Effect of salt intake and potassium supplementation on serum renalase levels in Chinese adults: a randomized trial

Coexistence of Cardiovascular Risk Factors and Blood Renalase Concentration

Cardiovascular diseases (CVDs) are one of the biggest health challenges facing health systems around the world. There are certain risk factors (CVRFs) that contribute to CVD. Risk factors associated with lifestyle such as tobacco consumption are particularly essential. Renalase is a recently discovered flavoprotein that may be involved in the progression of cardiometabolic diseases. The aim of the study was to investigate the relation between CVRFs and blood renalase concentration (BRC). The study group consisted of 96 people (51% women) who were hospitalized in the internal medicine department. CVRFs were measured using the AHA Life 7 scale. The E3109Hu ELISA kit was used to assess BRC. We found higher BRC in groups with a lower number of CVRFs (p < 0.05). We found a negative correlation between BRC and the number of CVRFs (r = -0.41). With the regression analysis, obesity, smoking, and a lack of physical activity (LoPE) were independently associated with lower blood renalase concentration. ROC analysis indicated the highest accuracy of BRC < 38.98 ng/mL in patients with ≥5 CVRFs. In conclusion, patients with a higher number of CVRFs had lower BRCs. The CVRFs particularly associated with a lower BRC were obesity, smoking, and LoPE.

Associations of genetic variations in NEDD4L with salt sensitivity, blood pressure changes and hypertension incidence in Chinese adults

Neural precursor cell expressed developmentally downregulated 4-like (NEDD4L), a member of the E3 ubiquitin-protein ligases, encoded by NEDD4L gene, was found to be involved in in salt sensitivity by regulating sodium reabsorption in salt-sensitive rats. The authors aimed to explore the associations of NEDD4L genetic variants with salt sensitivity, blood pressure (BP) changes and hypertension incidence in Chinese adults. Participants from 124 families in Northern China in the Baoji Salt-Sensitive Study Cohort in 2004, who received the chronic salt intake intervention, including a 7-day low-salt diet (3.0 g/day) and a 7-day high-salt diet (18 g/day), were analyzed. Besides, the development of hypertension over 14 years was evaluated. NEDD4L single nucleotide polymorphism (SNP) rs74408486 was shown to be significantly associated with systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) responses to low-salt diet, while SNPs rs292449 and rs2288775 were significantly associated with pulse pressure (PP) response to high-salt diet. In addition, SNP rs4149605, rs73450471, and rs482805 were significantly associated with the longitudinal changes in SBP, DBP, MAP, or PP at 14 years of follow-up. SNP rs292449 was significantly associated with hypertension incidence over the 14-year follow-up. Finally, this gene-based analysis found that NEDD4L was significantly associated with longitudinal BP changes and the incidence of hypertension over the 14-year follow-up. This study indicated that gene polymorphism in NEDD4L serve an important function in salt sensitivity, longitudinal BP change and development of hypertension in the Chinese population.

Associations of plasma uromodulin and genetic variants with blood pressure responses to dietary salt interventions

Uromodulin, also named Tamm Horsfall protein, have been associated with renal function and sodium homeostasis regulation. The authors sought to examine the effects of salt intake on plasma and urinary uromodulin levels and the association of its genetic variants with salt sensitivity in Chinese adults. Eighty patients from our natural population cohort were maintained sequentially either on a usual diet for 3 days, a low-salt diet (3.0 g) for 7 days, and a high-salt diet (18.0 g) for an additional 7 days. In addition, the authors studied 514 patients of the Baoji Salt-Sensitive Study, recruited from 124 families who received the same salt intake intervention, and investigated the association of genetic variations in uromodulin gene with salt sensitivity. Plasma uromodulin levels were significantly lower on a high-salt diet than on a baseline diet (28.3 ± 4.5 vs. 54.9 ± 8.8 ng/ml). Daily urinary excretions of uromodulin were significantly decreased on a high-salt diet than on a low-salt diet (28.7 ± 6.7 vs. 157.2 ± 21.7 ng/ml). SNPs rs7193058 and rs4997081 were associated with the diastolic blood pressure (DBP), mean arterial pressure (MAP) responses to the high-salt diet. In addition, several SNPs in the uromodulin gene were significantly associated with pulse pressure (PP) response to the low-salt intervention. This study shows that dietary salt intake affects plasma and urinary uromodulin levels and that uromodulin may play a role in the pathophysiological process of salt sensitivity in the Chinese populations.

