Role of oxidative stress in remodeling of the myocardial microcirculation in hypertension

Redox Regulation of the Microcirculation

The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.

Hydrogen Sulfide Improves Myocardial Remodeling via Downregulated Angiotensin Ⅱ/AT1R Pathway in Renovascular Hypertensive Rats

BACKGROUND

Hydrogen sulfide (H₂S) is an important endogenous gaseous transmitter in many physiological functions. Plasma H₂S decreased, and angiotensin II (Ang II) type 1 receptor (AT1R) increased in the myocardial tissues in 2-kidney 1-clip (2K1C) rats than in normotensive rats. Accumulating evidences suggest that H₂S inhibited Ang II/AT1R pathway to regulate cardiovascular function. Therefore, we hypothesized that H₂S may exert beneficial effects on myocardial remodeling in 2K1C rat models of renovascular hypertension.

METHODS AND RESULTS

Sodium hydrosulfide (NaHS, 56 µmol/kg/day) was administered intraperitoneally to the rats from the 7th day after 2K1C operation. Systolic blood pressure was significantly increased from the first week after the operation and was lowered after NaHS treatment for 4 weeks. H₂S could also inhibit the ratio of left ventricle and septum weight to body weight, improve cross-sectional area, and ameliorate ventricular dysfunction. Additionally, the protein expression of AT1R and Ang II serum content were downregulated, whereas superoxide dismutase (SOD) protein was upregulated in 2K1C rats by NaHS treatment for 4 weeks. Furthermore, the reactive oxygen species level and AT1R protein were increased, whereas SOD protein was decreased in cardiomyocytes treated with Ang II compared with the control group. NaHS could reverse these changes. Losartan and N-acetylcysteine could also reverse Ang II-induced changes.

CONCLUSIONS

The protective effect of H₂S is attributable to the suppression of oxidative stress. This process involves the inhibition of the Ang II/AT1R pathway and upregulation of antioxidant enzymes in 2K1C rats.

Restoration of Mitochondrial Cardiolipin Attenuates Cardiac Damage in Swine Renovascular Hypertension

Background

Renovascular hypertension (RVH) impairs cardiac structure and left ventricular (LV) function, but whether mitochondrial injury is implicated in RVH‐induced myocardial damage and dysfunction has not been defined. We hypothesized that cardiac remodeling in swine RVH is partly attributable to cardiac mitochondrial injury.

Methods and Results

After 12 weeks of hypercholesterolemic (HC)‐RVH or control (n=14 each), pigs were treated for another 4 weeks with vehicle or with the mitochondrial‐targeted peptide (MTP), Bendavia (0.1 mg/kg subcutaneously, 5 days/week), which stabilizes mitochondrial inner‐membrane cardiolipin (n=7 each). Cardiac function was subsequently assessed by multidetector‐computed tomography and oxygenation by blood‐oxygen‐level–dependent magnetic resonance imaging. Cardiolipin content, mitochondrial biogenesis, as well as sarcoplasmic‐reticulum calcium cycling, myocardial tissue injury, and coronary endothelial function were assessed ex vivo. Additionally, mitochondrial cardiolipin content, oxidative stress, and bioenergetics were assessed in rat cardiomyocytes incubated with tert‐butyl hydroperoxide (tBHP) untreated or treated with MTP. Chronic mitoprotection in vivo restored cardiolipin content and mitochondrial biogenesis. Thapsigargin‐sensitive sarcoplasmic reticulum Ca²⁺‐ATPase activity that declined in HC‐RVH normalized in MTP‐treated pigs. Mitoprotection also improved LV relaxation (E/A ratio) and ameliorated cardiac hypertrophy, without affecting blood pressure or systolic function. Myocardial remodeling and coronary endothelial function improved only in MTP‐treated pigs. In tBHP‐treated cardiomyocytes, mitochondrial targeting attenuated a fall in cardiolipin content and bioenergetics.

Conclusions

Chronic mitoprotection blunted myocardial hypertrophy, improved LV relaxation, and attenuated myocardial cellular and microvascular remodeling, despite sustained HC‐RVH, suggesting that mitochondrial injury partly contributes to hypertensive cardiomyopathy.

Adipose tissue remodeling in a novel domestic porcine model of diet-induced obesity

OBJECTIVE

To establish and characterize a novel domestic porcine model of obesity.

