Muscle Sodium Content Research Articles

Abstract MP34: Muscle Sodium Content and Isolevuglandin Formation in Antigen Presenting Cells in Human Salt Sensitive Hypertension

Background: Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular mortality. However, the mechanisms by which salt exposure affects blood pressure in SSBP are still unclear. We have shown that under high sodium (Na + ) concentrations, Na + enters antigen-presenting cells (APCs) via epithelial Na + channel (ENaC), which leads to isolevuglandin (IsoLG) production and hypertension. Baseline %IsoLG+ APC correlates with SSBP. While the exact location where APCs are activated by salt and trigger an inflammatory response remains to be elucidated, muscle and skin are proposed as potential sites. We hypothesize that muscle and skin Na + levels are associated with SSBP. Methods: We assessed SSBP in 30 hypertensive subjects using an inpatient salt loading and depletion protocol. Flow cytometry was used to identify IsoLG-containing APCs; dendritic cells (DCs), classic (CD14+16-), non-classic (CD14-16+), and intermediate (CD14+16+) monocytes. Salt loading was achieved through saline infusion and a high-salt diet (460mmol/24 hours), while salt depletion was achieved via diuretic administration (furosemide 40mg x3) and a low-salt diet (10mmol/24hours). Baseline muscle and skin Na + levels were assessed with the 23 Na MRI technique. Spearman's correlation was used to analyze the associations. Demographic data are presented with mean and standard error of the mean. Results: Participants’ age was 53 ± 1.34 years, 53% female, baseline blood pressure was 140.2 ± 2.62 / 87.30 ± 1.77 mmHg, and salt sensitivity index was 3.72 ± 1.4 mmHg. We found an inverse correlation between baseline muscle Na + levels and the decrease in IsoLGs from salt loading to depletion (ΔIsoLGs) in DCs (r=-0.50, p=0.007), intermediate (r=-0.42 p=0.0284) and non-classic monocytes (r=-0.39 p=0.0432), but not in classical monocytes. Skin Na + levels were not correlated with any of these measures. There was a decreasing trend of salt sensitivity index with increasing muscle Na + , although this correlation did not reach statistical significance (r=-0.35 p=0.0686) Conclusion: This highlights the potential importance of muscle Na + in SSBP, such that patients with lower muscle Na + exhibited a higher trend of salt sensitivity index and increased variability in IsoLG+ APCs. Moreover, baseline tissue Na + assessment may emerge as a potential tool for evaluating the degree of salt sensitivity and IsoLG activation in SSBP.

#4196 MAGNETIC RESONANCE IMAGING ASSESSMENT OF SKIN AND MUSCLE SODIUM IN HAEMODIALYSIS

Abstract Background and Aims Haemodialysis (HD) is life sustaining for patients with end-stage kidney disease (ESKD) but is associated with a marked increase in incidence of cardiovascular disease (CVD) and high annual mortality rates. Sodium balance is regulated by the kidneys in health but has to be achieved by sodium removal during HD for those with ESKD. Recent evidence suggests that non-osmotically stored sodium in the muscle and/or skin may be a critical factor impacting the development of hypertension and CVD. Sodium magnetic resonance imaging (23Na MRI) allows assessment of skin and muscle sodium storage and may provide a valuable tool in evaluating sodium storage in dialysis patients. In this study, we used 23Na MRI to measure muscle and skin sodium content in younger and older healthy individuals and people receiving HD, and investigated the effect of a single dialysis session on muscle and skin sodium content. Method 23Na MRI was acquired on a 3T Philips Ingenia scanner using a custom-made 23Na RF coil. 3D GRE 23Na scans (3 × 3 × 30mm3, 10 slices) were acquired in a 15-minute scan. Four reference bottles of increasing sodium concentration were placed in the RF coil above the leg to calibrate sodium concentration. In the same imaging session, 1H MR images were acquired to delineate muscle groups, skin structures and tissue water content. 23Na concentration maps were generated using custom software and regions of interest of each muscle and the skin were manually segmented. Data was collected on 14 younger (23-38yrs,7M:7F) and three older (66-77yrs,3M:1F) healthy volunteers (HVs), and 5 male HD patients (55-68 yrs) who had been on HD for more than 3-months. HD patients underwent a pre-dialysis 23Na MRI calf scan, then had their usual dialysis session with a dialysate Na prescription of 137 mmol/L, followed by a repeat 23Na MRI calf scan post dialysis. Patient demographics, dialysis vintage, residual renal function, and ultrafiltration volume were collected, along with blood samples at the start and end of the dialysis session, including serum sodium. Results Figure 1 shows 23Na images in the younger and older HV group and HD patients pre-dialysis. Muscle and skin sodium was increased in older HVs compared to younger, with HD patients pre-dialysis tending to be lower than older HVs (Fig. 2). HD patients’ demographics and clinical measures pre- and post-dialysis are shown in Table 1. HD treatment reduced muscle sodium whilst skin sodium showed little change (Fig. 3). Conclusion We have optimised methods for measuring muscle and skin sodium. 23Na concentration in muscle and skin is higher in older subjects. HD patients’ 23Na values fall between those observed in the older and younger HV groups. These values are consistent with published data from patients dialysed against 137mmol/l sodium dialysate, but lower than other studies in which dialysate sodium levels were higher. Further studies are planned to study the effect of dialysate sodium on skin and muscle sodium concentrations and mechanistic links to cardiovascular disease.

