The new visceral adiposity index outperforms traditional obesity indices as a predictor of subclinical renal damage in Chinese individuals: a cross-sectional study.

BACKGROUND: The new visceral adiposity index (NVAI) was superior to previous obesity indices in predicting cardiovascular diseases among Asians. Nevertheless, the utility of the NVAI for predicting chronic kidney disease is still unclear. The objective of this research was to explore the relationship between the NVAI and subclinical renal damage (SRD) and to investigate whether the NVAI outperforms other common obesity indices in predicting SRD in the Chinese population. METHODS: Participants in this cross-sectional study were from the Hanzhong Adolescent Hypertension Cohort. The NVAI and seven other common obesity indices were calculated, including body mass index, waist circumference, lipid accumulation product, visceral adiposity index, Chinese visceral adiposity index, a body shape index and metabolic score for visceral fat. Logistic regression models revealed the association between NVAI and SRD. The odds ratio (OR) and the 95% confidence interval (CI) were calculated to show the association between the two variables. The predictive power of eight obesity indices for SRD was evaluated through the receiver operating characteristic curve and area under the curve (AUC). In addition, the net reclassification index (NRI) and integrated discrimination improvement (IDI) were also applied to compare the incremental predictive value for SRD of different obesity indices. RESULTS: The median age of the 2358 subjects was 42.00 years. Across NVAI tertiles, the prevalence of SRD was 7.25%, 11.21%, and 21.60%, respectively. After adjusting for confounders, a high level of NVAI remained a risk factor for SRD. The ORs of the middle and top NVAI tertiles for SRD were 1.920 (95% CI: 1.322, 2.787) and 4.129 (95% CI: 2.750, 6.202), respectively. The AUC of the NVAI was 0.666 (95% CI: 0.647, 0.685), which was significantly larger than the AUC of any of the other obesity indicators. Moreover, the NRI and IDI were significantly improved when NVAI was added to the basic model for predicting SRD. Among eight obesity indices, NVAI had the highest NRI (0.392; 95% CI: 0.280, 0.503), and its IDI (0.021; 95% CI: 0.014, 0.027) was second only to that of the body mass index (0.023; 95% CI: 0.014, 0.032). CONCLUSIONS: NVAI is independently and positively associated with SRD. Among the eight obesity indices, the NVAI shows the strongest predictive power for SRD in the Chinese population. The NVAI may be useful as an effective warning indicator of chronic kidney disease in Chinese adults.

Lipid goal attainment in diabetes mellitus patients after acute coronary syndrome: a subanalysis of Dyslipidemia International Study II-China.

BACKGROUND: Lipid management with a low-density lipoprotein cholesterol (LDL-C) goal of < 1.4 mmol/L is recommended for patients with acute coronary syndrome (ACS) and diabetes mellitus (DM) due to a high risk for adverse cardiovascular events. This study evaluated the lipid-lowering treatment (LLT) pattern and the LDL-C goal attainment rate in this special population. METHODS: DM patients were screened from the observational Dyslipidemia International Study II-China study which assessed LDL-C goal attainment in Chinese ACS patients. The baseline characteristics between the LLT and no pre-LLT groups were compared. The proportions of patients obtaining LDL-C goal at admission and at 6-months, the difference from the goal, and the pattern of the LLT regimen were analyzed. RESULTS: Totally 252 eligible patients were included, with 28.6% taking LLT at admission. Patients in the LLT group were older, had a lower percentage of myocardial infarction, and had decreased levels of LDL-C and total cholesterol compared to those in the no pre-LLT group at baseline. The overall LDL-C goal attainment rate was 7.5% at admission and increased to 30.2% at 6 months. The mean difference between the actual LDL-C value and LDL-C goal value dropped from 1.27 mmol/L at baseline to 0.80 mmol/L at 6 months. At 6 months, 91.4% of the patients received statin monotherapy, and only 6.9% received a combination of statin and ezetimibe. The atorvastatin-equivalent daily statin dosage was moderate during the study period. CONCLUSION: The low rate of lipid goal attainment observed was in line with the outcomes of other DYSIS-China studies.

