High Salt Intake Research Articles

S-28-6: URINARY METABOLOMICS, DIETARY SALT INTAKE AND BLOOD PRESSURE: THE AFRICAN-PREDICT STUDY

Objective: Excessive salt intake is the leading dietary risk factor for cardiovascular disease (CVD). This increased risk may be attributed to alterations in the human metabolome. Salt sensitivity is associated with ethnicity, and ethnic differences in the interaction between sodium intake and the metabolome may play an integral part in CVD development. We therefore investigated 1) the urinary metabolomic profiles of Black and White adults according to low, moderate and high dietary salt intake; and 2) explored the relationships of identified metabolites with blood pressure. Design and Methods: This study included data of White (N = 447) and Black (N = 380) adults aged 20 to 30 years from the African-PREDICT study. Estimated salt intake was determined from 24hr urinary sodium. Urinary amino acids and acylcarnitines were measured using liquid chromatography tandem mass spectrometry. Clinic, 24hr and central systolic blood pressure (SBP) were measured. Results: Whites with a high salt intake (> 10 g/day) had higher SBP (clinic, 24hr and central) compared to those with low (< 5 g/day) or moderate (5 to 10 g/day) salt intakes (all p < 0.05). The metabolites GABA (q = 0.020), citrulline (q = 0.020), glutamic acid (q = 0.046), serine (q = 0.054) and proline (q = 0.054) were lower in those with higher salt intake. In stepwise multivariable adjusted regression analyses, we found that clinic SBP of white adults were inversely associated with GABA (Adj. R2 = 0.35; Std. β=-0.123; p = 0.005), serine (Adj. R2 = 0.35; Std. β=-0.099; p = 0.022) and proline (Adj. R2 = 0.35; Std. β=-0.099; p = 0.021), and central SBP with GABA (Adj. R2 = 0.34; Std. β=-0.094; p = 0.036), glutamic acid (Adj. R2 = 0.34; Std. β=-0.090; p = 0.035) and proline (Adj. R2 = 0.034; Std. β=-0.106; p = 0.015). In Black adults, there were no differences in SBP or metabolites between low, moderate or high salt intake groups, with no relationships between SBP and GABA, glutamic acid, citrulline, serine or proline. Conclusion: In White adults, high salt intake was associated with low levels of GABA, glutamic acid, serine and proline, which in turn were related to high SBP. We hypothesise that metabolomic changes are related to salt intake and may contribute to pathophysiological mechanisms associated with increased blood pressure.

PS-BPB10-3: MOLECULAR INSIGHT INTO SALT-SENSITIVITY; THE ROLE OF ATF3 AND THE GENERATION OF TUBULAR SPECIFIC KO MICE. (2)

Objective: Atf3 is transcriptionally activated according to intracellular Na concentrations. We found about 1.6 fold to 2.5 fold gene expression enhancements in kidney of Nedd4 2 C2 KO mice due to oral salt intakes and diuretics treatments. Aim of this study is to elucidate significance of Atf3 gene for salt-sensitivity by dietary salt loading and furosemide treatment for tubular specific Atf3 KO mice examining blood pressure, body weight, urine volume, water intake with genetic analyses. Methods: We performed metabolic cage experiments for male Ksp-cre (minus) Atf3 flox/flox mice (N = 5) and male Ksp-cre (+) Atf3 flox/flox mice (N = 10) with 7–8 wks old for subsequent protocol. After 1 week habituation period, experiments were done for 3 days normal salt intake, 5 days high salt intake, and 5 days high salt intake with furosemide treatment (40 mg/kg, ip), respectively. We measured blood pressure by tail cuff methods at day 0, day 8, and day 12. During experimental periods, body weight, water intake and urine volumes are measured daily. Results: We could not find significant differences among body weight, water intake and urine volume between two groups. After high oral salt intake and intra-peritoneal furosemide injection, we found blood pressure of cre (+) Atf3 flox/flox mice were significantly higher than cre (minus) Atf 3 flox/flox mice. (p < 0.001, 119.6 ± 1.4 mmHg vs 112.8 mmHg) Additionally, we found significant expression change of both classic renin and alternative renin in tubules between two groups by quantitative RT PCR and immunohisto chemistry imaging for kidney. Conclusions: Tubular-specific Atf3 KO mice have elevated blood pressure sensitive to salt and furosemide treatment. Because furosemide treatment might induce enhancement of intra-cellular Na ion concentration, Atf3 gene is responsible for adaptations for intra-cellular Na concentration change through tubular renin expressions.

