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Inverse Salt Sensitivity of Blood Pressure Is Associated with an Increased Renin-Angiotensin System Activity. Biomedicines 2022; 10:biomedicines10112811. [PMID: 36359330 PMCID: PMC9687845 DOI: 10.3390/biomedicines10112811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
High and low sodium diets are associated with increased blood pressure and cardiovascular morbidity and mortality. The paradoxical response of elevated BP in low salt diets, aka inverse salt sensitivity (ISS), is an understudied vulnerable 11% of the adult population with yet undiscovered etiology. A linear relationship between the number of single nucleotide polymorphisms (SNPs) in the dopamine D2 receptor (DRD2, rs6276 and 6277), and the sodium myo-inositol cotransporter 2 (SLC5A11, rs11074656), as well as decreased expression of these two genes in urine-derived renal proximal tubule cells (uRPTCs) isolated from clinical study participants suggest involvement of these cells in ISS. Insight into this newly discovered paradoxical response to sodium is found by incubating cells in low sodium (LS) conditions that unveil cell physiologic differences that are then reversed by mir-485-5p miRNA blocker transfection and bypassing the genetic defect by DRD2 re-expression. The renin-angiotensin system (RAS) is an important counter-regulatory mechanism to prevent hyponatremia under LS conditions. Oversensitive RAS under LS conditions could partially explain the increased mortality in ISS. Angiotensin-II (AngII, 10 nmol/L) increased sodium transport in uRPTCs to a greater extent in individuals with ISS than SR. Downstream signaling of AngII is verified by identifying lowered expression of nuclear factor erythroid 2-related factor 2 (NRF2), CCCTC-binding factor (CTCF), and manganese-dependent mitochondrial superoxide dismutase (SOD2) only in ISS-derived uRPTCs and not SR-derived uRPTCs when incubated in LS conditions. We conclude that DRD2 and SLC5A11 variants in ISS may cause an increased low sodium sensitivity to AngII and renal sodium reabsorption which can contribute to inverse salt-sensitive hypertension.
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Inverse Salt Sensitivity of Blood Pressure: Mechanisms and Potential Relevance for Prevention of Cardiovascular Disease. Curr Hypertens Rep 2022; 24:361-374. [PMID: 35708819 DOI: 10.1007/s11906-022-01201-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE OF REVIEW To review the etiology of inverse salt sensitivity of blood pressure (BP). RECENT FINDINGS Both high and low sodium (Na+) intake can be associated with increased BP and cardiovascular morbidity and mortality. However, little is known regarding the mechanisms involved in the increase in BP in response to low Na+ intake, a condition termed inverse salt sensitivity of BP, which affects approximately 15% of the adult population. The renal proximal tubule is important in regulating up to 70% of renal Na+ transport. The renin-angiotensin and renal dopaminergic systems play both synergistic and opposing roles in the regulation of Na+ transport in this nephron segment. Clinical studies have demonstrated that individuals express a "personal salt index" (PSI) that marks whether they are salt-resistant, salt-sensitive, or inverse salt-sensitive. Inverse salt sensitivity results in part from genetic polymorphisms in various Na+ regulatory genes leading to a decrease in natriuretic activity and an increase in renal tubular Na+ reabsorption leading to an increase in BP. This article reviews the potential mechanisms of a new pathophysiologic entity, inverse salt sensitivity of BP, which affects approximately 15% of the general adult population.
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Graudal NA, Hubeck-Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database Syst Rev 2020; 12:CD004022. [PMID: 33314019 PMCID: PMC8094404 DOI: 10.1002/14651858.cd004022.pub5] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Recent cohort studies show that salt intake below 6 g is associated with increased mortality. These findings have not changed public recommendations to lower salt intake below 6 g, which are based on assumed blood pressure (BP) effects and no side-effects. OBJECTIVES To assess the effects of sodium reduction on BP, and on potential side-effects (hormones and lipids) SEARCH METHODS: The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to April 2018 and a top-up search in March 2020: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions. The top-up search articles are recorded under "awaiting assessment." SELECTION CRITERIA Studies randomizing persons to low-sodium and high-sodium diets were included if they evaluated at least one of the outcome parameters (BP, renin, aldosterone, noradrenalin, adrenalin, cholesterol, high-density lipoprotein, low-density lipoprotein and triglyceride,. DATA COLLECTION AND ANALYSIS Two review authors independently collected data, which were analysed with Review Manager 5.3. Certainty of evidence was assessed using GRADE. MAIN RESULTS Since the first review in 2003 the number of included references has increased from 96 to 195 (174 were in white participants). As a previous study found different BP outcomes in black and white study populations, we stratified the BP outcomes by race. The effect of sodium reduction (from 203 to 65 mmol/day) on BP in white participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.14 mmHg (95% confidence interval (CI): -1.65 to -0.63), 5982 participants, 95 trials; DBP: MD + 0.01 mmHg (95% CI: -0.37 to 0.39), 6276 participants, 96 trials. Hypertension: SBP: MD -5.71 mmHg (95% CI: -6.67 to -4.74), 3998 participants,88 trials; DBP: MD -2.87 mmHg (95% CI: -3.41 to -2.32), 4032 participants, 89 trials (all high-quality evidence). The largest bias contrast across studies was recorded for the detection bias element. A comparison of detection bias low-risk studies versus high/unclear risk studies showed no differences. The effect of sodium reduction (from 195 to 66 mmol/day) on BP in black participants was as follows: Normal blood pressure: SBP: mean difference (MD) -4.02 mmHg (95% CI:-7.37 to -0.68); DBP: MD -2.01 mmHg (95% CI:-4.37, 0.35), 253 participants, 7 trials. Hypertension: SBP: MD -6.64 mmHg (95% CI:-9.00, -4.27); DBP: MD -2.91 mmHg (95% CI:-4.52, -1.30), 398 participants, 8 trials (low-quality evidence). The effect of sodium reduction (from 217 to 103 mmol/day) on BP in Asian participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.50 mmHg (95% CI: -3.09, 0.10); DBP: MD -1.06 mmHg (95% CI:-2.53 to 0.41), 950 participants, 5 trials. Hypertension: SBP: MD -7.75 mmHg (95% CI:-11.44, -4.07); DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15), 254 participants, 8 trials (moderate-low-quality evidence). During sodium reduction renin increased 1.56 ng/mL/hour (95%CI:1.39, 1.73) in 2904 participants (82 trials); aldosterone increased 104 pg/mL (95%CI:88.4,119.7) in 2506 participants (66 trials); noradrenalin increased 62.3 pg/mL: (95%CI: 41.9, 82.8) in 878 participants (35 trials); adrenalin increased 7.55 pg/mL (95%CI: 0.85, 14.26) in 331 participants (15 trials); cholesterol increased 5.19 mg/dL (95%CI:2.1, 8.3) in 917 participants (27 trials); triglyceride increased 7.10 mg/dL (95%CI: 3.1,11.1) in 712 participants (20 trials); LDL tended to increase 2.46 mg/dl (95%CI: -1, 5.9) in 696 participants (18 trials); HDL was unchanged -0.3 mg/dl (95%CI: -1.66,1.05) in 738 participants (20 trials) (All high-quality evidence except the evidence for adrenalin). AUTHORS' CONCLUSIONS In white participants, sodium reduction in accordance with the public recommendations resulted in mean arterial pressure (MAP) decrease of about 0.4 mmHg in participants with normal blood pressure and a MAP decrease of about 4 mmHg in participants with hypertension. Weak evidence indicated that these effects may be a little greater in black and Asian participants. The effects of sodium reduction on potential side effects (hormones and lipids) were more consistent than the effect on BP, especially in people with normal BP.
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Affiliation(s)
- Niels Albert Graudal
- Department of Rheumatology VRR4242, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | | | - Gesche Jurgens
- Clinical Pharmacology Unit, Roskilde Hospital, Roskilde, Denmark
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Huang L, Trieu K, Yoshimura S, Neal B, Woodward M, Campbell NRC, Li Q, Lackland DT, Leung AA, Anderson CAM, MacGregor GA, He FJ. Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials. BMJ 2020; 368:m315. [PMID: 32094151 PMCID: PMC7190039 DOI: 10.1136/bmj.m315] [Citation(s) in RCA: 208] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/08/2020] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To examine the dose-response relation between reduction in dietary sodium and blood pressure change and to explore the impact of intervention duration. DESIGN Systematic review and meta-analysis following PRISMA guidelines. DATA SOURCES Ovid MEDLINE(R), EMBASE, and Cochrane Central Register of Controlled Trials (Wiley) and reference lists of relevant articles up to 21 January 2019. INCLUSION CRITERIA Randomised trials comparing different levels of sodium intake undertaken among adult populations with estimates of intake made using 24 hour urinary sodium excretion. DATA EXTRACTION AND ANALYSIS Two of three reviewers screened the records independently for eligibility. One reviewer extracted all data and the other two reviewed the data for accuracy. Reviewers performed random effects meta-analyses, subgroup analyses, and meta-regression. RESULTS 133 studies with 12 197 participants were included. The mean reductions (reduced sodium v usual sodium) of 24 hour urinary sodium, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 130 mmol (95% confidence interval 115 to 145, P<0.001), 4.26 mm Hg (3.62 to 4.89, P<0.001), and 2.07 mm Hg (1.67 to 2.48, P<0.001), respectively. Each 50 mmol reduction in 24 hour sodium excretion was associated with a 1.10 mm Hg (0.66 to 1.54; P<0.001) reduction in SBP and a 0.33 mm Hg (0.04 to 0.63; P=0.03) reduction in DBP. Reductions in blood pressure were observed in diverse population subsets examined, including hypertensive and non-hypertensive individuals. For the same reduction in 24 hour urinary sodium there was greater SBP reduction in older people, non-white populations, and those with higher baseline SBP levels. In trials of less than 15 days' duration, each 50 mmol reduction in 24 hour urinary sodium excretion was associated with a 1.05 mm Hg (0.40 to 1.70; P=0.002) SBP fall, less than half the effect observed in studies of longer duration (2.13 mm Hg; 0.85 to 3.40; P=0.002). Otherwise, there was no association between trial duration and SBP reduction. CONCLUSIONS The magnitude of blood pressure lowering achieved with sodium reduction showed a dose-response relation and was greater for older populations, non-white populations, and those with higher blood pressure. Short term studies underestimate the effect of sodium reduction on blood pressure. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42019140812.
