High salt intake increases blood pressure in normal rats: putative role of 20-HETE and no evidence on changes in renal vascular reactivity

Salt-sensitive hypertension in GR mutant rats is associated with altered plasma polyunsaturated fatty acid levels and aortic vascular reactivity

In humans, glucocorticoid resistance is attributed to mutations in the glucocorticoid receptor (GR). Most of these mutations result in decreased ligand binding, transactivation, and/or translocation, albeit with normal protein abundances. However, there is no clear genotype‒phenotype relationship between the severity or age at disease presentation and the degree of functional loss of the receptor. Previously, we documented that a GR+/- rat line developed clinical features of glucocorticoid resistance, namely, hypercortisolemia, adrenal hyperplasia, and salt-sensitive hypertension. In this study, we analyzed the GR+/em4 rat model heterozygously mutant for the deletion of exon 3, which encompasses the second zinc finger, including the domains of DNA binding, dimerization, and nuclear localization signals. On a standard diet, mutant rats exhibited a trend toward increased corticosterone levels and a normal systolic blood pressure and heart rate but presented with adrenal hyperplasia. They exhibited increased adrenal soluble epoxide hydroxylase (sEH), favoring an increase in less active polyunsaturated fatty acids. Indeed, a significant increase in nonactive omega-3 and omega-6 polyunsaturated fatty acids, such as 5(6)-DiHETrE or 9(10)-DiHOME, was observed with advanced age (10 versus 5 weeks old) and following a switch to a high-salt diet accompanied by salt-sensitive hypertension. In thoracic aortas, a reduced soluble epoxide hydrolase (sEH) protein abundance resulted in altered vascular reactivity upon a standard diet, which was blunted upon a high-salt diet. In conclusion, mutations in the GR affecting the ligand-binding domain as well as the dimerization domain resulted in deregulated GR signaling, favoring salt-sensitive hypertension in the absence of obvious mineralocorticoid excess.

Effect of low sodium and high potassium diet on lowering blood pressure and cardiovascular events

Incorporating aggressive lifestyle modifications along with antihypertensive medication therapy is a crucial treatment strategy to enhance the control rate of hypertension. Dietary modification is one of the important lifestyle interventions for hypertension, and it has been proven to have a clear effect. Among food ingredients, sodium and potassium have been found to have the strongest association with blood pressure. The blood pressure-lowering effect of a low sodium diet and a high potassium diet has been well established, especially in hypertensive population. A high intake of potassium, a key component of the Dietary Approaches to Stop Hypertension (DASH) diet, has also shown a favorable impact on the risk of cardiovascular events. Additionally, research conducted with robust measurement methods has shown cardiovascular benefits of low-sodium intake. In this review, we aim to discuss the evidence regarding the relationship between the low sodium and high potassium diet and blood pressure and cardiovascular events.

Hordeum vulgare ethanolic extract mitigates high salt-induced cerebellum damage via attenuation of oxidative stress, neuroinflammation, and neurochemical alterations in hypertensive rats

High salt intake increases inflammatory and oxidative stress responses and causes an imbalance of neurotransmitters involved in the pathogenesis of hypertension that is related to the onset of cerebral injury. Using natural compounds that target oxidative stress and neuroinflammation pathways remains a promising approach for treating neurological diseases. Barley (Hordeum vulgare L.) seeds are rich in protein, fiber, minerals, and phenolic compounds, that exhibit potent neuroprotective effects in various neurodegenerative diseases. Therefore, this work aimed to investigate the efficacy of barley ethanolic extract against a high salt diet (HSD)-induced cerebellum injury in hypertensive rats. Forty-eight Wistar rats were divided into six groups. Group (I) was the control. The second group, the HSD group, was fed a diet containing 8% NaCl. Groups II and III were fed an HSD and simultaneously treated with either amlodipine (1 mg /kg b.wt p.o) or barley extract (1000 mg /kg b.wt p.o) for five weeks. Groups IV and V were fed HSD for five weeks, then administered with either amlodipine or barley extract for another five weeks. The results revealed that barley treatment significantly reduced blood pressure and effectively reduced oxidative stress and inflammation in rat's cerebellum as indicated by higher GSH and nitric oxide levels and lower malondialdehyde, TNF-α, and IL-1ß levels. Additionally, barley restored the balance of neurotransmitters and improved cellular energy performance in the cerebellum of HSD-fed rats. These findings suggest that barley supplementation exerted protective effects against high salt-induced hypertension by an antioxidant, anti-inflammatory, and vasodilating effects and restoring neurochemical alterations.