AST-120 to Target Protein-Bound Uremic Toxins Improves Cardiac Output and Kidney Oxygenation in Experimental Chronic Kidney Disease

Introduction: Chronic kidney disease (CKD) is a global health problem with increasing incidence which is closely associated with cardiac dysfunction. In CKD, uremic toxins accumulate as kidney function declines. Additionally, high salt intake is a growing health issue worldwide which can exacerbate kidney disease. In this study, we investigated the effect of reducing plasma levels of protein-bound uremic toxins in a rat model of CKD, challenged with high salt intake and compared the effects to those of conventional treatment using an angiotensin-converting enzyme inhibitor (ACEI). Methods: In rats, the right kidney and 2/3 of the left kidney were surgically removed (5/6 nephrectomy). Animals were fed a normal-salt diet and randomized to either no treatment (control) or chronic treatment with either the oral absorbent AST-120 to reduce plasma levels of protein-bound uremic toxins or the ACEI enalapril to inhibit angiotensin II signaling for 5 weeks. Following treatment, kidney function was measured before and after a week of high salt intake. Cardiac output and markers of oxidative stress were measured at the end of the study period. Results: Treatment with AST-120 resulted in decreased levels of the uremic toxin indoxyl sulfate, improved cardiac output (mL/min: AST-120 44.9 ± 5.4 compared to control 26.6 ± 2.0; p < 0.05), and decreased urinary oxidative stress. ACEI reduced oxidative stress in kidney tissue and improved the glomerular filtration rate in response to high salt intake (mL/min: ACEI 1.5 ± 0.1; compared to control 1.1 ± 0.1; p < 0.05). Both interventions improved intrarenal oxygen availability (mm Hg: AST-120 42.8 ± 0.8; ACEI 43.2 ± 1.9; compared to control 33.4 ± 1.3; p < 0.05). Conclusion: AST-120 administered to reduce plasma levels of uremic toxins, such as indoxyl sulfate, has potential beneficial effects on both cardiac and kidney function. Targeting uremic toxins and angiotensin II signaling simultaneously could be an efficient strategy to target both cardiac and kidney dysfunction in CKD, to further slow progression of disease in patients with CKD.

PS-B08-5: EFFECT OF HIGH SALT INTAKE ON THE SODIUM CONTENT OF EACH BONE IN RATS

Objective: It has been reported that salt intake affects sodium content at the tissue level. Salt intake alters bone sodium content, which shifts the balance of osteoblasts and osteoclasts population and thereby affects bone density. However, it remains to be clarified whether there are site-specific changes in bone sodium content. In the present study, we examined the effect of high salt intake on the sodium content of each bone in normal rats. Design and method: Male Sprague Dawley rats (9 weeks old) were fed with a 0.2% normal salt diet with tap water to drink or a 4% high salt diet with 0.9% NaCl water to drink for 3 weeks. Each bone sodium content was measured by the ashing-flame photometer method. Results: High salt intake significantly increased total bone sodium content. Compared with normal salt group, high salt group exhibited a significant increase in the bone sodium content of skulls, ribs, or tailbones. On the other hand, high salt intake did not alter bone sodium content in the scapula, pelvis, vertebrae, and limb bones. Conclusions: There is a site-specificity of bone sodium accumulation with high salt intake. These findings suggest that each bone has local sodium regulation independently of whole bones and that bones could be separated into whether or not to store sodium. It may be necessary to evaluate the sodium content of each bone in various pathological models, rather than a simple measurement of the total bone sodium content.

PS-P03-10: SETTING UP OF MYWASSH, THE MALAYSIAN SOCIETY FOR WORLD ACTION ON SALT, SUGAR AND HEALTH: PROMOTE SALT REDUCTION IN MALAYSIA

In response to non-communicable diseases in particular cardiovascular diseases being the leading cause of premature deaths in high as well as middle income countries, the World Health Organisation in 2013, proposed several targets to address this problem. One of the targets set was reduction of salt intake to less than 5gm per day by 2030 - to reduce the prevalence of hypertension. Salt intake is of particular importance because intake of salt in Asia is high, ranging from 9–17 gm/day. Furthermore, high salt intake is more important in Asia as salt sensitivity is higher in Asians causing a rise greater rise in blood pressure (BP) compared to Caucasians. Furthermore, the impact of BP in Asians is again higher than in Caucasians, making it even more important to reduce BP as much as possible. Reduction in salt intake needs a multi-prong, multi-sectorial approach. One strategy to help reduce salt intake is public education. We cannot rely only on the government and health authorities alone to ensure the reduction of intake of salt. To this end, a group of interested health care professionals, dietitians, scientists got together to set the society to help educate the public. This society was successfully formed and registered under the Malaysian Registrar of Societies in November 2021 and launched by the Deputy Minister of Health Malaysia in May 2022. A website was also created and language specific educational materials including videos were created by the members themselves. To strengthen the Society activities and aligned with international organisations, the society sought and was granted affiliated membership with the World Hypertension League and the International Society of Hypertension. A memorandum of understanding was signed with UK WASSH and Sunway University (SU) as SU is very much committed to UN Sustainable Development Goals - health is one the arms and willing to provide a lot of support for our educational activities. Furthermore, a monetary grant was successfully secured to help defray expenditure related to our educational activities. We need more salt warriors- i.e., the people who will help educate the public, food vendors, the food manufacturers and lobby public policy as well. The young and enthusiastic members have already embarked educational activities at various sites throughout the country. We believe the efforts of this new Society will have impact and by sharing this, we hope other countries in Asia will also start the battle against a high salt intake.