A KETOGENIC DIET REDUCES TISSUE SODIUM CONTENT: AN EXPLORATORY STUDY

Objective: Hypertension and diabetes are a substantial global public health problem. The prevalence of these diseases will further increase in the near future, leading to increased health and socioeconomic costs. Hence efficient therapeutic approaches are urgently needed. It has been previously shown that nutritional approaches including a very-low carbohydrate, or a ketogenic diet potentially decrease body weight, blood pressure and glucose levels in patients with type 2 diabetes along with an overall significant reduction in their pill burden. However, the detailed physiological mechanisms underlying the observed induction and maintenance of diabetes remission remain largely unknown. Previous studies have shown that the skin could be a buffer system for sodium and that skin sodium content could be both a pathogenic cause and a marker of hypertension and salt sensitivity. Since a nutritionally created metabolic milieu such as nutritional ketosis can lower blood pressure, we hypothesize that this dietary approach also reduces tissue sodium content. Design and method: By using 7-T 23Na MRI technique, we performed an exploratory study and analyzed skin and muscle sodium concentration before, and after a 6-week ketogenic diet in three healthy probands. Nutritional ketosis was verified by frequent check of blood ketone (beta-hydroxybutyrate; BOHB) levels greater than 0.3 mmol/L. Results: Preliminary data of our planned exploratory study (in patients with chronic kidney disease and type 2 diabetes mellitus and healthy probands) demonstrated that compared to baseline 6 weeks of ketogenic diet decreased tissue sodium content in the skin (16.6 ± 2.1 vs. 12.6 ± 2.1 mmol/L), in the medial gastrocnemius muscle (20.5 ± 0.9 vs. 16.7 ± 0.7 mmol/L), in the lateral gastrocnemius muscle (19.7 ± 1.0 vs. 16.0 ± 1.0 mmol/L) and in the soleus muscle (13.1 ± 0.8 vs. 11.5 ± 0.5 mmol/L). Conclusions: Our results indicate a massive reduction of tissue sodium concentration in healthy volunteers in response to a ketogenic diet which might be associated with the observed clinical benefits and be implicated in the anti-hypertensive effects of this powerful dietary intervention. Findings of this study could have an impact on future treatment strategies of various chronic diseases.

Potassium-Induced Changes in Muscle Free Amino Acid Concentrations in Chicks

Two experiments with purified crystalline amino acid diets were conducted to determine the effect of dietary potassium level on chick breast muscle free amino acid concentrations. In both experiments, concentrations of muscle free glutamine, lysine and arginine increased as dietary potassium increased from 0.12 to 0.18% and decreased as dietary potassium exceeded 0.18%. As dietary potassium increased, muscle potassium concentration increased linearly with an equivalent linear decrease in muscle sodium concentration. Peak concentrations of muscle free glutamine, lysine and arginine occurred in muscle with a K+:Na+ ratio of approximately 1.4. Concentrations of the three amino acids were less in muscle with K+:Na+ ratios either less than or greater than 1.4. Breast muscle concentrations of free histidine decreased slightly, while muscle free carnosine increased substantially when dietary potassium exceeded 0.18%.amino acids glutamine lysine arginine potassium

Muscle sodium content in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

BackgroundMuscle fatigue and pain are key symptoms of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Although the pathophysiology is not yet fully understood, there is ample evidence for hypoperfusion which may result in electrolyte imbalance and sodium overload in muscles. Therefore, the aim of this study was to assess levels of sodium content in muscles of patients with ME/CFS and to compare these to healthy controls.MethodsSix female patients with ME/CFS and six age, BMI and sex matched controls underwent 23Na-MRI of the left lower leg using a clinical 3T MR scanner before and after 3 min of plantar flexion exercise. Sodium reference phantoms with solutions of 10, 20, 30 and 40 mmol/L NaCl were used for quantification. Muscle sodium content over 40 min was measured using a dedicated plugin in the open-source DICOM viewer Horos. Handgrip strength was measured and correlated with sodium content.ResultsBaseline tissue sodium content was higher in all 5 lower leg muscle compartments in ME/CFS compared to controls. Within the anterior extensor muscle compartment, the highest difference in baseline muscle sodium content between ME/CFS and controls was found (mean ± SD; 12.20 ± 1.66 mM in ME/CFS versus 9.38 ± 0.71 mM in controls, p = 0.0034). Directly after exercise, tissue sodium content increased in gastrocnemius and triceps surae muscles with + 30% in ME/CFS (p = 0.0005) and + 24% in controls (p = 0.0007) in the medial gastrocnemius muscle but not in the extensor muscles which were not exercised. Compared to baseline, the increase of sodium content in medial gastrocnemius muscle was stronger in ME/CFS than in controls with + 30% versus + 17% to baseline at 12 min (p = 0.0326) and + 29% versus + 16% to baseline at 15 min (p = 0.0265). Patients had reduced average handgrip strength which was associated with increased average muscle tissue sodium content (p = 0.0319, R2 = 0.3832).ConclusionMuscle sodium content before and after exercise was higher in ME/CFS than in healthy controls. Furthermore, our findings indicate an inverse correlation between muscle sodium content and handgrip strength. These findings provide evidence that sodium overload may play a role in the pathophysiology of ME/CFS and may allow for potential therapeutic targeting.