Hordeum vulgare ethanolic extract mitigates high salt-induced cerebellum damage via attenuation of oxidative stress, neuroinflammation, and neurochemical alterations in hypertensive rats.. [DOI: 10.21203/rs.3.rs-2576993/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

High salt intake increases inflammatory and oxidative stress responses and causes an imbalance of neurotransmitters involved in the pathogenesis of hypertension that is related to the onset of cerebral injury. Using natural compounds that target oxidative stress and neuroinflammation pathways remains a promising approach for treating neurological diseases. Barley (Hordeum vulgare L.) seeds are rich in protein, fiber, minerals, and phenolic compounds, that exhibit potent neuroprotective effects in various neurodegenerative diseases. Therefore, this work aimed to investigate the efficacy of barley ethanolic extract against a high salt diet (HSD)-induced cerebellum injury in hypertensive rats. Forty-eight Wistar rats were divided into six groups. Group (I) was the control. The second group, the HSD group, was fed a diet containing 8% NaCl. Groups II and III were fed an HSD and simultaneously treated with either amlodipine (1 mg /kg b.wt p.o) or barley extract (1000 mg /kg b.wt p.o) for five weeks. Groups IV and V were fed HSD for five weeks, then administered with either amlodipine or barley extract for another five weeks. The results revealed that barley treatment significantly reduced blood pressure and effectively reduced oxidative stress and inflammation in rat's cerebellum as indicated by higher GSH and nitric oxide levels and lower malondialdehyde, TNF-α, and IL-1ß levels. Additionally, barley restored the balance of neurotransmitters and improved cellular energy performance in the cerebellum of HSD-fed rats. These findings suggest that barley supplementation exerted protective effects against high salt-induced hypertension by an antioxidant, anti-inflammatory, and vasodilating effects and restoring neurochemical alterations.

The impact of a high-sodium diet regimen on cerebrovascular morphology and cerebral perfusion in Alzheimer's disease

Introduction

Various lifestyle factors such as chronic hypertension and a high-sodium diet regimen are shown to impact cerebrovascular morphology and structure. Unusual cerebrovascular morphological and structural changes may contribute to cerebral hypoperfusion in Alzheimer's disease (AD). The objective of this study was to examine whether a high-sodium diet mediates cerebrovascular morphology and cerebral perfusion alterations in AD.

Methods

Double transgenic mice harboring Aβ precursor protein (APPswe) and presenilin-1 (PSEN1) along with wild-type controls were divided into four groups. Group A (APP/PS1) and B (controls) were both fed a high-sodium (4.00%), while group C (APP/PS1) and D (controls) were both fed a low-sodium (0.08% a regular chow diet) for three months. Then, changes in regional cerebral perfusion and diffusion, cerebrovascular morphology, and structure were quantified.

Results

A 3-month high-sodium diet causes pyknosis and deep staining in hippocampal neurons and reduced vascular density in both hippocampal and cortical areas (p <0.001) of APP/PS1. Despite vascular density changes, cerebral perfusion was not increased markedly (p = 0.3) in this group, though it was increased more in wild-type controls (p = 0.022).

Conclusion

A high-sodium diet regimen causes cerebrovascular morphology alteration in APP/PS1 mouse model of AD.

Sodium Intake and Disease: Another Relationship to Consider

Sodium (Na+) is crucial for numerous homeostatic processes in the body and, consequentially, its levels are tightly regulated by multiple organ systems. Sodium is acquired from the diet, commonly in the form of NaCl (table salt), and substances that contain sodium taste salty and are innately palatable at concentrations that are advantageous to physiological homeostasis. The importance of sodium homeostasis is reflected by sodium appetite, an "all-hands-on-deck" response involving the brain, multiple peripheral organ systems, and endocrine factors, to increase sodium intake and replenish sodium levels in times of depletion. Visceral sensory information and endocrine signals are integrated by the brain to regulate sodium intake. Dysregulation of the systems involved can lead to sodium overconsumption, which numerous studies have considered causal for the development of diseases, such as hypertension. The purpose here is to consider the inverse-how disease impacts sodium intake, with a focus on stress-related and cardiometabolic diseases. Our proposition is that such diseases contribute to an increase in sodium intake, potentially eliciting a vicious cycle toward disease exacerbation. First, we describe the mechanism(s) that regulate each of these processes independently. Then, we highlight the points of overlap and integration of these processes. We propose that the analogous neural circuitry involved in regulating sodium intake and blood pressure, at least in part, underlies the reciprocal relationship between neural control of these functions. Finally, we conclude with a discussion on how stress-related and cardiometabolic diseases influence these circuitries to alter the consumption of sodium.