S-08-2: RESTORATION OF SIRT3 EXPRESSION IN LIVER ALLEVIATES HIGH-SALT-INDUCED HYPERTENSION

Objective: High salt intake is the leading dietary risk factor for hypertension. Although clinical evidence suggests that high salt intake is associated with non-alcoholic fatty liver disease (NAFLD) that is an independent risk factor for hypertension, it remains elusive whether salt-induced hepatic damage leads to the development of hypertension. SIRT3 is the main protector in liver metabolism, and knockout of SIRT3 in mice results in fatty liver and metabolic syndrome. Therefore, we asked whether SIRT3 in liver participated in salt-induced hypertension and investigated the underlying mechanism. Design and method: 6-week male wild-type or SIRT3-knockout (SIRT3−/−) mice were fed with 0.4% normal salt diet (NSD) or 8% high salt diet (HSD) for 16 weeks. Liver weight, body weight and blood pressure were measured. H&amp;E, Oil-O red, and Sirius Red staining were performed on liver frozen sections to detect steatosis, lipid accumulation and fibrosis, respectively. Hepatic inflammation was reflexed by immunofluorescent staining of Cd11b, Mpo and F4/80, the markers of neutrophils, macrophages and Kupffer cells, respectively. Adeno-associated virus 8 (AAV8) with a Thyroxine-Binding Globulin (TBG) promoter was used to overexpress SIRT3 in liver. Chromatin immunoprecipitation sequencing (ChIP-seq) with an antibody against acetylated histone 3 lysine 27 (H3K27ac), an activated promoter marker, was used to explore the possible mechanism underlying the effect of SIRT3 on salt-induced hepatic inflammation. Results: HSD induced a significant increase in systolic blood pressure, a higher liver weight to body weight ratio, and stimulated lipid accumulation, steatosis, and fibrosis in the liver, accompanied by a lowered expression of SIRT3 in liver. Knockout of SIRT3 further exacerbated HSD-induced hepatic steatosis and inflammation, resulting in a more severe hypertension. Restoration of hepatic SIRT3 expression in SIRT3−/− mice by injection of AAV8-TBG-SIRT3 lowered all these pathological changes induced by HSD. ChIP-seq results suggest that knockout of SIRT3 mainly affected the H3K27ac level of promoters of genes related to AMP-activated protein kinase (AMPK) and insulin signaling pathways. Activation of AMPK by metformin significantly blocked salt-induced hepatic inflammation and hypertension, accompanied with an elevated SIRT3 expression in liver. Conclusions: The present study proves that the reduced SIRT3 expression in liver plays a critical role in salt-induced hypertension by inducing hepatic inflammation. Restoration of hepatic SIRT3 expression or treatment with metformin helps to stave off hepatic inflammation that underlies salt-induced hypertension in clinical practice.

S-18-6: SALT AND AGE-RELATED HYPERTENSION

Hypertension is the greatest risk factor for cardiovascular disease and stroke, and its incidence increases with age. Clinical studies have shown that salt intake is involved in the development of age-related hypertension and that salt sensitivity of blood pressure (BP) increases with age, but the mechanism was unknown. On the other hand, it was reported that circulating Klotho level, an anti-aging factor protein, decreased with age, and there was an inverse relationship between circulating Klotho and mean BP changes after saline infusion. We hypothesized that the decrease in circulating Klotho levels might be involved in the increase in salt sensitivity of BP with aging. We found that circulating Klotho significantly decreased in aged mice and Klotho heterozygous knockout (KO) mice than in young wild-type mice. They showed salt-sensitive hypertension unlike young wild-type mice, suggesting that a decrease in circulating Klotho was involved in the pathogenesis of salt-sensitive hypertension in aged mice. In both aged mice and Klotho heterozygous KO mice, it was revealed that vascular Wnt5a-RhoA pathway was activated and vasoconstriction was enhanced during high salt intake, resulting in hypertension. We also demonstrated that Klotho supplementation and Wnt and Rho kinase inhibitors significantly suppressed the BP elevation during high salt intake in these mice. Furthermore, we found that Wnt5a was essential for the activation of RhoA by Angiotensin II, an important agent in the formation of hypertension. Since increased vascular resistance of the renal arteries and decreased renal blood flow are involved in the pathogenesis of salt-sensitive hypertension. We analyzed the effects of Angiotensin II and RhoA stimulators to the renal arteries of high-salt fed aged mice and Klotho heterozygous KO mice. Marked vasoconstriction of the renal arteries and decrease in renal blood flow with BP elevation were observed, while responses were less in young mice. Augmented responses observed in aged mice and Klotho heterozygous KO mice were normalized by Klotho supplementation. These findings suggest that in aged mice with low circulating Klotho, salt intake causes activation of the vascular Wnt5a-RhoA pathway, resulting in increased contraction of the renal arteries as well as peripheral blood vessels, which reduces renal blood flow and eventually caused hypertension. We suggest that reducing salt consumption is highly important and lifestyle habits preserving adequate levels of Klotho are useful in the prevention of age-related hypertension. Wnt and Rho inhibitors may be new treatment options. Therapeutic development focusing on the unique background of aging may be applied to other age-related diseases.

