Association between adding salt in food and dementia in European descent: A mendelian randomization study.

BACKGROUND: High salt intake has been proposed as a risk factor for dementia. However, causal relationship between salt intake and dementia remains uncertain. PURPOSE: The aim of this study was to employ a mendelian randomization (MR) design to investigate the causal impact of salt intake on the risk of dementia. METHODS: Genome-wide association study (GWAS) data of exposures and outcomes (any dementia, cognitive performance, different types of dementia, Alzheimer's disease [AD], and Parkinson's disease) were obtained from the IEU database. MR estimates were generated though inverse-variance weighted model. MR-Egger, weighted median, and MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) method also used in our study. Sensitivity analyses included Cochran's Q test, MR-Egger intercept, MR-PRESSO global test and outlier test, leave-one-out analysis, and funnel plot assessment. RESULTS: Our MR analysis provided evidence of a causal association between high salt added to food and dementia (odds ratio [OR] = 1.73, 95% confidence interval [CI]: 1.21-2.49, and p = .003), dementia in AD (OR = 2.10, 95% CI: 1.15-3.83, and p = .015), and undefined dementia (OR = 2.61, 95% CI: 1.26-5.39, and p = .009). Higher salt added was also associated with increased risk of AD (OR = 1.80, 95% CI: 1.12-2.87, and p = .014) and lower cognitive performance (ß = -.133, 95% CI: -.229 to -.038, and p = .006). CONCLUSION: This study provides evidence suggesting that high salt intake is causally associated with an increased risk of developing dementia, including AD and undefined dementia, highlighting the potential importance of reducing salt consumption as a preventive measure.

Role of the median preoptic nucleus in the development of chronic deoxycorticosterone acetate (DOCA)-salt hypertension.

We have previously reported that the subfornical organ (SFO) does not contribute to the chronic hypertensive response to DOCA-salt in rats, and yet the organum vasculosum of the lamina terminalis (OVLT) plays a significant role in the development of deoxycorticosterone acetate (DOCA)-salt hypertension. Since efferent fibers of the OVLT project to and through the median preoptic nucleus (MnPO), the present study was designed to test the hypothesis that the MnPO is necessary for DOCA-salt hypertension in the rat. Male Sprague-Dawley rats underwent SHAM (MnPOsham; n = 5) or electrolytic lesion of the MnPO (MnPOx; n = 7) followed by subsequent unilateral nephrectomy and telemetry instrumentation. After recovery and during the experimental protocol, rats consumed a 0.1% NaCl diet and 0.9% NaCl drinking solution. Mean arterial pressure (MAP) was recorded telemetrically 5 days before and 21 days after DOCA implantation (100 mg/rat; SQ). The chronic pressor response to DOCA was attenuated in MnPOx rats by Day 11 of treatment and continued such that MAP increased 25 ± 3 mmHg in MnPOsham rats by Day 21 of DOCA compared to 14 ± 3 mmHg in MnPOx rats. These results support the hypothesis that the MnPO is an important brain site of action and necessary for the full development of DOCA-salt hypertension in the rat.

Salt Sensitivity of Blood Pressure.

The year 2024 marks the centennial of the initiation of the American Heart Association. Over the past 100 years, the American Heart Association has led groundbreaking discoveries in cardiovascular disease including salt sensitivity of blood pressure, which has been studied since the mid-1900s. Salt sensitivity of blood pressure is an important risk factor for cardiovascular events, but the phenotype remains unclear because of insufficient understanding of the underlying mechanisms and lack of feasible diagnostic tools. In honor of this centennial, we commemorate the initial discovery of salt sensitivity of blood pressure and chronicle the subsequent scientific discoveries and efforts to mitigate salt-induced cardiovascular disease with American Heart Association leading the way. We also highlight determinants of the pathophysiology of salt sensitivity of blood pressure in humans and recent developments in diagnostic methods and future prospects.

Long Noncoding RNA MALAT1: Salt-Sensitive Hypertension.