METHODS

Fourteen domestic pigs were fed normal (lean, n=7) or high-fat/high-fructose diet (obese, n=7) for 16 weeks. Subcutaneous abdominal adipose tissue biopsies were obtained after 8, 12, and 16 weeks of diet, and pericardial adipose tissue after 16 weeks, for assessments of adipocyte size, fibrosis, and inflammation. Adipose tissue volume and cardiac function were studied with multidetector computed tomography, and oxygenation was studied with magnetic resonance imaging. Plasma lipids profile, insulin resistance, and markers of inflammation were evaluated.

RESULTS

Compared with lean pigs, obese pigs had elevated cholesterol and triglyceride levels, blood pressure, and insulin resistance. Both abdominal and pericardial fat volume increased in obese pigs after 16 weeks. In abdominal subcutaneous adipose tissue, adipocyte size and both tumor necrosis factor (TNF)-α expression progressively increased. Macrophage infiltration showed in both abdominal and pericardial adipose tissues. Circulating TNF-α increased in obese pigs only at 16 weeks. Compared with lean pigs, obese pigs had similar global cardiac function, but myocardial perfusion and oxygenation were significantly impaired.

CONCLUSIONS

A high-fat/high-fructose diet induces in domestic pigs many characteristics of metabolic syndrome, which is useful for investigating the effects of the obesity.

Intra-renal delivery of mesenchymal stem cells attenuates myocardial injury after reversal of hypertension in porcine renovascular disease

Introduction

Percutaneous transluminal renal angioplasty (PTRA) fails to fully improve cardiac injury and dysfunction in patients with renovascular hypertension (RVH). Mesenchymal stem cells (MSCs) restore renal function, but their potential for attenuating cardiac injury after reversal of RVH has not been explored. We hypothesized that replenishment of MSCs during PTRA would improve cardiac function and oxygenation, and decrease myocardial injury in porcine RVH.

Methods

Pigs were studied after 16 weeks of RVH, RVH treated 4 weeks earlier with PTRA with or without adjunct intra-renal delivery of MSC (10^6 cells), and controls. Cardiac structure, function (fast-computed tomography (CT)), and myocardial oxygenation (Blood-Oxygen-Level-Dependent- magnetic resonance imaging) were assessed in-vivo. Myocardial microvascular density (micro-CT) and myocardial injury were evaluated ex-vivo. Kidney venous and systemic blood levels of inflammatory markers were measured and their renal release calculated.

Results

PTRA normalized blood pressure, yet stenotic-kidney glomerular filtration rate, similarly blunted in RVH and RVH + PTRA, normalized only in PTRA + MSC-treated pigs. PTRA attenuated left ventricular remodeling, whereas myocardial oxygenation, subendocardial microvascular density, and diastolic function remained decreased in RVH + PTRA, but normalized in RVH + PTRA-MSC. Circulating isoprostane levels and renal release of inflammatory cytokines increased in RVH and RVH + PTRA, but normalized in RVH + PTRA-MSC, as did myocardial oxidative stress, inflammation, collagen deposition, and fibrosis.

Conclusions

Intra-renal MSC delivery during PTRA preserved stenotic-kidney function, reduced systemic oxidative stress and inflammation, and thereby improved cardiac function, oxygenation, and myocardial injury four weeks after revascularization, suggesting a therapeutic potential for adjunctive MSC delivery to preserve cardiac function and structure after reversal of experimental RVH.

Experimental coronary artery stenosis accelerates kidney damage in renovascular hypertensive swine

The impact of coronary artery stenosis (CAS) to renal injury is unknown. Here we tested whether the existence of CAS, regardless of concurrent atherosclerosis, would induce kidney injury and magnify its susceptibility to damage from co-existing hypertension (HT). Pigs (7 each) were assigned to Sham, left-circumflex CAS, renovascular HT, and CAS plus HT groups. Cardiac and non-stenotic kidney functions, circulating and renal inflammatory and oxidative markers, and renal and microvascular remodeling, were assessed 10 weeks later. Myocardial perfusion declined distal to CAS. Systemic levels of PGF2-α isoprostane, a marker of oxidative stress, increased in CAS and CAS plus HT, while single-kidney blood flow responses to acetylcholine were significantly blunted only in CAS plus HT compared to sham, HT, and CAS, indicating renovascular endothelial dysfunction. Tissue expression of inflammatory and oxidative markers were elevated in the CAS pig kidney, and further magnified in CAS plus HT, whereas angiogenic factor expression was decreased. Bendavia, a mitochondria-targeted peptide, decreased oxidative stress and improved renal function and structure in CAS. Furthermore, CAS and HT synergistically amplified glomerulosclerosis and renal fibrosis. Thus, mild myocardial ischemia, independent of systemic atherosclerosis, induced renal injury, possibly mediated by increased oxidative stress. Superimposed HT aggravates renal inflammation and endothelial dysfunction caused by CAS, and synergistically promotes kidney fibrosis, providing impetus to preserve cardiac integrity in order to protect the kidney.