Overexpression of FGF19 alleviates hypoxia/reoxygenation-induced injury of cardiomyocytes by regulating GSK-3ß/Nrf2/ARE signaling.

Fibroblast growth factor 19 (FGF19) has emerged as a crucial cytoprotective regulator that antagonizes cell apoptosis and oxidative stress under adverse conditions. However, whether FGF19 plays a cytoprotective role in preventing myocardial damage during myocardial ischemia/reperfusion injury remains unknown. In this study, we aimed to investigate the potential role of FGF19 in regulating hypoxia/reoxygenation (H/R)-induced injury of cardiomyocytes in vitro. We found that FGF19 expression was upregulated in response to H/R treatment in cardiomyocytes. Silencing of FGF19 significantly inhibited viability and increased apoptosis and reactive oxygen species (ROS) generation in cardiomyocytes with H/R treatment. In contrast, overexpression of FGF19 improved viability and inhibited apoptosis and ROS generation induced by H/R treatment, showing a cardioprotective effect. Moreover, we found that FGF19 regulated the phosphorylation of glycogen synthase kinase-3ß (GSK-3ß) and the nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2). In addition, FGF19 promoted the activation of Nrf2-mediated antioxidant response element (ARE) antioxidant signaling. Notably, treatment with a GSK-3ß inhibitor significantly abrogated the adverse effects of FGF19 silencing on H/R-induced injury, whereas silencing of Nrf2 partially blocked the FGF19-mediated cardioprotective effect against H/R-induced injury in cardiomyocytes. Taken together, our findings demonstrate that FGF19 alleviates H/R-induced apoptosis and oxidative stress in cardiomyocytes by inhibiting GSK-3ß activity and promoting the activation of Nrf2/ARE signaling, providing a potential therapeutic target for prevention of myocardial injury.

Genetic variants in renalase and blood pressure responses to dietary salt and potassium interventions: a family-based association study.

BACKGROUND/AIMS: Renalase (gene name RNLS), a recently discovered enzyme with monoamine oxidase activity, is implicated in the degradation of catecholamines. Recent studies indicate that common variations in the gene with RNLS are associated with hypertension. The aim of this study was to examine the association between genetic variants in RNLS and blood pressure (BP) responses to strict dietary interventions of salt and potassium intake. METHODS: A total of 334 subjects from 124 families were selected and sequentially maintained on a low-salt diet for 7 days (3.0 g/day, NaCl), then a high-salt diet for 7 days (18.0 g/day, NaCl), high-salt diet with potassium supplementation for another 7 days (4.5 g/day, KCl). RESULTS: SNPs rs919115 and rs792205 of the RNLS gene were significantly associated with diastolic BP (DBP) and mean arterial pressure (MAP) responses to high-salt intervention. In addition, rs12356177 was significantly associated with systolic BP (SBP) and DBP responses to low-salt diet, and SBP, DBP or MAP during the high-salt intervention. Unfortunately, no associations for the 7 RNLS SNPs with BP response to high-salt diet with potassium supplementation reached nominal statistical significance. CONCLUSIONS: This family-based study indicates that genetic variants in the RNLS gene are significantly associated with BP responses to dietary salt intake.

Lack of family-based association between common variations in WNK1 and blood pressure level.

BACKGROUND: WNK1 (With No-lysine Kinase 1) modulates numerous sodium transport-related ion channels involved in regulation of blood pressure. Several studies have indicated associations between the common variants of the WNK1 gene and hypertension or blood pressure levels. However, little data exists on Asian populations and normotensive or pre-hypertensive subjects. Our aim was to detect whether the common variations in the WNK1 gene are potential contributors to individual variations in blood pressure in a family-based sample. MATERIAL AND METHODS: 525 individuals from 116 families were selected from a rural community of Northern China. Five single-nucleotide polymorphisms were selected from the WNK1 gene. Single-marker and haplotype analyses were conducted using the Family-Based Association Test program. RESULTS: Regretful, no associations for the 5 WNK1 SNPs and the constructed haplotype blocks of WNK1 with blood pressure level reached nominal statistical significance. CONCLUSIONS: We conclude that although multiple candidate genes are involved in development of hypertension, the genetic polymorphism in WNK1 is not a major contributor to the observed variability in blood pressure and familial clustering risk of hypertension.