Hypertension stands as the leading global cause of mortality, affecting one billion individuals and serving as a crucial risk indicator for cardiovascular morbidity and mortality. Elevated salt intake triggers inflammation and hypertension by activating antigen-presenting cells (APCs). We found that one of the primary reasons behind this pro-inflammatory response is the epithelial sodium channel (ENaC), responsible for transporting sodium ions into APCs and the activation of NADPH oxidase, leading to increased oxidative stress. Oxidative stress increases lipid peroxidation and the formation of pro-inflammatory isolevuglandins (IsoLG). Long noncoding RNAs (lncRNAs) play a crucial role in regulating gene expression, and MALAT1, broadly expressed across cell types, including blood vessels and inflammatory cells, is also associated with inflammation regulation. In hypertension, the decreased transcriptional activity of nuclear factor erythroid 2-related factor 2 (Nrf2 or Nfe2l2) correlates with heightened oxidative stress in APCs and impaired control of various antioxidant genes. Kelch-like ECH-associated protein 1 (Keap1), an intracellular inhibitor of Nrf2, exhibits elevated levels of hypertension. Sodium, through an increase in Sp1 transcription factor binding at its promoter, upregulates MALAT1 expression. Silencing MALAT1 inhibits sodium-induced Keap1 upregulation, facilitating the nuclear translocation of Nrf2 and subsequent antioxidant gene transcription. Thus, MALAT1, acting via the Keap1-Nrf2 pathway, modulates antioxidant defense in hypertension. This review explores the potential role of the lncRNA MALAT1 in controlling the Keap1-Nrf2-antioxidant defense pathway in salt-induced hypertension. The inhibition of MALAT1 holds therapeutic potential for the progression of salt-induced hypertension and cardiovascular disease (CVD).

Sodium overload during postnatal phases impairs diastolic function and exacerbates reperfusion arrhythmias in adult rats.

Sodium overload during childhood impairs baroreflex sensitivity and increases arterial blood pressure and heart rate in adulthood; these effects persist even after high-salt diet (HSD) withdrawal. However, the literature lacks details on the effects of HSD during postnatal phases on cardiac ischemia/reperfusion responses in adulthood. The current study aimed to elucidate the impact of HSD during infancy adolescence on isolated heart function and cardiac ischemia/reperfusion responses in adulthood. Male 21-day-old Wistar rats were treated for 60 days with hypertonic saline solution (NaCl; 0.3M; experimental group) or tap water (control group). Subsequently, both groups were maintained on a normal sodium diet for 30 days. Subsequently, the rats were euthanized, and their hearts were isolated and perfused according to the Langendorff technique. After 30 min of the basal period, the hearts were subjected to 20 min of anoxia, followed by 20 min of reperfusion. The basal contractile function was unaffected by HSD. However, HSD elevated the left ventricular end-diastolic pressure during reperfusion (23.1 ± 5.2 mmHg vs. 11.6 ± 1.4 mmHg; p < 0.05) and increased ectopic incidence period during reperfusion (208.8 ± 32.9s vs. 75.0 ± 7.8s; p < 0.05). In conclusion, sodium overload compromises cardiac function after reperfusion events, diminishes ventricular relaxation, and increases the severity of arrhythmias, suggesting a possible arrhythmogenic effect of HSD in the postnatal phases.

Dietary salt promotes cognition impairment through GLP-1R/mTOR/p70S6K signaling pathway.

Dietary salt has been associated with cognitive impairment in mice, possibly related to damaged synapses and tau hyperphosphorylation. However, the mechanism underlying how dietary salt causes cognitive dysfunction remains unclear. In our study, either a high-salt (8%) or normal diet (0.5%) was used to feed C57BL/6 mice for three months, and N2a cells were cultured in normal medium, NaCl medium (80 mM), or NaCl (80 mM) + Liraglutide (200 nM) medium for 48 h. Cognitive function in mice was assessed using the Morris water maze and shuttle box test, while anxiety was evaluated by the open field test (OPT). Western blotting (WB), immunofluorescence, and immunohistochemistry were utilized to assess the level of Glucagon-like Peptide-1 receptor (GLP-1R) and mTOR/p70S6K pathway. Electron microscope and western blotting were used to evaluate synapse function and tau phosphorylation. Our findings revealed that a high salt diet (HSD) reduced the level of synaptophysin (SYP) and postsynaptic density 95 (PSD95), resulting in significant synaptic damage. Additionally, hyperphosphorylation of tau at different sites was detected. The C57BL/6 mice showed significant impairment in learning and memory function compared to the control group, but HSD did not cause anxiety in the mice. In addition, the level of GLP-1R and autophagy flux decreased in the HSD group, while the level of mTOR/p70S6K was upregulated. Furthermore, liraglutide reversed the autophagy inhibition of N2a treated with NaCl. In summary, our study demonstrates that dietary salt inhibits the GLP-1R/mTOR/p70S6K pathway to inhibit autophagy and induces synaptic dysfunction and tau hyperphosphorylation, eventually impairing cognitive dysfunction.