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Affiliation(s)
- Liping Huang
- Sydney School of Public Health, University of Sydney, Sydney, NSW, Australia
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
| | - Kathy Trieu
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
| | - Sohei Yoshimura
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
- National Cerebral and Cardiovascular Centre, Osaka, Japan
| | - Bruce Neal
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
- Department of Epidemiology and Biostatistics, Imperial College London, London, UK
| | - Mark Woodward
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
- The George Institute for Global Health, University of Oxford, Oxford, UK
| | - Norm R C Campbell
- Departments of Medicine and Community Health Science, University of Calgary, Calgary, AB, Canada
| | - Qiang Li
- The George Institute for Global Health, UNSW Sydney, Sydney, NSW, Australia
| | | | - Alexander A Leung
- Departments of Medicine and Community Health Science, University of Calgary, Calgary, AB, Canada
| | | | - Graham A MacGregor
- Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK
| | - Feng J He
- Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK
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Graudal NA, Hubeck‐Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database Syst Rev 2017; 4:CD004022. [PMID: 28391629 PMCID: PMC6478144 DOI: 10.1002/14651858.cd004022.pub4] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND In spite of more than 100 years of investigations the question of whether a reduced sodium intake improves health is still unsolved. OBJECTIVES To estimate the effects of low sodium intake versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides. SEARCH METHODS The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to March 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 3), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the reference lists of relevant articles. SELECTION CRITERIA Studies randomising persons to low-sodium and high-sodium diets were included if they evaluated at least one of the above outcome parameters. DATA COLLECTION AND ANALYSIS Two review authors independently collected data, which were analysed with Review Manager 5.3. MAIN RESULTS A total of 185 studies were included. The average sodium intake was reduced from 201 mmol/day (corresponding to high usual level) to 66 mmol/day (corresponding to the recommended level).The effect of sodium reduction on blood pressure (BP) was as follows: white people with normotension: SBP: mean difference (MD) -1.09 mmHg (95% confidence interval (CI): -1.63 to -0.56; P = 0.0001); 89 studies, 8569 participants; DBP: + 0.03 mmHg (MD 95% CI: -0.37 to 0.43; P = 0.89); 90 studies, 8833 participants. High-quality evidence. Black people with normotension: SBP: MD -4.02 mmHg (95% CI:-7.37 to -0.68; P = 0.002); seven studies, 506 participants; DBP: MD -2.01 mmHg (95% CI:-4.37 to 0.35; P = 0.09); seven studies, 506 participants. Moderate-quality evidence. Asian people with normotension: SBP: MD -0.72 mmHg (95% CI: -3.86 to 2.41; P = 0.65); DBP: MD -1.63 mmHg (95% CI:-3.35 to 0.08; P =0.06); three studies, 393 participants. Moderate-quality evidence.White people with hypertension: SBP: MD -5.51 mmHg (95% CI: -6.45 to -4.57; P < 0.00001); 84 studies, 5925 participants; DBP: MD -2.88 mmHg (95% CI: -3.44 to -2.32; P < 0.00001); 85 studies, 6001 participants. High-quality evidence. Black people with hypertension: SBP MD -6.64 mmHg (95% CI:-9.00 to -4.27; P = 0.00001); eight studies, 619 participants; DBP -2.91 mmHg (95% CI:-4.52, -1.30; P = 0.0004); eight studies, 619 participants. Moderate-quality evidence. Asian people with hypertension: SBP: MD -7.75 mmHg (95% CI:-11,44 to -4.07; P < 0.0001) nine studies, 501 participants; DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15; P = 0.0006). Moderate-quality evidence.In plasma or serum, there was a significant increase in renin (P < 0.00001), aldosterone (P < 0.00001), noradrenaline (P < 0.00001), adrenaline (P < 0.03), cholesterol (P < 0.0005) and triglyceride (P < 0.0006) with low sodium intake as compared with high sodium intake. All effects were stable in 125 study populations with a sodium intake below 250 mmol/day and a sodium reduction intervention of at least one week. AUTHORS' CONCLUSIONS Sodium reduction from an average high usual sodium intake level (201 mmol/day) to an average level of 66 mmol/day, which is below the recommended upper level of 100 mmol/day (5.8 g salt), resulted in a decrease in SBP/DBP of 1/0 mmHg in white participants with normotension and a decrease in SBP/DBP of 5.5/2.9 mmHg in white participants with hypertension. A few studies showed that these effects in black and Asian populations were greater. The effects on hormones and lipids were similar in people with normotension and hypertension. Renin increased 1.60 ng/mL/hour (55%); aldosterone increased 97.81 pg/mL (127%); adrenalin increased 7.55 pg/mL (14%); noradrenalin increased 63.56 pg/mL: (27%); cholesterol increased 5.59 mg/dL (2.9%); triglyceride increased 7.04 mg/dL (6.3%).
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Affiliation(s)
- Niels Albert Graudal
- Copenhagen University Hospital RigshospitaletDepartment of Rheumatology VRR4242Blegdamsvej 9CopenhagenDenmarkDK‐2100 Ø
| | | | - Gesche Jurgens
- Roskilde HospitalClinical Pharmacology UnitRoskildeDenmark
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Liu J, Yan Y, Nie Y, Shapiro JI. Na/K-ATPase Signaling and Salt Sensitivity: The Role of Oxidative Stress. Antioxidants (Basel) 2017; 6:E18. [PMID: 28257114 PMCID: PMC5384181 DOI: 10.3390/antiox6010018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 02/10/2017] [Accepted: 02/22/2017] [Indexed: 02/07/2023] Open
Abstract
Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium reabsorption in renal proximal tubules, from cardiotonic steroids-mediated to reactive oxygen species (ROS)-mediated Na/K-ATPase signaling that contributes to experimental salt sensitivity.
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Affiliation(s)
- Jiang Liu
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA.
| | - Yanling Yan
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA.
| | - Ying Nie
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA.
| | - Joseph I Shapiro
- Department of Medicine, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25701, USA
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Kazi RN, Sattar MA, Johns EJ. Antidiuretic and antinatriuretic response to high salt load in normotensive Wistar-Kyoto rats: Role of alpha-1A-adrenoreceptors. AUTONOMIC & AUTACOID PHARMACOLOGY 2017; 37:13-18. [PMID: 28332265 DOI: 10.1111/aap.12053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/29/2016] [Accepted: 01/18/2017] [Indexed: 06/06/2023]
Abstract
Altered renal adrenergic responses have been recognized as pathophysiological responses to high salt intake. This study aims to investigate the influence of 6 weeks of high salt diet on α1A -adrenoceptor regulation of renal tubular antinatriuretic and antidiuretic response in normal Wistar Kyoto rats. To achieve the above objective, antinatriuretic and antidiuretic response to phenylephrine was measured in the absence and presence of 5-methylurapidil (5-MeU) using the inulin clearance method. Systemic mean arterial blood pressure and renal haemodynamics were also measured simultaneously. Six weeks of high salt intake in Wistar-Kyoto (WKY) rats did not bring any significant increase in mean arterial blood pressure. WKY rat on high salt diet (WKYHNa) showed an exaggerated increase in absolute and fractional sodium excretion. There was a significant involvement of α1A -adrenoceptor in carrying out renal tubular antinatriuretic and antidiuretic response in Wistar Kyoto rats on normal sodium diet (WKYNNa). However, α1A -adrenoceptor played a minimal role in handling the tubular reabsorptive response in WKY rats on high salt diet.
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Affiliation(s)
- R N Kazi
- College of Applied Medical Science, Prince Sattam Bin Abdul-Aziz University, Wadi Ad Dawaser, Saudi Arabia
- School of Pharmaceutical Sciences, University Sains Malaysia, Penang, Malaysia
| | - M A Sattar
- School of Pharmaceutical Sciences, University Sains Malaysia, Penang, Malaysia
| | - E J Johns
- Department of Physiology, Aras Windle, University College Cork, Cork, Ireland
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Elijovich F, Weinberger MH, Anderson CAM, Appel LJ, Bursztyn M, Cook NR, Dart RA, Newton-Cheh CH, Sacks FM, Laffer CL. Salt Sensitivity of Blood Pressure: A Scientific Statement From the American Heart Association. Hypertension 2016; 68:e7-e46. [PMID: 27443572 DOI: 10.1161/hyp.0000000000000047] [Citation(s) in RCA: 326] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Rhee OJ, Rhee MY, Oh SW, Shin SJ, Gu N, Nah DY, Kim SW, Lee JH. Effect of sodium intake on renin level: Analysis of general population and meta-analysis of randomized controlled trials. Int J Cardiol 2016; 215:120-6. [PMID: 27111173 DOI: 10.1016/j.ijcard.2016.04.109] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 04/11/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND We evaluated the association between sodium intake and plasma renin levels in the cross sectional study and meta-analysis of randomized controlled trials, whether there is a persistent elevation of plasma renin by longer-term sodium intake restriction. METHODS Plasma renin activity (PRA) and 24-h urine sodium (24HUNa) excretion were measured from individuals randomly selected from a community. Simple and multiple linear regression analyses adjusted for age, 24-h systolic blood pressure, 24-h average heart rate, fasting blood glucose and gender were performed. For meta-analysis, 74 studies published from 1975 to mid-2014 were identified in a systematic literature search using EMBASE, CINAHL, and MEDLINE. Random effects meta-analyses and a meta-regression analysis were performed. RESULTS Among the 496 participants recruited, 210 normotensive and 87 untreated hypertensive subjects were included in the analysis. There was no significant association between PRA and 24HUNa in the total population, or hypertensive and normotensive individuals. In the meta-analysis, the standard mean difference (SMD) of renin level by sodium intake reduction was 1.26 (95% CI: 1.08 to 1.44, Z=12.80, P<0.001, I(2)=87%). In the meta-regression analysis, an increase in a day of intervention was associated with a fall in SMD by -0.04 (95% CI: -0.05 to -0.02, Z=-5.27, P<0.001, I(2)=86%), indicating that longer duration of reduced sodium intake would lead to lesser SMD of renin level. CONCLUSIONS The present population based cross-sectional study and meta-analysis suggests that prolonged reduction in sodium intake is very unlikely associated with elevation of plasma renin levels.
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Affiliation(s)
- O J Rhee
- Department of Social Welfare, Soongsil University, Seoul, Republic of Korea
| | - M Y Rhee
- Cardiovascular Center, Dongguk University Ilsan Hospital, Goyang, Republic of Korea.
| | - S W Oh
- Department of Family Medicine, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - S J Shin
- Division of Nephrology, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - N Gu
- Department of Clinical Pharmacology and Therapeutics, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
| | - D Y Nah
- Division of Cardiology, Department of Internal Medicine, College of Medicine, Dongguk University, Gyeongju, Republic of Korea
| | - S W Kim
- Department of Statistics, Survey and Health Policy Research Center, Dongguk University, Seoul, Republic of Korea
| | - J H Lee
- Department of Thoracic and Cardiovascular Surgery, Dongguk University Ilsan Hospital, Goyang, Republic of Korea
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Association between pre hemodialysis serum sodium concentration and blood pressure: results from a retrospective analysis from the international monitoring dialysis outcomes (MONDO) initiative. J Hum Hypertens 2015. [PMID: 26223346 DOI: 10.1038/jhh.2015.79] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A recent study from the United Kingdom indicates an association between pre hemodialysis (HD) serum sodium (SNa(+)) and systolic and diastolic blood pressure (SBP and DBP) in chronic HD patients. We extend this analysis to an international cohort of incident HD patients. The Monitoring Dialysis Outcomes initiative encompasses patients from 41 countries. Over 2 years monthly pre-HD SNa(+) levels were used as predictors of pre-HD SBP and DBP in a linear mixed model (LMM) adjusted for age, gender, interdialytic weight gain, diabetes, serum albumin and calcium. Similar models were constructed with DBP as outcome. Analyses were carried out stratified by continent (North and South America; Europe and Asia). LMMs were also constructed for the entire observation period of 2 years, and separately the first and the second year after HD initiation. We studied 17 050 incident patients and found SNa(+) to have a significant slope estimate in the LMM predicting pre-HD SBP and DBP (ranging from 0.22 to 0.29 and 0.10 to 0.21 mm Hg per mEq l(-1), respectively, between the continents). The findings were similar in subsets of SBP and SNa(+) tertiles, and separately analyzed for the first and second year. Our analysis shows an independent association between SNa, SBP and DBP in a large intercontinental database, indicating that this relation is a profound biological phenomenon in incident and prevalent HD patients, generalizable to an international level and independent of SBP and DBP magnitude.
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11
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Schweda F. Salt feedback on the renin-angiotensin-aldosterone system. Pflugers Arch 2014; 467:565-76. [DOI: 10.1007/s00424-014-1668-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 12/02/2014] [Accepted: 12/02/2014] [Indexed: 12/21/2022]
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Abstract
Resistant hypertension in diabetes is associated with poor cardiovascular and renal outcomes. This brief review will examine the definitions and epidemiology of resistant hypertension and consider the differences between apparent resistant hypertension and truly resistant or refractory hypertension. It will review the role of the sympathetic nervous system in resistant hypertension. It will consider the relationship between obesity and leptin resistance and sympathetic signaling; the role of obstructive sleep apnea in resistant hypertension; and the role of aldosterone in resistant hypertension. It will conclude by mentioning briefly renal nerve ablation.
