Human Hypertension Research Articles

Epithelial Na+ Channels, Immune Cells, and Salt.

Epithelial Na+ channels (ENaCs) are known to affect blood pressure through their role in transporting Na+ in the distal nephron of the kidney. While expressed in other epithelial tissues, there is growing evidence that ENaCs are also expressed in nonepithelial tissues where their activity influences blood pressure. This review provides an overview of ENaCs and key mechanisms that regulate channel activity. The role of ENaCs in antigen-presenting dendritic cells is discussed, where ENaC-dependent sensing of increases in the extracellular Na+ concentration leads to activation of a signaling cascade, T cell activation with the release of proinflammatory cytokines, and an increase in blood pressure. The potential contribution of this pathway to human hypertension is discussed.

Vitamin D receptor and its antiproliferative effect in human pulmonary arterial hypertension

Vitamin D (vitD) deficiency is frequently observed in patients with pulmonary arterial hypertension (PAH) and, in these patients, low levels of vitD correlate with worse prognosis. The aim of this study was to examine the expression and the antiproliferative role of vitD receptor (VDR) and its signalling pathway in the human pulmonary vasculature. VDR presence and expression was analyzed in lungs, pulmonary artery smooth muscle cells (PASMC) and endothelial cells (PAEC) from controls and PAH-patients. VDR expression and VDR-target genes were examined in PASMC treated with calcitriol. The antiproliferative effect of 48 h-calcitriol was studied in PASMC by MTT and BrdU assays. VDR is expressed in PASMC. It is downregulated in lungs and in PASMC, but not in PAEC, from PAH-patients compared to non-hypertensive controls. Calcitriol strongly upregulated VDR expression in PASMC and the VDR target genes KCNK3 (encoding TASK1), BIRC5 (encoding survivin) and BMP4. Calcitriol produced an antiproliferative effect which was diminished by silencing or by pharmacological inhibition of survivin or BMPR2, but not of TASK1. In conclusion, the expression of VDR is low in PAH-patients and can be rescued by calcitriol. VDR exerts an antiproliferative effect in PASMC by modulating survivin and the BMP signalling pathway.

Recruitment of CCR5-positive T cells in pulmonary vascular lesions in idiopathic- and connective tissue disease associated- pulmonary arterial hypertension

Abstract Background C-C chemokine receptor type 5 (CCR5) is a chemokine receptor predominantly expressed on leukocytes including T cells, macrophages, and dendritic cells, and is involved in the process by which T cells are attracted to specific tissues and organs. Although CCR5 has been shown to be expressed on macrophages and pulmonary artery smooth muscle cells in lung samples from human idiopathic pulmonary arterial hypertension (PAH) and some animal models, its expression on T cells in human PAH lungs has not been investigated. Purpose To investigate the immunohistochemical expression of CCR5 on T cells infiltrating in pulmonary vascular lesions of human PAH tissues, particularly from patients with idiopathic PAH and PAH associated with connective tissue disease (CTD-PAH), where inflammation has been implicated in the pathogenesis. Methods Subjects included 25 postmortem cases of idiopathic PAH (14 cases, a mean age of 34 ± 10 years, 8 female cases) and CTD-PAH (11 cases, 48 ± 13 years, all female). We performed immunohistochemistry using antibodies against CCR5 and CD3 (for T cells) on formalin-fixed paraffin-embedded sections. To semi-quantify, we selected the three small muscular pulmonary arteries (80-150 µm in external diameter) with the strongest CCR5-positive cell infiltration in each case, counted the number of positive cells, and the average were shown as the number of cells per vessel. Results In all cases, regardless of whether IPAH or CTD-PAH, a subset of infiltrating inflammatory cells into or accumulating around vessels was CCR5-positive. Specifically, CCR5-positive inflammatory cells were found in remodelled pulmonary arteries, such as plexiform lesions and constrictive lesions with intimal thickening and/or medial hypertrophy, as well as perivascular space. The average number of CCR5-positive cells per small muscular pulmonary artery was 8.1/vessel. Where pulmonary venous occlusive lesions were seen, CCR5-positive cells were also present in and around them. The majority of CCR5-positive inflammatory cells appeared to be T cells, based on morphology and CD3 immunopositivity in the serial sections. Conclusion(s) Activated T cells showing CCR5 immunopositivity were recruited to remodelled pulmonary vascular lesions in both idiopathic PAH and CTD-PAH. This implicates CCR5-positive T cells as a common key player and that CCR5 signalling is involved in the pathogenesis of PAH in concert with other inflammatory cells, vascular endothelial cells, and pulmonary artery smooth muscle cells.