The SGLT2 inhibitor empagliflozin reduces tissue sodium content in patients with chronic heart failure: results from a placebo-controlled randomised trial

IntroductionSodium-glucose co-transporter 2 (SGLT2) inhibitors have cardiovascular protective properties in addition to the metabolic effects and represent a cornerstone of treating patients with chronic heart failure (CHF). We hypothesised that empagliflozin reduces tissue sodium content in patients with CHF.MethodsIn a double-blind, randomised (2:1), placebo-controlled, parallel-group, clinical trial, 74 patients with NYHA class II–III CHF and an ejection fraction of 49% or less received empagliflozin 10 mg once daily or placebo for 3 months. In each patient, tissue sodium content of the lower leg was assessed non-invasively by sodium-MRI (23Na-MRI) at baseline, after 1 and 3 months of treatment.ResultsAfter 1 and 3 months treatment with empagliflozin (n = 48), a significant decrease in skin sodium content was observed (1 month: 22.8 ± 6.1 vs. 21.6 ± 6.0 AU, p = 0.039; 3 months: 22.9 ± 6.1 vs. 21.6 ± 6.1 AU, p = 0.013), while there was no change in muscle sodium and muscle water content. In direct comparison, the change in skin sodium content between baseline and 3 months was − 1.3 ± 3.5 AU in the empagliflozin group versus 0.6 ± 3.5 AU in the placebo group (p for between-group difference = 0.022). No significant difference regarding change in muscle sodium and in muscle water content was observed after 3 months treatment between the two groups.ConclusionThis trial showed a significant decrease in skin sodium content after 1 and 3 months of treatment with empagliflozin. The decrease in skin sodium content may reflect a decrease in subclinical micro-oedema or/and in non-osmotic bound tissue sodium, both reported to impair left ventricular function.Trial registration numberNCT03128528 (http://www.clinicaltrials.gov).Trial registration date25th April 2017.

Tissue Sodium Storage in Patients With Heart Failure: A New Therapeutic Target?

Preclinical data suggest sodium deposited (without water) in tissues may lead to aberrant remodeling and systemic inflammation, independently of fluid overload in patients with heart failure (HF). Tissue salt storage can be measured noninvasively and quantitatively with 23Na-magnetic resonance imaging. We aimed to investigate the possibility that patients with HF complicated by renal dysfunction are subject to higher tissue sodium concentration exposure than patients with chronic kidney disease alone. We conducted an exploratory study including 18 patients with HF, 34 hemodialysis patients (with no meaningful renal clearance of sodium), and 31 patients with chronic kidney disease, with glomerular filtration rate matched to the patients with HF. Every patient underwent 23Na-magnetic resonance imaging of the calf, to quantify tissue sodium and allow comparison among the 3 patient groups. There were no differences in age, sex, and body mass index between groups. Median (interquartile range) skin sodium content in HF (31 [23-37] mmol/L) was very high and indistinguishable from skin sodium content in hemodialysis patients (30 [22-35] mmol/L), P=0.6. Patients with HF exhibited significantly higher skin sodium content than matched estimated glomerular filtration rate chronic kidney disease patients (22 [19-26] mmol/L), P=0.005. Median muscle sodium content in patients with HF was significantly higher than in patients with chronic kidney disease, P=0.002. There was no relationship with estimated glomerular filtration rate in patients with HF. We report a significant correlation between skin sodium and urinary sodium (P=0.04) but no correlation with muscle sodium. Patients who were assessed as being volume depleted (sodium excretion fraction <1%) had lower skin sodium content than patients with sodium excretion fraction >1% (P=0.03). We have demonstrated that patients with HF characteristically have very high levels of skin sodium storage, comparable to well-characterized extreme levels seen in patients with end-stage kidney disease requiring hemodialysis. 23Na-magnetic resonance imaging may allow precision medicine in the management of this challenging group of patients with HF. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03004547.