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Affiliation(s)
- George Bayliss
- Division of Kidney Diseases and Hypertension, Rhode Island Hospital, APC 9, 593 Eddy St., Providence, RI, 02906, USA,
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Abstract
BACKGROUND A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis. OBJECTIVES To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. SEARCH METHODS We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles. SELECTION CRITERIA We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks. DATA COLLECTION AND ANALYSIS Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed. MAIN RESULTS Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I (2)=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I (2)=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic BP of 5.8 mmHg (95%CI: 2.5 to 9.2, P=0.001) after adjusting for age, ethnic group and BP status. For diastolic BP, age, ethnic group, BP status and the change in 24-h urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that, in hypertensives, the mean effect was -5.39 mmHg (95% CI: -6.62 to -4.15, I (2)=61%) for systolic and -2.82 mmHg (95% CI: -3.54 to -2.11, I (2)=52%) for diastolic BP. In normotensives, the mean effect was -2.42 mmHg (95% CI: -3.56 to -1.29, I (2)=66%) for systolic and -1.00 mmHg (95% CI: -1.85 to -0.15, I (2)=66%) for diastolic BP. Further subgroup analysis showed that the decrease in systolic BP was significant in both whites and blacks, men and women. Meta-analysis of hormone and lipid data showed that the mean effect was 0.26 ng/ml/hr (95% CI: 0.17 to 0.36, I (2)=70%) for plasma renin activity, 73.20 pmol/l (95% CI: 44.92 to 101.48, I (2)=62%) for aldosterone, 31.67 pg/ml (95% CI: 6.57 to 56.77, I (2)=5%) for noradrenaline, 6.70 pg/ml (95% CI: -0.25 to 13.64, I (2)=12%) for adrenaline, 0.05 mmol/l (95% CI: -0.02 to 0.11, I (2)=0%) for cholesterol, 0.05 mmol/l (95% CI: -0.01 to 0.12, I (2)=0%) for LDL, -0.02 mmol/l (95% CI: -0.06 to 0.01, I (2)=16%) for HDL, and 0.04 mmol/l (95% CI: -0.02 to 0.09, I (2)=0%) for triglycerides. AUTHORS' CONCLUSIONS A modest reduction in salt intake for 4 or more weeks causes significant and, from a population viewpoint, important falls in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. With salt reduction, there is a small physiological increase in plasma renin activity, aldosterone and noradrenaline. There is no significant change in lipid levels. These results provide further strong support for a reduction in population salt intake. This will likely lower population BP and, thereby, reduce cardiovascular disease. Additionally, our analysis demonstrates a significant association between the reduction in 24-h urinary sodium and the fall in systolic BP, indicating the greater the reduction in salt intake, the greater the fall in systolic BP. The current recommendations to reduce salt intake from 9-12 to 5-6 g/d will have a major effect on BP, but are not ideal. A further reduction to 3 g/d will have a greater effect and should become the long term target for population salt intake.
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Affiliation(s)
- Feng J He
- Wolfson Institute of PreventiveMedicine, Barts and The London School of Medicine & Dentistry, QueenMary University of London, London, UK.
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Salt-inducible kinase 1 influences Na(+),K(+)-ATPase activity in vascular smooth muscle cells and associates with variations in blood pressure. J Hypertens 2012; 29:2395-403. [PMID: 22045124 DOI: 10.1097/hjh.0b013e32834d3d55] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Essential hypertension is a complex condition whose cause involves the interaction of multiple genetic and environmental factors such as salt intake. Salt-inducible kinase 1 (SIK1) is a sucrose-nonfermenting-like kinase isoform that belongs to the AMPK (5' adenosine monophosphate-activated protein kinase) family. SIK1 activity is increased by high salt intake and plays an essential role in regulating the plasma membrane Na(+),K(+)-ATPase. The objective of this study was to examine whether SIK1 is present in vascular smooth muscle cells (VSMCs) and endothelial cells, whether it affects VSMC Na(+),K(+)-ATPase activity and whether human SIK1 (hSIK1) represents a potential candidate for blood pressure regulation. METHODS Localization of SIK1 was performed using immunohistochemistry, mRNA and western blot. Functional assays (Na(+),K(+)-ATPase activity) were performed in VSMCs derived from rat aorta. Genotype-phenotype association studies were performed in three Swedish and one Japanese population-based cohorts. RESULTS SIK1 was localized in human VSMCs and endothelial cells, as well as a cell line derived from rat aorta. A nonsynonymous single nucleotide polymorphism in the hSIK1 gene exon 3 (C→T, rs3746951) results in the amino acid change (15)Gly→Ser in the SIK1 protein. SIK1-(15)Ser was found to increase plasma membrane Na(+),K(+)-ATPase activity in cultured VSMC line from rat aorta. Genotype-phenotype association studies in three Swedish and one Japanese population-based cohorts suggested that T allele (coding for (15)Ser) was associated with lower blood pressure (P = 0.005 for SBP and P = 0.002 for DBP) and with a decrease in left ventricular mass (P = 0.048). CONCLUSION The hSIK1 appears to be of potential relevance within VSMC function and blood pressure regulation.
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Graudal NA, Hubeck-Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database Syst Rev 2011:CD004022. [PMID: 22071811 DOI: 10.1002/14651858.cd004022.pub3] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND In spite of more than 100 years of investigations the question of reduced sodium intake as a health prophylaxis initiative is still unsolved. OBJECTIVES To estimate the effects of low sodium versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides. SEARCH METHODS PUBMED, EMBASE and Cochrane Central and reference lists of relevant articles were searched from 1950 to July 2011. SELECTION CRITERIA Studies randomizing persons to low sodium and high sodium diets were included if they evaluated at least one of the above outcome parameters. DATA COLLECTION AND ANALYSIS Two authors independently collected data, which were analysed with Review Manager 5.1. MAIN RESULTS A total of 167 studies were included in this 2011 update.The effect of sodium reduction in normotensive Caucasians was SBP -1.27 mmHg (95% CI: -1.88, -0.66; p=0.0001), DBP -0.05 mmHg (95% CI: -0.51, 0.42; p=0.85). The effect of sodium reduction in normotensive Blacks was SBP -4.02 mmHg (95% CI:-7.37, -0.68; p=0.002), DBP -2.01 mmHg (95% CI:-4.37, 0.35; p=0.09). The effect of sodium reduction in normotensive Asians was SBP -1.27 mmHg (95% CI: -3.07, 0.54; p=0.17), DBP -1.68 mmHg (95% CI:-3.29, -0.06; p=0.04). The effect of sodium reduction in hypertensive Caucasians was SBP -5.48 mmHg (95% CI: -6.53, -4.43; p<0.00001), DBP -2.75 mmHg (95% CI: -3.34, -2.17; p<0.00001). The effect of sodium reduction in hypertensive Blacks was SBP -6.44 mmHg (95% CI:-8.85, -4.03; p=0.00001), DBP -2.40 mmHg (95% CI:-4.68, -0.12; p=0.04). The effect of sodium reduction in hypertensive Asians was SBP -10.21 mmHg (95% CI:-16.98, -3.44; p=0.003), DBP -2.60 mmHg (95% CI: -4.03, -1.16; p=0.0004).In plasma or serum there was a significant increase in renin (p<0.00001), aldosterone (p<0.00001), noradrenaline (p<0.00001), adrenaline (p<0.0002), cholesterol (p<0.001) and triglyceride (p<0.0008) with low sodium intake as compared with high sodium intake. In general the results were similar in studies with a duration of at least 2 weeks. AUTHORS' CONCLUSIONS Sodium reduction resulted in a 1% decrease in blood pressure in normotensives, a 3.5% decrease in hypertensives, a significant increase in plasma renin, plasma aldosterone, plasma adrenaline and plasma noradrenaline, a 2.5% increase in cholesterol, and a 7% increase in triglyceride. In general, these effects were stable in studies lasting for 2 weeks or more.
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Affiliation(s)
- Niels Albert Graudal
- Department of Rheumatology TA4242/Internal Medicine, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
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Augustyniak RA, Singh K, Zeldes D, Singh M, Rossi NF. Maternal protein restriction leads to hyperresponsiveness to stress and salt-sensitive hypertension in male offspring. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1375-82. [PMID: 20200128 PMCID: PMC2867525 DOI: 10.1152/ajpregu.00848.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 02/27/2010] [Indexed: 01/06/2023]
Abstract
Low birth weight humans often exhibit hypertension during adulthood. Studying the offspring of rat dams fed a maternal low-protein diet is one model frequently used to study the mechanisms of low birth weight-related hypertension. It remains unclear whether this model replicates key clinical findings of hypertension and increased blood pressure responsiveness to stress or high-salt diet. We measured blood pressure via radiotelemetry in 13-wk-old male offspring of maternal normal- and low-protein dams. Neither group exhibited hypertension at baseline; however, 1 h of restraint was accompanied by a significantly greater blood pressure response in low-protein compared with normal-protein offspring. To enhance the effect of a high-salt diet on blood pressure, normal- and low-protein offspring underwent right uninephrectomy, while controls underwent sham surgery. After 5 weeks on a high-salt diet (4% NaCl), mean arterial pressure in the Low-Protein+Sham offspring was elevated by 6 +/- 2 mmHg (P < 0.05 vs. baseline), while it remained unchanged in the normal-protein offspring. In the two uninephrectomized groups, blood pressure increased further, but was of similar magnitude. Glomerular filtration rate in the low-protein uninephrectomized offspring was 50% less than that in normal-protein offspring with intact kidneys. These data indicate that, while male low-protein offspring are not hypertensive during young adulthood, their blood pressure is hyperresponsive to restraint stress and is salt sensitive, and their glomerular filtration rate is more sensitive to hypertension-causing insults. Collectively, these may predispose for the development of hypertension later in life.
