulated tyrosine phosphorylation of insulin receptor (IR)-β, insulin receptor substrate (IRS)-1, and IRS-2. Wistar rats were fed normal-sodium (NS-0.5%), low-sodium (LS-0.06%), or high-sodium diets (HS-3.12%) for 9 wk and were killed under pentobarbital anesthesia. Compared with NS rats, HS rats increased ( P < 0.05) the GLUT4 protein in adipose tissue and skeletal muscle, whereas GLUT4 mRNA was increased only in adipose tissue. GLUT4 expression was unchanged in LS rats compared with NS rats. The GLUT4 translocation in HS rats was higher ( P < 0.05) both in basal and insulin-stimulated conditions. On the other hand, LS rats did not increase the GLUT4 translocation after insulin stimulus. Compared with NS rats, LS rats showed reduced ( P < 0.01) basal and insulin-stimulated tyrosine phosphorylation of IRS-1 in skeletal muscle and IRS-2 in liver, whereas HS rats showed enhanced basal tyrosine phosphorylation of IRS-1 in skeletal muscle ( P < 0.05) and of IRS-2 in liver. In summary, increased insulin sensitivity in HS rats is related to increased GLUT4 gene expression, enhanced insulin signaling, and GLUT4 translocation, whereas decreased insulin sensitivity of LS rats does not involve changes in GLUT4 gene expression but is related to impaired insulin signaling.
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Affiliation(s)
- Maristela Mitiko Okamoto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, 1524 05508-900, São Paulo, Brazil
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15
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Prada P, Okamoto MM, Furukawa LN, Machado UF, Heimann JC, Dolnikoff MS. High- or low-salt diet from weaning to adulthood: effect on insulin sensitivity in Wistar rats. Hypertension 2000; 35:424-9. [PMID: 10642336 DOI: 10.1161/01.hyp.35.1.424] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Because of conflicting results in the literature, further studies are needed to confirm an association between the degree of salt consumption and insulin sensitivity. The aim of this study was to measure insulin sensitivity in rats fed from weaning to adulthood with a low (LSD), normal (NSD), or high (HSD) salt diet. Body weight, carcass lipid content, blood glucose, nonesterified fatty acids, plasma insulin, plasma renin activity, and a glucose transporter (GLUT4) were measured. A euglycemic hyperinsulinemic clamp was used in 52 anesthetized rats. Body weight was higher in rats on LSD than in those on NSD (P<0.05) or HSD (P<0.001). Percentage fat carcass content was higher (P<0.05) in rats on LSD than in those on NSD. Basal plasma insulin and glucose levels were not altered (P>0.05) by salt consumption. Nonesterified fatty acids were lower in rats on HSD than in those on LSD (P<0.05) or NSD (P<0.01). Glucose uptake was lower in rats on LSD than in those on NSD (P<0.05) or HSD (P<0. 001). When a euglycemic hyperinsulinemic clamp was used on pair-weight rats, similar results were obtained, which suggests that the effect of LSD on insulin sensitivity was not due to higher body weight. GLUT4 in insulin-sensitive tissues was increased in rats on HSD except in the cardiac muscle. Captopril treatment partially reversed low insulin sensitivity in LSD rats, whereas losartan did not change it, which indicates that the effect of LSD on insulin sensitivity is angiotensin independent. In conclusion, the present results demonstrate that chronic dietary salt restriction induces a decrease in insulin sensitivity not associated with renin-angiotensin system activity or body weight changes.