Knowledge, attitudes, and behaviors related to dietary salt intake and the acceptability of salt substitute among the Australian culturally and linguistically diverse community: An online survey.

The Australian culturally and linguistically diverse (CALD) communities may be at higher risk of salt intake than recommended given the use of a combination of discretionary sources and exposure to processed foods within a western country. This survey aimed to understand the knowledge, attitudes, and behaviors toward dietary salt and the acceptability of salt substitutes in the CALD communities. An online cross-sectional survey was conducted among adults who self-reported being a part of a CALD community, which was defined as non-Indigenous cultural groups in Australia having cultural or linguistic connections with their overseas place of birth, ancestry or ethnic origin, religion, preferred language or language spoken at home. A total of 218 respondents opened the survey link. A total of 196 completed the entire survey. The majority of respondents (162, 83%) were aware that high salt intake causes serious health problems. Altogether 134 (69%) respondents were aware that there is a recommended amount for daily salt consumption although only 59 (44%) knew precise recommendations as <5 g salt per day. Around one quarter of the respondents rarely or never looked for ?low in salt'' or ?reduced salt'' messages on food labels when shopping. Over half specified they always or often added salt during cooking or preparing foods in the household. Almost 4 in 5 CALD respondents were willing to reduce their salt intake for health and 3 in 4 were open to trying a salt substitute. Further research into the utility of a salt substitute intervention in the Australian CALD community is warranted.

Renal macrophages induce hypertension and kidney fibrosis in Angiotensin II salt mice model.

The immune system is involved in hypertension development with different immune cells reported to have either pro or anti-hypertensive effects. In hypertension, immune cells have been thought to infiltrate blood pressure-regulating organs, resulting in either elevation or reduction of blood pressure. There is controversy over whether macrophages play a detrimental or beneficial role in the development of hypertension, and the few existing studies have yielded conflicting results. This study aimed to determine the effects of angiotensin II (Ang II) salt-induced hypertension on renal immune cells and to determine whether renal macrophages are involved in the induction of hypertension. Hypertension was induced by administration of Ang II and saline for two weeks. The effects of hypertension on kidney immune cells were assessed using flow cytometry. Macrophage infiltration in the kidney was assessed by immunohistochemistry and kidney fibrosis was assessed using trichrome stain and kidney real time-qPCR. Liposome encapsulated clodronate was used to deplete macrophages in C57BL/6J mice and investigate the direct role of macrophages in hypertension induction. Ang II saline mice group developed hypertension, had increased renal macrophages, and had increased expression of Acta2 and Col1a1 and kidney fibrotic areas. Macrophage depletion blunted hypertension development and reduced the expression of Acta2 and Col1a1 in the kidney and kidney fibrotic areas in Ang II saline group. The results of this study demonstrate that macrophages infiltrate the kidneys and increase kidney fibrosis in Ang II salt-induced hypertension, and depletion of macrophages suppresses the development of hypertension and decreases kidney fibrosis. This indicates that macrophages play a direct role in hypertension development. Hence macrophages have a potential to be considered as therapeutic target in hypertension management.

Long-Term Effect of Salt Substitution for Cardiovascular Outcomes : A Systematic Review and Meta-analysis.

