Blood pressure and endocrine responses to changes in dietary sodium intake in cardiac transplant recipients. Implications for the control of sodium balance.

The present study was performed to investigate the role of type 1A ANG II (AT1A) receptors in regulating sodium balance and blood pressure maintenance during chronic dietary sodium variations in AT1A receptor-deficient (−/−) mice. Groups of AT1A (−/−) and wild-type mice were placed on a low (LS)-, normal (NS)-, or high-salt (HS) diet for 3 wk. AT1A(−/−) mice on an LS diet had high urinary volume and low blood pressure despite increased renin and aldosterone levels. On an HS diet, (−/−) mice demonstrated significant diuresis, yet blood pressure increased to levels greater than control littermates. There was no effect of dietary sodium intake on systolic blood pressures in wild-type animals. The pressure-natriuresis relationship in AT1A (−/−) mice demonstrated a shift to the left and a decreased slope compared with wild-type littermates. These studies demonstrate that mice lacking the AT1A receptor have blood pressures sensitive to changes in dietary sodium, marked alterations of the pressure-natriuresis relationship, and compensatory mechanisms capable of maintaining normal sodium balance across a wide range of sodium intakes.

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A Double-Blind Study of the Response to Changes in Dietary Sodium Intake in Orthotopic Cardiac Transplant Recipients

Clinical Science ◽

10.1042/cs078018p ◽

1990 ◽

Vol 78 (s22) ◽

pp. 18P-18P

Author(s):

D.R.J. Singer ◽

N.D. Markandu ◽

M.G. Buckley ◽

G.A. MacGregor ◽

M. Yacoub

Keyword(s):

Sodium Intake ◽

Blind Study ◽

Dietary Sodium ◽

Cardiac Transplant ◽

Double Blind Study ◽

Transplant Recipients ◽

Double Blind

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Role of renal nerves in maintaining sodium balance in unrestrained conscious rats

AJP Renal Physiology ◽

10.1152/ajprenal.1985.249.6.f819 ◽

1985 ◽

Vol 249 (6) ◽

pp. F819-F826 ◽

Cited By ~ 3

Author(s):

E. Fernandez-Repollet ◽

C. R. Silva-Netto ◽

R. E. Colindres ◽

C. W. Gottschalk

Keyword(s):

Blood Pressure ◽

Renal Denervation ◽

Sodium Intake ◽

Plasma Renin ◽

Dietary Sodium ◽

Sodium Balance ◽

Renal Nerves ◽

Sodium Restriction ◽

Low Sodium ◽

Dietary Sodium Restriction

This study was designed to investigate the effects of bilateral renal denervation on sodium and water balance, the renin-angiotensin system, and systemic blood pressure in unrestrained conscious rats maintained on a normal- or low-sodium diet. Renal denervation was proven by chemical and functional tests. Both bilaterally denervated rats (n = 18) and sham-denervated rats (n = 15) maintained positive sodium balance while on a normal sodium intake. Both groups were in negative sodium balance for 1 day after dietary sodium restriction was instituted but were in positive sodium balance for the following 9 days. Systolic blood pressure was higher in sham-denervated (115 +/- 3 mmHg) than in denervated rats (102 +/- 3 mmHg) while on a normal diet (P less than 0.05) and remained so during sodium restriction. Plasma renin concentration (PRC) and plasma aldosterone concentration (PAC) were significantly diminished in the denervated rats during normal sodium intake (P less than 0.05). After dietary sodium restriction, PRC increased in both groups but remained significantly lower in the denervated rats (P less than 0.05). Following dietary sodium restriction, PAC also increased significantly to levels that were similar in both groups of rats. These results demonstrate that awake unrestrained growing rats can maintain positive sodium balance on a low sodium intake even in the absence of the renal nerves. However, efferent renal nerve activity influenced plasma renin activity in these animals.