High-salt intake suppressed microRNA-133a expression in Dahl SS rat myocardium.

Salt-sensitive individuals show earlier and more serious cardiac damage than nonsalt-sensitive ones. Some studies have suggested that microRNA-133a could reduce cardiac hypertrophy and myocardial fibrosis. The current study aims to investigate the different functions of high-salt intake on salt-sensitive (SS) rats and Sprague-Dawley (SD) rats and the involvement of microRNA-133a in these roles. After high-salt intervention, the left ventricular mass (LVW) and left ventricular mass index (LVMI) of the salt-sensitive high salt (SHS) group were obviously higher than those of the salt-sensitive low salt (SLS) group. However, the difference between the Sprague-Dawley high salt (DHS) group and the Sprague-Dawley low salt (DLS) group was not significant. Compared with SLS group, collagen I and connective tissue growth factor (CTGF) in the heart of SHS group were significantly higher, whereas no statistical difference was observed between the DHS group and the DLS group. Compared with low-salt diet, microRNA-133a in the heart of both strains were significantly decreased, but that in the SHS group decreased more significantly. These results suggest that high salt intervention could down-regulate the expression of myocardial microRNA-133a, which may be one of the mechanisms involved in myocardial fibrosis in salt-sensitive hypertension.

The association of long-term trajectories of BMI, its variability, and metabolic syndrome: a 30-year prospective cohort study.

Background: Limited data exists on how early-life weight changes relate to metabolic syndrome (MetS) risk in midlife. This study examines the association between long-term trajectories of body mass index (BMI), its variability, and MetS risk in Chinese individuals. Methods: In the Hanzhong Adolescent Hypertension study (March 10, 1987-June 3, 2017), 1824 participants with at least five BMI measurements from 1987 to 2017 were included. Using group-based trajectory modeling, different BMI trajectories were identified. BMI variability was assessed through standard deviation (SD), variability independent of the mean (VIM), and average real variability (ARV). Logistic regression analyzed the relationship between BMI trajectory, BMI variability, and MetS occurrence in midlife (URL: https://www.clinicaltrials.gov; Unique identifier: NCT02734472). Findings: BMI trajectories were categorized as low-increasing (34.4%), moderate-increasing (51.8%), and high-increasing (13.8%). Compared to the low-increasing group, the odds ratios (ORs) [95% CIs] for MetS were significantly higher in moderate (4.27 [2.63-6.91]) and high-increasing groups (13.11 [6.30-27.31]) in fully adjusted models. Additionally, higher BMI variabilities were associated with increased MetS odds (ORs for SDBMI, VIMBMI, and ARVBMI: 2.30 [2.02-2.62], 1.22 [1.19-1.26], and 4.29 [3.38-5.45]). Furthermore, BMI trajectories from childhood to adolescence were predictive of midlife MetS, with ORs in moderate (1.49 [1.00-2.23]) and high-increasing groups (2.45 [1.22-4.91]). Lastly, elevated BMI variability in this period was also linked to higher MetS odds (ORs for SDBMI, VIMBMI, and ARVBMI: 1.24 [1.08-1.42], 1.00 [1.00-1.01], and 1.21 [1.05-1.38]). Interpretation: Our study suggests that both early-life BMI trajectories and BMI variability could be predictive of incident MetS in midlife. Funding: This work was supported by the National Natural Science Foundation of China No. 82070437 (J.-J.M.), the Clinical Research Award of the First Affiliated Hospital of Xi'an Jiaotong University of China (No. XJTU1AF-CRF-2022-002, XJTU1AF2021CRF-021, and XJTU1AF-CRF-2023-004), the Key R&D Projects in Shaanxi Province (Grant No. 2023-ZDLSF-50), the Chinese Academy of Medical Sciences & Peking Union Medical College (2017-CXGC03-2), and the International Joint Research Centre for Cardiovascular Precision Medicine of Shaanxi Province (2020GHJD-14).