BACKGROUND: Salt substitution is a simple yet increasingly promising strategy to improve cardiovascular outcomes. PURPOSE: To evaluate the long-term effects of salt substitution on cardiovascular outcomes. DATA SOURCES: PubMed, EMBASE, Cochrane CENTRAL, and CINAHL searched from inception to 23 August 2023. Trial registries, citation analysis, and hand-search were also done. STUDY SELECTION: Randomized controlled trials (RCTs) comparing provision of or advice to use a salt substitute with no intervention or use of regular salt among adults for 6 months or longer in total study duration. DATA EXTRACTION: Two authors independently screened articles, extracted data, and assessed risk of bias. Primary outcomes include mortality, major cardiovascular events (MACE), and adverse events at 6 months or greater. Secondary and post hoc outcomes include blood pressure, cause-specific mortality, and urinary excretion at 6 months or greater. Random-effects meta-analyses were done and certainty of effect estimates were assessed using GRADE (Grading of Recommendations Assessment, Development and Evaluation). DATA SYNTHESIS: Of the 16 included RCTs, 8 reported on primary outcomes. Most (n = 7 of 8) were done in China or Taiwan, 3 were done in residential facilities, and 7 included populations of older age (average 62 years) and/or with higher-than-average cardiovascular risk. In this population, salt substitute may reduce risk for all-cause mortality (6 RCTs; 27 710 participants; rate ratio [RR], 0.88 [95% CI, 0.82 to 0.93]; low certainty) and cardiovascular mortality (4 RCTs; 25 050 participants; RR, 0.83 [CI, 0.73 to 0.95]; low certainty). Salt substitute may result in a slight reduction in MACE (3 RCTs; 23 215 participants; RR, 0.85 [CI, 0.71 to 1.00]; very low certainty), with very low-certainty evidence of serious adverse events (6 RCTs; 27 995 participants; risk ratio, 1.04 [CI, 0.87 to 1.25]). LIMITATIONS: The evidence base is dominated by a single, large RCT. Most RCTs were from China or Taiwan and involved participants with higher-than-average cardiovascular risk; therefore, generalizability to other populations is very limited. CONCLUSION: Salt substitution may reduce all-cause or cardiovascular mortality, but the evidence for reducing cardiovascular events and for not increasing serious adverse events is uncertain, particularly for a Western population. The certainty of evidence is higher among populations at higher cardiovascular risk and/or following a Chinese diet. PRIMARY FUNDING SOURCE: National Health and Medical Research Council. (PROSPERO: CRD42022327566).

Dietary High Salt Intake Exacerbates SGK1-Mediated T Cell Pathogenicity in L-NAME/High Salt-Induced Hypertension.

Sodium chloride (NaCl) activates Th17 and dendritic cells in hypertension by stimulating serum/glucocorticoid kinase 1 (SGK1), a sodium sensor. Memory T cells also play a role in hypertension by infiltrating target organs and releasing proinflammatory cytokines. We tested the hypothesis that the role of T cell SGK1 extends to memory T cells. We employed mice with a T cell deletion of SGK1, SGK1fl/fl × tgCD4cre mice, and used SGK1fl/fl mice as controls. We treated the mice with L-NAME (0.5 mg/mL) for 2 weeks and allowed a 2-week washout interval, followed by a 3-week high-salt (HS) diet (4% NaCl). L-NAME/HS significantly increased blood pressure and memory T cell accumulation in the kidneys and bone marrow of SGK1fl/fl mice compared to knockout mice on L-NAME/HS or groups on a normal diet (ND). SGK1fl/fl mice exhibited increased albuminuria, renal fibrosis, and interferon-γ levels after L-NAME/HS treatment. Myography demonstrated endothelial dysfunction in the mesenteric arterioles of SGK1fl/fl mice. Bone marrow memory T cells were adoptively transferred from either mouse strain after L-NAME/HS administration to recipient CD45.1 mice fed the HS diet for 3 weeks. Only the mice that received cells from SGK1fl/fl donors exhibited increased blood pressure and renal memory T cell infiltration. Our data suggest a new therapeutic target for decreasing hypertension-specific memory T cells and protecting against hypertension.

Dissociation of Hypertension and Renal Damage After Cessation of High-Salt Diet in Dahl Rats.

BACKGROUND: Every year, thousands of patients with hypertension reduce salt consumption in an effort to control their blood pressure. However, hypertension has a self-sustaining character in a significant part of the population. We hypothesized that chronic hypertension leads to irreversible renal damage that remains after removing the trigger, causing an elevation of the initial blood pressure. METHODS: Dahl salt-sensitive rat model was used for chronic, continuous observation of blood pressure. Rats were fed a high salt diet to induce hypertension, and then the diet was switched back to normal sodium content. RESULTS: We found that developed hypertension was irreversible by salt cessation: after a short period of reduction, blood pressure grew even higher than in the high-salt phase. Notably, the self-sustaining phase of hypertension was sensitive to benzamil treatment due to sustaining epithelial sodium channel hyperactivity, as shown with patch-clamp analysis. Glomerular damage and proteinuria were also irreversible. In contrast, some mechanisms, contributing to the development of salt-sensitive hypertension, normalized after salt restriction. Thus, flow cytometry demonstrated that dietary salt reduction in hypertensive animals decreased the number of total CD45+, CD3+CD4+, and CD3+CD8+ cells in renal tissues. Also, we found tubular recovery and improvement of glomerular filtration rate in the postsalt period versus a high-salt diet. CONCLUSIONS: Based on earlier publications and current data, poor response to salt restriction is due to the differential contribution of the factors recognized in the developmental phase of hypertension. We suggest that proteinuria or electrolyte transport can be prioritized over therapeutic targets of inflammatory response.