Mitochondrial targeted peptides attenuate residual myocardial damage after reversal of experimental renovascular hypertension

BACKGROUND

Renovascular hypertension (RVHT) increases cardiovascular morbidity and mortality. Renal revascularization with percutaneous transluminal renal angioplasty and stenting (PTRS) may reverse RVHT but may not fully regress cardiac remodeling and damage, possibly due to persistent myocardial insults. Bendavia is a mitochondrial targeted peptide that reduces ischemic cardiomyopathy by improving mitochondrial function. However, its potential for attenuating residual myocardial damage after reversal of RVHT has not been explored. We hypothesized that treatment with Bendavia as an adjunct to PTRS would improve cardiac function and oxygenation, and decrease myocardial injury in swine RVHT.

METHODS AND RESULTS

After 6 weeks of RVHT (unilateral renal artery stenosis) or control, pigs underwent PTRS (or sham), with adjunct continuous infusion of Bendavia (0.05  mg/kg intravenously, 30  min before to 3.5  h after PTRS) or vehicle (n = 7 each). Four weeks later, systolic and diastolic function were assessed by multidetector computed tomography, myocardial oxygenation by blood oxygen level-dependent MRI, and myocardial morphology, apoptosis, mitochondrial biogenesis, and fibrosis evaluated ex vivo. PTRS restored blood pressure in both groups, yet E/A ratio remained decreased. Myocardial oxygenation and mitochondrial biogenesis improved, and myocardial inflammation, oxidative stress, and fibrosis normalized in association with improvement in diastolic function in RVHT + PTRS + Bendavia animals.

CONCLUSION

Adjunct Bendavia during PTRS in swine RVHT improved diastolic function and oxygenation and reversed myocardial tissue damage. This approach may allow a novel strategy for preservation of cardiac function and structure in RVHT.

Polycystic kidneys have decreased vascular density: a micro-CT study

OBJECTIVE

Polycystic kidney disease (PKD) is a common cause of end-stage renal failure and many of these patients suffer vascular dysfunction and hypertension. It remains unclear whether PKD is associated with abnormal microvascular structure. Thus, this study examined the renovascular structure in PKD.

METHODS

PKD rats (PCK model) and controls were studied at 10 weeks of age, and mean arterial pressure (MAP), renal blood flow, and creatinine clearance were measured. Microvascular architecture and cyst number and volume were assessed using micro-computed tomography, and angiogenic pathways evaluated.

RESULTS

Compared with controls, PKD animals had an increase in MAP (126.4 ± 4.0 vs. 126.2 ± 2.7 mmHg) and decreased clearance of creatinine (0.39 ± 0.09 vs. 0.30 ± 0.05 mL/min), associated with a decrease in microvascular density, both in the cortex (256 ± 22 vs. 136 ± 20 vessels per cm2) and medullar (114 ± 14 vs. 50 ± 9 vessels/cm2) and an increase in the average diameter of glomeruli (104.14 ± 2.94 vs. 125.76 ± 9.06 mm). PKD animals had increased fibrosis (2.2 ± 0.2 fold vs. control) and a decrease in the cortical expression in hypoxia inducible factor 1-α and vascular endothelial growth factor.

CONCLUSIONS

PKD animals have impaired renal vascular architecture, which can have significant functional consequences. The PKD microvasculature could represent a therapeutic target to decrease the impact of this disease.

Mesenchymal stem cells and endothelial progenitor cells decrease renal injury in experimental swine renal artery stenosis through different mechanisms