High Salt Diet Impacts the Risk of Sarcopenia Associated with Reduction of Skeletal Muscle Performance in the Japanese Population

The World Health Organization has recommended 5 g/day as dietary reference intakes for salt. In Japan, the averages for men and women were 11.0 g/day and 9.3 g/day, respectively. Recently, it was reported that amounts of sodium accumulation in skeletal muscles of older people were significantly higher than those in younger people. The purpose of this study was to investigate whether the risk of sarcopenia with decreased muscle mass and strength was related to the amount of salt intake. In addition, we investigated its involvement with renalase. Four groups based on age and salt intake ("younger low-salt," "younger high-salt," "older low-salt," and "older high-salt") were compared. Stratifying by age category, body fat percentage significantly increased in high-salt groups in both younger and older people. Handgrip strength/body weight and chair rise tests of the older high-salt group showed significant reduction compared to the older low-salt group. However, there was no significant difference in renalase concentrations in plasma. The results suggest that high-salt intake may lead to fat accumulation and muscle weakness associated with sarcopenia. Therefore, efforts to reduce salt intake may prevent sarcopenia.

Risk factors for subclinical renal damage and its progression: Hanzhong Adolescent Hypertension Study

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a global public health problem, including in China. The aim of this study was to identify the risk factors for the development and progression of subclinical renal disease (SRD) in a Chinese population. We also examined whether the impact of the risk factors on SRD changed over time.

SUBJECTS/METHODS

To identify the predictors of SRD, we performed a cross-sectional study of the 2432 subjects in our Hanzhong Adolescent Hypertension Cohort. A subgroup of 202 subjects was further analyzed over a 12-year period from 2005 to 2017 to determine the risk factors for the development and progression of SRD.

RESULTS

In cross-sectional analysis, elevated blood pressure, male gender, diabetes, body mass index, and triglyceride were independently associated with a higher risk of SRD. In longitudinal analysis, an increase in total cholesterol over a 4-year period and an increase in serum triglyceride over a 12-year period were independently associated with progression of albuminuria. Finally, increases in both total cholesterol and serum uric acid over a 4-year follow-up showed an independent association with a modest reduction in estimated glomerular filtration rate (eGFR).

CONCLUSIONS

In this study of a Chinese cohort, we show several metabolic abnormalities as independent risk factors for subclinical renal disease in a Chinese cohort. In addition, we demonstrate that the effects of total cholesterol, triglycerides and uric acid on the development and progression of albuminuria or the decline in eGFR vary at different points of follow-up. These findings highlight the importance of early detection of metabolic abnormalities to prevent SRD.

Association of Uric Acid in Serum and Urine with Arterial Stiffness: Hanzhong Adolescent Hypertension Study

Background

Hyperuricemia has long been associated with increased cardiovascular risk, and arterial stiffness is proposed as a mediator. The present study is aimed at examining the associations of uric acid (UA) in blood and urine with arterial stiffness in a Chinese cohort.

Methods

A total of 2296 participants (mean age: 43.0 years) from our previously established cohort of Hanzhong Adolescent Hypertension Study were included. The participants were classified as subjects with or without arterial stiffness, which was defined as brachial-ankle pulse wave velocity (baPWV) ≥ 1400 cm/s and/or carotid intima-media thickness (CIMT) ≥ 0.9 mm. Multivariate regression analyses were used to examine the relationship between serum and urinary UA and the risk of arterial stiffness after adjusting for age, gender, systolic blood pressure, fasting glucose, BMI, heart rate, total cholesterol, and triglycerides.

Results

baPWV was positively correlated with urinary uric acid/creatinine ratio (uUA/Cre) (β = 0.061, P < 0.001), while CIMT was correlated with uUA/Cre (β = 0.085, P < 0.001) and fractional excretion of uric acid (FEUA) (β = 0.044, P = 0.033) in all subjects. In addition, uUA/Cre was significantly associated with the risk of high baPWV [1.032 (1.019-1.045)] and arterial stiffness [1.028 (1.016-1.040)].

Conclusion

Our study showed that urinary UA excretion was significantly associated with the risk of arterial stiffness in Chinese adults. These findings suggest that UA, especially urinary UA, may be used as a simple, noninvasive marker for early detection of arterial stiffness in otherwise healthy subjects.