Lysine and salt-sensitive hypertension.

PURPOSE OF REVIEW: Salt-sensitive (SS) hypertension and its associated kidney damage have been extensively studied, yet proper therapeutic strategies are lacking. The interest in altering the metabolome to affect renal and cardiovascular disease has been emerging. Here, we discuss the effect and potential mechanism behind the protective effect of lysine, an essential amino acid, on the progression of SS hypertension. RECENT FINDINGS: We have recently demonstrated that administering lysine in an SS rodent model can control the progression of hypertension. Both the animal and pilot human studies showed that lysine can efficiently inhibit tubular reabsorption of albumin and protect the kidneys from further damage. In addition, we conducted multilevel omics studies that showed increased lysine conjugation and excretion, leading to the depletion of harmful metabolites and an increase in useful ones. SUMMARY: Lysine's twofold action involves both mechanically flushing protein from proximal tubules to shield the kidneys and initiating metabolic adaptations in the kidneys. This results in a net positive impact on SS hypertension. While further research is necessary to apply the current findings in clinical settings, this study offers some evidence suggesting that lysine supplementation holds promise as a therapeutic approach for hypertensive kidney disease.

Adequate iodine nutrition and higher salt intake in Chinese adults aged 18-59 years recommended by international organizations.

Iodine deficiency and excessive salt intake have adverse health effects. This study evaluated the iodine level and salt intake in Chinese adults aged 18-59 years after implementing the salt reduction program and compared with both the World Health Organization (WHO) and Chinese recommendations. Adults aged 18-59 years were randomly selected using multi-stage stratified random sampling in coastal urban area (CUA), non-coastal urban area (Non-CUA), coastal rural area (CRA), and non-coastal rural area (Non-CRA) of Fujian Province, China. Iodine, sodium, and creatinine concentrations in spot urine samples were measured. Knudsen equation was used to determine 24-h urinary iodine and sodium excretion. The median urinary iodine concentration (mUIC) and urinary sodium concentration (mUNaC) among adults (n = 3513) were 132.0 µg/L and 4.0 g/d, respectively. The mUIC and median daily iodine intake in CUA, Non-CUA, CRA and Non-CRA were 112.1, 127.5, 128.5, 167.5 µg/L and 189.6, 182.5, 199.4, 236.0 µg/d, respectively. The mUNaC and median daily salt intake (mDSI) in these four areas were 2.4, 2.8, 2.9, 2.9 g/L and 9.8, 10.4, 10.4, 10.6 g/d, respectively. The mUIC and DII of residents were higher in the Non-CRA than in the other three areas (P < 0.05). The UNaC and DSI of residents were lower in the CUA than in the other three areas (P < 0.05). The logistic regression demonstrated that the people living in CUA and Non-CUA consumed less salt compared with those in Non-CRA. Except for Non-CUA, the DII was lower (< 150 µg/d) among women of childbearing age in the low-salt intake group (< 5 g/d) compared with the high-salt intake group (≥ 5 g/d) (P < 0.05). Iodine nutrition in Chinese adults aged 18-59 years was sufficient, but the salt intake was substantially higher than the WHO and Chinese recommendations. Further policy implementation is needed to reduce salt intake and improve the monitoring of iodine levels in Chinese adults, especially in women of childbearing age.

Adherence to Mediterranean Diet, Dietary Salt Intake, and Susceptibility to Nephrolithiasis: A Case-Control Study.