Endothelial progenitor cells (EPC) and mesenchymal stem cells (MSC) augment tissue repair but possess slightly different properties. How the cellular phenotype affects the efficacy of this approach in renovascular disease is incompletely understood. This study tested the hypothesis that EPC and MSC protect the poststenotic kidney by blunting different disease pathways. Peripheral blood EPC and adipose-derived MSC were expanded and characterized by cell surface markers (e.g., CD34/kinase insert domain receptor, or CD44/CD90). Single-kidney hemodynamics and function were assessed in pigs after 10 weeks of renal artery stenosis (RAS) treated 4 weeks earlier with an intrarenal infusion of vehicle (n = 7), EPC (RAS+EPC) or MSC (RAS+MSC) (both 10 × 10(6), n = 6), and normal controls (n = 7). Kidney disease mechanisms were evaluated ex vivo. The ability of EPC and MSC to attenuate endoplasmic reticulum (ER) stress was also studied in isolated ER and in tubular cells cocultured with EPC and MSC. Glomerular filtration rate in RAS was lower than controls, increased in RAS+EPC, and further improved in RAS+MSC, although both improved renal blood flow similarly. EPC prominently enhanced renal growth factor expression and decreased oxidative stress, while MSC more significantly attenuated renal inflammation, ER stress, and apoptosis. Furthermore, MSC induced a greater decrease in caspase-3 and CHOP expression in cultured tubular cells through mechanisms involving cell contact. EPC and MSC achieve a comparable decrease of kidney injury in RAS by different mechanisms, although MSC elicited slightly superior improvement of renal function. These results support development of cell-based approaches for management of renovascular disease and suggest cell selection based on the underlying pathophysiology of kidney injury.

The involvement of a polyphenol-rich extract of black chokeberry in oxidative stress on experimental arterial hypertension

The aim of this study is to characterize the content of Aronia melanocarpa Elliott (black chokeberry) extract and also to estimate the influence of polyphenolic compounds contained in chokeberries on oxidative stress, on an L-NAME-induced experimental model of arterial hypertension. The rat blood pressure values were recorded using a CODA Noninvasive Blood Pressure System. HPLC/DAD coupled with ElectroSpray Ionization-Mass Spectrometry allowed identification of five phenolic compounds in berries ethanolic extract as follows: chlorogenic acid, kuromanin, rutin, hyperoside, and quercetin. The serous activity of glutathione-peroxidase (GSH-Px) has significantly lower values in the hypertensive (AHT) group as compared to the group protected by polyphenols (AHT + P). The total antioxidant capacity (TAC) values are lower in the AHT group and they are significantly higher in the AHT + P group. All the measured blood pressure components revealed a biostatistically significant blood pressure drop between the AHT group and the AHT + P group. The results reveal the normalization of the reduced glutathion (GSH) concentration as well as a considerable reduction in the malondialdehyde (MDA) serum concentration in the AHT + P group. Ethanolic extract of black chokeberry fruits not only has a potential value as a prophylactic agent but also may function as a nutritional supplement in the management of arterial hypertension.

Hydrogen peroxide-mediated oxidative stress and collagen synthesis in cardiac fibroblasts: blockade by tanshinone IIA

ETHNOPHARMACOLOGICAL RELEVANCE

We have recently reported that tanshinone IIA attenuated cardiac fibrosis in two-kidney, two-clip renovascular hypertensive rats via inhibiting NAD(P)H oxidase. However, little is known about the cellular and molecular mechanisms of tanshinone IIA mediated anti-fibrotic effects in cardiac fibroblasts after H(2)O(2) stimulation. The present study was performed to investigate whether H(2)O(2) may increase collagen synthesis in cardiac fibroblasts by affecting the expression and activity of NAD(P)H oxidase and whether the effects of H(2)O(2) on cardiac fibroblasts can be blocked by treatment of tanshinone IIA.

MATERIALS AND METHODS

Cardiac fibroblasts were treated with H(2)O(2) (100 μmol/L) in the presence or absence of tanshinone IIA (1 μmol/L), NAD(P)H oxidase inhibitors diphenyleneiodonium (10 μmol/L), siRNA-p47phox, siRNA-Nox2 and siRNA-Nox4. Collagen synthesis was measured by [(3)H]proline incorporation, O(2)(-) production were determined by flow cytometry and DHE fluorescence microscopy. NAD(P)H oxidase activity was measured by lucigenin-enhanced chemiluminescence.

RESULTS

H(2)O(2) induced the activity of NAD(P)H oxidase, O(2)(-) production, collagen synthesis and fibronectin expression in cardiac fibroblasts, and DPI abolished this induction. Exposure of adult rat cardiac fibroblasts to H(2)O(2) had time-dependent increase in the expression of p47phox, Nox2 and Nox4 oxidases. In addition, tanshinone IIA significantly inhibited H(2)O(2)-induced collagen synthesis via attenuation of O(2)(-) generation and NAD(P)H oxidase activity. Moreover, siRNA-mediated knockdown of p47phox, Nox2 and Nox4 inhibited H(2)O(2)-induced NADPH oxidase activity. H(2)O(2)-induced collagen synthesis and fibronectin expression were also inhibited by p47phox, Nox2 and Nox4 knock down.