Associations of E-proteinoid 3 receptor genetic polymorphisms with salt sensitivity, longitudinal blood pressure changes, and hypertension incidence in Chinese adults.

The E-proteinoid 3 receptor (PTGER3), a member of the prostaglandin E2 (PGE2) subtype receptor, belongs to the G-protein-coupled superfamily of receptors. Animal studies have demonstrated its involvement in salt sensitivity by regulating sodium reabsorption. This study aimed to investigate the association between genetic variants of PTGER3 and salt sensitivity, longitudinal blood pressure (BP) changes, and the incidence of hypertension in Chinese adults. A chronic salt intake intervention was conducted involving 514 adults from 124 families in the 2004 Baoji Salt-Sensitivity Study Cohort in northern China. These participants followed a 3-day regular baseline diet, followed by a 7-day low-salt diet (3.0 g/d) and a 7-day high-salt diet (18 g/d), and were subsequently followed for 14 years. The findings revealed a significant relationship between the single nucleotide polymorphism (SNP) rs17482751 of PTGER3 and diastolic blood pressure (DBP) response to high salt intervention. Additionally, SNPs rs11209733, rs3765894, and rs2268062 were significantly associated with longitudinal changes in systolic blood pressure (SBP), DBP, and mean arterial pressure (MAP) during the 14-year follow-up period. SNP rs6424414 was significantly associated with longitudinal changes in DBP over 14 years. Finally, SNP rs17482751 showed a significant correlation with the incidence of hypertension over 14 years. These results emphasize the significant role of PTGER3 gene polymorphism in salt sensitivity, longitudinal BP changes, and the development of hypertension in the Chinese population.

Effects of salt loading and potassium supplement on the circadian blood pressure profile in salt-sensitive Chinese patients.

BACKGROUND AND OBJECTIVE: Salt-sensitive (SS) patients more frequently showed a nondipper blood pressure pattern and were associated with more serious target organ damage than non-SS patients. We aimed to investigate whether potassium supplement can improve the blunted nocturnal blood pressure fall in SS patients exposed to a high-salt diet. PATIENTS AND METHODS: Approximately 49 normotensive and mildly hypertensive Chinese patients received a study protocol of a 3 days of baseline examination, 7 days of a low-salt diet (3 g NaCl/day), 7 days of a high-salt diet (18 g NaCl/day), and 7 days of a high-salt diet with a potassium supplement (18 g NaCl and 4.5 g KCl/day). The 24 h ambulatory blood pressure was determined at the end of each period. RESULTS: A total of 14 patients were classified as SS according to the at least 10% increase in their 24-h mean arterial pressure after high-salt loading. The night-to-day blood pressure ratio was significantly higher in SS patients than in non-SS patients during the high-salt loading period (systolic 0.96±0.01 vs. 0.89±0.01, P<0.01; diastolic 0.96±0.01 vs. 0.92±0.01, P<0.05). Compared with the high-salt loading period, the night-to-day blood pressure ratio was significantly reversed by potassium supplement in SS patients (systolic 0.91±0.01 vs. 0.96±0.01, P<0.05; diastolic 0.91±0.01 vs. 0.96±0.01, P<0.05). CONCLUSION: Potassium supplement can improve the blunted nocturnal blood pressure fall in SS patients exposed to a high-salt diet, but the related mechanism needs to be studied further.

Associations of risk factors in childhood with arterial stiffness 26 years later: the Hanzhong adolescent hypertension cohort.