Blood pressure and the kidney cortex transcriptome response to high-sodium diet challenge in female nonhuman primates

Blood pressure (BP) is influenced by genetic variation and sodium intake with sex-specific differences; however, studies to identify renal molecular mechanisms underlying the influence of sodium intake on BP in nonhuman primates (NHP) have focused on males. To address the gap in our understanding of molecular mechanisms regulating BP in female primates, we studied sodium-naïve female baboons (n = 7) fed a high-sodium (HS) diet for 6 wk. We hypothesized that in female baboons variation in renal transcriptional networks correlates with variation in BP response to a high-sodium diet. BP was continuously measured for 64-h periods throughout the study by implantable telemetry devices. Sodium intake, blood samples for clinical chemistries, and ultrasound-guided kidney biopsies were collected before and after the HS diet for RNA-Seq and bioinformatic analyses. We found that on the LS diet but not the HS diet, sodium intake and serum 17 β-estradiol concentration correlated with BP. Furthermore, kidney transcriptomes differed by diet-unbiased weighted gene coexpression network analysis revealed modules of genes correlated with BP on the HS diet but not the LS diet. Our results showed variation in BP on the HS diet correlated with variation in novel kidney gene networks regulated by ESR1 and MYC; i.e., these regulators have not been associated with BP regulation in male humans or rodents. Validation of the mechanisms underlying regulation of BP-associated gene networks in female NHP will inform better therapies toward greater precision medicine for women.

Animal models of hypertension: The status of nitric oxide and oxidative stress and the role of the renal medulla

Hypertension significantly contributes to overall morbidity and mortality worldwide, and animal models of hypertension provide important tools to verify the physiological and molecular mechanisms underlying the development of the disease. A review of the most important models available would provide an insight into the appropriate targets to be addressed in the treatment of different forms of human hypertension. In the animal models discussed a special attention is given to the status and pathophysiological role of nitric oxide and its interaction with reactive oxygen species and oxidative stress. Another focus of the review are the processes running in the renal medulla which are still insufficiently explored. Deficient nitric oxide synthesis and its reduced bioavailability are important determinants of hypertension since NO is recognized as a major control factor of vascular tone homeostasis. For decades perfusion of the renal medulla has also been regarded as one of the blood pressure control factors and, noteworthily, the renal medulla belongs to the tissues with the highest NO content. The list of most often applied animal hypertension models reviewed here includes variants of salt-induced hypertension, the models with genetic background: such as spontaneously hypertensive rats (SHR) and Dahl salt sensitive (SS/SR) rats, Goldblatt 2K-1C hypertensive rats, and also the pharmacologically-plus-dietary salt-induced model known as DOCA-salt hypertension.

European Society of Cardiology: cardiovascular disease statistics 2021

AIMS

This report from the European Society of Cardiology (ESC) Atlas Project updates and expands upon the widely cited 2019 report in presenting cardiovascular disease (CVD) statistics for the 57 ESC member countries.