CONCLUSIONS

Our data show that NAD(P)H oxidase plays a significant role in regulating collagen synthesis in H(2)O(2)-stimulated cardiac fibroblasts. Inhibition of NAD(P)H oxidase with tanshinone IIA completely blocked the H(2)O(2)-stimulated collagen production, which will raise the experimental basis for using tanshinone IIA to cardiac fibrosis in clinic.

Compensatory remodeling of coronary microvasculature maintains shear stress in porcine left-ventricular hypertrophy

BACKGROUND

Hypertension-induced left-ventricular hypertrophy (LVH) is generally accompanied with coronary neovascularization. The extent of vascular growth or rarefaction depends on many factors (e.g. age, duration of hypertension, degree of hypertrophy). Here, we hypothesize that there is a compensatory vascular growth that maintains uniform wall shear stress (WSS) in perfusion arterioles (diameters of 8-60 μm) in LVH of young porcine.

METHOD

To test this hypothesis, we investigated LVH in young porcine after 5 weeks of supravalvular aortic stenosis (3 months of age). The morphometry (diameters, lengths, number and connectivity of vessels) of the entire left circumflex (LCx) arterial tree was determined and a hemodynamic network analysis was used to calculate the distribution of pressure, flow and WSS throughout the tree in the control and LVH groups.

RESULTS

It was found that the number of vessels and the weight of left ventricle (LV) in hypertrophy increased 1.5 and 1.2 times, respectively, and the length of the LCx main trunk increased by 3 cm (36% increase), as compared with those in control group. There were similar myocardial blood flows of 0.87 ± 0.24 and 0.94 ± 0.38 ml/min per g in control and LVH hearts, respectively. The compensatory remodeling in early LVH restores WSS in the smaller perfusion arterioles, but not in the larger epicardial branches.

CONCLUSION

The present findings quantify the structural and functional remodeling in the entire LCx arterial tree in response to LVH, which reflect heterogeneity in vascular morphometry and hemodynamics from small to large vessels. These conclusions enhance our understanding of compensatory vascular remodeling in LVH of pediatric heart.

Increased glomerular filtration rate in early metabolic syndrome is associated with renal adiposity and microvascular proliferation

Metabolic syndrome (MetS) is associated with glomerular hyperfiltration and is a risk factor for chronic kidney disease, but the underlying mechanisms are poorly defined. This study tested the hypothesis that increased glomerular filtration rate (GFR) in early MetS is associated with renal adiposity and microvascular proliferation. Twelve MetS-prone Ossabaw pigs were randomized to 10 wk of a standard (lean, n = 6) or atherogenic (MetS, n = 6) diet. Kidney hemodynamics and function, perirenal fat volume, and tubular dynamics were assessed in vivo by multidetector computed tomography (CT) and blood oxygen level-dependent (BOLD)-MRI. Microvascular architecture was assessed ex vivo with micro-CT. Candidate injury mechanisms were evaluated in kidney tissue by Western blotting and histology. Basal GFR, renal blood flow, and renal cortical perfusion and volume were elevated in the MetS group. Perirenal and kidney tissue fat, proximal-nephron intratubular fluid concentration, and endothelial nitric oxide synthase expression were increased in MetS. GFR levels correlated with tissue triglyceride levels. Elevated spatial density of 20- to 40-μm cortical microvessels was accompanied by mild oxidative stress, inflammation, and with proximal tubular vacuolization. Medullary size and perfusion were relatively preserved, and BOLD-MRI showed intact medullary tubular response to furosemide. Increased GFR in early MetS is associated with renal adiposity and microvascular proliferation, which involve mainly the renal cortex and precede significant activation of oxidative stress and inflammation. Renal adiposity and proliferative microvessels may represent novel therapeutic targets for preserving renal function in early MetS.

Selective improvement in renal function preserved remote myocardial microvascular integrity and architecture in experimental renovascular disease

AIM

Atherosclerotic renovascular disease (ARVD) may impair renal function and increase cardiovascular morbidity and mortality, but the mechanism by which ARVD impacts cardiovascular function is unclear. We tested the hypothesis that preservation of renal function can reverse cardiac dysfunction in ARVD.