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Ferrari P, Travaglini M, Schild C, Allemann Y, Shaw S, Weidmann P. Enhanced Blood Pressure Response to Mineralocorticoid Stimulation in Normotensive Members of Hypertensive Families. Blood Press 2009; 1:86-91. [PMID: 1366264 DOI: 10.3109/08037059209077498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Currently normotensive offspring of essential hypertensive parents often have disturbances in blood pressure (BP) regulation such as abnormalities in electrolyte homoeostasis, increased salt-sensitivity and/or impaired renal Na(+)-excretion. Whether an altered reactivity to mineralocorticoids may also play a role is presently unknown. Therefore, we investigated BP (recorded during 24 h), plasma atrial natriuretic factor (ANF), cyclic guanosine monophosphate (cGMP), aldosterone (PA) and renin activity (PRA), 24-h urine electrolyte and cGMP excretions measured on 4 consecutive days, as well as other variables, after 1 week on placebo and after 3 weeks of 9 alpha-fludrocortisone-acetate (9 alpha F) administration, 0.6 mg/d in 12 normotensive sons of essential hypertensive parents (SEH) and 12 body-mass-index- and age-matched (25 +/- 1[+/-SEM]yr) sons of normotensive parents (SN). On placebo, the 2 groups did not differ significantly in average 24 h BP (mean BP 95 +/- 2 vs 95 +/- 2 mmHg), plasma-ANF (40 +/- 7 vs 30 +5 pg/ml), cGMP (6 +/- 0.4 vs 6 +/- 0.5 nmol/l), PRA (1.3 +/- 0.1 vs 1.6 +/- 0.2 ng/ml/h), PA (9 +/- 0.5 vs 10 +/- 0.9 ng/dl), hematocrit (44 +/- 0.7 vs 44 +/- 0.4%) and 96-h urinary-Na+ (mean 205 +/- 13 vs 195 +/- 16 mmol/d), -K+ (69 +/- 6 vs 78 +/- 7 mmol/d) or -cGMP (461 +/- 35 vs 483 +/- 32 nmol/d). 9 alpha F significantly increased BP in SEH (p < 0.005) but not SN (107 +/- 2 vs 100 +/- 2 mmHg, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P Ferrari
- Medizinische Poliklinik, University of Berne, Switzerland
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Salt-sensitive men show reduced heart rate variability, lower norepinephrine and enhanced cortisol during mental stress. J Hum Hypertens 2008; 22:423-31. [PMID: 18337758 DOI: 10.1038/jhh.2008.11] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Salt sensitivity (SS) represents a risk factor for essential hypertension, which has been related to enhanced cardiovascular stress reactivity possibly mediated by increased noradrenergic susceptibility. We investigated biophysiological responses to mental stress in salt-sensitive (ss) and salt-resistant (sr) subjects, hypothesizing lower heart rate variability (HRV) and higher cortisol in the ss. A total of 48 healthy normotensive Caucasian men (age 25.6+/-2.6, body mass index 22.9+/-2.3) were phenotyped for SS (defined as significant drop in mean arterial pressure>3 mm Hg under the low-salt diet) by a 2-week high- versus low-salt diet. Subjects underwent a standardized mental stress task with continuous cardiovascular monitoring before, during and after the test (Finapres; Ohmeda, Louisville, CO, USA). Blood samples were drawn to examine cortisol and catecholamines before, after and 20 min after stress. The task elicited significant increases of systolic blood pressure (SBP), diastolic BP (DBP) and heart rate (HR) and a significant decrease of HRV (all time effects P<0.0001). The ss subjects showed lower norepinephrine (NE) and higher cortisol, indicated by significant group effects (P=0.009 and 0.025, respectively). HR increased and HRV decreased more in the ss under the stress, shown by significant time by group interactions (P=0.045 and 0.003, respectively). The observation of a more pronounced HR rise coupled with a greater decrease of HRV in healthy ss men under the influence of brief mental stress confirms their enhanced physiological stress reactivity. The lower peripheral NE may represent an effort to compensate for increased noradrenergic receptor sensitivity. The enhanced cortisol levels are backed by recent genetic findings on HSD11B2 polymorphisms and may promote hypertension.
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King AJ, Novotny M, Swain GM, Fink GD. Whole body norepinephrine kinetics in ANG II-salt hypertension in the rat. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1262-7. [PMID: 18256139 DOI: 10.1152/ajpregu.00819.2007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The purpose of this study was to investigate total body norepinephrine (NE) kinetics as an index of global sympathetic nervous system (SNS) outflow in a rat model of chronic ANG II-salt hypertension. Male Sprague-Dawley rats fed a 0.4% (normal salt, NS) or 2% (HS) NaCl diet were instrumented with arterial and venous catheters. After 5 days of recovery and a 3-day control period, ANG II (150 ng.kg(-1).min(-1)) was given subcutaneously by minipump for 14 days. Plasma NE levels and total body NE spillover and clearance were determined on control day 3 and ANG II infusion days 7 and 14 using radioisotope dilution principles. To perform this analysis, 3H-NE and NE were measured in arterial plasma after a 90-min infusion of tracer amounts of 3H-NE. Mean arterial pressure (MAP) was similar during the control period in NS and HS rats; however, MAP increased to a higher level in HS rats. During the control period, plasma NE tended to be lower in rats on HS, whereas NE clearance tended to be higher in HS rats. As a result NE spillover was similar in NS and HS rats during the control period. In NS rats, plasma NE, NE spillover, and NE clearance were unchanged by ANG II. In contrast, in rats on the HS diet, plasma NE and NE spillover increased during ANG II infusion, whereas NE clearance was unchanged. In conclusion, a HS diet alone or ANG II infusion in animals fed NS do not affect global sympathetic outflow. However, the additional hypertensive response to ANG II in animals fed HS is accompanied by SNS activation.
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Affiliation(s)
- Andrew J King
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
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Carey RM. Pathophysiology of Primary Hypertension. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00020-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Barba G, Galletti F, Cappuccio FP, Siani A, Venezia A, Versiero M, Della Valle E, Sorrentino P, Tarantino G, Farinaro E, Strazzullo P. Incidence of hypertension in individuals with different blood pressure salt-sensitivity: results of a 15-year follow-up study. J Hypertens 2007; 25:1465-71. [PMID: 17563570 DOI: 10.1097/hjh.0b013e3281139ebd] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To evaluate the incidence of hypertension and the rate of decline in renal function in a sample of 47 Olivetti Heart Study (OHS) participants whose blood pressure (BP) salt-sensitivity and renal tubular sodium handling had been assessed in 1987-88. METHODS During the 2002-04 OHS follow-up examination, medical history, physical examination and blood and urine sampling were performed in 36 of the 47 participants to the baseline study (age 60 +/- 6 years; average follow-up = 15.1 +/- 0.6 years). The renal length was measured in 23 participants by kidney ultrasonography. Based on the baseline salt-sensitivity evaluation, the subjects were classified into a lower salt-sensitivity (LSS, n = 20) and a higher salt-sensitivity group (HSS, n = 16). RESULTS In comparison with the LSS group, HSS participants had a significantly higher incidence of hypertension (87.5 versus 50.0%, P = 0.02), a higher glomerular filtration rate (median, first to fourth quartile: 81.9, 72.3-95.2 versus 72.3, 59.9-81.2 ml/min; P = 0.03) and greater kidney length (median, first to fourth quartile: 68.2, 63.3-72.1 versus 61.9, 58.7-62.7 mm/m of height; P = 0.003). The incidence of hypertension remained significantly higher in HSS individuals after adjustment for age, intercurrent changes in body mass index and baseline blood pressure on low sodium diet (P = 0.04). CONCLUSION Our findings indicate that individuals with higher BP salt-sensitivity have a higher rate of incident hypertension and suggest an altered renal tubular sodium handling involving a trend to increased glomerular filtration rate and blood pressure over time as a possible mechanism.
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Affiliation(s)
- Gianvincenzo Barba
- Epidemiology and Population Genetics, Institute of Food Sciences, CNR, Avellino, Italy.
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Melander O, von Wowern F, Frandsen E, Burri P, Willsteen G, Aurell M, Hulthén UL. Moderate salt restriction effectively lowers blood pressure and degree of salt sensitivity is related to baseline concentration of renin and N-terminal atrial natriuretic peptide in plasma. J Hypertens 2007; 25:619-27. [PMID: 17278979 DOI: 10.1097/hjh.0b013e328013cd50] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The effect of salt restriction on blood pressure is under intense debate. We tested the effect of 100 mmol salt reduction on ambulatory blood pressure (ABP) in 46 Swedish individuals, 39 of whom completed the study, using a double-blind, placebo-controlled, cross-over design. Furthermore, we tested whether the basal plasma concentration of renin or N-terminal atrial natriuretic peptide (Nt-proANP) predict the degree of salt sensitivity. METHODS Participants received all meals and drinks with a total daily NaCl content of 50 mmol during 8 weeks. In addition, NaCl capsules (100 mmol/day) and corresponding placebo capsules were administered for 4 weeks each in random order. ABP after high-salt intake (150 mmol/day) was compared with ABP after low-salt intake (50 mmol/day). Salt sensitivity was defined as the difference between 24-h systolic ABP at the high-salt versus the low-salt periods. Baseline renin and Nt-proANP were related to salt sensitivity. RESULTS Lowering of salt intake from 150 to 50 mmol/day induced significant blood pressure reductions (mean reduction, 95% confidence interval) in systolic and diastolic 24-h ABP (5.8, 3.4-8.2 and 2.6, 0.91-4.4 mmHg), daytime ABP (5.5, 2.9-8.1 and 2.3, 0.42-4.1 mmHg) and night-time ABP (6.4, 3.5-9.3 and 3.4, 1.4-5.5 mmHg). Baseline ln(renin) correlated inversely with salt sensitivity (r = -0.50, P = 0.001) whereas baseline ln(Nt-proANP) correlated directly (r = 0.33, P = 0.04). CONCLUSION Lowering of salt intake with 100 mmol/day induces clinically relevant ABP reductions. Renin and Nt-proANP, measured with individuals on their habitual diet, could be useful biomarkers to identify individuals with the greatest blood pressure-lowering benefit from reduced salt intake.
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Affiliation(s)
- Olle Melander
- Department of Clinical Sciences, Malmö University Hospital and Lund University, Malmö, Sweden.
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Anomalies du transport rénal du sodium et sensibilité au sel de la pression artérielle. Nephrol Ther 2007; 3 Suppl 2:S94-8. [DOI: 10.1016/s1769-7255(07)80015-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
Blood pressure response to changes in dietary salt intake is highly variable among individuals. This heterogeneity results from the combined effects of genetic and environmental determinants. In recent years, considerable progress has been made in our understanding of the pathogenic mechanisms leading to the development of salt-sensitive hypertension. Much information has come from the investigation of rare monogenic forms of salt-sensitive hypertension, which has focused attention on alterations of renal sodium handling occurring essentially in the distal nephron. In this paper, we review the experimental, clinical, genetic, and epidemiologic evidence suggesting that proximal tubular function is also an important determinant of the blood pressure response to salt, which deserves greater attention.
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Affiliation(s)
- Michel Burnier
- Service de Néphrologie, CHUV, Rue du Bugnon 17, 1011 Lausanne, Switzerland.
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Seidlerová J, Staessen JA, Maillard M, Nawrot T, Zhang H, Bochud M, Kuznetsova T, Richart T, Van Bortel LM, Struijker-Boudier HA, Manunta P, Burnier M, Fagard R, Filipovský J. Association Between Arterial Properties and Renal Sodium Handling in a General Population. Hypertension 2006; 48:609-15. [PMID: 16966578 DOI: 10.1161/01.hyp.0000240516.60040.ba] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mean arterial pressure drives pressure-natriuresis and determines arterial structure and function. In a population sample, we investigated the relation between arterial characteristics and renal sodium handling as assessed by the clearance of endogenous lithium. We ultrasonographically measured diameter, cross-sectional compliance (CC) and distensibility (DC) of the carotid, brachial, and femoral arteries in 1069 untreated subjects (mean age: 41.6 years; 50.1% women; 18.8% hypertensive subjects). While accounting for covariates and standardizing for the sodium excretion rate in both sexes, CC and DC of the femoral artery increased with higher fractional distal sodium reabsorption. Differences associated with a 1-SD change in fractional distal reabsorption of sodium were 51.7 mm(2)/kPax10(-3) (95% CI: 23.9 to 79.5; P=0.0002) and 0.56x10(-3)/kPa (95% CI: 0.17 to 0.94; P=0.004) for femoral CC and DC, respectively. In women as well as in men, a 1-SD increment in fractional proximal sodium reabsorption was associated with decreases in femoral and brachial diameter, amounting to 111.6 mum (95% CI: 38.2 to 185.1; P=0.003) and 52.5 mum (95% CI: 10.0 to 94.9; P=0.016), respectively. There was no consistent association between the properties of the elastic carotid artery and renal sodium handling. In conclusion, higher fractional sodium reabsorption in the distal nephron is associated with higher femoral CC and DC, and higher proximal sodium reabsorption is associated with decreased brachial and femoral diameters. These findings demonstrate that there might be an influence of renal sodium handling on arterial properties or vice versa or that common mechanisms might influence both arterial and renal function.