METHODS AND RESULTS

Statistics pertaining to 2019, or the latest available year, are presented. Data sources include the World Health Organization, the Institute for Health Metrics and Evaluation, the World Bank, and novel ESC sponsored data on human and capital infrastructure and cardiovascular healthcare delivery. New material in this report includes sociodemographic and environmental determinants of CVD, rheumatic heart disease, out-of-hospital cardiac arrest, left-sided valvular heart disease, the advocacy potential of these CVD statistics, and progress towards World Health Organization (WHO) 2025 targets for non-communicable diseases. Salient observations in this report: (i) Females born in ESC member countries in 2018 are expected to live 80.8 years and males 74.8 years. Life expectancy is longer in high income (81.6 years) compared with middle-income (74.2 years) countries. (ii) In 2018, high-income countries spent, on average, four times more on healthcare than middle-income countries. (iii) The median PM2.5 concentrations in 2019 were over twice as high in middle-income ESC member countries compared with high-income countries and exceeded the EU air quality standard in 14 countries, all middle-income. (iv) In 2016, more than one in five adults across the ESC member countries were obese with similar prevalence in high and low-income countries. The prevalence of obesity has more than doubled over the past 35 years. (v) The burden of CVD falls hardest on middle-income ESC member countries where estimated incidence rates are ∼30% higher compared with high-income countries. This is reflected in disability-adjusted life years due to CVD which are nearly four times as high in middle-income compared with high-income countries. (vi) The incidence of calcific aortic valve disease has increased seven-fold during the last 30 years, with age-standardized rates four times as high in high-income compared with middle-income countries. (vii) Although the total number of CVD deaths across all countries far exceeds the number of cancer deaths for both sexes, there are 15 ESC member countries in which cancer accounts for more deaths than CVD in males and five-member countries in which cancer accounts for more deaths than CVD in females. (viii) The under-resourced status of middle-income countries is associated with a severe procedural deficit compared with high-income countries in terms of coronary intervention, ablation procedures, device implantation, and cardiac surgical procedures.

CONCLUSION

Risk factors and unhealthy behaviours are potentially reversible, and this provides a huge opportunity to address the health inequalities across ESC member countries that are highlighted in this report. It seems clear, however, that efforts to seize this opportunity are falling short and present evidence suggests that most of the WHO NCD targets for 2025 are unlikely to be met across ESC member countries.

Role of Ang1-7 in renal haemodynamics and excretion in streptozotocin diabetic rats

The contribution of angiotensin (1-7) (Ang1-7) to control of extrarenal and renal function may be modified in diabetes. We investigated the effects of Ang1-7 supplementation on blood pressure, renal circulation and intrarenal reactivity (IVR) to vasoactive agents in normoglycaemic (NG) and streptozotocin diabetic rats (DM). In Sprague Dawley DM and NG rats, 3 weeks after streptozotocin (60 mg/kg i.p.) or solvent injection, Ang1-7 was administered (400 ng/min) over the next 2 weeks using subcutaneously implanted osmotic minipumps. For a period of 5 weeks, blood pressure (BP), 24 h water intake and diuresis were determined weekly. In anaesthetised rats, BP, renal total and cortical (CBF), outer (OMBF) and inner medullary (IMBF) perfusion and urine excretion were determined. To check IVR, a short-time infusion of acetylcholine or norepinephrine was randomly given to the renal artery. Unexpectedly, BP did not differ between NG and DM, and this was not modified by Ang-1-7 supplementation. Baseline IMBF was higher in NG vs. DM, and Ang1-7 treatment did not change it in NG but decreased it in DM. In the latter, Ang1-7 increased cortical IVR to vasoconstrictor and vasodilator stimuli. IMBF decrease after high acetylcholine dose seen in untreated NG was reverted to an increase in Ang1-7 treated rats. Irrespective of the glycaemia level, Ang1-7 did not modify BP. However, it impaired medullary circulation in DM, whereas in NG it rendered the medullary vasculature more sensitive to vasodilators. Possibly, the medullary hypoperfusion in DM was mediated by Ang1-7 activation of angiotensin AT-1 receptors which are upregulated by hyperglycaemia.

Impact of Brazil Nut (Bertholletia excelsa, H.B.K.) Supplementation on Body Composition, Blood Pressure, and the Vascular Reactivity of Wistar Rats When Submitted to a Hypersodium Diet

Introdution: Endothelium integrity is a key that maintains vascular homeostasis but it can suffer irreversible damage by blood pressure changes, reflecting an imbalance in the maintenance of vascular homeostasis.Objective: The aim of this study was to investigate the impact of Brazil nut (Bertholletia excelsa, H.B.K.) (BN) supplementation (10% in chow, wt/wt) on the vascular reactivity of Wistar rats during chronic exposure to a sodium overload (1% in water).Methods: First, male Wistar rats were allocated into two groups: Control Group (CG) and the Hypersodic Group (HG) for 4 weeks. Afterward, the CG was divided into the Brazil Nut Group (BNG) and the HG Group into the Hypersodic Brazil Nut Group (HBNG) for a further 8 weeks, totaling 4 groups. Blood pressure was measured during the protocol. At the end of the protocol, the vascular reactivity procedure was performed. Glucose, lipid profile, lipid peroxidation, and platelet aggregation were analyzed in the serum. Body composition was determined by the carcass technique.Results: The groups that were supplemented with the BN chow presented less body mass gain and body fat mass, together with lower serum glucose levels. The HG Group presented an increase in blood pressure and a higher platelet aggregation, while the BN supplementation was able to blunt this effect. The HG Group also showed an increase in contractile response that was phenylephrine-induced and a decrease in maximum relaxation that was acetylcholine-induced when compared to the other groups.Conclusion: The BN supplementation was able to prevent an impaired vascular function in the early stages of arterial hypertension, while also improving body composition, serum glucose, and platelet aggregation.