METHODS AND RESULTS

Endothelial progenitor cells (EPC) were injected intra-renally (ARVD+EPC) after 6 weeks of swine ARVD (concurrent hypercholesterolemia and renovascular hypertension), and single-kidney function and myocardial blood-flow and microvascular permeability (MP) responses to adenosine were assessed using CT 4 weeks later. Myocardial microvascular density was evaluated by micro-CT. Inflammation and oxidative-stress were assessed in kidney venous and systemic blood samples. Normal and untreated ARVD pigs served as controls. Blood pressure was similarly increased in ARVD and ARVD+EPC. Compared to normal, ARVD showed lower glomerular filtration rate, elevated renal vein and systemic oxidized LDL (ox-LDL), aldosterone, uric acid, isoprostanes, transforming growth factor (TGF)-β, and interleukine-6. Renal vein ox-LDL and TGF-β showed a positive gradient across the stenotic kidney, indicating increased renal oxidative stress and fibrogenic activity. Furthermore, ARVD impaired myocardial blood-flow and MP response to adenosine, decreased microvascular density, and induced myocardial fibrosis. Improvement of renal function in ARVD+EPC decreased systemic aldosterone, inflammation, and oxidative stress, and improved myocardial microvascular integrity and density.

CONCLUSION

Selective improvement in renal function, which reduced renal and systemic oxidative stress and inflammation, preserved remote myocardial microvascular function and architecture, despite enduring hypertension. These findings underscore functionally important cardiorenal crosstalk possibly mediated by renal injury signals.

Elevated oxidative stress and endothelial dysfunction in right coronary artery of right ventricular hypertrophy

Remodeling of right coronary artery (RCA) occurs during right ventricular hypertrophy (RVH) induced by banding of the pulmonary artery (PA). The effect of RVH on RCA endothelial function and reactive oxygen species (ROS) in vessel wall remains unclear. A swine RVH model (n = 12 pigs) induced by PA banding was used to study RCA endothelial function and ROS level. To obtain longitudinal coronary hemodynamic and geometric data, digital subtraction angiography was used during the progression of RVH. Blood flow in the RCA increased by 82% and lumen diameter of RCA increased by 22% over a 4-wk period of RVH. The increase in blood flow and the commensurate increase in diameter resulted in a constant wall shear stress in RCA throughout the RVH period. ROS was elevated by ∼100% in RCA after 4 wk of PA banding. The expressions of p47(phox), NADPH oxidase (NOX1, NOX2, and NOX4) were upregulated in the range of 20-300% in RCA of RVH. The endothelial function was compromised in RCA of RVH as attributed to insufficient endothelial nitric oxide synthase cofactor tetrahydrobiopterin. In vivo angiographic analysis suggests an increased basal tone in the RCA during RVH. In conclusion, stretch due to outward remodeling of RCA during RVH (at constant wall shear stress), similar to vessel stretch in hypertension, appears to induce ROS elevation, endothelial dysfunction, and an increase in basal tone.

Reversal of experimental renovascular hypertension restores coronary microvascular function and architecture

BACKGROUND

Hypertension (HTN) may lead to left ventricular hypertrophy and vascular dysfunction, which are independent factors for adverse cardiovascular outcomes. We hypothesized that decreased blood pressure by percutaneous transluminal renal angioplasty (PTRA) would improve the function and architecture of coronary microvessels, in association with decreased inflammation and fibrosis.

METHODS

Three groups of pigs were studied: normal, HTN, and HTN+PTRA. After 6 weeks of renovascular HTN, induced by placing a local-irritant coil in the renal artery, pigs underwent PTRA or sham. Four weeks later multidetector-computed tomography (CT) was used to assess systolic, diastolic, and microvascular function, and responses to adenosine. Microvascular architecture, oxygen sensors, inflammation, and fibrosis were then explored in cardiac tissue.

RESULTS

PTRA successfully decreased blood pressure and left ventricular hypertrophy. Basal fractional vascular volume (FVV) was similar among the groups, but its response to adenosine was significantly attenuated in HTN, whereas microvascular permeability (MP) and response to adenosine were greater than normal. Both were restored by PTRA. These were accompanied by increased myocardial expression of hypoxia-inducible factor (HIF)-1α, inflammation, and microvascular remodeling, including increased density of epicardial microvessels (20-200 µm), as well as cardiac diastolic dysfunction, all of which improved by reversal of HTN. However, PTRA only partially decreased myocardial fibrosis.

CONCLUSIONS

Reversal of early renovascular HTN improved coronary microvascular function and architecture and reversed myocardial hypertrophy and diastolic dysfunction, in association with decreased levels of myocardial ischemia and inflammation markers, underscoring the benefits of blood pressure normalization for preservation of cardiovascular function and structure.