Unhealthy dietary habits play a key role in the pathogenesis of nephrolithiasis (NL). The aims of this case-control study were to evaluate (i) the adherence to the Mediterranean Diet (MD) and the dietary salt intake in stone-forming patients (SF), (ii) the relationship occurring between MD adherence, salt intake and NL-related metabolic risk factors in SF, and (iii) the impact of combined high MD adherence and low salt intake on NL susceptibility. From 1 January 2018 to 31 December 2019, we recruited all SF consecutively referred to the Extracorporeal Shock Wave Lithotripsy (ESWL) center of Federico II University, and at least two control subjects without a personal history of NL, age-, sex-, and body mass index-matched to SF (NSF). All study participants were interviewed using the validated MEDI-LITE and MINISAL questionnaires. In an SF subgroup, the NL-related metabolic risk factors were also evaluated. SF showed a lower MD adherence and a higher salt intake compared with NSF. The NL susceptibility decreased by 36% [OR: 0.64 (0.59-0.70); p < 0.01] for each point of increase in MEDI-LITE score, while it increased by 13% [OR: 1.13 (1.03-1.25); p = 0.01] for each point of increase in MINISAL score. The SF prevalence was higher among subjects showing combined low MD adherence and high salt intake. In SF, the MEDI-LITE score directly correlated with 24 h-citraturia, whereas the MINISAL score directly correlated with urinary sodium and uric acid excretion. In conclusion, high MD adherence and low salt intake are associated with a reduced NL susceptibility, both separately and in combination.

In utero exposure to maternal diabetes exacerbates dietary sodium intake-induced endothelial dysfunction by activating cyclooxygenase 2-derived prostanoids.

Prenatal exposure to maternal diabetes has been recognized as a significant cardiovascular risk factor, increasing the susceptibility to the emergence of conditions such as high blood pressure, atherosclerosis, and heart disease in later stages of life. However, it is unclear if offspring exposed to diabetes in utero have worse vascular outcomes on a high-salt (HS) diet. To test the hypothesis that in utero exposure to maternal diabetes predisposes to HS-induced vascular dysfunction, we treated adult male wild-type offspring (DM_Exp, 6 mo old) of diabetic Ins2+/C96Y mice (Akita mice) with HS (8% sodium chloride, 10 days) and analyzed endothelial function via wire myograph and cyclooxygenase (COX)-derived prostanoids pathway by ELISA, quantitative PCR, and immunochemistry. On a regular diet, DM_Exp mice did not manifest any vascular dysfunction, remodeling, or inflammation. However, HS increased aortic contractility to phenylephrine and induced endothelial dysfunction (analyzed by acetylcholine-induced endothelium-dependent relaxation), vascular hydrogen peroxide production, COX2 expression, and prostaglandin E2 (PGE2) overproduction. Interestingly, ex vivo antioxidant treatment (tempol) or COX1/2 (indomethacin) or COX2 (NS398) inhibitors improved or reverted the endothelial dysfunction in DM_Exp mice fed a HS diet. Finally, DM_Exp mice fed with HS exhibited greater circulating cytokines and chemokines accompanied by vascular inflammation. In summary, our findings indicate that prenatal exposure to maternal diabetes predisposes to HS-induced vascular dysfunction, primarily through the induction of oxidative stress and the generation of COX2-derived PGE2. This supports the concept that in utero exposure to maternal diabetes is a cardiovascular risk factor in adulthood.NEW & NOTEWORTHY Using a unique mouse model of prenatal exposure to maternal type 1 diabetes, our study demonstrates the novel observation that prenatal exposure to maternal diabetes results in a predisposition to high-salt (HS) dietary-induced vascular dysfunction and inflammation in adulthood. Mechanistically, we demonstrated that in utero exposure to maternal diabetes and HS intake induces vascular oxidative stress, cyclooxygenase-derived prostaglandin E2, and inflammation.

Salt-Sensitive Hypertension and the Kidney.

Salt-sensitive hypertension (SS-HT) is characterized by blood pressure elevation in response to high dietary salt intake and is considered to increase the risk of cardiovascular and renal morbidity. Although the mechanisms responsible for SS-HT are complex, the kidneys are known to play a central role in the development of SS-HT and the salt sensitivity of blood pressure (SSBP). Moreover, several factors influence renal function and SSBP, including the renin-angiotensin-aldosterone system, sympathetic nervous system, obesity, and aging. A phenotypic characteristic of SSBP is aberrant activation of the renin-angiotensin system and sympathetic nervous system in response to excessive salt intake. SSBP is also accompanied by a blunted increase in renal blood flow after salt loading, resulting in sodium retention and SS-HT. Obesity is associated with inappropriate activation of the aldosterone mineralocorticoid receptor pathway and renal sympathetic nervous system in response to excessive salt, and mineralocorticoid receptor antagonists and renal denervation attenuate sodium retention and inhibit salt-induced blood pressure elevation in obese dogs and humans. SSBP increases with age, which has been attributed to impaired renal sodium handling and a decline in renal function, even in the absence of kidney disease. Aging-associated changes in renal hemodynamics are accompanied by significant alterations in renal hormone levels and renal sodium handling, resulting in SS-HT. In this review, we focus mainly on the contribution of renal function to the development of SS-HT.