Predictors for progressions of brachial-ankle pulse wave velocity and carotid intima-media thickness over a 12-year follow-up: Hanzhong Adolescent Hypertension Study

Objective:

Atherosclerotic diseases are the leading cause of death worldwide. This study aimed to investigate the predictors of brachial–ankle pulse wave velocity (baPWV) and carotid intima–media thickness (CIMT) progression in a Chinese cohort over a 12-year follow-up period and to determine whether these predictors differ by follow-up time.

Methods:

A total of 202 participants were recruited from a previously established cohort in Shaanxi Province, China. Both baPWV and CIMT were measured in 2013 and 2017. Multivariable regression was used to determine the predictors of CIMT and baPWV progression.

Results:

Men had higher CIMT and baPWV and a higher rate of CIMT progression during two follow-ups than women. A 4-year change in SBP was associated with baPWV progression, whereas a 12-year change in DBP was associated with baPWV progression. The increased progression of baPWV presented a linear trend when subgrouping all the participants according to SBP and DBP changes over 4 and 12 years, respectively. In addition, heart rate (HR) change over 4 and 12 years was consistently associated with CIMT progression, and a linear trend was also seen when subgrouping the population.

Conclusion:

Our study demonstrated that SBP and DBP contributed differently in different stages to the progression of arterial stiffness in this Chinese cohort. Moreover, HR was consistently involved in the increased progression of CIMT in all periods. These findings underline the importance of early detection and control of blood pressure and resting HR for the prevention of arterial stiffness progression.

Joint Association of Serum Homocysteine and High-Sensitivity C-Reactive Protein with Arterial Stiffness in Chinese Population: A 12-Year Longitudinal Study

BACKGROUND

Elevated plasma homocysteine (Hcy) and high-sensitivity C-reactive protein (hsCRP) levels are independent risk factors for cardiovascular diseases. However, it is unclear whether the coexistence of these conditions accelerates the risk of arterial stiffness. Our study aimed to evaluate the association of combined Hcy and hsCRP with arterial stiffness in Chinese middle-aged adults.

MATERIAL/METHODS

We conducted a 12-year longitudinal study in 220 individuals in Hanzhong, China, from 2005 to 2017. The average age at follow-up was 41.83 ± 3.10 years. Demographic information, medical history, anthropometric measurements, and blood pressure as well as urine and fasting blood samples, including Hcy, hsCRP, and brachial-ankle pulse wave velocity (baPWV) were measured and analyzed.

RESULTS

BaPWV levels showed a linear growth trend with the increasing of hsCRP (p for trend <0.01). The ORs in the highest quartile compared to the lowest quartile were 1.985 (95% CI 0.776-5.077; p = 0.152) and 3.960 (95% CI 1.468-10.684; p= 0.007) for Hcy and hsCRP, respectively. When Hcy and hsCRP were combined, subjects in both the highest quartile of Hcy and hsCRP (Hcy ≥15.50 μmol/L and hsCRP ≥0.82 μmol/L) had a 12.68-fold increased risk of developing arterial stiffness at the 12-year follow-up compared to those in the lowest quartile of Hcy and hsCRP (Hcy ≤9.91 μmol/L and hsCRP ≤0.19 μmol/L) after adjusting for potential confounders.

CONCLUSIONS

The present study demonstrated that the combination of elevated serum Hcy and hsCRP may contribute to an increased risk of arterial stiffness.

Association between urinary sodium excretion and uric acid, and its interaction on the risk of prehypertension among Chinese young adults

High uric acid (UA) level and high salt intake are reportedly associated with cardiovascular disease. This study investigated the association between UA and urinary sodium excretion, as well as its interaction on the risk of prehypertension. A total of 1869 participants without hypertension were recruited from a previously established cohort in Shaanxi Province, China. The participants were classified as normotensive or prehypertensive on the basis of their blood pressure. Increasing quartiles of sodium excretion were associated with high urinary UA/creatinine levels in prehypertensive participants. Estimated sodium excretion positively correlated with urinary UA/creatinine excretions in the prehypertensive group. In addition, the multivariate-adjusted odds ratios for prehypertension compared with normotension were 1.68 (1.27–2.22) for sodium excretion and 1.71 (1.21–2.42) for serum UA. Increasing sodium excretion and serum UA were associated with higher risk of prehypertension. Compared with the lowest quartiles, the highest sodium excretion and serum UA quartiles entailed 3.48 times greater risk of prehypertension. Sodium excretion is associated with urinary UA excretion in prehypertensive participants. The present study shows that high levels of salt intake and serum UA simultaneously are associated with a higher risk of prehypertension.