Somatic GNAQ, CTNNB1, and CACNA1C Mutations in Cat Aldosterone-Secreting Tumors.

Primary aldosteronism (PA) is a common cause of human hypertension. Somatic mutations in KCNJ5, CACNA1D, ATP1A1, and ATP2B3 are found in at least 80% of aldosterone-producing adenomas, which cause unilateral PA in humans. Somatic mutations have been identified infrequently in 7 other genes; few of these were known to play a role in aldosterone secretion before the discovery of their mutations. Interrogating somatic mutations in the domestic cat, in which spontaneous PA is also known to occur, might improve the understanding of normal adrenal gland physiology and the pathophysiology of PA. DNA and RNA extracted from tissue from 13 cats with unilateral aldosterone-secreting tumors, including 8 carcinomas and 5 adenomas, underwent whole genome sequencing, targeted Sanger sequencing, and RNA sequencing. Single-nucleotide substitution variants were filtered to select those with a predicted deleterious effect on protein function and a suspected role in aldosterone secretion. Probable functional somatic single-nucleotide polymorphisms (n=8) were found in 3 adenomas and 2 carcinomas. Mutations with predicted significant effects were identified in 2 genes also mutated in human PA; GNAQ and CTNNB1, and in a residue of CACNA1C analogous to a common CACNA1D mutation. In contrast to humans, CACNA1C expression was much greater than CACNA1D in both feline tumor and nontumor adrenal tissue. No mutations were identified in KCNJ5, CACNA1D, ATP1A1, or ATP2B3. Similar mutations were identified in cats to those found in humans. It is, therefore, likely that both species have shared underlying selection pressures for mutations that increase aldosterone secretion.

The role of T-cells in vascular aging, hypertension, and atherosclerosis.

Vascular dysfunction has emerged as a significant risk factor for the development of cardio- and cerebrovascular diseases (CVDs), which are currently the leading cause of morbidity and mortality worldwide. T-lymphocytes (T-cells) have been shown to be important modulators of vascular function in primary aging and CVDs, likely by producing inflammatory cytokines and reactive oxygen species that influence vasoprotective molecules. This review summarizes the role of T-cells on vascular function in aging, hypertension, and atherosclerosis in animals and humans, and discusses potential T-cell targeted therapeutics to prevent, delay, or reverse vascular dysfunction.

Investigating the causal relationship between human blood metabolites and pulmonary hypertension: a two-sample Mendelian randomization study.

Several recent investigations have posited that distinct metabolites in the bloodstream may be correlated with the pathogenesis of Pulmonary Hypertension (PH). Nonetheless, the interrelationship between the pathogenesis of PH and metabolite fluctuations remains incompletely elucidated, and findings may differ across studies. In the extant research, data from 486 metabolite-and PH-related genetic variants in human subjects were procured based on Genome-Wide Association Studies (GWAS) and Finnish databases. Univariate Mendelian Randomization analyses were deployed to evaluate the causal relationships between them. The utilization of the randomized Inverse Variance weighted(IVW) method served as the primary analytic framework in this Mendelian Randomization (MR) study. Additionally, four alternative computational strategies, encompassing MR-Egger, were employed as auxiliary methods. A myriad of tests, including Cochran's Q Test, MR-Egger intercept test, MR-PRESSO, leave-one-out analysis, and linkage disequilibrium score were incorporated to assess the robustness of the study outcomes. Metabolite pathway analysis was also executed to identify potential metabolic pathways. After a series of validations and corrected for False discovery rate (FDR), we found a significant association between 1,5-anhydroglucitol (OR = 2.00, 95% CI: 1.39-2.89, P = 0.0002) and PH, and a significant association between pyridoxalate (OR = 0.59, 95% CI: 0.43-0.81, P = 0.0009) and 1-a achidonoylglycerophosphocholine (OR = 1.78, 95% CI: 1.22-2.58, P = 0.0026) had a suggested association with PH. In addition, the vitamin B6 metabolic pathway was also determined to be associated with PH. Conclusively, we isolated 1,5-anhydroglucitol, 1-arachidonoylglycerophosphocholine, and pyridoxate as causally implicated in PH, thereby proffering substantial theoretical substantiation for the formulation of future PH prevention and screening paradigms.

