Reactive oxygen species in hypertension

Design, synthesis, and biological evaluation of TRPV4-KCa2.3 coupling enhancers as novel therapeutic agents for hypertension

Although current treatment strategies for hypertension are well-developed, there remains a group of patients who do not respond adequately to available medications. As a result, the identification of new therapeutic targets and the design of target-specific drugs are crucial directions for the future management of hypertension. Our previous research identified the TRPV4-KCa2.3 complex as a novel target for hypertension treatment, leading to the discovery of the positive compound JNc-440. Using JNc-440 as a lead molecule, 21 compounds were designed and synthesized across five distinct series. Among these, representative compounds IB-2 and II-9 demonstrated the ability to restore the coupling of the decoupled complex under hypertensive conditions and significantly reduced blood pressure in a high salt-induced hypertensive mouse model. This work lays a foundation for the future development of novel therapeutics targeting hypertension.

Reactivity of trinuclear ruthenium acetates with nitrite and nitric oxide ligands in aqueous media

The chemical reactivity of nitrosyl- and nitrite-coordinated compounds in an aqueous environment is a vital part of understanding the action of these compounds as potential nitric oxide-releasing molecules (NORMs). This work reports the behaviour of the [Ru3O(CH3COO)6(py)2NO2] (1) complex, which is an isomeric mixture of nitrite-N and nitrite-O, and the nitrosyl complex [Ru3O(CH3COO)6(py)2NO]PF6 (2) in aqueous medium with and without light irradiation. NO release under light irradiation was detected through chronoamperometry, which showed that nitrite complex 1 produces NO but is less effective than nitrosyl complex 2. This difference is due to the mechanism of NO production by complex 1, which depends on the nitrite-O isomer, present in minor proportion in the synthetic sample, as shown by computational and NMR data. The reactivity of these compounds in the dark was investigated under various pH values. The nitrite complex 1 had the coordinated nitrite converted to NO+, with a pK = 4.2. NO+ was readily released, yielding the solvate species [Ru3O(CH3COO)6(py)2S]+. For the nitrosyl complex 2, two successive nucleophilic attacks by hydroxide ions were observed producing the [Ru3O(CH3COO)6(py)2HNO2] (3) and [Ru3O(CH3COO)6(py)2NO2]- (4) compounds, with pK values of 9.8 and 12.3, respectively. In buffered solutions (TRIS.HCl and PBS), the kinetic trace for the conversion of 2 to 3 suggested an induction period followed by the complete conversion to [Ru3O(CH3COO)6(py)2HNO2] at pH values where the nitrosyl [Ru3O(CH3COO)6(py)2NO]+ should be the major species. Based on these observations, our data suggest a sequence of steps in which compound 3 accumulates and then, with the aid of the buffer components, increases the rate of its own formation.

iPSC-derived cardiomyocytes and engineered heart tissues reveal suppressed JAK2/STAT3 signaling in LMNA-related emery-dreifuss muscular dystrophy

LMNA mutation related Emery-Dreifuss muscular dystrophy (LMNA-related EDMD), is a rare genetic disorder often involving life-threatening cardiac complications. However, the molecular links between LMNA mutations and their related EDMD cardiac phenotypes have remained unclear. Here, using EDMD patient-specific and genome-edited induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), we link the LMNA L204P mutation with the pathogenic phenotypes of arrhythmia and contractile dysfunction. Using multi-omics analysis, we then show that LMNA L204P results in decreased chromatin accessibility, leading to the downregulation of JAK2 in EDMD iPSC-CMs. Mechanistically, JAK2/STAT3 signaling pathway suppression in EDMD iPSC-CMs is shown to cause mitochondrial dysfunction and oxidative stress, ultimately resulting in the above phenotypes. Conversely, pharmacological or genetic activation of JAK2/STAT3 signaling effectively rescues both the arrhythmic and contractile dysfunction phenotypes in EDMD iPSC-CMs via improvements in mitochondrial function. In addition, whilst EDMD engineered heart tissues (EHTs) display dysfunctional contractile force generation, this can also be significantly alleviated by STAT3 activation. Taken together, we present chromatin compartment change-mediated JAK2/STAT3 suppression as a novel mechanism underlying cardiac pathogenic phenotypes in LMNA-related EDMD. Our findings indicate that activating the JAK2/STAT3 signaling pathway may hold the potential to serve as a novel therapeutic strategy for this condition.