PS-BPB04-4: RENAL DENERVATION IMPROVES THE SURVIVAL RATE VIA A REDUCTION IN HEART RATE IN HIGH SALT-FED DAHL SALT-SENSITIVE RATS

Objective: We reported that high salt intake decreases heart rates via a reduction in renal sympathetic activity in normal Sprague Dawley rats to compensate for high salt-driven catabolism. We also revealed that Dahl salt-sensitive (DSS) rats cannot reduce heart rates during high salt intake because of the abnormal activation of renal sympathetic nerve activity. It is known that high heart rates are negatively associated with life span. Therefore, we hypothesized that renal denervation ontributes to the long life span in high salt-fed DSS rats. Design and Method: (Experiment 1) We performed renal denervation (n = 9) or sham operation (n = 9) on male DSS rats at 4 weeks of age. At the same time, we implanted a radiotelemetry transmitter for blood pressure measurements in the above rats (sham (n = 4), renal denervation (n = 5)). After two weeks of recovery, we started feeding them a 4% NaCl diet with 0.9% NaCl water to drink (HS). We observed the survival rates, blood pressure, and heart rates. (Experiment 2) Male, 4-week-old DSS rats were divided into three groups: i) sham operation + 0.2% NaCl diet with tap water to drink, ii) sham operation + HS, and iii) renal denervation + HS (n = 6 per group). At 2 weeks post-surgery, the rats were fed the respective diets for 6 weeks. We weekly measured systolic blood pressure by a tail-cuff method. After 6 weeks of observation, we harvested their skin and skinned carcass to measure their body. Results: The renal-denervated DSS rats showed a higher survival rate compared to the sham-operated DSS rats (p &lt; 0.05). While renal denervation showed a decrease in heart rate, there was no significant decrease in mean arterial pressure throughout the experimental period. High salt intake significantly increased body Na content (mmol/g dry weight), whereas renal denervation did not alter body Na content in DSS rats. Conclusion: Renal denervation improved the survival rate in high salt-fed Dahl salt-sensitive rats, which may be mediated by a reduction in heart rate, but not body Na content nor blood pressure.

PS-P13-11: ASSOCIATION BETWEEN SPOT URINE SODIUM-TO-POTASSIUM RATIO AND BLOOD PRESSURE IN HEALTHY ADOLESCENTS: THE WAKAYAMA STUDY

Objective: Spot urine sodium to potassium ratio (Na/K) is a simple measure of sodium loading and has been shown to be associated with blood pressure (BP) levels. This study aimed to evaluate the association between spot urine Na/K and BP in a cross sectional sample of healthy adolescent population. Design and method: The study participants consisted of 457 healthy adolescents (217 males and 240 females) aged 12 to 15 years (mean age: 13.9 years). Brachial arterial BP was measured in the supine position using digital BP monitor with an appropriate cuff size. Urinary Na, K, and creatinine levels were measured using spot urine specimens collected in the early morning of the sampling day. Results: The spot urine Na/K levels of participants was 4.99 ± 2.76 (Na, 148.1 ± 58.4 mEq/L; K, 36.1 ± 18.7 mEq/L), and there was no significant difference between males and females. When the participants were stratified based on the quartiles of urinary Na/K distribution (&lt; 2.95, 2.95 to 4.54, 4.55 to 6.59, &gt; = 6.6), systolic and diastolic BP gradually increased with an increase in Na/K levels (systolic BP, 106.1, 106.9, 108.2, and 111.5 mmHg, P for trend &lt; 0.001; diastolic BP, 62.0, 62.4, 63.1, 64.3 mmHg, P for trend = 0.022). The Na/K was more closely associated with BP than urinary Na and K levels, as well as daily salt intake estimated from urinary Na. In multiple regression analysis, Na/K was significantly associated with systolic BP (β; = 0.144, P &lt; 0.001) and diastolic BP (β; = 0.114, P = 0.015), independent of potential confounding factors. The BP of the subgroup with high Na/K (&gt; = 6.6) and high salt intake (&gt; = 8.5 g/day) was significantly higher than that of those with only high salt intake (systolic BP, 115.0 mmHg vs. 109.1 mmHg, P &lt; 0.001; diastolic BP, 66.0 mmHg vs. 62.5 mmHg, P = 0.017). Conclusions: High Na/K levels is associated with elevated BP in healthy adolescents, and Na/K may be useful in assessing the effect of salt loading on BP than Na excretion alone.