Endoplasmic Reticulum Stress Immediate Early Response 3 Gene Mediates Myeloid-Specific Salt-Sensitive Hypertension in Humans

Endoplasmic Reticulum Stress Immediate Early Response 3 Gene Mediates Myeloid-Specific Salt-Sensitive Hypertension in Humans

Effects of Oral Butyrate on Blood Pressure in Patients With Hypertension: A Randomized, Placebo-Controlled Trial.

The microbiota-derived short chain fatty acid butyrate has been shown to lower blood pressure (BP) in rodent studies. Nonetheless, the net effect of butyrate on hypertension in humans remains uncovered. In this study, for the first time, we aimed to determine the effect of oral butyrate on BP in patients with hypertension. We performed a double-blind randomized placebo-controlled trial including 23 patients with hypertension. Antihypertensive medication was discontinued for the duration of the study with a washout period of 4 weeks before starting the intervention. Participants received daily oral capsules containing either sodium butyrate or placebo with an equivalent dosage of sodium chloride for 4 weeks. The primary outcome was daytime 24-hour systolic BP. Differences between groups over time were assessed using linear mixed models (group-by-time interaction). Study participants (59.0±3.7 years; 56.5% female) had an average baseline office systolic BP of 143.5±14.6 mm Hg and diastolic BP of 93.0±8.3 mm Hg. Daytime 24-hour systolic and diastolic BP significantly increased over the intervention period in the butyrate compared with the placebo group, with an increase of +9.63 (95% CI, 2.02-17.20) mm Hg in daytime 24-hour systolic BP and +5.08 (95% CI, 1.34-8.78) mm Hg in diastolic BP over 4 weeks. Butyrate levels significantly increased in plasma, but not in feces, upon butyrate intake, underscoring its absorption. Four-week treatment with oral butyrate increased daytime systolic and diastolic BP in subjects with hypertension. Our findings implicate that butyrate does not have beneficial effects on human hypertension, which warrants caution in future butyrate intervention studies. URL: https://onderzoekmetmensen.nl/; Unique identifier: NL8924.

Impairment of microvascular endothelial Kir2.1 channels contributes to endothelial dysfunction in human hypertension.

Hypertension is associated with decreased endothelial function through reduced contributions of nitric oxide (NO). We previously discovered that flow-induced NO production in resistance arteries of mice and humans critically depends on endothelial inwardly rectifying K+ (Kir2.1) channels. The goal of this study was to establish whether these channels contribute to the impairment of endothelial function, measured by flow-induced vasodilation (FIV) in peripheral resistance arteries of humans with hypertension. We measured FIV in vessels isolated from subcutaneous fat biopsies from 32 subjects: normotensive [n = 19; 30.6 ± 9.8 yr old; systolic blood pressure (SBP): 115.2 ± 7 mmHg; diastolic blood pressure (DBP): 75.3 ± 5.7 mmHg] and hypertensive (n = 13; 45.3 ± 15.3 yr old; SBP: 146.1 ± 15.2 mmHg; DBP: 94.4 ± 6.9 mmHg). Consistent with previous studies, we find that FIV is impaired in hypertensive adults as demonstrated by a significant reduction in FIV when compared with the normotensive adults. Furthermore, our data suggest that the impairment of FIV in hypertensive adults is partially attributed to a reduction in Kir2.1-dependent vasodilation. Specifically, we show that blocking Kir2.1 with ML133 or functionally downregulating Kir2.1 with endothelial-specific adenoviral vector containing dominant-negative Kir2.1 (dnKir2.1) result in a significant reduction in FIV in normotensive subjects but with a smaller effect in hypertensive adults. The Kir2.1-dependent vasodilation was negatively correlated to both SBP and DBP, indicating that the Kir2.1 contribution to FIV decreases as blood pressure increases. In addition, we show that exposing vessels from normotensive adults to acute high-pressure results in loss of Kir2.1 contribution, as high pressure impairs vasodilation. No effect is seen when these vessels were incubated with dnKir2.1. Overexpressing wtKir2.1 in the endothelium resulted in some improvement in vasodilation in arteries from all participants, with a greater recovery in hypertensive adults. Our data suggest that hypertension-induced suppression of Kir2.1 is an important mechanism underlying endothelial dysfunction in hypertension.NEW & NOTEWORTHY Impairment of endothelial function under high blood pressure is linked to the loss of inwardly rectifying K+ (Kir2.1) channels activity in human resistance arteries, leading to a reduction in flow-induced vasodilation and possibly leading to a vicious cycle between elevation of blood pressure, and further impairment of Kir2.1 function and flow-induced vasodilation.