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Affiliation(s)
- Jitka Seidlerová
- Studies Coordination Centre, Division of Hypertension and Cardiovascular Rehabilitation, Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium
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Abstract
The purpose of this study was to identify changes in venomotor tone in the chronic low-dose angiotensin II (Ang II) model of hypertension and to establish the contribution of sympathetic nerve activation to these venomotor tone changes. Male Sprague-Dawley rats were acclimatized to a 0.4% or 2.0% NaCl diet for 7 days and then catheterized to allow chronic and repeated measures of arterial pressure, central venous pressure, and mean circulatory filling pressure (MCFP), an index of venous smooth muscle tone, in conscious undisturbed rats. After 4 days of recovery and a 3-day control period, an Ang II or physiological saline-filled osmotic minipump was implanted subcutaneously to deliver Ang II (150 ng/kg per minute) or vehicle control for 14 days. MCFP was measured in duplicate before and after acute ganglionic blockade with hexamethonium (30 mg/kg i.v.) on control day 2 and Ang II infusion on days 1, 3, 7, and 14. Blood volume was also measured on these days and was unchanged for the duration of the study in all of the groups. Arterial pressure was increased for the duration of Ang II infusion in rats on both 0.4% and 2% NaCl diets, but the increase was significantly greater in the 2% NaCl group and completely abolished by hexamethonium. MCFP was significantly increased for the entire Ang II infusion period only in rats fed 2% NaCl, and this increase was completely abolished by hexamethonium. We conclude that the combination of chronic low-dose Ang II infusion and high dietary salt intake engages the sympathetic nervous system to increase venomotor tone.
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Affiliation(s)
- Andrew J King
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
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Hernandez Schulman I, Raij L. Salt sensitivity and hypertension after menopause: role of nitric oxide and angiotensin II. Am J Nephrol 2006; 26:170-80. [PMID: 16645264 DOI: 10.1159/000092984] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 03/23/2006] [Indexed: 12/16/2022]
Abstract
Hypertension is a major risk factor for cardiovascular disease and renal disease. After menopause, the incidence of hypertension increases in women to levels that equal or exceed that in men, suggesting a protective role of female sex hormones. Salt sensitivity of blood pressure is associated with an increased risk for development of hypertension and cardiovascular disease. We and others have demonstrated that after menopause, the prevalence of salt sensitivity increases, suggesting that female sex hormones influence renal sodium handling and blood pressure regulation. A homeostatic balance between the counteracting effects of nitric oxide (NO) and angiotensin (Ang) II on pressure natriuresis, renal hemodynamics, tubular sodium reabsorption, and oxidative stress plays an important role in modulating salt sensitivity as well as hypertensive end-organ injury. Estrogens modulate the activity and expression of NO and Ang II. We infer that after menopause, estrogen deficiency promotes an unbalance between NO and Ang II, resulting in disturbed renal sodium handling, oxidative stress, and hypertension, particularly in genetically prone women. A better understanding of the mechanisms underlying the development of postmenopausal hypertension and associated cardiovascular and renal diseases should provide insights into preventive and therapeutic strategies.
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Affiliation(s)
- Ivonne Hernandez Schulman
- Nephrology and Hypertension Section, Veterans Affairs Medical Center and Division of Nephrology and Hypertension and Vascular Biology Institute, University of Miami Miller School of Medicine, Miami, Florida 33125, USA
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Jürgens G, Graudal NA. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterols, and triglyceride. Cochrane Database Syst Rev 2004:CD004022. [PMID: 14974053 DOI: 10.1002/14651858.cd004022.pub2] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND One of the controversies in preventive medicine is, whether a general reduction in sodium intake can decrease the blood pressure of a population and thereby reduce cardiovascular mortality and morbidity. In recent years the debate has been extended by studies indicating that reducing sodium intake has effects on the hormone and lipid profile. OBJECTIVES To estimate the effects of low sodium versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol and triglycerides. SEARCH STRATEGY "MEDLINE" and reference lists of relevant articles were searched from 1966 through December 2001. SELECTION CRITERIA Studies randomising persons to low sodium and high sodium diets were included if they evaluated at least one of the above outcome parameters. DATA COLLECTION AND ANALYSIS Two authors independently extracted the data, which were analysed by means of Review Manager 4.1. MAIN RESULTS In 57 trials of mainly Caucasians with normal blood pressure, low sodium intake reduced SBP by -1.27 mm Hg (CI: -1.76; -0.77)(p<0.0001) and DBP by -0.54 mm Hg (CI: -0.94; -0.14) (p = 0.009) as compared to high sodium intake. In 58 trials of mainly Caucasians with elevated blood pressure, low sodium intake reduced SBP by -4.18 mm Hg (CI: -5.08; - 3.27) (p < 0.0001) and DBP by -1.98 mm Hg (CI: -2.46; -1.32) (p < 0.0001) as compared to high sodium intake. The median duration of the intervention was 8 days in the normal blood pressure trials (range 4-1100) and 28 days in the elevated blood pressure trials (range 4-365). Multiple regression analyses showed no independent effect of duration on the effect size. In 8 trials of blacks with normal or elevated blood pressure, low sodium intake reduced SBP by -6.44 mm Hg (CI: -9.13; -3.74) (p < 0.0001) and DBP by -1.98 mm Hg (CI: -4.75; 0.78) (p = 0.16) as compared to high sodium intake. The magnitude of blood pressure reduction was also greater in a single trial in Japanese patients. There was also a significant increase in plasma or serum renin, 304% (p < 0.0001), aldosterone, 322%, (p < 0.0001), noradrenaline, 30% (p < 0.0001), cholesterol, 5.4% (p < 0.0001) and LDL cholesterol, 4.6% (p < 0.004), and a borderline increase in adrenaline, 12% (p = 0.04) and triglyceride, 5.9% (p = 0.03) with low sodium intake as compared with high sodium intake. REVIEWER'S CONCLUSIONS The magnitude of the effect in Caucasians with normal blood pressure does not warrant a general recommendation to reduce sodium intake. Reduced sodium intake in Caucasians with elevated blood pressure has a useful effect to reduce blood pressure in the short-term. The results suggest that the effect of low versus high sodium intake on blood pressure was greater in Black and Asian patients than in Caucasians. However, the number of studies in black (8) and Asian patients (1) was insufficient for different recommendations. Additional long-term trials of the effect of reduced dietary sodium intake on blood pressure, metabolic variables, morbidity and mortality are required to establish whether this is a useful prophylactic or treatment strategy.
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Abstract
BACKGROUND Many randomised trials assessing the effect of salt reduction on blood pressure show reduction in blood pressure in individuals with high blood pressure. However, there is controversy about the magnitude and the clinical significance of the fall in blood pressure in individuals with normal blood pressure. Several meta-analyses of randomised salt reduction trials have been published in the last few years. However, most of these included trials of very short duration (e.g. 5 days) and included trials with salt loading followed by salt deprivation (e.g. from 20 to 1 g/day) over only a few days. These short-term experiments are not appropriate to inform public health policy which is for a modest reduction in salt intake over a prolonged period of time. A meta-analysis by Hooper et al is an important attempt to look at whether advice to achieve a long-term salt reduction (i.e. more than 6 months) in randomised trials causes a fall in blood pressure. However, most trials included in this meta-analysis achieved a small reduction in salt intake; on average, salt intake was reduced by 2 g/day. It is, therefore, not surprising that this analysis showed a small fall in blood pressure, and that a dose-response to salt reduction was not demonstrable. OBJECTIVES To assess the effect of the currently recommended modest reduction in salt intake (WHO 2003; SACN 2003; Whelton 2002), on blood pressure in individuals with normal and elevated blood pressure. To assess whether the magnitude of the reduction in blood pressure is dependent on the magnitude of the reduction in salt intake. SEARCH STRATEGY We searched MEDLINE, EMBASE, Cochrane library, CINAHL, and reference list of original and review articles. SELECTION CRITERIA We included randomised trials with a modest reduction in salt intake and a duration of 4 or more weeks. DATA COLLECTION AND ANALYSIS Data were extracted independently by two persons. Mean effect sizes were calculated using both fixed and random effect models using Review Manager 4.2.1 software. Weighted linear regression was used to examine the relationship between the change in urinary sodium and the change in blood pressure. We used funnel plots to detect publication and other biases in the meta-analysis. MAIN RESULTS Seventeen trials in individuals with elevated blood pressure (n=734) and 11 trials in individuals with normal blood pressure (n=2220) were included. In individuals with elevated blood pressure the median reduction in 24-h urinary sodium excretion was 78 mmol (4.6 g/day of salt), the mean reduction in systolic blood pressure was -4.97 mmHg (95%CI:-5.76 to -4.18), and the mean reduction in diastolic blood pressure was -2.74 mmHg (95% CI:-3.22 to -2.26). In individuals with normal blood pressure the median reduction in 24-h urinary sodium excretion was 74 mmol (4.4 g/day of salt), the mean reduction in systolic blood pressure was -2.03 mmHg (95% CI: -2.56 to -1.50) mmHg, and the mean reduction in diastolic blood pressure was -0.99 mmHg (-1.40 to -0.57). Weighted linear regression analyses showed a correlation between the reduction in urinary sodium and the reduction in blood pressure. REVIEWERS' CONCLUSIONS Our meta-analysis demonstrates that a modest reduction in salt intake for a duration of 4 or more weeks has a significant and, from a population viewpoint, important effect on blood pressure in both individuals with normal and elevated blood pressure. These results support other evidence suggesting that a modest and long-term reduction in population salt intake could reduce strokes, heart attacks, and heart failure. Furthermore, our meta-analysis demonstrates a correlation between the magnitude of salt reduction and the magnitude of blood pressure reduction. Within the daily intake range of 3 to 12 g/day, the lower the salt intake achieved, the lower the blood pressure.
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Wright JT, Rahman M, Scarpa A, Fatholahi M, Griffin V, Jean-Baptiste R, Islam M, Eissa M, White S, Douglas JG. Determinants of salt sensitivity in black and white normotensive and hypertensive women. Hypertension 2003; 42:1087-92. [PMID: 14610097 DOI: 10.1161/01.hyp.0000101687.89160.19] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2003] [Accepted: 10/07/2003] [Indexed: 11/16/2022]
Abstract
Salt sensitivity (SS) has been linked to human hypertension. We examined ethnic differences in the relation between SS; erythrocyte sodium (Na+i), calcium (Ca2+i), potassium (K+i), and magnesium (Mg2+i); and sodium pump activity in African-American (AA) and white women. In a crossover protocol, similar numbers of normotensive, hypertensive, AA, and white women were randomized to 7 days of a 20 meq/d and a >200 meq/d salt diet (n=199). After an overnight inpatient stay, group differences in supine blood pressure (BP), heart rate, erythrocyte cations, and sodium pump activity were measured. The prevalence of SS (53.5% vs 51%) and salt resistance (26.3% vs 30.0%) was similar in both races. Greater mean BP increase with salt loading was seen in AA vs white hypertensives but not between the normotensive women. In hypertensives, increase in mean arterial pressure was 12.6 vs 8.2 mm Hg in AAs vs whites, respectively (P<0.01), and for systolic BP, it was 23 vs 14.8 mm Hg (P<0.01). Higher Na+i and Ca2+i were noted in SS and salt-intermediate AA than in the corresponding white subjects. Na+i, Ca2+i, and the ratios of Na+i to K+i and of Ca2+i to Mg2+i were positively correlated with salt responsiveness in AA but not in white women. Sodium pump activity was similar between groups, although the change in maximal activity trended to vary inversely with SS in AA. In closely matched AA and white women, the prevalence of SS is similarly high in both races, although the magnitude of BP increase is greater in AA hypertensives. In AA but not in whites, SS is positively associated with Na+i, Ca2+i, and the ratios of Na+i to K+i and of Ca2+i to Mg2+i.