S-54-4: DIETARY SALT INTAKE ASSESSED BY SPOT URINARY SODIUM EXCRETION FROM CHILD TO ADULTHOOD IN A JAPANESE TOWN

In clinical practice, a high salt intake is strongly associated with elevation of blood pressure. To prevent and treat hypertension, it is important to restrict salt in one’s diet from child and adolescence. However, data are lacking regarding dietary salt intake from child to adulthood in general population. Therefore, we evaluated the dietary salt intake assessed by spot urinary sodium excretion from child to adulthood in a Japanese town. A total of 534 persons of both sexes, aged from 3 to 91 years were under study. The Tanaka formula was used to estimate 24-h urinary sodium excretion, which reflects salt intake. The average salt intake was 8.0 ± 2.7 g/day (n = 534); that of the men was 8.2 ± 2.8 g/day (n = 206), and that of the women was 7.8 ± 2.6 g/day (n = 249). When we assessed by age group, the average salt intake was 3.8 ± 2.2 g/day in 3 years old (n = 79), 6.8 ± 1.5 g/day in 11 years old (n = 36), 8.0 ± 1.5 g/day in 14 years old (n = 37), 8.6 ± 2.8 g/day in 20 s and 30 s (n = 37), 8.0 ± 1.7 g/day in 40 s (n = 24), 8.9 ± 2.2 g/day in 50 s (n = 32), 8.9 ± 2.1 g/day in 60 s (n = 108), 9.2 ± 1.9 g/day in 70 s (n = 182), and 9.0 ± 2.2 g/day in over 80 s (n = 22). Notably, dietary salt intake was over 6 g/day even in 11 years old. The salt intake was significantly higher in the older age group (P &lt; 0.001 for trend) and was significantly associated with higher systolic and diastolic blood pressure. In conclusion, it is important to educate children, their parents, childcare professionals, and society about proper salt restriction and potassium supplementation, as well as to improve the food environment.

Hypertension and its Risk Factors among College Students of Jodhpur, Rajasthan

Background: High blood pressure (BP) in adolescents and young adults is a rising concern in today’s world. Behavioral factors largely contribute toward the development of hypertension. Once these are established, they often persist throughout life, and if identified timely, might play a significant role in prevalence reduction. This study was conducted to assess the prevalence and association of hypertension and its risk factors in college students of Jodhpur district. Methodology: A cross-sectional study was conducted in ten colleges across five zones of Jodhpur district using modified WHO STEPS questionnaire and by taking physical measurements of BP, height, and weight. Descriptive analysis was done using means and percentages, and statistical significance was established using prevalence odds ratio (POR). Results: Of the 421 study participants, 251 (59.60%) were males and 170 (40.20%) were females, with a mean age of 20.12. The prevalence of risk factors and significant association were observed between gender and educational level with behavioral habits. Further, hypertension prevalence (16.15%) was found to be associated with smoking (POR = 2.72), high salt intake (POR = 3.21), physical activity (POR = 0.30), overweight (POR = 2.34), and obese body mass index (POR = 4.02). Conclusion: The study provided evidence of high prevalence of hypertension and its associated behavioral risk factors such as tobacco, salt, and physical inactivity. Such evidences may be utilized for health promotion programs for the specific age group and region.

S-24-1: OLD HABITS DIE HARD. REDUCED-SODIUM SCHOOL LUNCHES IN ELEMENTARY SCHOOLS WILL CREATE A NEW LOW-SODIUM EATING HABIT IN JAPAN

To prevent future cerebrovascular disorders, the most important lifestyle improvement measure for Japanese people, who have a high prevalence of hypertension and especially high salt intake, is to reduce salt intake by less than 6 g/day, but progress is slow. If this trend continues, medical and nursing care costs are expected to increase further in the future. However, it is frustrating to verbally instruct patients who have already developed the habit of eating a high-salt diet on how to reduce salt intake, and younger people, who are less health-conscious, are less interested in salt reduction. Therefore, it is desirable to create a society in which people can reduce salt intake naturally living a normal life. As a first step toward this goal, we need to promote a low-sodium dietary education for children and low-sodium school lunches at elementary schools. This is because high-salt eating habits do not begin in adulthood, but rather are the accumulation of eating habits from childhood, and we think that acquiring the basics of healthy eating habits as a child will be a major prevention of lifestyle-related diseases, including hypertension, throughout life. In 2012, a group led by the Japanese Society of Hypertension held the “Salt Reduction Summit in Kure 2012’’, combining research with a salt reduction experience event for the public. One of the goals of the summit was to educate on the importance of salt reduction to children through a program involving children, teachers, government officials, and chefs. This led to the start of reduced-sodium school lunches in elementary schools in Kure City. Initially, the amount of salt per school lunch was 3.1 g, but this was reduced to 2.0 g by 2021. The salt content was gradually reduced every year, so the goal was achieved without any discomfort and there were no leftover meals. With the introduction of low salt school lunches and providing education on salt reduction by school nutrition teachers, children and their parents’ generation are becoming more interested in salt reduction. The Japanese Society of Hypertension also holds various events for children. If reduced-sodium school lunch programs spread not only through Japan but also around the world, by the time children become adults, the public's preference will be for low-sodium foods, and food companies will appreciate benefits of selling low-sodium products and thereby creating a low-sodium society. As a result, we hope that healthy life expectancy will increase.