OBJECTIVE: The relationship between childhood risk factors and long-term arterial stiffness was explored. METHODS: A baseline survey was conducted in 4623 school children aged 6-15 years in rural areas of Hanzhong city, Shaanxi, in 1987. According to three independent measurements of SBP in 1987, 1989, and 1992, cases of the same age and sex with continuous SBP at least 75 percentile were classified as the high-blood pressure (BP) group, whereas those with SBP less than 50 percentile were classified as the normal-BP group. The cohort was followed up again after 26 years (in 2013). Blood biochemistry indexes, including fasting glucose, uric acid, and blood lipid, were measured. Brachial-ankle pulse wave velocity (baPWV) was recorded by noninvasive automatic waveform analyzer. RESULTS: Follow-up rate was 71.6%. The high-BP group had a higher incidence of hypertension (39.5 vs. 18.0%, P < 0.01) and baPWV (1337.2 ±â€Š198.3 vs. 1271.7 ±â€Š204.3 cm/s, P = 0.028) than the normal-BP group during the follow-up period. Positive correlation was found during follow-up between baPWV and childhood SBP, as well as SBP, DBP, BMI, heart rate, total cholesterol, low-density lipoprotein cholesterol, triacylglycerol, fasting glucose, and uric acid in adulthood (all P < 0.05). Results from stepwise multivariate regression analysis showed that men, family history of hypertension, SBP at both baseline and follow-up, fasting glucose, and uric acid in adulthood are independent impact factors of baPWV in adults. CONCLUSION: Higher SBP in children and adolescents, family history of hypertension, and male sex may increase the risk of developing long-term arterial stiffness.

Effects of salt intake and potassium supplementation on renalase expression in the kidneys of Dahl salt-sensitive rats.

Renalase is currently the only known amine oxidase in the blood that can metabolize catecholamines and regulate sympathetic activity. High salt intake is associated with high blood pressure (BP), possibly through the modulation of renalase expression and secretion, whereas potassium can reverse the high salt-mediated increase in blood pressure. However, whether potassium could also modulate BP through renalase is unclear. In this study, we aim to investigate how salt intake and potassium supplementation affect the level of renalase in rats. Eighteen salt-sensitive (SS) and 18 SS-13BN rats were divided into six groups, receiving normal salt (0.3% NaCl), high salt (8% NaCl) and high salt/potassium (8% NaCl and 8% KCl) dietary intervention for four weeks. At the end of experiments, blood and kidneys were collected for analysis. mRNA level of renalase was measured by quantitative real-time PCR and protein level was determined by Western blot. We found that mRNA and protein levels of renalase in the kidneys of SS and SS-13BN rats were significantly decreased (P < 0.05) after high salt intervention, whereas dopamine in plasma was increased (P < 0.05) compared with rats received normal salt, suggesting that salt may induce salt-sensitive hypertension through inhibition of renalase expression. We also found increased mRNA level and protein level of renalase, decreased catecholamine levels in plasma, and decreased BP in SS rats treated with high salt/potassium, compared with that of the high salt SS group. Taken together, the salt-induced increase and potassium-induced decrease in BP could be mediated through renalase. More studies are needed to confirm our findings and understand the underlying mechanisms.

Association of Renalase SNPs rs2296545 and rs2576178 with the Risk of Hypertension: A Meta-Analysis.

BACKGROUND/AIMS: Two renalase single nucleotide polymorphisms (SNPs) rs2296545 and rs2576178 have been reported to be associated with the susceptibility to hypertension (HT). Given the inconsistent results, we conducted a meta-analysis to assess the association between these two SNPs and the risk of HT. METHODS: Electronic databases were systematically searched to find relevant studies. Subgroup analysis was conducted according to the different concomitant diseases and ethnicities in the study population. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using fixed-effect or random-effect models. RESULTS: A total of six case-control studies on rs2296545 and six studies on rs2576178 were included. In the combined analysis, results showed a significant association between SNP rs2296545 and risk of HT in all genetic models (dominant model CG+CC/GG: OR = 1.43, 95% CI = 1.24-1.65; recessive model CC/CG+GG: OR = 1.36, 95% CI = 1.09-1.69; codominant model CC/GG: OR = 1.63, 95% CI = 1.20-2.20, CG/GG: OR = 1.30, 95% CI = 1.12-1.52; allelic model C/G: OR = 1.29, 95% CI = 1.10-1.51). In subgroup analysis, we observed a significant association between rs2296545 and risk of essential HT. Although we did not observe an association between rs2576178 polymorphism and HT in the combined analysis, an increased risk was observed in the essential HT patients versus healthy controls (subgroup 1) analysis under the dominant, recessive, and codominant genetic models. CONCLUSIONS: Renalase gene rs2296545 polymorphism is significantly associated with increased risk of HT, whereas rs2576178 polymorphism may not be associated with the susceptibility to HT.