Early Renal Vasodilator and Hypotensive Action of Epoxyeicosatrienoic Acid Analog (EET-A) and 20-HETE Receptor Blocker (AAA) in Spontaneously Hypertensive Rats

Cytochrome P450 (CYP-450) metabolites of arachidonic acid: epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE) have established role in regulation of blood pressure (BP) and kidney function. EETs deficiency and increased renal formation of 20-HETE contribute to hypertension in spontaneously hypertensive rats (SHR). We explored the effects of 14,15-EET analog (EET-A) and of 20-HETE receptor blocker (AAA) on BP and kidney function in this model. In anesthetized SHR the responses were determined of mean arterial blood pressure (MABP), total renal (RBF), and cortical (CBF) and inner-medullary blood flows, glomerular filtration rate and renal excretion, to EET-A, 5 mg/kg, infused i.v. for 1 h to rats untreated or after blockade of endogenous EETs degradation with an inhibitor (c-AUCB) of soluble epoxide hydrolase. Also examined were the responses to AAA (10 mg/kg/h), given alone or together with EET-A. EET-A significantly increased RBF and CBF (+30% and 26%, respectively), seen already within first 30 min of infusion. The greatest increases in RBF and CBF (by about 40%) were seen after AAA, similar when given alone or combined with EET-A. MABP decreased after EET-A or AAA but not significantly after the combination thereof. In all groups, RBF, and CBF increases preceded the decrease in MABP. We found that in SHR both EET-A and AAA induced renal vasodilation but, unexpectedly, no additive effect was seen. We suggest that both agents have a definite therapeutic potential and deserve further experimental and clinical testing aimed at introduction of novel antihypertensive therapy.

Modulation of Cellular Biochemistry, Epigenetics and Metabolomics by Ketone Bodies. Implications of the Ketogenic Diet in the Physiology of the Organism and Pathological States

Ketone bodies (KBs), comprising β-hydroxybutyrate, acetoacetate and acetone, are a set of fuel molecules serving as an alternative energy source to glucose. KBs are mainly produced by the liver from fatty acids during periods of fasting, and prolonged or intense physical activity. In diabetes, mainly type-1, ketoacidosis is the pathological response to glucose malabsorption. Endogenous production of ketone bodies is promoted by consumption of a ketogenic diet (KD), a diet virtually devoid of carbohydrates. Despite its recently widespread use, the systemic impact of KD is only partially understood, and ranges from physiologically beneficial outcomes in particular circumstances to potentially harmful effects. Here, we firstly review ketone body metabolism and molecular signaling, to then link the understanding of ketone bodies’ biochemistry to controversies regarding their putative or proven medical benefits. We overview the physiological consequences of ketone bodies’ consumption, focusing on (i) KB-induced histone post-translational modifications, particularly β-hydroxybutyrylation and acetylation, which appears to be the core epigenetic mechanisms of activity of β-hydroxybutyrate to modulate inflammation; (ii) inflammatory responses to a KD; (iii) proven benefits of the KD in the context of neuronal disease and cancer; and (iv) consequences of the KD’s application on cardiovascular health and on physical performance.

Effect of dose and duration of reduction in dietary sodium on blood pressure levels: systematic review and meta-analysis of randomised trials

OBJECTIVE

To examine the dose-response relation between reduction in dietary sodium and blood pressure change and to explore the impact of intervention duration.

DESIGN

Systematic review and meta-analysis following PRISMA guidelines.

DATA SOURCES

Ovid MEDLINE(R), EMBASE, and Cochrane Central Register of Controlled Trials (Wiley) and reference lists of relevant articles up to 21 January 2019.