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Affiliation(s)
- Jackson T Wright
- Department of Medicine, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Louis Stokes Cleveland VAMC, 11100 Euclid Ave, RB&C 7311, Cleveland, OH 44106-5041, USA.
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Izzo JL. Hypertension in the metabolic syndrome and diabetes: pathogenesis, clinical studies, and treatment. J Clin Hypertens (Greenwich) 2003; 5:3-10. [PMID: 14688488 PMCID: PMC8099212 DOI: 10.1111/j.1524-6175.2003.02670.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The increasing prevalence of obesity, hypertension, and abnormal glucose metabolism is a major challenge to health care in industrialized societies. This brief review summarizes the mechanistic evidence and clinical studies related to the problem of hypertension in the metabolic syndrome and diabetes to allow clinicians to provide more effective and enlightened management of these common, interrelated problems.
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Affiliation(s)
- Joseph L Izzo
- Department of Medicine, State University of New York at Buffalo, Buffalo, NY 14209, USA.
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Abstract
PURPOSE OF REVIEW Defective transduction of the dopamine receptor signal in the kidney has been shown to be important in the pathogenesis of hypertension This review will discuss the genetic mechanism for the defective renal dopaminergic function and the interaction with other gene variant products in the pathogenesis of salt sensitivity and essential hypertension. RECENT FINDINGS Single nucleotide polymorphisms of G protein-coupled receptor kinase type 4 (GRK4) phosphorylate, desensitize, and diminish the inhibitory action of D receptors on sodium transport in the kidney. Inhibition of GRK4 expression normalizes renal proximal tubule D receptor function in humans and rodents and ameliorates the hypertension in genetically hypertensive rats. Expression of the GRK4 variant, GRK4gammaA142V, produces hypertension and impairs the natriuretic effect of D receptor stimulation in mice. In humans, GRK4 single nucleotide polymorphisms are associated with essential hypertension, particularly salt sensitive hypertension. The prediction of the hypertensive phenotype is most accurate when elements of the renin-angiotensin system and GRK4 are included in the analysis. SUMMARY GRK4 single nucleotide polymorphisms, by preventing the natriuretic function of the dopaminergic system and by allowing the antinatriuretic function of angiotensin II type 1 receptors to predominate, may be responsible for salt sensitivity. Hypertension develops with additional perturbations caused by the variants of other genes (e.g., alpha-adducin, angiotensin converting enzyme, angiotensinogen, angiotensin II type 1 receptor, aldosterone synthase, 11beta-hydroxysteroid dehydrogenase type 2), the quantitative interaction of which may vary depending upon the genetic background.
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Affiliation(s)
- Pedro A Jose
- Georgetown University Medical Center, Washington, DC 20007, USA.
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Yang LE, Leong PKK, Ye S, Campese VM, McDonough AA. Responses of proximal tubule sodium transporters to acute injury-induced hypertension. Am J Physiol Renal Physiol 2003; 284:F313-22. [PMID: 12388425 DOI: 10.1152/ajprenal.00134.2002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Renal injury-induced by phenol injection activates renal sympathetic afferent pathways, increases norepinephrine release from the posterior hypothalamus, activates renal efferent pathways, and provokes a rapid and persistent hypertension. This study aimed to determine whether phenol injury provoked a redistribution of proximal Na(+) transporters from internal stores to the apical cell surface mediated by sympathetic activation, a response that could contribute to generation or maintenance of hypertension. Anesthetized rats were cannulated for arterial blood pressure tracing and saline infusion and then 50 microl 10% phenol or saline was injected into one renal cortex (n = 7 each). Fifty minutes after injection, kidneys were removed and renal cortex membranes from injected kidneys were fractionated on sorbitol gradients and pooled into three windows (WI-WIII) that contained enriched apical brush border (WI); mixed apical, intermicrovillar cleft and dense apical tubules (WII); and intracellular membranes (WIII). Na(+) transporter distributions were determined by immunoblot and expressed as percentage of total in gradient. Acute phenol injury increased blood pressure 20-30 mmHg and led to redistribution of Na(+)/H(+) exchanger type 3 (NHE3) out of WIII (from 22.79 +/- 4.75 to 10.79 +/- 2.01% of total) to WI (13.07 +/- 1.97 to 27.15 +/- 4.08%), Na(+)-P(i) cotransporter 2 out of WII (68.72 +/- 1.95 to 59.76 +/- 2.21%) into WI (9.5 +/- 1.62 to 18.7 +/- 1.45%), and a similar realignment of dipeptidyl-peptidase IV immunoreactivity and alkaline phosphatase activity to WI. Renal denervation before phenol injection prevented the NHE3 redistribution. By confocal microscopy, NHE3 localized to the brush border after phenol injection. The results indicate that phenol injury provokes redistribution of Na(+) transporters from intermicrovillar cleft/intracellular membrane pools to apical membranes associated with sympathetic nervous system activation, which may contribute to phenol injury-induced hypertension.
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Affiliation(s)
- Li E Yang
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, California 90089-9142, USA
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35
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Jürgens G, Graudal NA. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterols, and triglyceride. Cochrane Database Syst Rev 2003:CD004022. [PMID: 12535503 DOI: 10.1002/14651858.cd004022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND One of the controversies in preventive medicine is, whether a general reduction in sodium intake can decrease the blood pressure of a population and thereby reduce cardiovascular mortality and morbidity. In recent years the debate has been extended by studies indicating that reducing sodium intake has effects on the hormone and lipid profile. OBJECTIVES To estimate the effects of low sodium versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol and triglycerides. SEARCH STRATEGY "MEDLINE" and reference lists of relevant articles were searched from 1966 through December 2001. SELECTION CRITERIA Studies randomising persons to low sodium and high sodium diets were included if they evaluated at least one of the above outcome parameters. DATA COLLECTION AND ANALYSIS Two authors independently extracted the data, which were analysed by means of Review Manager 4.1. MAIN RESULTS In 57 trials of mainly Caucasians with normal blood pressure, low sodium intake reduced SBP by -1.27 mm Hg (CI: -1.76; -0.77)(p<0.0001) and DBP by -0.54 mm Hg (CI: -0.94; -0.14) (p = 0.009) as compared to high sodium intake. In 58 trials of mainly Caucasians with elevated blood pressure, low sodium intake reduced SBP by -4.18 mm Hg (CI: -5.08; - 3.27) (p < 0.0001) and DBP by -1.98 mm Hg (CI: -2.46; -1.32) (p < 0.0001) as compared to high sodium intake. The median duration of the intervention was 8 days in the normal blood pressure trials (range 4-1100) and 28 days in the elevated blood pressure trials (range 4-365). Multiple regression analyses showed no independent effect of duration on the effect size. In 8 trials of blacks with normal or elevated blood pressure, low sodium intake reduced SBP by -6.44 mm Hg (CI: -9.13; -3.74) (p < 0.0001) and DBP by -1.98 mm Hg (CI: -4.75; 0.78) (p = 0.16) as compared to high sodium intake. The magnitude of blood pressure reduction was also greater in a single trial in Japanese patients. There was also a significant increase in plasma or serum renin, 304% (p < 0.0001), aldosterone, 322%, (p < 0.0001), noradrenaline, 30% (p < 0.0001), cholesterol, 5.4% (p < 0.0001) and LDL cholesterol, 4.6% (p < 0.004), and a borderline increase in adrenaline, 12% (p = 0.04) and triglyceride, 5.9% (p = 0.03) with low sodium intake as compared with high sodium intake. REVIEWER'S CONCLUSIONS The magnitude of the effect in Caucasians with normal blood pressure does not warrant a general recommendation to reduce sodium intake. Reduced sodium intake in Caucasians with elevated blood pressure has a useful effect to reduce blood pressure in the short-term. The results suggest that the effect of low versus high sodium intake on blood pressure was greater in Black and Asian patients than in Caucasians. However, the number of studies in black (8) and Asian patients (1) was insufficient for different recommendations. Additional long-term trials of the effect of reduced dietary sodium intake on blood pressure, metabolic variables, morbidity and mortality are required to establish whether this is a useful prophylactic or treatment strategy.
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Affiliation(s)
- G Jürgens
- Department of Internal Medicine and Rheumatology Q 107, Copenhagen University hospital at Herlev, Herlev Ringvej, Herlev, Copenhagen County, Denmark, 2730
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Buchholz K, Schächinger H, Wagner M, Schorr U, Sharma AM, Deter HC. Enhanced affective startle modulation in salt-sensitive subjects. Hypertension 2001; 38:1325-9. [PMID: 11751712 DOI: 10.1161/hy1101.096055] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Salt-sensitive normotensive men exhibit an enhanced pressor response to mental stress. Although an enhanced pressor response is associated with higher affective startle modulation in men, an association between salt sensitivity of blood pressure and affective startle modulation has not been studied so far. We studied reactivity to mental stress and startle modulation in 14 salt-sensitive healthy white male students and 14 salt-resistant control subjects, who were well matched for age, body mass index, physical fitness, and family history of hypertension. Subjects performed a computerized information-processing task under time pressure (manometer test), while heart rate and blood pressure were continuously registered. In a separate session, subjects viewed a series of 42 pictures of the International Affective Picture System (IAPS), varying in pleasure and arousal, while acoustic startle probes were administered randomly, and electromyogram activity of the orbicular eye muscle was continuously recorded. Startle modulation was calculated as the difference between startle responses under negative and positive affective stimuli. In contrast to salt-resistant subjects, salt-sensitive subjects showed significantly enhanced startle amplitudes under negative stimuli and diminished amplitudes under positive stimuli. Thus, salt-sensitive subjects displayed a significantly higher startle modulation than did salt-resistant subjects (P<0.05). Subjective ratings of the presented IAPS pictures did not differ between the groups. The increased startle modulation of salt-sensitive subjects suggests an enhanced activity of the central nucleus of the amygdala. This enhanced central nervous responsiveness may contribute to higher sympathetic pressor reactivity and, thus, to the later development of hypertension in salt-sensitive individuals.
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Affiliation(s)
- K Buchholz
- Division of Psychosomatic Medicine, Benjamin Franklin Medical Center, Freie Universität Berlin, Berlin, Germany
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ter Maaten JC, Bakker SJ, Serné EH, Donker AJ, Gans RO. Renal sodium handling and haemodynamics are equally affected by hyperinsulinaemia in salt-sensitive and salt-resistant hypertensives. J Hypertens 2001; 19:1633-41. [PMID: 11564984 DOI: 10.1097/00004872-200109000-00016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE It is well-known that insulin induces renal sodium retention. It is not yet known whether insulin's renal effects are involved in the development of salt-sensitive hypertension. We assessed the effects of insulin on renal sodium handling and haemodynamics in 10 salt-sensitive (SS) and 10 salt-resistant (SR) essential hypertensives. DESIGN After a baseline period of 90 min, all subjects underwent a euglycaemic clamp with sequential infusion of a physiological and supraphysiological dose of insulin (50 and 150 mU/kg per h) during 90 min periods each. Time-control studies were performed in the same subjects. Clearances of 131I-hippuran, 125I-iothalamate, sodium and lithium were used to evaluate renal plasma flow (RPF), CNa/glomerular filtration rate (GFR) and fractional proximal and distal sodium reabsorption. RESULTS Plasma insulin levels and insulin-mediated glucose uptake did not differ between both groups. RPF and GFR showed similar increases during both insulin infusions in both groups. During physiological hyperinsulinaemia, fractional sodium excretion decreased 38% (P = 0.009) in the SS group and 36% (P = 0.002) in the SR group. During supraphysiological hyperinsulinaemia, fractional sodium excretion decreased 49% (P = 0.01) in the SS group and 19% (P = 0.2) in the SR group, not statistically different between both groups. Fractional proximal sodium reabsorption was unaffected and fractional distal sodium reabsorption increased to a similar magnitude in both groups. CONCLUSION The comparable renal effects of acute exogenous hyperinsulinaemia in SS and SR hypertensives do not support a role for insulin in the development of salt-sensitive hypertension. However, the results do not yet exclude a role for chronic hyperinsulinaemia.