S-36-2: SOCIAL FRAMEWORK TO PROMOTE SALT REDUCTION AND HEALTHY DIETS WITHIN HYPERTENSION AND STROKE PREVENTION

Beyond the physiological effects of sodium and potassium strong evidence from animal, clinical and epidemiological studies, has implicated excess dietary sodium and low potassium intake as major factors associated with the development of hypertension and increase in stroke risk. Daily salt intake of 5–6 g 85–100 mmol was recommended for the general population i.e. 2.0–2.4 g Na along with K intake to at least 90 mmol d 3.51 g perd. Randomized trials demonstrate that salt reduction and potassium increase in diet lowers blood pressure and reduces the risk of brain damage and cardiovascular disease. Population studies showed that 15 percent reduction of salt intake from 9.5 g/day was associated with a 40 percent reduction of stroke and CHD mortality. Potassium lowers BP via multiple mechanisms, by acting directly on the vasculature and by triggering a signalling cascade mediated by endothelium and also reduces salt-sensitivity. A meta-analysis of 21 RCTs reported that increasing potassium intake lowers BP 3.5/2.0 mm Hg and the risk of stroke. Eating more than 11 g of salt /day was associated with 2.5 times more likely to have a stroke than those who got less than 4.5 g /day. Switching from regular salt to a salt substitute reduced the risk for stroke, major CV events and death in a large trial of adults in rural China with a history of stroke or high risk for stroke. High salt intake reduces resting cerebral blood flow and induces endothelial dysfunction in mice and impairs vasodilatory responses of cerebral vessels. Gut-brain relation links dietary salt to cognitive impairment though a gut-initiated adaptative immune response damaging brain function via increase in circulating IL-17. A high potassium diet reduces cerebral infact size and improves vascular function independently of BP changes. Thus high salt and low potassium intake interfere in multtiple brain vascular strutural complex processes including fluid homeostasis and inflammatory mechanisms, immune responses and gut-microbiome-brain axis.

RAG-APAC-1: SOCIAL AGING IN THE ASIA-PACIFIC REGION

There will be twice as many individuals over the age of sixty worldwide, including in the Asia-Pacific region by the year 2050, according to a report by WHO. The rise in hypertension prevalence, therefore, will be fueled by the anticipated rise in the elderly population. Even though cardiovascular (CV) risk factors continue throughout a lifespan, older people are more likely to develop cardiovascular diseases (CVDs). Hypertension accounts for a significant share of major morbidities and mortalities in the Asia-Pacific area. Therefore, the main objectives of integrated healthcare for older populations are to minimize CV risks as well as to provide optimal treatment of CVDs and life-threatening conditions. Another critical factor is the continuity of healthy metabolic profiles including blood pressure from childhood to old age. There are many challenges in hypertension management with social aging in the Asia-Pacific region. First, the common type of hypertension in the elderly is isolated systolic hypertension. Its prevalence is expected to rise in many parts of Asia, however, clear guidance for the management is not yet provided. Second, a relatively high salt intake which is known as one of the most important risk factors for hypertension has been reported in the Asia-Pacific region. The genetic epidemiology network of salt sensitivity dietary feeding study reported that nearly 40 percent of Chinese adults were salt-sensitive. Moreover, salt sensitivity is more common in older individuals who are more susceptible to CVDs. Therefore, the action to lower salt intake is an immediate requirement. Finally, relatively poor compliance is more common in older individuals, whether it is because of their impaired functions or because of possible intolerance of medications, and drug-drug interactions. The recent trials of fixed-dose combinations and polypills showed that they may help improve compliance. However, reimbursement is still a problem in some areas. The Asia-Pacific regional strategy including adapting the healthcare systems to solve these challenges is needed to reduce CVD-associated morbidity and mortality in our older populations.

Twenty-four-hour Urinary Salt Excretion on Admission Predicts Significant Weight Loss with Seven-day Dietary Salt Restriction in Hospitalized Patients with Chronic Kidney Disease: A Single-center Study.

In patients with chronic kidney disease (CKD), restricting dietary salt is recommended to prevent fluid retention. Rapid weight loss is often observed when CKD patients with a high salt intake are hospitalized and started on a low-salt diet. We investigated the effects of 7-day dietary salt restriction on weight loss in hospitalized patients with CKD. During the 7-day hospitalization, a low-salt (6 g/day) and low-protein (0.6-0.8 g/kg/day ideal body weight) diet was served to all patients. Urine samples were collected for the first 24 h after admission, and patients were divided into quartiles (Q1-Q4) by urinary salt excretion. Body weight was measured on days 1 and 7. Weight loss after admission was compared among the groups. Factors associated with weight loss were evaluated by multivariate logistic regression. The mean age of the patients was 70.3 ± 11.7 years, and 73% were male. Mean weight loss was 1.6 ± 1.7 kg on day 7. Weight loss was significantly greater in Q3 and Q4 than in Q1 (P = 0.009 and P <0.001, respectively). In the univariate analysis, weight loss correlated positively with 24-h urinary salt excretion on admission (γ2 = 0.146) and body mass index (γ2 = 0.223). The 24-h urinary salt excretion on admission and BMI were independently associated with weight loss of >2 kg. The adjusted odds ratios (95% confidence interval) were 1.24 (1.13-1.36) and 1.15 (1.07-1.22), respectively. Twenty-four-hour urinary salt excretion on admission is useful for predicting significant weight loss with short-term dietary salt restriction.