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.

Effects of a high salt intake and potassium supplementation on QT interval dispersion in normotensive healthy subjects.

OBJECTIVE: To evaluate the effects of dietary sodium intake on QT interval dispersion (QTd) in normotensive healthy subjects and assess the protective effects of dietary potassium. Methods All subjects were sequentially maintained on a protocol with a three-day baseline investigation, seven-day low-salt period (3 g/day (d), NaCL), seven-day salt loading period (18 g/d, NaCL) and a seven-day salt loading with potassium supplementation period (4.5 g/d, KCL). On the last day of each period, 24-hour urine samples were collected, the blood pressure values were measured and an electrocardiogram was recorded. The QT interval, QTd and T peak-T end interval (Tp-Te) were subsequently measured and calculated. Patients Sixty-four normotensive subjects, men and women, ranging from 28 to 60 years of age, were enrolled. Results There were no great fluctuations in heart rate after salt loading, whereas the systolic blood pressure (SBP, mmHg) and diastolic blood pressure (DBP, mmHg) increased and the corrected QT interval (QTc), corrected QT interval dispersion (QTdc) and Tp-Te values were significantly prolonged compared to that observed in the low-salt period (SBP, 118.6 ± 13.5 vs. 111.7 ± 11.3, p<0.01; DBP, 76.9 ± 8.6 vs. 71.7 ± 7.7, p<0.01; QTdc, 60.3 ± 19.4 vs. 55.6 ± 19.4, p<0.05; Tp-Te, 83.0 ± 10.1 vs. 79.8 ± 8.5, p<0.01). Surprisingly, all of these changes were reversed by potassium supplementation (SBP, 114.5 ± 12.3 vs.118.6 ± 13.5, p<0.01; DBP, 72.2 ± 7.9 vs.76.9 ± 8.6, p<0.01;QTd, 42.6 ± 15.1 vs. 47.4 ± 19.0, p<0.05; QTdc, 52.2 ± 18.0 vs. 60.3 ± 19.4, p<0.05; Tp-Te, 79.1 ± 8.5 vs. 83.0 ± 10.1, p<0.01). Conclusion Salt loading prolongs the QT interval, QTd and Tp-Te, while dietary potassium supplementation reverses these alterations. These findings suggest that potassium supplementation may improve variation in the healing time and prevent arrhythmia.

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

Renalase, a recently discovered enzyme released by the kidneys, breaks down blood-borne catecholamines and may thus regulate blood pressure (BP). Animal studies have suggested that high levels of dietary salt might reduce blood and kidney renalase levels. We conducted a randomized trial to assess the effects of altered salt and potassium intake on serum renalase levels and the relationship between serum renalase levels and BP in humans.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 additional 7 days (18.0 g/day of NaCl), and a high-salt diet with potassium supplementation for final 7 days (18.0 g/day of NaCl + 4.5 g/day of KCl).Serum renalase levels were significantly higher than baseline levels during the low-salt diet intervention period. Renalase levels decreased with the change from the low-salt to high-salt diet, whereas dietary potassium prevented the decrease in serum renalase induced by the high-salt diet. There was a significant inverse correlation between the serum renalase level and 24-h urinary sodium excretion. No significant correlation was found between the renalase level and BP among the different dietary interventions.The present study indicates that variations in dietary salt intake and potassium supplementation affect the serum renalase concentration in Chinese subjects.