Knocking Out Sodium Glucose-Linked Transporter 5 Prevents Fructose-Induced Renal Oxidative Stress and Salt-Sensitive Hypertension.

BACKGROUND: A fructose high-salt (FHS) diet increases systolic blood pressure and Ang II (angiotensin II)-stimulated proximal tubule (PT) superoxide (O2-) production. These increases are prevented by scavenging O2- or an Ang II type 1 receptor antagonist. SGLT4 (sodium glucose-linked cotransporters 4) and SGLT5 are implicated in PT fructose reabsorption, but their roles in fructose-induced hypertension are unclear. We hypothesized that PT fructose reabsorption by SGLT5 initiates a genetic program enhancing Ang II-stimulated oxidative stress in males and females, thereby causing fructose-induced salt-sensitive hypertension. METHODS: We measured systolic blood pressure in male and female Sprague-Dawley (wild type [WT]), SGLT4 knockout (-/-), and SGLT5-/- rats. Then, we measured basal and Ang II-stimulated (37 nmol/L) O2- production by PTs and conducted gene coexpression network analysis. RESULTS: In male WT and female WT rats, FHS increased systolic blood pressure by 15±3 (n=7; P<0.0027) and 17±4 mm Hg (n=9; P<0.0037), respectively. Male and female SGLT4-/- had similar increases. Systolic blood pressure was unchanged by FHS in male and female SGLT5-/-. In male WT and female WT fed FHS, Ang II stimulated O2- production by 14±5 (n=6; P<0.0493) and 8±3 relative light units/µg protein/s (n=7; P<0.0218), respectively. The responses of SGTL4-/- were similar. Ang II did not stimulate O2- production in tubules from SGLT5-/-. Five gene coexpression modules were correlated with FHS. These correlations were completely blunted in SGLT5-/- and partially blunted by chronically scavenging O2- with tempol. CONCLUSIONS: SGLT5-mediated PT fructose reabsorption is required for FHS to augment Ang II-stimulated proximal nephron O2- production, and increases in PT oxidative stress likely contribute to FHS-induced hypertension.

Co-activation of Mas and pGCA receptors suppresses Endothelin-1-induced endothelial dysfunction via nitric oxide/cGMP system.

BACKGROUND: The aortic endothelium is crucial in preserving vascular tone through endothelium-derived vasodilators and vasoconstrictors. Dysfunction in the endothelium is an early indicator of cardiovascular diseases. Our study explores the therapeutic potential of a dual-acting peptide (DAP) to co-activate Mas and pGCA receptors and restore the balance between vasodilators and vasoconstrictors on endothelial dysfunction in DOCA-salt-induced hypertensive rats. METHODS: DOCA-salt was administered to male wistar rats to induce hypertension, and various parameters, including blood pressure (BP), water intake and body weight were monitored. DAP, Ang1-7, BNP, and losartan were administered to hypertensive rats for three weeks. Histological analysis and isometric tension studies were carried out to assess endothelial function. In addition to this, we used primary aortic endothelial cells for detailed mechanistic investigations. RESULTS: DOCA-salt administration significantly elevated systolic, diastolic, mean arterial BP, and water intake whereas, downregulated the gene expression of Mas and pGCA receptors. However, DAP co-administration attenuated BP increase, upregulated the gene expression of Mas and pGCA receptors, normalized serum and urinary parameters, and effectively reduced fibrosis, inflammation, and vascular calcification. Notably, DAP outperformed the standard drug, Losartan. Our findings indicate that DAP restores aortic function by balancing the NO and ET1-induced pathways. CONCLUSION: Co-activating Mas and pGCA receptors with DAP mitigates vascular damage and enhances endothelial function, emphasizing its potential to maintain a delicate balance between vasodilatory NO and vasoconstrictor ET1 in endothelial dysfunction.