Non-central symmetric 2D bismuth-based perovskites for piezoelectric-enhanced sonodynamic immunotherapy

Sonodynamic therapy (SDT), an emerging treatment modality, exhibits great potential in cancer therapy owing to its excellent tissue penetration, immune activation ability, and relatively low side effects. The lattice distortion of inorganic perovskite is challenging to control, which leads to an unsatisfactory SDT effect. This study presents a two-dimensional bismuth-based halide perovskite material, MA3Bi2Cl9-PEG (MBCP), with favorable piezoelectric properties, being first applied to tumor sonodynamic immunotherapy. By introducing methylamine cations, the central symmetry of MBC is effectively disrupted, resulting in a non-centrosymmetric crystal structure. This structural modification remarkably enhances the piezoelectric performance, enabling more robust charge separation effects under ultrasound excitation and thus facilitating the efficient generation of reactive oxygen species (ROS). Moreover, the generated ROS triggers immunogenic cell death in tumor cells, through the depletion of excessive glutathione and the inhibition of glutathione peroxidase 4, induces ferroptosis. The combined therapeutic strategy substantially enhances the anti-tumor efficacy and effectively suppresses lung metastasis. This research offers a promising example of the application of perovskite piezoelectric materials in sonodynamic immunotherapy.

Reactive oxygen species-dependent nanomedicine therapeutic modalities for gastric cancer

Reactive oxygen species (ROS) play a double-edged role in gastric cancer (GC). Higher levels of ROS in tumor cells compared to normal cells facilitate tumor progression. Once ROS concentrations rise rapidly to toxic levels, they cause GC cell death, which is instead beneficial for GC treatment. Based on these functions, nano-delivery systems taking the therapeutic advantages of ROS have been widely employed in tumor therapy in recent years, overcoming the drawbacks of conventional drug delivery techniques, such as non-specific systemic effects. In this review, the precise impacts of ROS on GC have been detailed, along with ROS-based nanomedicine therapeutic schemes. These strategies mainly focused on the use of excess ROS in the tumor microenvironment for controlled drug release and a substantial enhancement of ROS concentrations for tumor killing. The challenges and opportunities for the advancement of these anticancer therapies are also emphasized.

Linking oxidative stress biomarkers to disease progression and antioxidant therapy in hypertension and diabetes mellitus

Oxidative stress (OS) is increasingly recognized as a key factor linking hypertension (HTN) and diabetes mellitus (DM). This review summarizes recent evidence regarding the dual role of OS as both an instigator and an amplifier of cardiometabolic dysfunction. In HTN, reactive oxygen species (ROS) produced by NADPH oxidases (NOXs) and mitochondrial dysfunction contribute to endothelial impairment and vascular remodeling. In DM, hyperglycemia-induced ROS production worsens beta-cell failure and insulin resistance through pathways such as the AGE-RAGE signaling, protein kinase C (PKC) activation, and the polyol pathway. Clinically validated biomarkers of OS, such as F2-isoprostanes (which indicate lipid peroxidation), 8-OHdG (which indicates DNA damage), and the activities of redox enzymes like superoxide dismutase (SOD) and glutathione peroxidase (GPx), show strong correlations with disease progression and end-organ complications. Despite promising preclinical results, the application of antioxidant therapies in clinical settings has faced challenges due to inconsistent outcomes, highlighting the need for targeted approaches. Emerging strategies include: 1. Mitochondria-targeted antioxidants to enhance vascular function in resistant HTN; 2. Nrf2 activators to restore redox balance in early diabetes; and 3. Specific inhibitors of NOX isoforms. We emphasize three transformative areas of research: (i) the interaction between the microbiome and ROS, where modifying gut microbiota can reduce systemic OS; (ii) the use of nanotechnology to deliver antioxidants directly to pancreatic islets or atherosclerotic plaques; and (iii) phenotype-specific diagnosis and therapy guided by redox biomarkers and genetic profiling (for example, KEAP1/NRF2 polymorphisms). Integrating these advances with lifestyle modifications, such as following a Mediterranean diet and exercising regularly, may provide additional benefits. This review outlines a mechanistic framework for targeting OS in the comorbidity of HTN and DM while identifying critical knowledge gaps, particularly regarding the timing of antioxidant signaling and the development of personalized redox medicine, which may serve as a reference for researchers and clinicians working in this area.