Effect of Salt Intervention on Serum Levels of Fibroblast Growth Factor 23 (FGF23) in Chinese Adults: An Intervention Study

Background

Fibroblast growth factor 23 (FGF23), a prominent regulator of phosphate and calcium metabolism, regulates sodium excretion in distal tubules through sodium-chloride cotransporter. This effect regulates blood pressure. Salt intake exerts effects on serum levels of FGF23 in mice. The aim of this study was to explore whether salt intervention affects serum concentrations of FGF23 in Chinese adults.

Material/Methods

We enrolled 44 participants from Lantian, a rural community of Shaanxi, China. All participants were maintained on a three-day normal diet, which was sequentially followed by a seven-day low-Na⁺ diet and seven-day high-Na⁺ diet. Serum FGF23 concentrations were assessed by ELISA.

Results

Serum FGF23 concentrations elevated during low-salt diet compared with levels at baseline (66.20±44.21 pg/mL versus 86.77±53.74 pg/mL, p<0.05) and remarkably decreased when changed from low to high salt intake (86.77±53.74 pg/mL versus 49.26±42.67 pg/mL, p<0.001). Responses of FGF23 to salt intervention were more prominent in normotensive, older than 60 years, BMI <24 kg/m² and salt-resistant individuals. Furthermore, a significant inverse correlation was observed between 24-hour urinary sodium and serum concentrations of FGF23 after adjusting age, sex, BMI and hypertension status.

Conclusions

Dietary salt intervention significantly affects serum FGF23 in Chinese adults.

Effect of Salt Intake on Plasma and Urinary Uric Acid Levels in Chinese Adults: An Interventional Trial

Uric acid (UA) has been proposed as an important risk factor for cardiovascular and renal morbidity. We conducted an interventional trial to assess effects of altered salt intake on plasma and urine UA levels and the relationship between UA levels and salt sensitivity in humans. Ninety subjects (18–65 years old) were sequentially maintained on a normal diet for 3 days at baseline, a low-salt diet for 7 days (3.0 g/day, NaCl), and a high-salt diet for an additional 7 days (18.0 g/day of NaCl). Plasma UA levels significantly increased from baseline to low-salt diet and decreased from low-salt to high-salt diet. By contrast, daily urinary levels of UA significantly decreased from baseline to low-salt diet and increased from low-salt to high-salt diet. The 24 h urinary sodium excretions showed inverse correlation with plasma UA and positive correlation with urinary UA excretions. Additionally, salt-sensitive subjects presented significantly higher plasma UA changes in comparison to salt-resistant subjects, and a negative correlation was observed between degree of salt sensitivity and plasma UA difference. The present study indicates that variations in dietary salt intake affect plasma and urine UA levels, and plasma UA may be involved in pathophysiological process of salt sensitivity.

The Science of Salt: A Systematic Review of Quality Clinical Salt Outcome Studies June 2014 to May 2015

Studies identified from an updated systematic review (from June 2014 to May 2015) on the impact of dietary salt intake on clinical and population health are reviewed. Randomized controlled trials, cohort studies, and meta-analyses of these study types on the effect of sodium intake on blood pressure, or any substantive adverse health outcomes were identified from MEDLINE searches and quality indicators were used to select studies that were relevant to clinical and public health. From 6920 studies identified in the literature search, 144 studies were selected for review, of which only three (n=233,680) met inclusion criteria. Between them, the three studies demonstrated a harmful association between excess dietary salt and all-cause mortality, noncardiovascular and cardiovascular disease mortality, and headache. None of the included studies found harm from lowering dietary salt. The findings of this systematic review are consistent with the large body of research supportive of efforts to reduce population salt intake and congruent with our last annual review from June 2013 to May 2014.

Elevation of Fasting Ghrelin in Healthy Human Subjects Consuming a High-Salt Diet: A Novel Mechanism of Obesity?