Peripheral chemoreflex restrains skeletal muscle blood flow during exercise in participants with treated hypertension.

We tested the hypothesis that in human hypertension, an increased tonicity/sensitivity of the peripheral chemoreflex causes a sympathetically mediated restraint of nutritive blood flow to the exercising muscles. Fourteen patients with treated hypertension (age 69±11 years, 136±12/80±11mmHg; mean±SD) were studied under conditions of intravenous 0.9% saline (control) and low-dose dopamine (2µgkg-1min-1) to inhibit the peripheral chemoreflex, at baseline, during isocapnic hypoxic rebreathing and during rhythmic handgrip exercise (3min, 50% maximum voluntary contraction). At baseline, dopamine did not change mean blood pressure (95±10 vs. 98±10mmHg, P=0.155) but increased brachial artery blood flow (59±20 vs. 48±16mlmin-1, P=0.030) and vascular conductance (0.565±0.246 vs. 0.483±0.160mlmin-1mmHg-1; P=0.039). Dopamine attenuated the increase in mean blood pressure (∆3±4 vs. ∆8 ±6mmHg, P=0.007) to isocapnic hypoxic rebreathing and reduced peripheral chemoreflex sensitivity by 28±37% (P=0.044). Rhythmic handgrip exercise induced increases in brachial artery blood flow and vascular conductance (both P<0.05 vs. rest after 45s) that were greater with dopamine than saline (e.g. Δ76±54 vs. Δ60±43mlmin-1 and Δ0.730±0.440 vs. Δ0.570±0.424mlmin-1mmHg-1, respectively, at 60s; main effect of condition both P<0.0001). Our results indicate that the peripheral chemoreflex is tonically active at rest and restrains the blood flow and vascular conductance increases to exercise in treated human hypertension. KEY POINTS: It was hypothesised that in human hypertension, an increased tonicity/sensitivity of the peripheral chemoreflex causes a sympathetically mediated restraint of nutritive blood flow to the exercising muscles. Treated patients with hypertension (n=14) were studied under conditions of intravenous 0.9% saline (control) and low-dose dopamine (2 µgkg-1min-1) to inhibit the peripheral chemoreflex. Low-dose dopamine reduced resting ventilation and peripheral chemoreflex sensitivity, and while mean blood pressure was unchanged, brachial artery blood flow and vascular conductance were increased. Low-dose dopamine augmented the brachial artery blood flow and vascular conductance responses to rhythmic handgrip. These findings indicate that the peripheral chemoreflex is tonically active at rest and restrains the blood flow, and vascular conductance increases to exercise in treated human hypertension.

Abstract P354: Endothelial Sirt3 deficiency and SOD2 acetylation voids female protection from hypertension