INCLUSION CRITERIA

Randomised trials comparing different levels of sodium intake undertaken among adult populations with estimates of intake made using 24 hour urinary sodium excretion.

DATA EXTRACTION AND ANALYSIS

Two of three reviewers screened the records independently for eligibility. One reviewer extracted all data and the other two reviewed the data for accuracy. Reviewers performed random effects meta-analyses, subgroup analyses, and meta-regression.

RESULTS

133 studies with 12 197 participants were included. The mean reductions (reduced sodium v usual sodium) of 24 hour urinary sodium, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were 130 mmol (95% confidence interval 115 to 145, P<0.001), 4.26 mm Hg (3.62 to 4.89, P<0.001), and 2.07 mm Hg (1.67 to 2.48, P<0.001), respectively. Each 50 mmol reduction in 24 hour sodium excretion was associated with a 1.10 mm Hg (0.66 to 1.54; P<0.001) reduction in SBP and a 0.33 mm Hg (0.04 to 0.63; P=0.03) reduction in DBP. Reductions in blood pressure were observed in diverse population subsets examined, including hypertensive and non-hypertensive individuals. For the same reduction in 24 hour urinary sodium there was greater SBP reduction in older people, non-white populations, and those with higher baseline SBP levels. In trials of less than 15 days' duration, each 50 mmol reduction in 24 hour urinary sodium excretion was associated with a 1.05 mm Hg (0.40 to 1.70; P=0.002) SBP fall, less than half the effect observed in studies of longer duration (2.13 mm Hg; 0.85 to 3.40; P=0.002). Otherwise, there was no association between trial duration and SBP reduction.

CONCLUSIONS

The magnitude of blood pressure lowering achieved with sodium reduction showed a dose-response relation and was greater for older populations, non-white populations, and those with higher blood pressure. Short term studies underestimate the effect of sodium reduction on blood pressure.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019140812.

Effects of High Salt-Low Potassium Diet on Blood Pressure and Vascular Reactivity in Male Sprague Dawley Rats

Sodium (Na) intake increases vascular reactivity. Whether low potassium (K) intake affects vascular reactivity-associated blood pressure (BP) changes is uncertain. This study aimed to determine whether Na-induced increases in BP and vascular reactivity are altered by low K intake. Male Sprague Dawley rats were assigned to 3 dietary groups for 6 weeks: a standard Na-K diet (control, n = 12), a high Na-normal K diet (HS-NormK, n = 12), and a high Na-low K diet (HS-LowK, n = 12). BP was measured at baseline and after the dietary intervention. Na and K excretions and vascular reactivity were measured after the dietary intervention. The Na/K ratio was significantly higher in the HS-LowK compared with the other groups. Systolic and diastolic BPs increased significantly in the HS-NormK and HS-LowK groups. In mesenteric arteries, the dose-response curves for phenylephrine-induced contractions shifted to the left and the EC50 (mean ± SD) was significantly lower in the HS-NormK (0.51 ± 0.17 μM, P = 0.003) and HS-LowK (0.69 ± 0.14 μM, P = 0.005) groups compared with the control (3.24 ± 0.79 μM). Systolic (r = -0.58 P = 0.002) and diastolic (r = -0.61 P = 0.001) BPs were associated with the EC50 of phenylephrine-induced contraction in mesenteric arteries. High Na intake induces increased alpha-1 receptor responsiveness in mesenteric arteries, which may be responsible for the increase in BP and is not affected by low dietary K intake.

NFAT5 is differentially expressed in Sprague-Dawley rat tissues in response to high salt and high fructose diets

Current diets contain an increasing amount of salt and high fructose corn syrup, but it remains unclear as to how dietary salt and fructose affect organ function at the molecular level. This study aimed to test the hypothesis that consumption of high salt and fructose diets would increase tissue-specific expression of two critical osmotically-regulated genes, nuclear factor of activated T-cells 5 (NFAT5) and aldose reductase (AR). Fifty Sprague-Dawley rats were placed on a control, 4% NaCl, 8% NaCl, or 64% fructose diet for eight weeks. Fourteen different tissue samples were harvested and snap-frozen, followed by RNA purification, cDNA synthesis, and NFAT5 and AR gene expression quantification by real-time PCR.Our findings demonstrate that NFAT5 and AR expression are up-regulated in the kidney medulla, liver, brain, and adipose tissue following consumption of a high salt diet. NFAT5 expression is also up-regulated in the kidney cortex following consumption of a 64% fructose diet. These findings highlight the kidney medulla, liver, brain, and adipose tissue as being “salt-responsive” tissues and reveal that a high fructose diet can lead to enhanced NFAT5 expression in the kidney cortex. Further characterization of signaling mechanisms involved could help elucidate how these diets affect organ function long term.