Reduced tissue sodium content is related to improvement of vascular function in patients with chronic heart failure treated with the SGLT2 inhibitor empagliflozin

Abstract Background Large randomized controlled trials have demonstrated that SGLT2 inhibitors produce cardiovascular benefits beyond their metabolic effects. One of the assumed underlying mechanisms is the reduction of the left ventricular afterload. Factors aggravating the afterload are impaired vascular function (ventricular-arterial coupling) as well as high tissue sodium content, which exerts enhanced hypertrophic stimuli and exaggerated response to vasoconstrictors. Purpose We hypothesized that the SGLT2 inhibitor empagliflozin leads to afterload reduction in patients with chronic heart failure (CHF) by reducing tissue sodium content and improving vascular function and that these changes are related to each other. Methods In a randomized (2:1), investigator initiated, double-blind, placebo controlled, parallel-group, prospective clinical study, patients with CHF NYHA II-III and an ejection fraction of 49% or less were randomized to empagliflozin 10mg once daily or placebo. In each patient, we assessed vascular parameters under resting conditions (Sphygmocor) and 24-hour daily life conditions (Mobilograph), including central systolic pressure (cSBP) and central pulse pressure (cPP) among others. In parallel, we measured tissue (skin and muscle) sodium content of the lower leg by Sodium-MRI, at baseline and after 1 month of therapy. Results A total of 74 patients (men: n=62), aged 66±9 years, with a mean ejection fraction of 39±9% were included. Only 24% of the patients had type 2 diabetes. After 1 month treatment with empagliflozin, a decrease of skin sodium content was observed (22.8±6.1 vs. 21.6±6.0 mmol/l, p=0.039), while there was no significant change in muscle sodium and muscle water content. A decrease of cSBP (117.1±14.5 vs. 110.7±11.3 mmHg, p&amp;lt;0.001) and cPP (41.4±8.8 vs. 38.4±8.5 mmHg, p=0.004) under resting conditions was observed after 1 month treatment with empagliflozin, while changes in the placebo group were not significant for cSBP (117.0±18.1 vs. 116.3±15.0 mmHg, p=0.759) and cPP (40.6±9.1 vs. 39.4±8.6 mmHg, p=0.422). Similarly, there was a decrease of cSBP and cPP in patients with empagliflozin treatment under ambulatory conditions, but not in the placebo group. In the whole group, we observed a significant correlation between change in skin sodium content and change in vascular parameters such as cSBP (r=0.364, p=0.004) and cPP (r=0.250, p=0.054) after 1 month of treatment with empagliflozin or placebo. Conclusion(s) Significant changes in skin sodium content induced by empagliflozin and a significant correlation between changes in skin sodium content and vascular function suggest that a reduction of tissue sodium content may be one of the mechanisms underlying the beneficial effects of SGLT2 inhibitors in heart failure. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Boehringer Ingelheim International GmbH.

Tissue sodium content correlates with hypertrophic vascular remodeling in type 2 diabetes

BackgroundProspective studies describe a linkage between increased sodium intake and higher incidence of cardiovascular organ damage and end points. We analyzed whether tissue sodium content in the skin and muscles correlate with vascular hypertrophic remodeling, a risk factor for cardiovascular disease. MethodsIn patients with type 2 diabetes we assessed tissue sodium content and vascular structural parameters of the retinal arterioles. The structural parameters of retinal arterioles assessed by Scanning Laser Doppler Flowmetry were vessel (VD) and lumen diameter (LD), wall thickness (WT), wall-to-lumen ratio (WLR) and wall cross sectional area (WCSA). Tissue sodium content was measured with a 3.0 T clinical 23Sodium-Magnetic Resonance Imaging (23Na-MRI) system. ResultsIn patients with type 2 diabetes (N = 52) we observed a significant correlation between muscle sodium content and VD (p = 0.005), WT (p = 0.003), WCSA (p = 0.002) and WLR (p = 0.013). With respect to skin sodium content a significant correlation has been found with VD (p = 0.042), WT (p = 0.023) and WCSA (p = 0.019). Further analysis demonstrated that tissue sodium content of skin and muscle is a significant determinant of hypertrophic vascular remodeling independent of age, gender, diuretic use and 24-hour ambulatory BP. ConclusionWith the 23Na-MRI technology we could demonstrate that high tissue sodium content is independently linked to hypertrophic vascular remodeling in type 2 diabetes. Trial registrationTrial registration number: NCT02383238Date of registration: March 9, 2015.