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Affiliation(s)
- P Prada
- Nephrology Department, Laboratory of Hypertension, University of São Paulo School of Medicine, Brazil
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Muntzel MS, Hamidou I, Barrett S. Metformin attenuates salt-induced hypertension in spontaneously hypertensive rats. Hypertension 1999; 33:1135-40. [PMID: 10334800 DOI: 10.1161/01.hyp.33.5.1135] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Metformin, an antihyperglycemic agent used for treatment of type 2 diabetes mellitus, lowers blood pressure in humans and experimental animals. We recently demonstrated that short-term administration of metformin may lower blood pressure by reducing sympathetic neural outflow. The present studies were initiated to determine whether long-term administration of metformin blunts salt-induced hypertension, a condition characterized by elevated sympathetic activity. Male spontaneously hypertensive rats, in which radiotelemeters had been implanted for continuous monitoring of heart rate and blood pressure, were randomly assigned to groups that received vehicle (drinking water) or metformin (500 mg/kg per day) and ate a normal 0.3% NaCl diet and to groups that received vehicle or metformin and ate a high 8.0% NaCl diet for a period of 4 weeks. Although metformin did not affect blood pressure in the animals that ate the normal-salt diet (vehicle, 130+/-3 mm Hg; metformin, 133+/-5 mm Hg; mean+/-SEM), drug treatment blunted the rise in pressure caused by a high-salt diet (vehicle, 153+/-4 mm Hg; metformin, 140+/-5 mm Hg; P<0.001). In agreement, during direct pressure recordings in anesthetized rats, the animals that ate the high-salt diet had higher pressures (136+/-13 mm Hg) than those in the control (98+/-5 mm Hg, P<0.01), metformin (100+/-7 mm Hg, P<0.01), and metformin/high-salt groups (92+/-3 mm Hg, P<0.01). Finally, metformin lowered heart rate in rats that ate the normal- and high-salt diets (310+/-3 and 305+/-4 bpm) compared with rats that ate normal- and high-salt diets given vehicle (332+/-3 and 324+/-2 bpm, P<0.01). These data indicate that the chronic depressor actions of metformin are enhanced in animals with hypertension exacerbated by a high-salt diet.
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Affiliation(s)
- M S Muntzel
- Department of Biological Sciences, Lehman College, Bronx Community College, Bronx, NY USA.
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dos Santos EA, Yamaguishi GA, Heimann JC. Effect of the heme/heme oxygenase pathway on the relationship between salt consumption and blood pressure. J Hypertens 1998; 16:1965-9. [PMID: 9886884 DOI: 10.1097/00004872-199816121-00017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Some studies have shown that heme oxygenase inhibition increases blood pressure in rats. This effect may be due to the consequent lower levels of the heme degradation products (carbon monoxide, biliverdin, and Fe3+) or due to heme accumulation. However, it is not yet known if the variable effect of NaCl on blood pressure levels is influenced by the heme/heme oxygenase pathway activity. This enzymatic system may be studied by blocking its activity with zinc protoporphyrin IX (ZnPP IX), a heme oxygenase inhibitor. DESIGN AND METHODS Male Wistar rats were fed from weaning with low (LSD--0.15% NaCl), normal (NSD--1.3% NaCl), or high (HSD--8% NaCl) salt diet On the 12th week of age, assessment of the tail-cuff blood pressure (tc-BP) response to acute inhibition of heme oxygenase with ZnPP IX or after vehicle (Na2CO3) was performed. RESULTS A higher tc-BP was observed on HSD both before ZnPP IX (P< 0.001) and vehicle (P = 0.003). After ZnPP IX, tc-BP decreased on HSD (P < 0.001) and increased on NSD (P = 0.003) and on LSD (P < 0.001). The area under the curve (AUC) of the percentage change in the blood pressure response was calculated. On putting all the rats from the three dietary groups together, an inverse correlation was observed between individual AUC after ZnPP IX and control tc-BP (r = -0.71; P< 0.001) but not after vehicle (r = 0.34; P < 0.05). CONCLUSIONS Chronic salt overload increases blood pressure in Wistar rats and the pressure response to heme oxygenase is modulated by the effect of NaCl consumption on blood pressure levels.
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Affiliation(s)
- E A dos Santos
- Nephrology Department, University of São Paulo School of Medicine, SP, Brazil
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