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Affiliation(s)
- J C ter Maaten
- Department of Medicine, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
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Deter HC, Buchholz K, Schorr U, Mathiak K, Sharma AM. Salt-sensitivity and other predictors of stress-related cardiovascular reactivity in healthy young males. Clin Exp Hypertens 2001; 23:213-25. [PMID: 11339688 DOI: 10.1081/ceh-100102661] [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: 11/03/2022]
Abstract
Individuals whose mean arterial blood pressure is depending on oral salt intake are considered salt-sensitive and are at risk of developing essential hypertension. This study investigates the role of salt-sensitivity with respect to systolic blood pressure reactions under standardized mental stress. Forty-three healthy young males, previously characterized as salt-sensitive (n=16) or salt-resistant (n=27) by a dietary regimen, were subjected to multimodal physiological measurement during a computerized stress test and underwent comprehensive psychometrical testing. The most important predictors for systolic blood pressure reactions to stress were the degree of salt-sensitivity, body mass index and psychological characteristics like anxiety. The highest correlations with the degree of salt-sensitivity were found for the parameters age, systolic blood pressure reaction under stress, high frequency band of heart rate variability and two psychological variables. The concept of salt-sensitivity is a novel biological component that might contribute to reactivity research in subjects at high risk for essential hypertension.
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Affiliation(s)
- H C Deter
- Department of Psychosomatic Medicine and Psychotherapy, Benjamin Franklin Hospital, Free University of Berlin, Germany
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Chiolero A, Würzner G, Burnier M. Renal determinants of the salt sensitivity of blood pressure. Nephrol Dial Transplant 2001; 16:452-8. [PMID: 11239015 DOI: 10.1093/ndt/16.3.452] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- A Chiolero
- Division of Hypertension and Vascular Medicine, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
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Chiolero A, Maillard M, Nussberger J, Brunner HR, Burnier M. Proximal sodium reabsorption: An independent determinant of blood pressure response to salt. Hypertension 2000; 36:631-7. [PMID: 11040249 DOI: 10.1161/01.hyp.36.4.631] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The purpose of this study was to evaluate the contribution of renal sodium handling by the proximal tubule as an independent determinant of blood pressure responsiveness to salt in hypertension. We measured blood pressure (BP), renal hemodynamics, and segmental renal sodium handling (with lithium used as a marker of proximal sodium reabsorption) in 38 hypertensive patients and 27 normotensive subjects (15 young and 12 age-matched) on a high and low sodium diet. In control subjects, changing the diet from a low to a high sodium content resulted in no change in BP and increases in glomerular filtration rate (P<0.05), renal plasma flow (P<0.05), and fractional excretion of lithium (FE(Li), P<0.01). In hypertensive patients, comparable variations of sodium intake induced an increase in BP with no change in renal hemodynamics and proximal sodium reabsorption. When analyzed by tertiles of their BP response to salt, salt-insensitive hypertensive patients of the first tertile disclosed a pattern of adaptation of proximal sodium reabsorption comparable to that of control subjects, whereas the most salt-sensitive patients of the third tertile had an inverse pattern with a high FE(Li) on low salt and a lower FE(Li) on high salt, suggesting an inappropriate modulation of proximal sodium reabsorption. The BP response to salt correlated positively with age (r=0.34, P=0.036) and negatively with the changes in FE(Li) (r=-0.37, P=0.029). In a multivariate analysis, the changes in FE(Li) were significantly and independently associated with the salt-induced changes in BP. These results suggest that proximal sodium reabsorption is an independent determinant of the BP response to salt in hypertension.
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Affiliation(s)
- A Chiolero
- Division of Hypertension and Vascular Medicine, CHUV, and Policlinique médicale universitaire, Lausanne, Switzerland
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Schorr U, Blaschke K, Beige J, Distler A, Sharma AM. G-protein beta3 subunit 825T allele and response to dietary salt in normotensive men. J Hypertens 2000; 18:855-9. [PMID: 10930182 DOI: 10.1097/00004872-200018070-00006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND AIMS A functional single-nucleotide variant of the gene encoding the beta3 subunit of heterotrimeric G proteins (Gbeta3 C825T), associated with enhanced G-protein activation and increased activity of the sodium-proton exchanger (NHE1), has been implicated in the development of hypertension. Given the possible involvement of NHE1 in sodium homeostasis, we tested the hypothesis that the Gbeta3 825T allele determines the response of the renin-angiotensin system and blood pressure to dietary salt restriction. METHODS Young normotensive men (20-30 years old, n = 193) were recruited within the framework of the Berlin Salt-Sensitivity Trial and studied on low- (20 mmol/day) and high-salt (220 mmol/day) dietary protocols. Subjects were characterized for parameters of the renin-angiotensin system and blood pressure response and genotyped for the Gbeta3 C825T polymorphism. RESULTS The genotype distribution was in Hardy-Weinberg equilibrium (CC = 90, CT = 81 and TT = 22). The responses of the renin-angiotensin system and blood pressure to the dietary protocol were virtually identical between the genotypic groups. Furthermore, when subjects were classified as salt-resistant (n = 145) or salt-sensitive (n = 48), genotype distribution was comparable between the two groups (salt-resistant: TT = 17, CT = 60, CC = 68, qT = 0.32; salt-sensitive: TT = 5, CT = 21, CC = 22, qT = 0.32). CONCLUSION These findings do not support the hypothesis that the Gbeta3 C825T polymorphism determines the response of the renin-angiotensin system to salt depletion or can serve as an early genetic marker of salt sensitivity in young normotensive men.
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Affiliation(s)
- U Schorr
- Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany
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Abstract
Renal sodium re-absorption is a closely regulated process serving to maintain both extracellular fluid volume and arterial blood pressure. Proteins participating in sodium re-absorption and its regulation are therefore important candidate proteins whose genes may contain sequence variation contributing to the inherited tendency for increased arterial blood pressure (essential hypertension). Important insight has come from rare forms of single-gene hypertension in human subjects and from polygenic animal models of genetic hypertension. Both indicate the primacy of altered renal function in the genesis of hypertension, and suggest that genes contributing to the disease are members of the subset of genes expressed in the kidney. This review examines evidence for abnormalities in renal sodium re-absorption in hypertension and focuses on the proximal tubule as a site of relevant dysfunction. Identification of the proteins participating in renal sodium re-absorption and its regulation, particularly those involved in the renal pressure-natriuresis mechanism, will allow gene cloning and sequencing which in turn may lead to the identification of novel gene sequence variation participating in hypertension.
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Affiliation(s)
- P A Doris
- Institute of Molecular Medicine, University of Texas Houston, 77030, USA.
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43
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Brand E, Schorr U, Ringel J, Beige J, Distler A, Sharma AM. Aldosterone synthase gene (CYP11B2) C-344T polymorphism in Caucasians from the Berlin Salt-Sensitivity Trial (BeSST). J Hypertens 1999; 17:1563-7. [PMID: 10608469 DOI: 10.1097/00004872-199917110-00009] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Aldosterone synthase (CYP11B2) is a key enzyme in the biosynthesis of aldosterone. Recently, the T allele of a polymorphism in the 5'-flanking region of the CYP11B2 gene (C-344T) has been reported to be more frequent in hypertensives than in normotensives, and has also been associated with increased plasma aldosterone levels. We therefore hypothesized that this variant may be related to increased blood-pressure response to dietary salt intake. SUBJECTS AND METHODS We genotyped 1 63 young normotensive men recruited within the framework of the Berlin Salt-Sensitivity Trial (BeSST) for the CYP11B2 C-344T polymorphism. Subjects were characterized for family history of hypertension, plasma parameters of the renin-angiotensin-aldosterone system and blood-pressure response to a high (220 mmol/day) and low (20 mmol/day) salt diet RESULTS The frequency of the -344T allele (0.45) was similar to that reported previously and genotype distribution was in Hardy-Weinberg equilibrium (CC, n = 55; CT, n = 71; TT, n = 37). There was a trend towards a higher frequency of the T allele in subjects with a positive family history of hypertension (0.48 versus 0.42), but the C-344T genotype was not related to blood pressure under either diet Furthermore, when subjects were classified into salt-sensitive and salt-resistant groups, allelic distribution did not differ between the two groups (qT = 0.43 versus qT = 0.45). While renin activity and plasma aldosterone levels were not related to genotype, plasma angiotensinogen was significantly higher in T-allele carriers under both the high (P = 0.02) and low (P = 0.008) salt diet. CONCLUSION Our findings do not support the hypothesis that the C-344T polymorphism of the CYP11B2 gene is associated with salt sensitivity or increased activity of the renin-angiotensin system in young normotensive subjects. It is, therefore, unlikely that the C-344T polymorphism is a genetic marker for salt sensitivity in young normotensive Caucasian men.
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Affiliation(s)
- E Brand
- Department of Internal Medicine, Universitätsklinkum Benjamin Franklin, Freie Universität Berlin, Germany
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44
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Okuguchi T, Osanai T, Kamada T, Kimura M, Takahashi K, Okumura K. Significance of sympathetic nervous system in sodium-induced nocturnal hypertension. J Hypertens 1999; 17:947-57. [PMID: 10419068 DOI: 10.1097/00004872-199917070-00011] [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: 11/26/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the effects of salt loading on circadian patterns of blood pressure (BP) and sympathetic nervous activity. SUBJECTS AND METHODS Seventy-six patients with essential hypertension were hospitalized and placed on a low-salt diet (2 g/day) for 7 days followed by a high-salt diet (20-23 g/day) for another 7 days. On the last day of each salt diet, 24 h ambulatory BP, plasma noradrenaline concentrations, urinary noradrenaline excretion, plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured. Patients whose average mean BP was increased by more than 10% by salt loading were assigned to the salt-sensitive (SS) group (n = 44); the remaining patients, whose mean BP was increased by less than 10%, were assigned to the non-salt-sensitive (NSS) group (n = 32). RESULTS Salt loading converted the circadian pattern of BP from dippers, whose mean BP during the night-time was decreased by more than 10% from the daytime BP, to non-dippers in the SS group but not in the NSS group. A nocturnal decrease in plasma noradrenaline concentration was unaffected after salt loading in the NSS group but dampened in the SS group. The night-time/daytime ratio of urinary noradrenaline excretion, which was increased after salt loading in the SS group only, was greater in the SS group than in the NSS group under the high-salt diet. The salt-induced suppression rate of PRA and PAC was similar between the SS and NSS groups. CONCLUSION BP fails to fall during the night under the high-salt diet in patients with the SS type of essential hypertension. This may be related to the lack of nocturnal decrease in sympathetic nervous activity.