Early experimental hypertension preserves the myocardial microvasculature but aggravates cardiac injury distal to chronic coronary artery obstruction

Coronary artery disease is a leading cause of death. Hypertension (HT) increases the incidence of cardiac events, but its effect on cardiac adaptation to coexisting coronary artery stenosis (CAS) is unclear. We hypothesized that concurrent HT modulates microvascular function in chronic CAS and aggravates microvascular remodeling and myocardial injury. Four groups of pigs (n=6 each) were studied: normal, CAS, HT, and CAS+HT. CAS and HT were induced by placing local irritant coils in the left circumflex coronary artery and renal artery, respectively. Six weeks later multidetector computerized tomography (CT) was used to assess systolic and diastolic function, microvascular permeability, myocardial perfusion, and responses to adenosine in the "area at risk." Microvascular architecture, inflammation, and fibrosis were then explored in cardiac tissue. Basal myocardial perfusion was similarly decreased in CAS and CAS+HT, but its response to adenosine was significantly more attenuated in CAS. Microvascular permeability in CAS+HT was greater than in CAS and was accompanied by amplified myocardial inflammation, fibrosis, and microvascular remodeling, as well as cardiac systolic and diastolic dysfunction. On the other hand, compared with normal, micro-CT-derived microvascular (20-200 μm) transmural density decreased in CAS but not in HT or CAS+HT. We conclude that the coexistence of early renovascular HT exacerbated myocardial fibrosis and vascular remodeling distal to CAS. These changes were not mediated by loss of myocardial microvessels, which were relatively preserved, but possibly by exacerbated myocardial inflammation and fibrosis. HT modulates cardiac adaptive responses to CAS and bears cardiac functional consequences.

Simvastatin decreases endothelial progenitor cell apoptosis in the kidney of hypertensive hypercholesterolemic pigs

OBJECTIVE

Hypertension and hypercholesterolemia might interfere with renal repair mechanisms. We hypothesized that simvastatin improves the survival of endothelial progenitor cells (EPC) in the renal microenvironment imposed by concurrent renovascular hypertension and dietary hypercholesterolemia (HTC).

METHODS AND RESULTS

Pigs were studied after 12 weeks of no intervention (n=6), HTC (n=6), or HTC+ oral simvastatin supplementation (80 mg/day, n=5). EPC were also isolated and studied in vitro after exposure to the proapoptotic oxidized low-density lipoprotein with or without coincubation with simvastatin. Renal hemodynamics, function, and endothelial function were evaluated in vivo, and the number of CD34+/KDR+ EPC, apoptosis, oxidative stress, inflammation, and fibrosis in renal tissue studied ex vivo. Compared with normal kidney, the HTC kidney showed endothelial dysfunction and increased oxidative stress, interstitial macrophage filtration, and fibrosis. The number of EPC in the kidney increased, as did their apoptosis (0.85+/-0.24% versus 0.22+/-0.07%, P<0.05 versus normal). Simvastatin did not affect blood pressure, cholesterol levels, basal renal function, or number of renal EPC in HTC, but it improved endothelial function; blunted renal oxidative stress, inflammation, and fibrosis; and attenuated EPC apoptosis (to 0.37+/-0.09%, P<0.05 versus HTC). Simvastatin also significantly decreased oxidized low-density lipoprotein-induced EPC apoptosis in vitro.

CONCLUSION

EPC are recruited but undergo apoptosis in the HTC kidney, likely because of a hostile microenvironment. Simvastatin rescues renal repair mechanisms in HTC and counteracts renal damage, which may account for its protective effects on the kidney during exposure to cardiovascular risk factors.

The chemokine monocyte chemoattractant protein-1 contributes to renal dysfunction in swine renovascular hypertension

Renal artery stenosis (RAS) causes renovascular hypertension and renal damage, which may result from tissue inflammation. We have previously shown that the kidney in RAS exhibits increased expression of monocyte chemoattractant protein (MCP)-1, but its contribution to renal injury remained unknown. This study tested the hypothesis that MCP-1 contributes to renal injury and dysfunction in the stenotic kidney.

METHODS

Kidney hemodynamics, function, and endothelial function were quantified in pigs after 10 weeks of experimental RAS (n = 7), RAS supplemented with the MCP-1 inhibitor bindarit (RAS + bindarit, 50 mg/kg/day orally, n = 6), and normal controls (n = 8). Renal inflammation was assessed by the immunoreactivity of MCP-1, its receptor chemotactic cytokine receptor 2, and NFkappaB, and oxidative stress by nicotinamide adenine dinucleotide phosphate-oxidase expression and in-situ superoxide production. Renal microvascular density was evaluated by micro-CT and fibrosis by trichrome staining, collagen-I immunostaining, and hydroxyproline content.