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The Effects of Short-Term Changes in Sodium Intake on Plasma Marinobufagenin Levels in Patients with Primary Salt-Sensitive and Salt-Insensitive Hypertension

Nutrients ◽

10.3390/nu13051502 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1502

Author(s):

Katarzyna Łabno-Kirszniok ◽

Agata Kujawa-Szewieczek ◽

Andrzej Wiecek ◽

Grzegorz Piecha

Keyword(s):

Blood Pressure ◽

Diastolic Blood Pressure ◽

Sodium Intake ◽

Left Ventricular ◽

Primary Hypertension ◽

Dietary Sodium ◽

Sodium Restriction ◽

Short Term ◽

Salt Loading ◽

Dietary Sodium Restriction

Increased marinobufagenin (MBG) synthesis has been suggested in response to high dietary salt intake. The aim of this study was to determine the effects of short-term changes in sodium intake on plasma MBG levels in patients with primary salt-sensitive and salt-insensitive hypertension. In total, 51 patients with primary hypertension were evaluated during acute sodium restriction and sodium loading. Plasma or serum concentrations of MBG, natriuretic pro-peptides, aldosterone, sodium, potassium, as well as hematocrit (Hct) value, plasma renin activity (PRA) and urinary sodium and potassium excretion were measured. Ambulatory blood pressure monitoring (ABPM) and echocardiography were performed at baseline. In salt-sensitive patients with primary hypertension plasma MBG correlated positively with diastolic blood pressure (ABPM) and serum NT-proANP concentration at baseline and with serum NT-proANP concentration after dietary sodium restriction. In this subgroup plasma MBG concentration decreased during sodium restriction, and a parallel increase of PRA was observed. Acute salt loading further decreased plasma MBG concentration in salt-sensitive subjects in contrast to salt insensitive patients. No correlation was found between plasma MBG concentration and left ventricular mass index. In conclusion, in salt-sensitive hypertensive patients plasma MBG concentration correlates with 24-h diastolic blood pressure and dietary sodium restriction reduces plasma MBG levels. Decreased MBG secretion in response to acute salt loading may play an important role in the pathogenesis of salt sensitivity.

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Abstract P276: A High Sodium Diet Reduces Cutaneous Microvascular Function In Normotensive Individuals With Salt Sensitive Blood Pressure

Hypertension ◽

10.1161/hyp.78.suppl_1.p276 ◽

2021 ◽

Vol 78 (Suppl_1) ◽

Author(s):

Jordan C Patik ◽

Joseph M Stock ◽

Nathan T Romberger ◽

Shannon L Lennon ◽

William B Farquhar ◽

...

Keyword(s):