KLF15 prevents ferroptosis in vascular smooth muscle cells via interacting with p53

The formation of intracranial aneurysm (IA) is intimately linked to the progressive loss of vascular smooth muscle cells (VSMCs). Reactive oxygen species (ROS) play a pivotal role in inducing VSMC death during IA progression. Krüppel-like factor 15 (KLF15) plays a crucial role in preserving vascular homeostasis. However, the potential impact of KLF15 on ROS-triggered VSMC death remains unexplored. Analysis of microarray datasets from the GEO database suggests reduced KLF15 levels in human IA tissues. This study further confirms decreased KLF15 expression in ROS-treated human brain VSMCs (HBVSMCs). An unbiased examination of the transcriptome in HBVSMCs transfected with siKLF15 reveals that KLF15 regulates the ferroptosis pathway upon ROS stress. Silencing KLF15 results in the upregulation of genes promoting ferroptosis, such as SAT1, HMOX1, and MAP1LC3B, while downregulation of the ferroptosis regulatory gene SLC7A11. Cell death increases in KLF15-silenced HBVSMCs and is rescued by the ferroptosis inhibitor frerrostain-1. Co-immunoprecipitation and in situ proximity ligation assay indicate that KLF15 interacts with p53. Knockdown of p53 rescues the effects of siKLF15 on ROS-induced ferroptosis, including elevated cell death, lipid ROS levels, and the malondialdehyde content, as well as reduced SLC7A11protin levels in HBVSMCs. These findings suggest that KLF15 may lower cell sensitivity to ferroptosis by interacting with p53 and preventing p53-mediated transcriptional repression of SLC7A11. Overall, our results reveal a protective function of KLF15 in preventing ROS-induced ferroptosis in HBVSMCs.

Luminal flow in the connecting tubule induces afferent arteriole vasodilation

BACKGROUND

Renal autoregulatory mechanisms modulate renal blood flow. Connecting tubule glomerular feedback (CNTGF) is a vasodilator mechanism in the connecting tubule (CNT), triggered paracrinally when high sodium levels are detected via the epithelial sodium channel (ENaC). The primary activation factor of CNTGF-whether NaCl concentration, independent luminal flow, or the combined total sodium delivery-is still unclear. We hypothesized that increasing luminal flow in the CNT induces CNTGF via O2- generation and ENaC activation.

METHODS

Rabbit afferent arterioles (Af-Arts) with adjacent CNTs were microperfused ex-vivo with variable flow rates and sodium concentrations ranging from < 1 to 80 mM and from 5 to 40 nL/min flow rates.

RESULTS

Perfusion of the CNT with 5 mM NaCl and increasing flow rates from 5 to 10, 20, and 40 nL/min caused a flow-rate-dependent dilation of the Af-Art (P < 0.001). Adding the ENaC blocker benzamil inhibited flow-induced Af-Art dilation, indicating a CNTGF response. In contrast, perfusion of the CNT with < 1 mM NaCl did not result in flow-induced CNTGF vasodilation (P > 0.05). Multiple linear regression modeling (R2 = 0.51; P < 0.001) demonstrated that tubular flow (β = 0.163 ± 0.04; P < 0.001) and sodium concentration (β = 0.14 ± 0.03; P < 0.001) are independent variables that induce afferent arteriole vasodilation. Tempol reduced flow-induced CNTGF, and L-NAME did not influence this effect.

CONCLUSION

Increased luminal flow in the CNT induces CNTGF activation via ENaC, partially due to flow-stimulated O2- production and independent of nitric oxide synthase (NOS) activity.

Is there a link between the abundance of nitrate-reducing bacteria and arterial hypertension? A systematic review

CONTEXT

Nitric oxide is a vasodilator molecule that acts on blood pressure (BP) control, and its production can occur through the reduction of nitrates by oral or intestinal nitrate-reducing bacteria. However, the relationship between nitrate-reducing bacteria and arterial hypertension (HTN) remains under debate.