The prevalence of hypertension in early adulthood among women is 3-times lower than in men; but with aging hypertension rate increases in women much steeper, and hypertensive vascular and kidney damage is significantly higher in women. Gender-specific aspects of hypertension are poorly understood and clinical studies did not show protection by estrogen hormone therapy. We found that human hypertension is linked to hyperacetylation of critical antioxidant and metabolic mitochondrial enzymes superoxide dismutase (SOD2) and long-chain acyl dehydrogenase (LCAD) due to vascular deficiency of mitochondrial deacetylase Sirt3. We hypothesized that endothelial Sirt3 depletion leads to the loss of female protective cardiovascular phenotype and exacerbates hypertension in female compared with male mice due to hyperacetylation of mitochondrial proteins. Indeed, infusion of angiotensin II in wild-type female mice showed protection of vascular metabolism, endothelial nitric oxide and lower blood pressure compared with male littermates which was coupled with reduced acetylation of mitochondrial LCAD and SOD2 in female mice. Endothelial specific Sirt3 knockout female mice showed increased mitochondrial acetylation, exacerbated angiotensin II-induced hypertension and higher blood pressure compared with male mice which models human hypertension. Hypertension is linked to SOD2 acetylation (Circ Res. 2020;126(4):439-452) which leads to SOD2 inactivation and vascular oxidative stress. We found that endothelial specific acetylation mimetic SOD2-K68Q knock-in female mice lost antihypertensive phenotype and had higher blood pressure compared with angiotensin II-infused male mice. These studies demonstrate critical role of mitochondrial acetylation in endothelial dysfunction and hypertension suggesting that female antihypertensive phenotype can be associated with reduced mitochondrial acetylation protecting mitochondrial and endothelial functions. It is conceivable that pharmacological targeting of mitochondrial metabolism and acetylation can rescue female cardiovascular protection and improve treatment of endothelial dysfunction and hypertension.

Abstract P181: Class 1 human leukocyte antigens exhibit marked variability in capacity to present isolevuglandin adducts

Introduction: Isolevuglandins (isoLGs) are lipid peroxidation products that covalently modify lysine residues on self-proteins. These modified self-proteins are processed to peptides that are presented in the context of class I major histocompatibility complexes (MHC-I). In hypertension, this modification enhances CD8 + T cell activation, contributing to inflammation and elevated blood pressure. In mice we found that IsoLG-adduct presentation is highly dependent on class I MHC structure. We sought to determine if human class I MHC (HLAs) exhibit similar variability in their ability to present these adducts by screening alleles representing 90% of the population. Hypothesis: We hypothesize that HLA subtypes exhibit variable capacity for isoLG presentation. Methods: HLA alleles representing 90% demographic frequency were identified from the US National Merit Donor Program Allele Frequency Database. HLA-null human K562 cells were transduced with these alleles, expanded, and enriched for HLA expression by flow cytometry to produce single HLA allele lines. To induce isoLG adduct presentation, cells were treated with 1mM tert-Butyl hydroperoxide (tBHP). After 24 hours, we employed Forster resonance energy transfer (FRET) between HLAs and isoLG-adducts using antibodies specific for both, which we have shown is indicative of IsoLG-adduct presentation (Fig 1A-C). Results: Substantial variability for isoLG-adduct presentation was observed between HLA subtypes A, B and C (Figure 1A-1C). Scikit-learn’s KMeans clustering revealed four patterns of isoLG-adduct presentation among HLAs: Low baseline/low activation, low baseline/high activation, intermediate baseline/intermediate activation, and high baseline/high activation alleles (Fig 1D). Conclusions: These findings identify specific HLA alleles as high isoLG presenters, potentially associated with increased immune activation risk. Combining these findings, HLA alleles, and diagnosis code databases could aid in identifying high-risk haplotypes for immune activation in human hypertension.

Abstract MP34: Muscle Sodium Content and Isolevuglandin Formation in Antigen Presenting Cells in Human Salt Sensitive Hypertension

Background: Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular mortality. However, the mechanisms by which salt exposure affects blood pressure in SSBP are still unclear. We have shown that under high sodium (Na + ) concentrations, Na + enters antigen-presenting cells (APCs) via epithelial Na + channel (ENaC), which leads to isolevuglandin (IsoLG) production and hypertension. Baseline %IsoLG+ APC correlates with SSBP. While the exact location where APCs are activated by salt and trigger an inflammatory response remains to be elucidated, muscle and skin are proposed as potential sites. We hypothesize that muscle and skin Na + levels are associated with SSBP. Methods: We assessed SSBP in 30 hypertensive subjects using an inpatient salt loading and depletion protocol. Flow cytometry was used to identify IsoLG-containing APCs; dendritic cells (DCs), classic (CD14+16-), non-classic (CD14-16+), and intermediate (CD14+16+) monocytes. Salt loading was achieved through saline infusion and a high-salt diet (460mmol/24 hours), while salt depletion was achieved via diuretic administration (furosemide 40mg x3) and a low-salt diet (10mmol/24hours). Baseline muscle and skin Na + levels were assessed with the 23 Na MRI technique. Spearman's correlation was used to analyze the associations. Demographic data are presented with mean and standard error of the mean. Results: Participants’ age was 53 ± 1.34 years, 53% female, baseline blood pressure was 140.2 ± 2.62 / 87.30 ± 1.77 mmHg, and salt sensitivity index was 3.72 ± 1.4 mmHg. We found an inverse correlation between baseline muscle Na + levels and the decrease in IsoLGs from salt loading to depletion (ΔIsoLGs) in DCs (r=-0.50, p=0.007), intermediate (r=-0.42 p=0.0284) and non-classic monocytes (r=-0.39 p=0.0432), but not in classical monocytes. Skin Na + levels were not correlated with any of these measures. There was a decreasing trend of salt sensitivity index with increasing muscle Na + , although this correlation did not reach statistical significance (r=-0.35 p=0.0686) Conclusion: This highlights the potential importance of muscle Na + in SSBP, such that patients with lower muscle Na + exhibited a higher trend of salt sensitivity index and increased variability in IsoLG+ APCs. Moreover, baseline tissue Na + assessment may emerge as a potential tool for evaluating the degree of salt sensitivity and IsoLG activation in SSBP.