Blood Pressure ◽

Vascular Function ◽

Sodium Intake ◽

Local Heating ◽

Urinary Sodium Excretion ◽

Microvascular Function ◽

Dietary Sodium ◽

Heating Unit ◽

Doppler Flowmetry ◽

High Sodium

Impaired vascular function likely contributes to the association between dietary sodium intake and the development of cardiovascular disease. Using the cutaneous microvasculature as a model, we have previously shown that a high sodium (HS) diet blunts local heating-induced vasodilation in normotensive individuals with salt resistant (SR) blood pressure (BP). However, the effect of a HS diet on the cutaneous microvasculature in normotensive salt sensitive (SS) individuals remains unclear. Therefore, we tested the hypothesis that cutaneous microvascular function is reduced by a HS diet to a greater degree in SS compared to SR individuals. After each 7-day controlled feeding diet (low sodium (LS) = 20 mmol/day; HS = 300 mmol/day), an intradermal microdialysis fiber was inserted in the ventral forearm and perfused with Ringer’s solution. Skin blood flow (SkBF) was continuously monitored via laser Doppler flowmetry and a local heating unit was placed over the fiber and heated to 42°C until SkBF reached a stable plateau. Site-specific maximal SkBF was determined by perfusing 28mM sodium nitroprusside and heating to 43°C. Mean arterial pressure (MAP) was assessed at regular intervals on the contralateral arm and was used to calculate cutaneous vascular conductance (CVC = SkBF / MAP). Subjects wore a 24-hr ambulatory BP monitor and collected their urine on the final day of each diet. Fourteen subjects (9W / 5M, 42 ± 14 yr) whose MAP increased >5 mmHg (Δ8 ± 1 mmHg) on the HS diet were defined as SS and were compared to 14 age- (43± 14 yr) and sex-matched SR subjects (Δ1 ± 3 mmHg). SS and SR had similar MAP at baseline (88 ± 9 vs. 90 ± 8 mmHg, P = 0.88) and urinary sodium excretion was increased similarly across groups by the HS diet (Δ239 ± 104 vs. Δ220 ± 66 mmol / 24 hr, P = 0.20). Cutaneous vasodilation in response to local heating was decreased on the HS diet relative to the LS diet in both SS (Δ-9 ± 9 %CVCmax, P = 0.005) and SR (Δ-9 ± 9 %CVCmax, P=0.005); however, there was not a group x diet interaction (P = 0.99). In contrast to our hypothesis, these results suggest that the deleterious effects of high sodium diets on cutaneous microvascular function are similar in normotensive salt sensitive and salt resistant individuals.

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Blood Pressure Effects of Sodium Reduction

Circulation ◽

10.1161/circulationaha.120.050371 ◽

2021 ◽

Vol 143 (16) ◽

pp. 1542-1567 ◽

Cited By ~ 2

Author(s):

Tommaso Filippini ◽

Marcella Malavolti ◽

Paul K. Whelton ◽

Androniki Naska ◽

Nicola Orsini ◽

...

Keyword(s):

Blood Pressure ◽

Clinical Trials ◽

Linear Relationship ◽

Dose Response ◽

Sodium Intake ◽

Experimental Studies ◽

Dietary Sodium ◽

Response Analysis ◽

Sodium Reduction

Background: The relationship between dietary sodium intake and blood pressure (BP) has been tested in clinical trials and nonexperimental human studies, indicating a direct association. The exact shape of the dose–response relationship has been difficult to assess in clinical trials because of the lack of random-effects dose–response statistical models that can include 2-arm comparisons. Methods: After performing a comprehensive literature search for experimental studies that investigated the BP effects of changes in dietary sodium intake, we conducted a dose–response meta-analysis using the new 1-stage cubic spline mixed-effects model. We included trials with at least 4 weeks of follow-up; 24-hour urinary sodium excretion measurements; sodium manipulation through dietary change or supplementation, or both; and measurements of systolic and diastolic BP at the beginning and end of treatment. Results: We identified 85 eligible trials with sodium intake ranging from 0.4 to 7.6 g/d and follow-up from 4 weeks to 36 months. The trials were conducted in participants with hypertension (n=65), without hypertension (n=11), or a combination (n=9). Overall, the pooled data were compatible with an approximately linear relationship between achieved sodium intake and mean systolic as well as diastolic BP, with no indication of a flattening of the curve at either the lowest or highest levels of sodium exposure. Results were similar for participants with or without hypertension, but the former group showed a steeper decrease in BP after sodium reduction. Intervention duration (≥12 weeks versus 4 to 11 weeks), type of study design (parallel or crossover), use of antihypertensive medication, and participants’ sex had little influence on the BP effects of sodium reduction. Additional analyses based on the BP effect of difference in sodium exposure between study arms at the end of the trial confirmed the results on the basis of achieved sodium intake. Conclusions: In this dose–response analysis of sodium reduction in clinical trials, we identified an approximately linear relationship between sodium intake and reduction in both systolic and diastolic BP across the entire range of dietary sodium exposure. Although this occurred independently of baseline BP, the effect of sodium reduction on level of BP was more pronounced in participants with a higher BP level.

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