OBJECTIVE

Systematically review if there is an association between the abundance of oral and intestinal nitrate-reducing bacteria and the occurrence of HTN in humans.

DATABASES AND ELIGIBILITY CRITERIA

MEDLINE, Scopus, Cochrane Library, EMBASE, LILACS, Web of Science, Livivo, ProQuest Dissertations, and Google Scholar were searched for eligible articles until February 10th, 2024. Studies were included if they: (1) were observational studies or clinical trials; (2) included adults (≥18 years old) with HTN (systolic BP ≥ 130 mmHg and/or diastolic BP > 80 mmHg and/or use of BP lowering medication); (3) compared (or not) to no-HTN adults; and (4) used next-generation sequencing microbiome analysis to identify bacterial taxa in the oral and/or gut nitrate-reducing bacteria.

RESULTS

The search identified 9365 articles, and 28 were included in the study after applying the inclusion and exclusion criteria; 23 articles assessed the gut microbiota, 4 assessed the oral microbiota, and 1 assessed both. Depletion of nitrate-reducing bacteria was not consistently shown in the studies. The included studies reported reduction, increase, and no change in the nitrate-reducing bacteria genera or species in oral or gut microbiota.

CONCLUSION

We found no association between the abundance of oral and gut nitrate-reducing bacteria and the occurrence of HTN in humans.

REGISTRATION

PROSPERO identification number CRD42022315891.

Mitochondrial dysfunction in AMI: mechanisms and therapeutic perspectives

Acute myocardial infarction (AMI) and the myocardial ischemia-reperfusion injury (MI/RI) that typically ensues represent a significant global health burden, accounting for a considerable number of deaths and disabilities. In the context of AMI, percutaneous coronary intervention (PCI) is the preferred treatment option for reducing acute ischemic damage to the heart. Despite the modernity of PCI therapy, pathological damage to cardiomyocytes due to MI/RI remains an important target for intervention that affects the long-term prognosis of patients. In recent years, mitochondrial dysfunction during AMI has been increasingly recognized as a critical factor in cardiomyocyte death. Damaged mitochondria play an active role in the formation of an inflammatory environment by triggering key signaling pathways, including those mediated by cyclic GMP-AMP synthase, NOD-like receptors and Toll-like receptors. This review emphasizes the dual role of mitochondria as both contributors to and regulators of inflammation. The aim is to explore the complex mechanisms of mitochondrial dysfunction in AMI and its profound impact on immune dysregulation. Specific interventions including mitochondrial-targeted antioxidants, membrane-stabilizing peptides, and mitochondrial transplantation therapies have demonstrated efficacy in preclinical AMI models.

Chemiluminescence Resonance Energy Transfer for Targeted Photoactivation of Ion Channels in Living Cells

The regulation of oxidative stress in living cells is essential for maintaining cellular processes and signal transduction. However, developing straightforward strategies to activate oxidative stress-sensitive membrane channels in situ poses significant challenges. In this study, we present a chemiluminescence resonance energy transfer (CRET) system based on a conjugated oligomer, oligo(p-phenylenevinylene)-imidazolium (OPV-Im), designed for the activation of transient receptor potential melastatin 2 (TRPM2) calcium channels in situ by superoxide anion (O2⋅-) without requiring external light sources. The OPV-Im oligomer targeted the cell membrane efficiently, leading to the activation of TRPM2 channels in situ by the CRET process and subsequent intracellular calcium overload. This cascade resulted in mitochondrial damage and inhibition of autophagy, ultimately inducing cell apoptosis. Additionally, this strategy could be applied for the selective killing of tumor cells that overexpress TRPM2 ion channels and for inhibiting the growth of three-dimensional (3D) tumor spheroids. Our system offers a novel approach for regulating ion channel activity and oxidative stress in living cells compared to optogenetics and photodynamic therapy.

Role of oxidative balance score in staging and mortality risk of cardiovascular-kidney-metabolic syndrome: Insights from traditional and machine learning approaches

OBJECTIVES

To evaluate the roles of oxidative balance score (OBS) in staging and mortality risk of cardiovascular-kidney-metabolic syndrome (CKM).