Lactobacillus Restructures the Micro/Mycobiome to Combat Glycoprotein-130 Associated Microtubule Remodeling and Right Ventricular Dysfunction in Pulmonary Arterial Hypertension.

Emerging data demonstrate systemic and local inflammation regulate right ventricular (RV) adaption in preclinical and human pulmonary arterial hypertension (PAH). Pathological RV inflammation is targetable as antagonism of glycoprotein-130 (GP130) signaling counteracts pathological microtubule remodeling and improves RV function in rodents. Microtubules control several aspects of cardiomyocyte biology including cellular and nuclear size/structure, t-tubule homeostasis, and the proper localization of connexin-43. The intestinal microbiome regulates systemic inflammation, but the impact of the gut microbiome on the GP130-microtubule axis in RV failure is unknown. Here, we examined how the anti-inflammatory bacteria, Lactobacillus , modulated cellular and physiological RV phenotypes in preclinical and clinical PAH. Lactobacillus supplementation restructured the gut micro/mycobiome, suppressed systemic inflammation, combatted pathological GP130-mediated RV cardiomyocyte microtubule remodeling, and augmented RV function in rodent PAH. Moreover, Lactobacillus was associated with superior RV adaption in human PAH. These data further support the hypothesis that inflammation negatively impacts RV adaption in PAH, and identify the gut microbiome as a potentially targetable regulator of RV function in PAH.

Abstract Mo064: Na + leak channel NALCN plays an essential role in mineralocorticoid-induced hypertension through nonrenal mechanisms.

In human and animal hyperaldosteronism-related hypertension, the increased blood volume has been regarded as a primary contributor to hypertension generation. However, increases in arterial contractility (and thus peripheral resistance) are also frequently reported in various hypertension models, including the mineralocorticoid-induced hypertensions such as DOCA-salt hypertension. Moreover, non-renal mechanisms (i.e., direct regulation on the cardiovascular ion channels) of the mineralocorticoid-induced hypertension are reportedly important. Na + -leak channel (NALCN) was first cloned as Na + /Ca 2+ channel family in 1999. However, its role in providing background cation conductance and contributing to normal neuronal excitability has been uncovered relatively recently and little is known about the roles of NALCN in cardiovascular system and pathogenesis of hypertension. Here, we show that aldosterone directly upregulates NALCN expression in arterial smooth muscle independent of kidney and contribute to the increases in arterial contractility, thereby contributing to the development of hypertension. Remarkably, mere the transient knockdown of arterial NALCN greatly ameliorated the development of hypertension along with arterial hypercontractility. Moreover, it is very interesting that our findings suggest that NALCN is activated by oxidative stimuli and this activation can be prevented by -gliflozin series SGLT2 inhibitors. From these, we propose that NALCN is a very promising and potent target for the treatment of various hypertensions including mineralocorticoid-related one.

Correction to: Eicosanoid-Regulated Myeloid ENaC and Isolevuglandin Formation in Human Salt-Sensitive Hypertension.

Correction to: Eicosanoid-Regulated Myeloid ENaC and Isolevuglandin Formation in Human Salt-Sensitive Hypertension.