Comparison of some meat and liver quality traits in Muscovy and Pekin ducks

ABSTRACT The objective of the study was to compare Muscovy and Pekin ducks for proximate analysis, colour attributes, tenderness, meat microstructure, and content of some minerals in meat and liver. The material of the study was sexed 51 Muscovy ducks and 47 Pekin ducks. At the end of the rearing period, 40 birds were selected for dissection. Duck genotype influenced the content of water, protein, fat, collagen, zinc, iron, haematin, and redness, chroma, hue angle, WB shear force, muscle fibre diameter and density of the breast muscle, and also protein, fat, magnesium, iron, haematin content, WB shear force and lightness of the leg muscle. The sex of ducks had an impact on the content of water, protein, fat, potassium, copper, on redness, chroma and muscle fibre diameter of breast muscle, and on water, protein, fat, sodium, potassium, magnesium and copper in liver content of the leg muscle. The genotype-sex interaction was significant for water, protein and sodium content, redness, chroma of breast muscles; for water, protein, sodium, magnesium and haematin content, redness and chroma of leg muscles; and for phosphorus content in the liver. Muscovy ducks had more favourable chemical composition and poorer tenderness and microstructural characteristics compared to the meat of Pekin ducks.

Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by 23-sodium magnetic resonance imaging.

Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation. In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements. Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman's rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements. Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Abstract 12895: Tissue Sodium Content Increases With Severity of Chronic Heart Failure

Introduction: Heart failure is strongly linked to renal sodium and water retention as well as intravascular and interstitial fluid shifts. Experimental studies demonstrated a non-osmotic sodium storage, bound to proteoglycans, in the extravascular space. New sodium magnetic resonance imaging ( 23 Na-MRI) enables us to quantify tissue (muscle and skin) sodium content in a reliable and accurate way. Hypothesis: We hypothesised that the increase of tissue sodium content is dependent on the severity of chronic heart failure (CHF). Methods: We investigated patients with stable CHF before initiating treatment with an SGLT2-inhibitor within a prospective, placebo-controlled study. We here report the baseline data of 64 patients with CHF, defined as patients with reduced (HFrEF) or mid-range ejection fraction (HFmEF). In each patient, tissue sodium content of the lower leg was assessed non-invasively by a clinical 3.0T 23 Na-MRI. The median NT-proBNP plasma level at baseline was 493.3pg/ml (IQR: 225.8-1122.0pg/ml) and was used as cut off value of CHF severity. Results: Our patients (men: n=54) were 66.9±8.9 years old and had NYHA class II-III; mean muscle sodium content was 19.1±3.8mmol/l and mean skin sodium content was 22.5±5.9mmol/l. Our reference for young healthy subjects are 18.7±2.0 mmol/l for muscle sodium content and 19.6±3.1 mmol/l for skin sodium content. Patients with CHF and NT-proBNP levels above the median showed higher muscle (20.2±3.5 vs 17.9±3.7mmol/l, p=0.008) and skin sodium content (24.1±6.8 vs 20.8±4.4mmol/l, p=0.005) than patients with CHF and NT-proBNP levels below the median. No difference in plasma sodium levels between the two groups (138.0±3.7 vs 138.8±2.1mmol/l, p=0.527) was observed, but patients with NT-proBNP levels above the median had lower urinary sodium excretion over 24 hours (167.0±78.8 vs 172.3±63.4mmol/l, p=0.009). Age was different in the two groups (69.88±8.2 vs 63.8±8.7, p&lt;0.001) with no difference in gender. The number of diagnosed coronary heart disease was similar in the two groups (62.5% vs 59.4%, p=0.802). Conclusion: Concluding, tissue sodium content in patients with stable CHF as assessed by 23 Na-MRI increases with the severity of CHF. A decrease of tissue sodium content might be a future therapeutic goal.

Pilot study to reduce interdialytic weight gain by provision of low-sodium, home-delivered meals in hemodialysis patients.

Patients with kidney failure undergoing maintenance hemodialysis (HD) therapy are routinely counseled to reduce dietary sodium intake to ameliorate sodium retention, volume overload, and hypertension. However, low-sodium diet trials in HD are sparse and indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake. This study aimed to determine whether 4 weeks of low-sodium, home-delivered meals in HD patients reduces interdialytic weight gain (IDWG). Secondary outcomes included changes in dietary sodium intake, thirst, xerostomia, blood pressure, volume overload, and muscle sodium concentration. Twenty HD patients (55 ± 12 years, body mass index [BMI] 40.7 ± 16.6 kg/m2 ) were enrolled in this study. Participants followed a usual (control) diet for the first 4 weeks followed by 4 weeks of three low-sodium, home-delivered meals per day. We measured IDWG, hydration status (bioimpedance), standardized blood pressure (BP), food intake (3-day dietary recall), and muscle sodium (magnetic resonance imaging) at baseline (0 M), after the 4-week period of usual diet (1 M), and after the meal intervention (2 M). The low-sodium meal intervention significantly reduced IDWG when compared to the control period (-0.82 ± 0.14 kg; 95% confidence interval, -0.55 to -1.08 kg; P < 0.001). There were also 1 month (1 M) to 2 month (2 M) reductions in dietary sodium intake (-1687 ± 297 mg; P < 0.001); thirst score (-4.4 ± 1.3; P = 0.003), xerostomia score (-6.7 ± 1.9; P = 0.002), SBP (-18.0 ± 3.6 mmHg; P < 0.001), DBP (-5.9 ± 2.0 mmHg; P = 0.008), and plasma phosphorus -1.55 ± 0.21 mg/dL; P = 0.005), as well as a 0 M to 2 M reduction in absolute volume overload (-1.08 ± 0.33 L; P = 0.025). However, there were no significant changes in serum or tissue sodium (all P > 0.05). Low-sodium, home-meal delivery appears to be an effective method for improving volume control and blood pressure in HD patients. Future studies with larger sample sizes are needed to examine the long-term effects of home-delivered meals on these outcomes and to assess cost-effectiveness.