METHODS

Data of this study were from the National Health and Nutrition Examination Survey 1999-2018. We performed cross-sectional analyses using multinomial logistic regression to investigate the relationship between OBS and CKM staging. Cox proportional hazards models were used to assess the impact of OBS on mortality outcomes in CKM patients. Additionally, mediation analyses were performed to explore whether OBS mediated the relationships between specific predictors (Life's Simple 7 score [LS7], systemic immune-inflammation index [SII], frailty score) and mortality outcomes. Then, machine learning models were developed to classify CKM stages 3/4 and predict all-cause mortality, with SHapley Additive exPlanations values used to interpret the contribution of OBS components.

RESULTS

21,609 participants were included (20,319 CKM, median [IQR] age: 52.0 [38.0-65.0] years, 54.3% male, median [IQR] follow-up: 9.4 [5.3-14.1] years). Lower OBS quartiles were associated with advanced CKM staging. Moreover, lower OBS quartiles were related to increased mortality risk, compared to Q4 of OBS (all-cause mortality: Q1: HR 1.31, 95% CI 1.18-1.46, Q2: HR 1.27, 95% CI 1.14-1.42, Q3: HR 1.18, 95% CI 1.06-1.32; cardiovascular mortality: Q1: HR 1.44, 95% CI 1.16-1.79, Q2: HR 1.39, 95% CI 1.11-1.74, Q3: HR 1.26, 95% CI 1.01-1.57; non-cardiovascular mortality, Q1: HR 1.27, 95% CI 1.12-1.44, Q2: HR 1.23, 95% CI 1.08-1.40, Q3: HR 1.16, 95% CI 1.02-1.31), with optimal risk stratification threshold for OBS was 22. Additionally, OBS mediated (ranging 4.25%-32.85 %) effects of SII, LS7, frailty scores on mortality outcomes. Moreover, light gradient boosting machine achieved the highest performance for predicting advanced CKM staging (area under curve: 0.905) and all-cause mortality (area under curve: 0.875). Cotinine increased risk, while magnesium, vitamin B6, physical activity were protective.

CONCLUSIONS

This study highlights OBS as a risk stratification tool for CKM, emphasizing oxidative stress's role in CKM staging and mortality risk management.

Endothelial Dysfunction: Redox Imbalance, NLRP3 Inflammasome, and Inflammatory Responses in Cardiovascular Diseases

Endothelial dysfunction (ED) is characterized by an imbalance between vasodilatory and vasoconstrictive factors, leading to impaired vascular tone, thrombosis, and inflammation. These processes are critical in the development of cardiovascular diseases (CVDs) such as atherosclerosis, hypertension and ischemia/reperfusion injury (IRI). Reduced nitric oxide (NO) production and increased oxidative stress are key contributors to ED. Aging further exacerbates ED through mitochondrial dysfunction and increased oxidative/nitrosative stress, heightening CVD risk. Antioxidant systems like superoxide-dismutase (SOD), glutathione-peroxidase (GPx), and thioredoxin/thioredoxin-reductase (Trx/TXNRD) pathways protect against oxidative stress. However, their reduced activity promotes ED, atherosclerosis, and vulnerability to IRI. Metabolic syndrome, comprising insulin resistance, obesity, and hypertension, is often accompanied by ED. Specifically, hyperglycemia worsens endothelial damage by promoting oxidative stress and inflammation. Obesity leads to chronic inflammation and changes in perivascular adipose tissue, while hypertension is associated with an increase in oxidative stress. The NLRP3 inflammasome plays a significant role in ED, being triggered by factors such as reactive oxygen and nitrogen species, ischemia, and high glucose, which contribute to inflammation, endothelial injury, and exacerbation of IRI. Treatments, such as N-acetyl-L-cysteine, SGLT2 or NLRP3 inhibitors, show promise in improving endothelial function. Yet the complexity of ED suggests that multi-targeted therapies addressing oxidative stress, inflammation, and metabolic disturbances are essential for managing CVDs associated with metabolic syndrome.