Reactive oxygen species in hypertension.

Hypertension is a leading risk factor for stroke, heart disease and chronic kidney disease. Multiple interacting factors and organ systems increase blood pressure and cause target-organ damage. Among the many molecular elements involved in the development of hypertension are reactive oxygen species (ROS), which influence cellular processes in systems that contribute to blood pressure elevation (such as the cardiovascular, renal, immune and central nervous systems, or the renin-angiotensin-aldosterone system). Dysregulated ROS production (oxidative stress) is a hallmark of hypertension in humans and experimental models. Of the many ROS-generating enzymes, NADPH oxidases are the most important in the development of hypertension. At the cellular level, ROS influence signalling pathways that define cell fate and function. Oxidative stress promotes aberrant redox signalling and cell injury, causing endothelial dysfunction, vascular damage, cardiovascular remodelling, inflammation and renal injury, which are all important in both the causes and consequences of hypertension. ROS scavengers reduce blood pressure in almost all experimental models of hypertension; however, clinical trials of antioxidants have yielded mixed results. In this Review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in hypertension. We focus on cellular sources of ROS, molecular mechanisms of oxidative stress and alterations in redox signalling in organ systems, and their contributions to hypertension.

Role of Vitamin D in Management of Diabetes and Unresolved Cardiovascular Diseases.

Vitamin D deficiency is becoming a widely recognized global health issue. Serum values of 25-(OH) vitamin D (<20 ng/ml) are used to identify vitamin D deficiency. By prompting vascular endothelial cells to activate their nuclear receptor in cardio-myocytes, Vitamin D regulates obesity, Renin-angiotensin system (RAS), energy consumption, and pancreatic cell function. Vitamin D deficiency has been associated with diabetes, asthma, hyperlipidaemia, and pulmonary hypertension in humans. PubMed and Google Scholar databases were utilised to search the literature on vitamin D and related diseases. It is also linked to an elevated risk of death and heart disease. On the other hand, metaanalyses of vitamin D intervention and trials have found no substantial changes in insulin sensitivity, lipid markers, or blood pressure, which result in the association between deficiency of vitamin D and cardiovascular disease. In this review, we present the most recent research on the effects of Vitamin D therapy on various cardiovascular diseases and diabetes, and explain the underlying mechanisms.

Carnitine consumption and effect of oral supplementation in human pulmonary arterial hypertension: A pilot study.

Carnitine is required to transport fatty acid across the mitochondrial membrane to undergo beta oxidation. In addition to disorders of fatty acid metabolism, a relative carnitine deficiency has been reported in pulmonary arterial hypertension (PAH). Here we performed an observational study in which food and supplement consumption were collected in an observation period followed by open label administration of a carnitine supplement to determine feasibility of increasing plasma carnitine levels in humans PAH. We confirmed that relative carnitine deficiency in PAH is not due to reduced dietary consumption and that plasma levels of carnitine can be increased in PAH patients with supplementation that is well tolerated.

Spontaneous vascular dysfunction in Dahl salt-sensitive male rats raised without a high-salt diet.

Dahl salt-sensitive (SS) rats fed a high-salt diet, but not low-salt, exhibit vascular dysfunction. Several substrains of SS rats exist that differ in their blood pressure phenotypes and salt sensitivity. The goal of this study was to investigate whether the John-Rapp-derived SS rat (SS/Jr), which exhibits spontaneous hypertension on a low-salt diet, presents with hallmarks of vascular dysfunction observed in another experimental model of hypertension independent of dietary salt, the spontaneously hypertensive rat (SHR). Endothelium-intact aortic rings and mesenteric resistance arteries were isolated from low-salt fed adult male SS/Jr rats and SHRs, or their respective controls, for isometric wire myography. Vessels were challenged with cumulative concentrations of various vasoactive substances, in the absence or presence of nitric oxide synthase or cyclooxygenase inhibitors. Despite showing some differences in their responses to various vasoactive substances, both SS/Jr rats and SHRs exhibited key features of vascular dysfunction, including endothelial dysfunction and hyperresponsiveness to vasocontractile agonists. In conclusion, this study provides evidence to support the utility of the SS/Jr rat strain maintained on a low-salt diet as a valid experimental model for vascular dysfunction, a key feature of human hypertension.