SO027ASSOCIATIONS OF MUSCLE SODIUM DEPOSITION WITH SODIUM-23 MRI IN HEMODIALYSIS PATIENTS

Abstract Background and Aims The development of sodium-23 magnetic resonance imaging (23Na MRI) allows the clinical quantification of tissue sodium. Recent studies have shown that hemodialysis (HD) patients have a tendency to retain tissue sodium due to impaired mechanisms in local tissue sodium clearance. However, the clinical significance of tissue sodium deposition in the HD patient population is unclear yet. The aim of this study was to investigate the association of tissue sodium deposition with well-established biomarkers of clinical outcomes. Method Chronic, thrice weekly HD patients underwent 23Na MRI of the leg on a non-dialysis day, during either the long or short interdialytic interval. Blood samples were also taken for the measurement of standard blood-based biomarkers. A multinuclear-capable 3.0-T MRI (GE Healthcare, Milwaukee WI) was used to acquire proton and sodium images. Maps of tissue 23Na concentration were generated using an in-house software developed within MATLAB (Mathworks, Natick, USA, R2018a). 23Na concentration maps were superimposed with the proton-anatomy images to delineate the regions of interest. Using the Horos (The Horos Project, Version 4.0.0) software, the soleus muscle was segmented (Figure, Panel A) and the sodium concentration in the region of interest was recorded for analysis. Results 28 HD patients completed both 23Na MRI and bloodwork; 7/28 (25%) patients were females; mean±SD age was 66.1±8.3 years, mean body mass index was 30.9±6.5 kg/m2, and mean HD vintage was 30.2±34.9 months. Soleus muscle sodium concentration showed a strong, negative correlation with serum albumin (Figure, Panel B; r=-0.66, p&amp;lt;0.0001). Furthermore, soleus muscle sodium concentration showed a minor association with plasma hemoglobin (r=-0.46, p=0.01). Conclusion Serum albumin is a recognized, powerful predictor of mortality in the hemodialysis patient population. The strong relationship between muscle sodium concentration and serum albumin levels suggests that tissue sodium deposition may be a relevant biomarker of clinical outcomes. In addition, muscle sodium deposition may be involved in the development of anemia. These findings warrant further studies investigating the consequences of sodium removal on these biomarkers.

Comparison of some meat quality and liver characteristics in Muscovy and mule ducks.

The aim of the study was to compare Muscovy ducks and mule ducks for proximate analysis, colour attributes, sensory properties of the meat, and concentration of some minerals in the meat and liver, with consideration of the effect of sex on the analysed traits. The study used 46 Muscovy and 44 mule ducks. At the end of the rearing period, 40 birds (10 males and 10 females of each genotype) were selected for slaughter. Meat and liver samples were collected from the slaughtered birds to determine quality traits. The analysed ducks of different genotypes differed significantly in the water content, sodium content, and redness of breast muscles; in the water, fat, and zinc content of leg muscles; and in the sodium, iron, and copper content of liver. Regardless of genotype, males had a higher sodium content in breast muscles; contained more protein, sodium, phosphorus, and magnesium and less potassium and copper in leg muscles; and had a significantly higher content of sodium, potassium, phosphorus, magnesium, zinc, iron, and copper in liver compared to females. The genotype–sex interaction was significant for the sodium and potassium content of breast muscles, for the water, protein, sodium, potassium, phosphorus, magnesium, and copper content of leg muscles, and for the copper content of liver. Our study provided information about differences in the quality of meat and liver in Muscovy and mule ducks.

P4993Tissue sodium concentration emerged as a determinant of hypertrophic vascular remodeling in type 2 diabetes