Transient receptor potential melastatin 7 cation channel, magnesium and cell metabolism in vascular health and disease

Preserving the balance of metabolic processes in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), is crucial for optimal vascular function and integrity. ECs are metabolically active and depend on aerobic glycolysis to efficiently produce energy for their essential functions, which include regulating vascular tone. Impaired EC metabolism is linked to endothelial damage, increased permeability and inflammation. Metabolic alterations in VSMCs also contribute to vascular dysfunction in atherosclerosis and hypertension. Magnesium (Mg2+) is the second most abundant intracellular divalent cation and influences molecular processes that regulate vascular function, including vasodilation, vasoconstriction, and release of vasoactive substances. Mg2+ is critically involved in maintaining cellular homeostasis and metabolism since it is an essential cofactor for ATP, nucleic acids and hundreds of enzymes involved in metabolic processes. Low Mg2+ levels have been linked to endothelial dysfunction, increased vascular tone, vascular inflammation and arterial remodeling. Growing evidence indicates an important role for the transient receptor potential melastatin-subfamily member 7 (TRPM7) cation channel in the regulation of Mg2+ homeostasis in EC and VSMCs. In the vasculature, TRPM7 deficiency leads to impaired endothelial function, increased vascular contraction, phenotypic switching of VSMCs, inflammation and fibrosis, processes that characterize the vascular phenotype in hypertension. Here we provide a comprehensive overview on TRPM7/Mg2+ in the regulation of vascular function and how it influences EC and VSMC metabolism such as glucose and energy homeostasis, redox regulation, phosphoinositide signaling, and mineral metabolism. The putative role of TRPM7/Mg2+ and altered cellular metabolism in vascular dysfunction and hypertension is also discussed.

Lymphocyte Subset Imbalance in Cardiometabolic Diseases: Are T Cells the Missing Link?

Cardiometabolic and cardiovascular diseases (CVDs) remain the leading cause of death worldwide, with well-established risk factors such as smoking, obesity, and diabetes contributing to plaque formation and chronic inflammation. However, emerging evidence suggests that the immune system plays a more significant role in the development and progression of CVD than previously thought. Specifically, the finely tuned regulation of lymphocyte subsets governs post-injury inflammation and tissue damage resolution and orchestrates the functions and activation of endothelial cells, cardiomyocytes, and fibroblasts in CVD-associated lesions (e.g., atherosclerotic plaques). A deeper understanding of the immune system's involvement in CVD development and progression will provide new insights into disease biology and uncover novel therapeutic targets aimed at re-establishing immune homeostasis. In this review, we summarize the current state of knowledge on the distribution and involvement of lymphocyte subsets in CVD, including atherosclerosis, diabetes, hypertension, myocardial infarction, and stroke.

The aging heart in focus: The advanced understanding of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) accounts for 50 % of heart failure (HF) cases, making it the most common type of HF, and its prevalence continues to increase in the aging society. HFpEF is a systemic syndrome resulting from many risk factors, such as aging, metabolic syndrome, and hypertension, and its clinical features are highly heterogeneous in different populations. HFpEF syndrome involves the dysfunction of multiple organs, including the heart, lung, muscle, and vascular system. The heart shows dysfunction of various cells, including cardiomyocytes, endothelial cells, fibroblasts, adipocytes, and immune cells. The complex etiology and pathobiology limit experimental research on HFpEF in animal models, delaying a comprehensive understanding of the mechanisms and making treatment difficult. Recently, many scientists and cardiologists have attempted to improve the clinical outcomes of HFpEF. Recent advances in clinically related animal models and systemic pathology studies have improved our understanding of HFpEF, and clinical trials involving sodium-glucose cotransporter 2 inhibitors have significantly enhanced our confidence in treating HFpEF. This review provides an updated comprehensive discussion of the etiology and pathobiology, molecular and cellular mechanisms, preclinical animal models, and therapeutic trials in animals and patients to enhance our understanding of HFpEF and improve clinical outcomes.

Magnesium and Potassium Supplementation for Systolic Blood Pressure Reduction in the General Normotensive Population: A Systematic Review and Subgroup Meta-Analysis for Optimal Dosage and Treatment Length

BACKGROUND/OBJECTIVES

Studies have shown that consistent reductions of 2 mm Hg in systolic blood pressure (SBP) for the general normotensive population can result in significant decreases in mortality from heart disease and stroke. The purpose of this meta-analysis was to determine the optimal dose and duration of treatment for magnesium and potassium supplementation, having previously discovered that both reduce SBP by -2.79 and -2.10 mm Hg, respectively.