Conflicting roles of 20-HETE in hypertension and renal end organ damage

20-HETE is a cytochrome P450-derived metabolite of arachidonic acid that has both pro- and anti-hypertensive actions that result from modulation of vascular and kidney function. In the vasculature, 20-HETE sensitizes vascular smooth muscle cells to constrictor stimuli and increases myogenic tone. By promoting smooth muscle cell migration and proliferation, as well as by acting on the vascular endothelium to cause endothelial dysfunction, angiotensin converting enzyme (ACE) expression, and inflammation, 20-HETE contributes to adverse vascular remodeling and increased blood pressure. A G protein-coupled receptor was recently identified as the effector for the vascular actions of 20-HETE. In addition, evidence suggests that 20-HETE contributes to hypertension via positive regulation of the renin-angiotensin-aldosterone system, as well as by causing renal fibrosis. On the other hand, 20-HETE exerts anti-hypertensive actions by inhibiting sodium reabsorption by the kidney in both the proximal tubule and thick ascending limb of Henle. This review discusses the pro- and anti-hypertensive roles of 20-HETE in the pathogenesis of hypertension-associated renal disease, the association of gene polymorphisms of cytochrome P450 enzymes with the development of hypertension and renal end organ damage in humans, and 20-HETE related pharmaceutical agents.

1-Aminobenzotriazole: A Mechanism-Based Cytochrome P450 Inhibitor and Probe of Cytochrome P450 Biology

1-Aminobenzotriazole (1-ABT) is a pan-specific, mechanism-based inactivator of the xenobiotic metabolizing forms of cytochrome P450 in animals, plants, insects, and microorganisms. It has been widely used to investigate the biological roles of cytochrome P450 enzymes, their participation in the metabolism of both endobiotics and xenobiotics, and their contributions to the metabolism-dependent toxicity of drugs and chemicals. This review is a comprehensive evaluation of the chemistry, discovery, and use of 1-aminobenzotriazole in these contexts from its introduction in 1981 to the present.

High-Sodium Diet Has Opposing Effects on Mean Arterial Blood Pressure and Cerebral Perfusion in a Transgenic Mouse Model of Alzheimer's Disease

BACKGROUND

Cerebral ionic homeostasis impairment, especially Ca2+, has been observed in Alzheimer's disease (AD) and also with hypertension. Hypertension and AD both have been implicated in impaired cerebral autoregulation. However, the relationship between the ionic homeostasis impairment in AD and hypertension and cerebral blood flow (CBF) autoregulation is not clear.

OBJECTIVE

To test the hypothesis that a high-salt diet regimen influences the accumulation of amyloid-β (Aβand CBF) and CBF, exacerbates cognitive decline, and increases the propensity to AD.

METHODS

Double transgenic mice harboring the amyloid-β protein precursor (APPswe), and presenilin-1 (PSEN1) along with control littermates, 2 months of age at initiation of special diet, were divided into 4 groups: Group A, APP/PS1 and Group B, controls fed a high-sodium (4.00%) chow diet for 3 months; Group C, APP/PS1 and Group D, controls fed a low-sodium (0.08%) regular chow diet for 3 months. Mean arterial blood pressure (MAP) and CBF were measured noninvasively using the tail MAP measurement device and magnetic resonance imaging, respectively. Aβ plaques numbers in the cortex and hippocampus of APP/PS1 were quantified.

RESULTS

In contrary to controls, APP/PS1 mice fed a high-salt diet did not show markedly elevated mean systolic and diastolic blood pressure (134±4.8 compared with 162±2.8 mmHg, and 114±5.0 compared with 137±20 mmHg, p< 0.0001). However, a high-salt diet increased CBF in both APP/PS1 and controls and did not alter the cerebral tissue integrity. Aβ plaques were significantly reduced in the cortex and hippocampus of mice fed a high-salt diet.

CONCLUSION

These data suggest that a high-salt diet differently affects MAP and CBF in APP/PS1 mice and controls.