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Affiliation(s)
- T Okuguchi
- Second Department of Internal Medicine, Hirosaki University School of Medicine, Japan
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45
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Gratze G, Fortin J, Labugger R, Binder A, Kotanko P, Timmermann B, Luft FC, Hoehe MR, Skrabal F. beta-2 Adrenergic receptor variants affect resting blood pressure and agonist-induced vasodilation in young adult Caucasians. Hypertension 1999; 33:1425-30. [PMID: 10373227 DOI: 10.1161/01.hyp.33.6.1425] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recent evidence suggests that the prodownregulatory Gly16 allele of the beta-2 adrenergic receptor (beta-2 AR) is associated with essential hypertension in African Caribbeans. To further investigate the effect of the glycine (Gly)16 and arginine (Arg)16 beta-2 AR variants on hemodynamics, we investigated the agonist-mediated in vivo vasodilation in normotensive Austrian Caucasians and analyzed the results with respect to the Gly16/Arg16 polymorphism. Fifty-seven normotensive men, 20 to 32 years of age with body mass index of 18.7 to 29.9 kg/m2, were genotyped for the Arg16/Gly16 beta-2 AR alleles. All 15 Gly16/Gly16 subjects, all 12 Arg16/Arg/16 subjects, and 27 of 30 heterozygous subjects underwent hemodynamic measurements while supine after an overnight fast. The observers were unaware of the subjects' genotypes. The subjects received a graded infusion of the selective beta-2 AR agonist salbutamol (0.07, 0.14, and 0.21 microgram/kg per minute, respectively), each dose over 8 minutes. Stroke volume and blood pressure were determined continuously by means of impedance cardiography and oscillometry, respectively. The last 4 minutes of each infusion were evaluated statistically. Basal mean blood pressure was higher in the Gly16/Gly16 subjects compared with Arg16/Arg16 subjects (mean+/-SD: 81.6+/-6.14 versus 75.2+/-4.93 mm Hg, P<0.01). Homozygous Gly16 subjects showed a significantly decreased vasodilation during the first dose of salbutamol infusion compared with Arg16/Arg16 subjects (Deltatotal peripheral resistance index -17.9+/-14.4 versus -30. 6+/-8.3%, P<0.01) despite increased sympathetic counterregulation in the Arg16/Arg16 group (Deltaheart rate +16.9+/-7.0% versus +8.6+/-7. 0%, P<0.01; Deltacardiac index +39.5+/-18.5% versus 21.4+/-18.8%, P<0.05). Our results provide additional evidence that the Gly16/Arg16 alleles of the beta-2 AR are intimately related to blood pressure regulation and deserve further studies in the pathogenesis of essential hypertension.
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Affiliation(s)
- G Gratze
- Department of Internal Medicine, Krankenhaus der Barmherzigen Brüder, Teaching Hospital of the Karl Franzens University Graz (Austria)
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46
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Schorr U, Blaschke K, Beige J, Distler A, Sharma AM. Angiotensinogen M235T variant and salt sensitivity in young normotensive Caucasians. J Hypertens 1999; 17:475-9. [PMID: 10404948 DOI: 10.1097/00004872-199917040-00004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND AIMS A single-nucleotide variant of the angiotensinogen gene (AGT 235T) has been associated with essential hypertension and increased plasma levels of angiotensinogen. This variant may also serve as a genetic marker for the increased blood pressure response to dietary salt intake, but the relationship between AGT genotype and salt sensitivity has not been studied until now. We therefore examined the relationship between the AGT 235T genotype and the blood pressure response to short-term dietary salt restriction in young normotensive men. SUBJECTS AND METHODS A total of 187 young normotensive men were characterized for family history of hypertension, salt sensitivity, plasma parameters of the renin-angiotensin system under high- and low-salt diets, and the AGT 235T genotype. RESULTS While the T allele was significantly associated with a positive family history of hypertension (chi2 = 7.0; P< 0.03) and higher plasma angiotensinogen levels (P< 0.015) and renin activity (P < 0.037), blood pressure under both diets was not significantly affected by the AGT genotype. When the subjects were classified into salt-resistant and salt-sensitive groups, genotypic distribution was nearly identical between both groups (frequency of T allele: 0.45 versus 0.46). CONCLUSION Our findings demonstrate that the AGT 235T allele is significantly associated with a positive family history of hypertension, but is not an important determinant of the blood pressure response to dietary salt intake in young normotensive subjects. It is therefore unlikely that the AGT 235T genotype can serve as an early genetic marker of salt sensitivity.
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Affiliation(s)
- U Schorr
- Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany
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47
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Schorr U, Turan S, Distler A, Sharma AM. Relationship between ambulatory and resting blood pressure responses to dietary salt restriction in normotensive men. J Hypertens 1997; 15:845-9. [PMID: 9280206 DOI: 10.1097/00004872-199715080-00007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To examine the relationship between changes in resting and ambulatory blood pressures induced by dietary salt restriction in 90 young normotensive men. METHODS Subjects were given a standardized low-salt diet containing 20 mmol sodium chloride per day for 14 days. To this diet, a daily supplement of 20 tablets of slow sodium (10 mmol NaCl per tablet) or placebo was added in a randomized single-blind cross-over fashion for 7 days. The ambulatory blood pressure was measured on the sixth day and the resting blood pressure was measured on the seventh day of each dietary period. RESULTS Although salt intake did not affect blood pressure levels in the whole group, the response of the blood pressure was quite variable among individual subjects. Salt-induced changes in resting systolic (r = 0.30, P = 0.006) and mean (r = 0.27, P = 0.014) blood pressures, but not diastolic blood pressure, were correlated positively to changes in daytime ambulatory blood pressure. The changes in resting systolic and mean blood pressures were also correlated significantly to the nocturnal falls in systolic (r = 0.26, P = 0.015) and mean (r = 0.27, P = 0.012) blood pressure levels and heart rate (r = 0.26, P= 0.015) under the high-salt diet. Diet-induced changes in resting mean blood pressure were correlated significantly to the daytime ambulatory blood pressure (r = 0.30, P < 0.005) and the resting heart rate (r = 0.24, P < 0.02) under the high-salt diet. CONCLUSION Salt-induced changes in resting blood pressure in young normotensive men are correlated positively to changes in ambulatory daytime blood pressure levels as well as to the daytime ambulatory blood pressure and the nocturnal fall in blood pressure under a high-salt diet. These findings suggest that dietary salt-intake restriction can lower both resting and daytime ambulatory blood pressure levels in some normotensive individuals who may be predisposed to the development of hypertension.
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Affiliation(s)
- U Schorr
- Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany
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48
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Sudhir K, Forman A, Yi SL, Sorof J, Schmidlin O, Sebastian A, Morris RC. Reduced dietary potassium reversibly enhances vasopressor response to stress in African Americans. Hypertension 1997; 29:1083-90. [PMID: 9149670 DOI: 10.1161/01.hyp.29.5.1083] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/1996] [Accepted: 10/29/1996] [Indexed: 02/04/2023]
Abstract
Acute vasopressor responses to stress are adrenergically mediated and hence potentially subject to differential modulation by dietary potassium and sodium. The greater vasopressor responsiveness in blacks compared with whites might then be consequent not only to a high dietary salt intake but also to a marginally reduced dietary potassium intake. Under controlled metabolic conditions, we compared acute vasopressor responses to cold and mental stress in black and white normotensive men during three successive dietary periods: (1) while dietary potassium was reduced (30 mmol K+/70 kg per day) and salt was restricted (10 to 14 days); (2) while salt was loaded (15 to 250 mmol Na+/70 kg per day) (7 days); and (3) while salt loading was continued and potassium was either supplemented (70 mmol K+/70 kg per day) (7 to 21 days) in 9 blacks and 6 whites or continued reduced (30 mmol K+/70 kg per day) (28 days) in 4 blacks (time controls). At the lower potassium intake, cold-induced increase in forearm vascular resistance in blacks was twice that in whites during both salt restriction and salt loading. Normalization of dietary potassium attenuated cold-induced increases in both forearm vascular resistance and systolic and diastolic blood pressures in blacks but only in systolic pressure in whites. In blacks but not in whites, normalization of dietary potassium attenuated mental stress-induced increases in systolic and diastolic pressures. In normotensive blacks but not whites, a marginally reduced dietary intake of potassium reversibly enhances adrenergically mediated vasopressor responsiveness to stress. That responsiveness so enhanced over time might contribute to the pathogenesis of hypertension in blacks.
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Affiliation(s)
- K Sudhir
- Department of Medicine, General Clinical Research Center, University of California, San Francisco, USA
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49
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Campese VM, Tawadrous M, Bigazzi R, Bianchi S, Mann AS, Oparil S, Raij L. Salt intake and plasma atrial natriuretic peptide and nitric oxide in hypertension. Hypertension 1996; 28:335-40. [PMID: 8794813 DOI: 10.1161/01.hyp.28.3.335] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In response to a high salt intake, salt-sensitive hypertensive individuals retain more sodium and manifest a rise in blood pressure greater than that in salt-resistant individuals. In this study, we tested whether salt sensitivity might be related at least in part to reduced secretion of atrial natriuretic peptide (ANP) or to abnormal nitric oxide production. We measured plasma ANP and NO2+NO3 in 7 normotensive individuals and 13 salt-sensitive and 14 salt-resistant blacks with essential hypertension under conditions of low (10 mEq/d) and high (250 mEq/d) salt intake. To evaluate possible racial differences in ANP secretion, we also measured plasma ANP in 6 salt-sensitive and 8 salt-resistant hypertensive whites during low and high salt intakes. Under low salt conditions, plasma ANP levels were not different in normotensive control subjects and salt-sensitive and salt-resistant hypertensive blacks. During high salt intake, plasma ANP levels did not change in control subjects and salt-resistant patients but decreased in salt-sensitive patients. ANP levels after high salt diet were lower (P < .01) in salt-sensitive than salt-resistant blacks. In hypertensive whites, high salt intake caused no significant change in plasma ANP. Under low salt conditions, plasma NO2+NO3 levels were higher (P < .05) in salt-sensitive (189 +/- 7.9 mumol/L) and salt-resistant (195 +/- 13.5 mumol/L) black patients than in control subjects (108 +/- 9.7 mumol/L). During high salt intake, plasma NO2+NO3 decreased significantly (P < .01) in both salt-sensitive (150 +/- 7.0 mumol/L) and salt-resistant (142 +/- 9.0 mumol/L) patients. These studies show that under conditions of high salt intake, salt-sensitive hypertensive blacks manifest a paradoxical decrease in ANP secretion. This abnormality may play a role in the reduced ability of these individuals to excrete a sodium load and in the sodium-induced rise in blood pressure. This study does not support the hypothesis that salt sensitivity depends on a deficit of nitric oxide production, but it suggests that high salt intake may alter the endothelium-dependent adaptation of peripheral resistance vessels.
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Affiliation(s)
- V M Campese
- University of Southern California, Los Angeles, USA
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50
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Barba G, Cappuccio FP, Russo L, Stinga F, Iacone R, Strazzullo P. Renal function and blood pressure response to dietary salt restriction in normotensive men. Hypertension 1996; 27:1160-4. [PMID: 8621211 DOI: 10.1161/01.hyp.27.5.1160] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The interindividual variability of the blood pressure response to changes in dietary sodium intake might be traced in part to heterogeneity in renal adaptation. To further explore this possibility, we evaluated glomerular filtration rate and tubular sodium handling in 47 healthy male volunteers from the Olivetti factory in Naples who were studied on their habitual sodium-rich diet (urinary sodium, 184 +/- 9 mmol/24 h) and after 3 days of a salt-restricted diet (urinary sodium, 69 +/- 5 mmol/24 h). Individual salt sensitivity, defined as the mean blood pressure change recorded after the shift from habitual to low sodium diet, significantly and directly correlated with glomerular filtration rate and absolute proximal sodium reabsorption during the habitual diet. When the entire population was divided into tertiles of salt sensitivity, the group with the highest salt sensitivity showed higher blood pressure, glomerular filtration rate, and absolute proximal sodium reabsorption during the habitual diet compared with the least salt-sensitive group; however, during the low NaCl diet, no differences were detectable between the groups. Twenty-four-hour urinary sodium was similar across the groups. We conclude that relative hyperfiltration and altered tubular sodium handling may occur in salt-sensitive normotensive individuals on a high sodium diet and that NaCl restriction may offset these abnormalities.
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Affiliation(s)
- G Barba
- Department of Clinical and Experimental Medicine, Federico II University of Naples Medical School, Italy
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