PS-B05-6: FABRY DISEASE MOUSE IS RESISTANT TO HIGH-SALT DIET-INDUCED HYPERTENSION PROBABLY VIA DYSFUNCTIONAL SODIUM TRANSPORTS AND AQUAPORIN 2

Background: Fabry disease is a rare X-linked lysosomal storage disorder resulting from an error in glycosphingolipid metabolism caused by the GLA gene mutation. Patients with Fabry disease often have near normal or even low systemic blood pressure although the mechanism underlying such observed finding remains unexplained. This study examined whether a high salt intake could affect transport of sodium and water and induce hypertension in mice with Fabry disease. Methods: Fabry disease model mice (B6;129-Glatm1Kul/J) and wild-type (WT) mice received 8% or normal NaCl salt diet for 2 weeks. Results: A high-salt diet for 2 weeks generated higher blood pressure in WT mice but not in Fabry disease mice. Free water clearance (FWC) and electrolyte free water clearance (EFWC) in groups fed with a high salt diet were lower than those in groups fed with a normal salt diet. Both high salt-fed WT and Fabry disease mice had decreased gamma-subunit of epithelial Na channel (ENaC) compared with normal salt-fed groups. In Fabry disease mice fed a high-salt diet, there was an decrease in renal expressions of Na+/H+ exchanger isoform 3 (NHE3) and Na+-Cl- cotransporter (NCC) compared with WT mice fed a high-salt diet. Although renal expression of vasopressin V2 receptor (V2R) was upregulated in Fabry mice fed with a high salt diet, renal aquaporin 2 (AQP2) level failed to increase up to the level in WT mice fed with a high salt diet. Conclusion: These findings suggest that the decreased expression of NHE3 and NCC and impaired response of AQP2 in kidneys of Fabry disease to a salt load could be one of mechanisms by which Fabry disease could have resistance to the development of hypertension.

PS-BPB10-2: MOLECULAR INSIGHT INTO SALT-SENSITIVITY; THE ROLE OF ATF3 AND THE GENERATION OF TUBULAR SPECIFIC KO MICE. (1)

Objectives: Current research including ours suggested pivotal roles of expressions of and regulations of tubular ion transporters for developments of sodium sensitivity and hypertension. Orlov et al. demonstrated using rat cardiomyocytes three different genes which are activated according to the elevation of intra-cellular Na ion concentration. (2015) To elucidate detailed biological roles of these genes in tubules, we performed current experiments. Methods: We tested expressions of three genes for cDNA from kidneys of Nedd4 2 C2 KO mice using quantitative RT PCR methods. Subsequently, we performed crossbreeding experiments between floxed target gene mice (generous gift from Prof. Kitamura, Tokyo Medical and Dental University) and Ksp-cre mice (Jackson Laboratory), which cre-recombinase expresses specifically along urinary tubules to generate mice with cre+, flox/flox genotype. Results: We found expressions of Atf3 are significantly changed due to oral sodium intake and diuretics treatment in Nedd4–2 C2 KO mice. We successfully generated mice with cre+, Atf3 flox/flox mice for current experiments. Under normal salt diet, we could not find any significant differences between cre + and minus mice in terms of systolic blood pressure, water intake, urine volume, urinary sodium excretions, urinary pH, and urinary osmotic pressures using metabolic cage experiments. We found, under high salt intake, gene expressions of both classic renin and tubular alternative renin are significantly suppressed for 30 to 70% in KO mice by quantitative RT PCR and immunohistochemistry imaging. Conclusions: Tubular epithelial Atf3 genes are involved in regulations of renin gene expressions in accordance with intracellular Na ion concentrations. Therefore, there are possibilities that tubular specific Atf3 KO mice shows blood pressure change under various salt intake and diuretics treatment.

S-44-1: SALTING A BIRD'S TAIL

It is needless to stress high-salt intake threaten cardiovascular diseases because of inrement of hypertension and social activities to reduce salt intake is beneficial for healthy longetivity. The pathophysiology of salt-induced hypertension has been studied and innapropriate handling of salt in the kidney, vascular reaction to the salt and recently interstitial accumulation of sodium are proposed mechanism. In addition to raise blood pressure, too much salt may cause systemic effect such as regulation of immune responses. Not all patients are salt-sensitive in terms of blood pressure and we do not know if there are salt-sensitive and resistant in other physiological effect of salt or not. It is required to develop the diagnositic tools to find who is salt-sensitive and tools to keep patients under appropriate salt intake chronically. In this review, I am going to discuss salt-sensitivity, pathological effect of high salt intake and possible markers for salt-sensitive hypertension.

S-49-4: URINARY BIOMARKER ANALYSES ON JAPANESE, MEDITERRANEAN AND EURO-WESTERN POPULATIONS: WHICH IS BETTER FOR POST-PANDEMIC LONGEVITY?