Abstract Background Studies describe a linkage between greater sodium intake and higher incidence of organ damage and cardiovascular end points. Sodium intake is usually assessed by measuring 24-hour urinary sodium excretion, which is prone to high fluctuation. For the assessment of tissue sodium a new technique (23Na-MRI) has been developed. We analyzed whether tissue sodium is linked to vascular remodeling of small resistance vessels in patients with type-2 diabetes. Methods In patients with type 2 diabetes we assessed tissue sodium content and vascular structural parameters of the retinal arterioles, since structural changes of resistance vessels (150–300 μm) can be non-invasively and reliably assessed in the retinal circulation by Scanning Laser Doppler Flowmetry (SLDF). Patients with antidiabetic medication were off the therapy (antihypertensives were kept constant) for 4 weeks. The structural parameters of retinal arterioles assessed were outer- and inner diameter (OD &amp; ID), wall thickness (WT), wall-to-lumen ratio (WLR) and wall cross sectional area (WCSA). Tissue sodium content was assessed non-invasively with a 3.0 T clinical MRI system in each patient. Subject placed their lower legs in the center of a 23Na knee coil and sodium content in skin and muscle (musculus triceps surae) were measured. Results In patients with type 2 diabetes (N=52) we observed a significant correlation between tissue sodium content (muscle and skin) and OD, WT and WCSA and a trend has been noticed between muscle sodium content and ID and WLR. Multiple linear regression analysis demonstrated that tissue sodium content is a significant determinant of hypertrophic vascular remodeling as indicated by increased WT and WCSA, independent of age, gender and 24-hour ambulatory diastolic blood pressure. Correlation coefficients Muscle sodium content (mmol/l) Skin sodium content (mmol/l) OD (μmol) r=0.402, p=0.003 r=0.299, p=0.033 ID (μmol) r=0.265, p=0.058 r=0.202, p=0.154 WT (μm) r=0.402, p=0.003 r=0.313, p=0.026 WLR r=0.247, p=0.078 r=0.171, p=0.230 WCSA (μm2) r=0.417, p=0.002 r=0.322, p=0.021 Conclusion With the novel 23Na-MRI technology, we could demonstrate that high tissue sodium concentration is linked to with hypertrophic vascular remodeling of retinal arterioles. Thus, the reduction of tissue sodium content may emerge as a therapeutic target.

SHORT-TERM CHANGES IN DIETARY SODIUM INTAKE INFLUENCE SWEAT SODIUM CONCENTRATION AND MUSCLE SODIUM CONTENT IN HEALTHY SUBJECTS

Objective: There is increasing evidence that sodium can be stored in the skin and muscles without being osmotically active, yet whether acute changes in dietary sodium intake alter sweat and muscle sodium content has not been investigated previously. Design and method: In a cross-over design, we assessed muscle sodium content by 23Na magnetic resonance imaging (MRI) in 38 healthy normotensive volunteers (aged 33.5 ± 11.1 years, 76.3% female) after 5 days of high sodium diet (HS) (6 g of salt added to their normal diet) and 5 days of a low-sodium diet (LS). Women performed each study visit during the same phase of the menstrual cycle. In a sub-group of 18 participants (72.2% female) we conducted quantitative pilocarpine iontophoretic sweat collections and measured the sodium concentration in sweat. Office blood pressure, electrolytes, creatinine and circulating aldosterone levels were measured in all participants, and 24 h urine was collected Results: Under HS conditions urinary sodium excretion, muscle sodium content and sweat sodium concentration all increased significantly (see Figure). Muscle sodium content by MRI (rm = 0.47, p = 0.03) and sodium sweat concentration (rm = 0.72, p < 0.001) correlated positively with salt intake as estimated by 24-hour urine sodium excretion. Age, gender or the phase of the menstrual cycle did not influence muscle or sweat sodium concentrations or their changes. In contrast, plasma aldosterone levels were strongly and negatively associated with both muscle sodium content (rs = −0.42, p = 0.0001) and sweat sodium (rs = −0.52, p = 0.002). Sweat and muscle sodium content were not different in participants with a salt-sensitive blood pressure compared to non-sensitives. Conclusions: Muscle and sweat sodium concentrations are significantly higher under high salt conditions in healthy male and female subjects, suggesting that muscle and sweat play a role in the dietary sodium balance in humans.

Carcass composition and selected meat quality traits of Pekin ducks from genetic resources flocks

The aim of the study was to compare P33 (Polish Pekin), P8 (Danish Pekin), and P9 ducks (French Pekin) for body weight, dressing percentage, carcass composition, and selected meat quality traits. A total of 180 ducks, 30 males and 30 females of each strain, were kept indoors on deep litter and fed complete commercial diets ad libitum. At the end of 8 wk, the ducks were weighed and 7 males and 7 females of each strain (42 birds in total) were slaughtered and dissected. The pH and electrical conductivity of breast and leg muscles were determined 24h postmortem. After dissection, samples of breast and leg muscles were collected to determine of selected meat quality characteristics. At the age of 8 wk, P8 ducks had significantly higher body weight and carcass weight compared to P9 and P33 birds. The carcasses of P8 ducks contained significantly more breast muscles compared to the carcasses of P9 birds. The proportion of abdominal fat was higher in P8 and P9 ducks than in P33 ducks. Regardless of the genetic origin, males had a significantly lower percentage of breast muscles and a higher proportion of neck in the carcass compared to females. P33, P8, and P9 ducks exhibited significant differences in the sodium and magnesium content of breast muscles and in the sodium, potassium, phosphorus, and magnesium content of leg muscles. Male breast muscles contained more sodium, and their leg muscles had a lower potassium, phosphorus, magnesium, and iron content compared to females. The breast and leg muscles of P9 ducks exhibited lower electrical conductivity (EC24) compared to P8 and P33 ducks, while the breast muscles of P9 ducks had a significantly higher cooking loss. The strains of ducks under study differed in lightness (L*) and redness (a*), and in hardness, chewiness and gumminess of pectoralis major muscle. Females showed higher hardness and chewiness of breast muscles compared to males.