Overweight/obesity is a chronic disease that carries an increased risk of hypertension, diabetes mellitus, and premature death. Several epidemiological studies have demonstrated a clear relationship between salt intake and obesity, but the pathophysiologic mechanisms remain unknown. We hypothesized that ghrelin, which regulates appetite, food intake, and fat deposition, becomes elevated when one consumes a high-salt diet, contributing to the progression of obesity. We, therefore, investigated fasting ghrelin concentrations during a high-salt diet. Thirty-eight non-obese and normotensive subjects (aged 25 to 50 years) were selected from a rural community in Northern China. They were sequentially maintained on a normal diet for three days at baseline, a low-salt diet for seven days (3 g/day, NaCl), then a high-salt diet for seven days (18 g/day). The concentration of plasma ghrelin was measured using an immunoenzyme method (ELISA). High-salt intake significantly increased fasting ghrelin levels, which were higher during the high-salt diet (320.7 ± 30.6 pg/mL) than during the low-salt diet (172.9 ± 8.9 pg/mL). The comparison of ghrelin levels between the different salt diets was statistically-significantly different (p < 0.01). A positive correlation between 24-h urinary sodium excretion and fasting ghrelin levels was demonstrated. Our data indicate that a high-salt diet elevates fasting ghrelin in healthy human subjects, which may be a novel underlying mechanism of obesity.

[The history of renalase from amine oxidase to a a-NAD(P)H-oxidase/anomerase]

Renalase is a recently discovered secretory protein, which plays a certain (still poorly understood) role in regulation of blood pressure. The review summarizes own and literature data accumulated since the first publication on relanase (2005). Initial reports on FAD-dependent amine oxidase activity of this protein were not confirmed in independent experiments performed in different laboratories. In addition, proposed amine oxidase activity of circulating extracellular renalase requires the presence of FAD, which has not been detected either in blood or urinary renalase. Moreover, renalase excreted into urine lacks its N-terminal peptide, which is ultimately needed for accommodation of the FAD cofactor. Results of the Aliverti's group on NAD(P)H binding by renalase and weak diaphorase activity of this protein stimulated further studies of renalase as NAD(P)H oxidase catalyzing reaction of catecholamine co-oxidation. However, physiological importance of such extracellular catecholamine-metabolizing activity (demonstrated in one laboratory and not detected in another laboratory) remains unclear due to existence of much more active enzymatic systems (e.g. neutrophil NAD(P)H oxidase, xanthine oxidase/xanthine) in circulation, which can perform such co-oxidation reactions. Recently a-NAD(P)H oxidase/anomerase activity of renalase, which also pomotes oxidative conversion of b-NADH isomers inhibiting activity of NAD-dependent dehydrogenases, has been described. However, its possible contribution to the antihypertensive effect of renalase remains unclear. Thus, the antihypertensive effect of renalase still remains a phenomenon with unclear biochemical mechanim(s) and functions of intracellular and extracellular (circulating) renalases obviously differ.

Bacterial Renalase: Structure and Kinetics of an Enzyme with 2- and 6-Dihydro-β-NAD(P) Oxidase Activity from Pseudomonas phaseolicola

Despite a lack of convincing in vitro evidence and a number of sound refutations, it is widely accepted that renalase is an enzyme unique to animals that catalyzes the oxidative degradation of catecholamines in blood in order to lower vascular tone. Very recently, we identified isomers of β-NAD(P)H as substrates for renalase (Beaupre, B. A. et al. (2015) Biochemistry, 54, 795-806). These molecules carry the hydride equivalent on the 2 or 6 position of the nicotinamide base and presumably arise in nonspecific redox reactions of nicotinamide dinucleotides. Renalase serves to rapidly oxidize these isomers to form β-NAD(P)⁺ and then pass the electrons to dioxygen, forming H₂O₂. We have also shown that these substrate molecules are highly inhibitory to dehydrogenase enzymes and thus have proposed an intracellular metabolic role for this enzyme. Here, we identify a renalase from an organism without a circulatory system. This bacterial form of renalase has the same substrate specificity profile as that of human renalase but, in terms of binding constant (K(d)), shows a marked preference for substrates derived from β-NAD⁺. 2-dihydroNAD(P) substrates reduce the enzyme with rate constants (k(red)) that greatly exceed those for 6-dihydroNAD(P) substrates. Taken together, k(red)/K(d) values indicate a minimum 20-fold preference for 2DHNAD. We also offer the first structures of a renalase in complex with catalytically relevant ligands β-NAD⁺ and β-NADH (the latter being an analogue of the substrate(s)). These structures show potential electrostatic repulsion interactions with the product and a unique binding orientation for the substrate nicotinamide base that is consistent with the identified activity.