Objective: Since nutrition could extend lifespan even in stroke-prone rats developing stroke genetically, our WHO-Collaborating Center for Primary Prevention of Cardio-vascular Diseases (CVD) started world-wide hearth examination to investigate nutrition good for healthy longevity by collecting 24-hour urine (24U) samples. Design: Urinary biomarkers of nutritions, sodium for salt, potassium (K) for vegetables and fruits, isoflavones(Is) for soy, taurine(Ta) for fish and magnesium (Mg) for beans and nuts were analyzed in 24U among 4211 participants (49.7% females(F)), aged 48–56 years in 50 populations from 22 countries according to WHO-CARDIAC(Cardiovascular Diseases and Alimentary Compression) Study Protocol, and studied comparatively in 6 Japanese(J), 6 Mediterranean(M) populations from Greece, Italy(2), Spain(2), Portugal and 6 Euro-Western(EW) populations from Sweden, Ireland, Scotland, Canada, Australia, New Zealand. Results with Discussion: The quintile analyses of Ta and Mg/creatine ratio in the world were inversely associated with CVD risks. The Odds ratios of obesity, hypercholesterolemia and hypertension in the lowest quintile of both Ta and Mg were 6.3, 4.6 and 1.8, respectively. J and M populations had significantly higher Ta and Mg therefore, lower CVD risks than EW, but J and M took more salt increasing the risk of stroke (Table 1). Despite the high salt intake, M had the merit of significantly high K intake to attenuate the adverse salt effect. J had a merit to take Is from soy containing Mg. Since Is intake was inversely associated with lower BMI in the world populations, high Japanese Mg intake was related to high Is intake which was inversely associated with obesity in Japan. In fact, the Japanese populations who took significantly higher T and Mg had lower BMI as well as higher HDL and folic acid in the blood, expected to prevent atherosclerosis and dementia. In contrast to M and EW, particularly severe obesity over BMI 30 was obviously less in J, ranking 182nd among 190 populations (WHO). The mortality rates of COVID-19 were significantly positively related to the ratio of severe obesity among 20 major countries in the world and this mortality was obviously lower in J, suggestive of the potential of J diet for post-pandemic longevity. Conclusion: 24U biomarker analyses indicated low-salted J and M diets are recommendable for CVD prevention. J diet is so far better than M diet because of lower CVD risks such as obesity and lipidemia, which were proven by urinary biomarkers to be related with traditional fish and soy intakes.

AW-NI-6: MINERALOCORTICOID RECEPTOR ACTIVATION LEADS TO HIGH BLOOD PRESSURE DUE TO BODY POTASSIUM AND WATER LOSS

Objective: Mineralocorticoid receptor (MR) activation is known to reduce renal Na+ elimination and increase body fluid, resulting in arterial hypertension. We have reported earlier that high salt intake, chronic renal failure and psoriasis occur blood pressure increases initiated by body water loss. Here we tested the hypothesis that DOCA treatment induces a similar adaptive water conservation response that also causes arterial hypertension. Design and method: Male C57BL/6J mice on the low-salt diet (&lt;0.1% NaCl) were divided into four groups: tap water (control), tap water with subcutaneous 25 mg DOCA (DOCA), 1% NaCl water with DOCA (DOCA salt), 1.44% NaHCO3 water with DOCA (DOCA NaBic). We performed continuous metabolic cage studies. Na+, K+, and water were measured in mice tissue by desiccation and consecutive dry ashing. Blood pressure was measured by telemetry. We also studied body composition, glucocorticoid-receptor (GR) protein/chromatin interaction, skin blood flow perfusion and renal vascular resistance. Metabolome and key enzyme activities of energy production in kidney, skeletal muscle and in liver were compared between four groups. Results: Compared to control mice, DOCA mice showed increased urine volume, lower urine osmolality and increased blood pressure. DOCA salt developed arterial hypertension within 3 days of the experiment (P &lt; 0.001, Fig. 1A). In DOCA salt mice, K+ and water loss occurs in the initiation phase of arterial hypertension (Fig. 1B), indicating solute and water loss from the intracellular space. Further water loss was then prevented by secondary Na+ accumulation, indicating that the initial MR-driven dehydration reverted back to normal body fluid level by means of Na+ accumulation. Additional physiological adaptation to DOCA salt-driven body water loss included increased vascular resistance (Fig. 1C) and catabolic amino acid breakdown (Fig. 1D). DOCA NaBic mice showed similar massive primary K+ loss and secondary Na+ retention, but no arterial hypertension occurred (Fig. 1A). While DOCA salt decreased skin blood flow, DOCA NaBic increased it (Fig. 1C). DOCA salt mice showed renal glutamine catabolism as well as muscle protein catabolism (Fig. 1D). This catabolic state was coupled with glucocorticoid receptor binding in skeletal muscle. Conclusions: DOCA salt leads to pronounced initial K+ and water loss with hypertension. Na+ retention occurs only secondarily and is a compensatory response that reverts initial body water loss back to normal body water levels. Additional NaBic feeding reveals that the blood pressure level in mice with MR activation is determined by changes in blood flow independent of body Na+ or water content.