Tissue sodium content in patients with type 2 diabetes mellitus

BackgroundTissue sodium content by 23Na magnetic resonance imaging (MRI) has been found to be increased in arterial hypertension. We analyzed whether tissue sodium content is increased in patients with type-2 diabetes (T2DM). MethodsPatients with T2DM were compared to those with primary hypertension. Patients with T2DM were off any antidiabetic and hypertensive patients off any antihypertensive therapy for at least 4 weeks. Skin and muscle sodium content was assessed non-invasively with a 3.0 T clinical MRI system (Magnetom Verio, Siemens Health Care, Erlangen, Germany) in each patient. ResultsIn patients with T2DM (N = 59) we observed significantly greater muscle sodium content (diabetes: 20.6 ± 3.5 vs hypertension: 16.3 ± 2.5 mmol/l, p < 0.001) and skin sodium content (diabetes: 24.5 ± 7.2 vs hypertension: 20.6 ± 5.7 mmol/l, p = 0.01) than in those with primary hypertension (N = 33). When potential confounders (age, body mass index, gender, systolic and diastolic blood pressure, estimated glomerular filtration rate) were entered in a covariance analysis, both skin sodium content (p = 0.037) and muscle sodium content (p < 0.001) were still clearly elevated. ConclusionPatients with T2DM have greater skin and muscle sodium content. These are the first known data to demonstrate increased tissue sodium content in patients with T2DM, measured by 23Na magnetic resonance imaging. Since tissue sodium content is related to organ damage, therapeutic intervention should aim at reducing tissue sodium content.

SAT-386 Assessment Of Tissue Sodium Content By23Na-MRI In Patients With Adrenal Insufficiency

Patients with chronic primary adrenal insufficiency (PAI) depend on lifelong replacement therapy with gluco- (GC) and mineralocorticoids (MC). Monitoring is based on clinical parameters assessing hemodynamic stability, electrolyte status and plasma renin concentration (PRC). Reduced subjective well-being is however often described by these patients in absence of objectifiable abnormalities, thus suggesting a gap between the concept of adequate hormone substitution and physiological requirements. This study investigated the potential role of 23Na-MRI for noninvasive assessment of sodium status in PAI. Tissue sodium was initially analyzed both in the calf muscle and in the skin of 16 patients with chronic PAI and 16 sex-, age- and BMI-matched controls. Patients were classified into 3 groups (optimal/subtherapeutic/supraphysiological) according to the quality of GC and MC substitution assessed separately by clinical scores based on subjective wellbeing and clinical/laboratory parameters. We additionally performed a longitudinal analysis in 8 patients with newly diagnosed PAI. Muscle and skin sodium content (Muscle-SC, Skin-SC) were determined using a 23NA-MRI protocol on a 3T scanner implementing a 3D sequence. A vial with 100mmol/L of sodium was scanned with every participant. Tissue sodium is presented as the ratio of tissue sodium signal intensity to sodium signal intensity of the reference vial. Muscle-SC was significantly higher in patients with chronic PAI compared to controls (19.1 vs. 16.0, p<0.05), whereas Skin-SC was similar between the two groups (16.1 vs. 17.1). These results were replicated in the subgroups classified as receiving optimal GC and MC replacement, respectively. Skin-SC was significantly correlated with 24h-urine sodium level in the whole cohort. When comparing Muscle-SC and Skin-SC with obtained clinical scores a trend from lower SC for low scores to higher SC for higher scores was observed. The longitudinal analysis of 8 patients with newly diagnosed PAI revealed that Skin-SC was significantly lower at primary diagnosis compared to sex-, age- and BMI-matched controls (12.1 vs. 15.8, p=0.05), whereas the difference in Muscle-SC was less pronounced (14 vs. 16.1, p=0.18). A significant increase in both Muscle- and Skin-SC at follow-up compared to first diagnosis was detected (19.4 vs. 14, p<0.05 and 19.3 vs. 12.1, p<0.05), consistent with a significant decrease in PRC (200 vs. 31.2 ng/l, p<0.05). Interestingly, patients with chronic PAI under replacement therapy exhibited significantly higher Muscle-SC compared to controls. The agreement between tissue SC and clinical scores as well as the significant increase in tissue SC under replacement therapy in newly diagnosed patients indicate that 23Na-MRI might be a quantitative method to assess steroid replacement. Further studies on a larger cohort are, however, needed to prove these initial findings.