Renalase does not catalyze the oxidation of catecholamines

It is widely accepted that the function of human renalase is to oxidize catecholamines in blood. However, this belief is based on experiments that did not account for slow, facile catecholamine autoxidation reactions. Recent evidence has shown that renalase has substrates with which it reacts rapidly. The reaction catalyzed defines renalase as an oxidase, one that harvests two electrons from either 2-dihydroNAD(P) or 6-dihydroNAD(P) to form β-NAD(P)(+) and hydrogen peroxide. The apparent metabolic purpose of such a reaction is to avoid inhibition of primary dehydrogenase enzymes by these β-NAD(P)H isomers. This article demonstrates that renalase does not catalyze the oxidation of neurotransmitter catecholamines. Using high-performance liquid chromatography we show that there is no evidence of consumption of epinephrine by renalase. Using time-dependent spectrophotometry we show that the renalase FAD cofactor spectrum is unresponsive to added catecholamines, that adrenochromes are not observed to accumulate in the presence of renalase and that the kinetics of single turnover reactions with 6-dihydroNAD are unaltered by the addition of catecholamines. Lastly we show using an oxygen electrode assay that plasma renalase activity is below the level of detection and only when exogenous renalase and 6-dihydroNAD are added can dioxygen be observed to be consumed.

The catalytic function of renalase: A decade of phantoms

Ten years after the initial identification of human renalase the first genuinely catalytic substrates have been identified. Throughout the prior decade a consensus belief that renalase is produced predominantly by the kidney and catalytically oxidizes catecholamines in order to lower blood pressure and slow the heart has prevailed. This belief was, however, based on fundamentally flawed scientific observations that did not include control reactions to account for the well-known autoxidation of catecholamines in oxygenated solutions. Nonetheless, the initial claims have served as the kernel for a rapidly expanding body of research largely predicated on the belief that catecholamines are substrates for this enzyme. The proliferation of scientific studies pertaining to renalase as a hormone has proceeded unabated despite well-reasoned expressions of dissent that have indicated the deficiencies of the initial observations and other inconsistencies. Our group has very recently identified isomeric forms of β-NAD(P)H as substrates for renalase. These substrates arise from non-specific reduction of β-NAD(P)(+) that forms β-4-dihydroNAD(P) (β-NAD(P)H), β-2-dihydroNAD(P) and β-6-dihydroNAD(P); the latter two being substrates for renalase. Renalase oxidizes these substrates with rate constants that are up to 10(4)-fold faster than any claimed for catecholamines. The electrons harvested are delivered to dioxygen via the enzyme's FAD cofactor forming both H2O2 and β-NAD(P)(+) as products. It would appear that the metabolic purpose of this chemistry is to alleviate the inhibitory effect of β-2-dihydroNAD(P) and β-6-dihydroNAD(P) on primary metabolism dehydrogenase enzymes. The identification of this genuinely catalytic activity for renalase calls for re-evaluation of much of the research of this enzyme, in which definitive links between renalase catecholamine consumption and physiological responses were reported. This article is part of a Special Issue entitled: Physiological enzymology and protein functions.

Effect of Salt Intake and Potassium Supplementation on Urinary Renalase and Serum Dopamine Levels in Chinese Adults

Objective: The aim of our study was to assess the effects of altered salt and potassium intake on urinary renalase and serum dopamine levels in humans. Methods: Forty-two subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day of NaCl), a high-salt diet for an additional 7 days (18.0 g/day of NaCl), and a high-salt diet with potassium supplementation for a final 7 days (18.0 g/day of NaCl + 4.5 g/day of KCl). Results: Urinary renalase excretions were significantly higher during the high-salt diet intervention than during the low-salt diet. During high-potassium intake, urinary renalase excretions were not significantly different from the high-salt diet, whereas they were significantly higher than the low-salt levels. Serum dopamine levels exhibited similar trends across the interventions. Additionally, a significant positive relationship was observed between the urine renalase and serum dopamine among the different dietary interventions. Also, 24-hour urinary sodium excretion positively correlated with urine renalase and serum dopamine in the whole population. Conclusions: The present study indicates that dietary salt intake and potassium supplementation increase urinary renalase and serum dopamine levels in Chinese subjects.