METHODS

Placebo-controlled, randomized clinical trials examining the effects of magnesium and potassium supplementation on SBP were identified. Pairwise meta-analyses with subgroups for dosage and treatment duration were run.

RESULTS

Magnesium at dosages of ≤360 mg/day and durations greater than 3 months reduced SBP by -3.03 and -4.31 mm Hg, respectively. Potassium at dosages of ≤60 mmol/day and durations greater than 1 month reduced SBP by -2.34 and -2.80 mm Hg, respectively.

CONCLUSIONS

Both supplements demonstrated greater reductions in SBP for the general population at lower dosages and longer treatment durations. Future studies are needed to validate these findings and provide tailored recommendations. These studies could investigate varying dosages over long-term follow-up to provide robust data on optimal dosages and treatment durations, as our findings were limited due to reliance on previously published trials.

Luminal Flow in the Connecting Tubule induces Afferent Arteriole Vasodilation

Background

Renal autoregulatory mechanisms modulate renal blood flow. Connecting tubule glomerular feedback (CNTGF) is a vasodilator mechanism in the connecting tubule (CNT), triggered paracrinally when high sodium levels are detected via the epithelial sodium channel (ENaC). The primary activation factor of CNTGF-whether NaCl concentration, independent luminal flow, or the combined total sodium delivery-is still unclear. We hypothesized that increasing luminal flow in the CNT induces CNTGF via O2- generation and ENaC activation.

Methods

Rabbit afferent arterioles (Af-Arts) with adjacent CNTs were microperfused ex-vivo with variable flow rates and sodium concentrations ranging from <1 mM to 80 mM and from 5 to 40 nL/min flow rates.

Results

Perfusion of the CNT with 5 mM NaCl and increasing flow rates from 5 to 10, 20, and 40 nL/min caused a flow rate-dependent dilation of the Af-Art (p<0.001). Adding the ENaC blocker benzamil inhibited flow-induced Af-Art dilation, indicating a CNTGF response. In contrast, perfusion of the CNT with <1 mM NaCl did not result in flow-induced CNTGF vasodilation (p>0.05). Multiple linear regression modeling (R2=0.51;p<0.001) demonstrated that tubular flow (β=0.163 ± 0.04;p<0.001) and sodium concentration (β=0.14 ± 0.03;p<0.001) are independent variables that induce afferent arteriole vasodilation. Tempol reduced flow-induced CNTGF, and L-NAME did not influence this effect.

Conclusion

Increased luminal flow in the CNT induces CNTGF activation via ENaC, partially due to flow-stimulated O2- production and independent of nitric oxide synthase (NOS) activity.

Purinergic Receptor Antagonists: A Complementary Treatment for Hypertension

The treatment of hypertension has improved in the last century; attention has been directed to restoring several altered pathophysiological mechanisms. However, regardless of the current treatments, it is difficult to control blood pressure. Uncontrolled hypertension is responsible for several cardiovascular complications, such as chronic renal failure, which is frequently observed in hypertensive patients. Therefore, new approaches that may improve the control of arterial blood pressure should be considered to prevent serious cardiovascular disorders. The contribution of purinergic receptors has been acknowledged in the pathophysiology of hypertension; this review describes the participation of these receptors in the alteration of kidney function in hypertension. Elevated interstitial ATP concentrations are essential for the activation of renal purinergic receptors; this becomes a fundamental pathway that leads to the development and maintenance of hypertension. High ATP levels modify essential mechanisms implicated in the long-term control of blood pressure, such as pressure natriuresis, the autoregulation of the glomerular filtration rate and renal blood flow, and tubuloglomerular feedback responses. Any alteration in these mechanisms decreases sodium excretion. ATP stimulates the release of vasoactive substances, causes renal function to decline, and induces tubulointerstitial damage. At the same time, a deleterious interaction involving angiotensin II and purinergic receptors leads to the deterioration of renal function.