RESULTS

After 10 weeks of RAS, blood pressure was similarly elevated in RAS and RAS + bindarit. Compared with normal controls, stenotic RAS kidneys had decreased renal blood flow (5.4 +/- 1.6 vs. 11.4 +/- 1.0 ml/min/kg, P < 0.05) and glomerular filtration rate and impaired endothelial function, which were significantly improved in bindarit-treated RAS pigs (to 8.4 +/- 0.8 ml/min/kg, P < 0.05 vs. RAS). Furthermore, bindarit markedly decreased tubulointerstitial (but not vascular) oxidative stress, inflammation, and fibrosis, and slightly increased renal microvascular density. The impaired renovascular endothelial function, increased oxidative-stress, and fibrosis in the contralateral kidney were also improved by bindarit.

CONCLUSION

MCP-1 contributes to functional and structural impairment in the kidney in RAS, mainly in the tubulointerstitial compartment. Its inhibition confers renoprotective effects by blunting renal inflammation and thereby preserving the kidney in chronic RAS.

Nitric oxide and coronary vascular endothelium adaptations in hypertension

This review highlights a number of nitric oxide (NO)-related mechanisms that contribute to coronary vascular function and that are likely affected by hypertension and thus become important clinically as potential considerations in prevention, diagnosis, and treatment of coronary complications of hypertension. Coronary vascular resistance is elevated in hypertension in part due to impaired endothelium-dependent function of coronary arteries. Several lines of evidence suggest that other NO synthase isoforms and dilators other than NO may compensate for impairments in endothelial NO synthase (eNOS) to protect coronary artery function, and that NO-dependent function of coronary blood vessels depends on the position of the vessel in the vascular tree. Adaptations in NOS isoforms in the coronary circulation to hypertension are not well described so the compensatory relationship between these and eNOS in hypertensive vessels is not clear. It is important to understand potential functional consequences of these adaptations as they will impact the efficacy of treatments designed to control hypertension and coronary vascular disease. Polymorphisms of the eNOS gene result in significant associations with incidence of hypertension, although mechanistic details linking the polymorphisms with alterations in coronary vasomotor responses and adaptations to hypertension are not established. This understanding should be developed in order to better predict those individuals at the highest risk for coronary vascular complications of hypertension. Greater endothelium-dependent dilation observed in female coronary arteries is likely related to endothelial Ca(2+) control and eNOS expression and activity. In hypertension models, the coronary vasculature has not been studied extensively to establish mechanisms for sex differences in NO-dependent function. Genomic and nongenomic effects of estrogen on eNOS and direct and indirect antioxidant activities of estrogen are discussed as potential mechanisms of interest in coronary circulation that could have implications for sex- and estrogen status-dependent therapy for hypertension and coronary dysfunction. The current review identifies some important basic knowledge gaps and speculates on the potential clinical relevance of hypertension adaptations in factors regulating coronary NO function.

Monocyte chemoattractant proteins mediate myocardial microvascular dysfunction in swine renovascular hypertension

BACKGROUND

Monocyte chemoattractant proteins (MCPs) play an important role in mediating inflammatory processes. Hypertension (HTN) is associated with inflammation as well as impaired cardiac microcirculatory function and structure, but the contribution of MCPs to these alterations remained unclear. This study tested the hypothesis that MCPs regulate cardiac microvascular function and structure in experimental HTN.

METHODS AND RESULTS

Pigs (n=6 per group) were studied after 10 weeks of normal, renovascular HTN, or renovascular HTN+ bindarit (MCPs inhibitor, 50 mg/kg/d PO). Left ventricular (LV) function, myocardial microvascular permeability, and fractional vascular volume were assessed by fast computed tomography before and after adenosine infusion (400 microg/kg/min). Myocardial fibrosis, inflammation, and microvascular remodeling were determined ex vivo. Hypertension was not altered by bindarit, but LV hypertrophy and diastolic function were improved. In response to adenosine, myocardial microvascular permeability increased in HTN (from 0.0083+/-0.0009 to 0.0103+/-0.0011 AU, P=0.038 versus baseline) and fractional vascular volume decreased, whereas both remained unchanged in normal and HTN+bindarit pigs. HTN upregulated endothelin-1 expression, myocardial inflammation, and microvascular wall thickening, which were inhibited by bindarit.

CONCLUSIONS

MCPs partly mediate myocardial inflammation, fibrosis, vascular remodeling, and impaired vascular integrity induced by hypertension. Inhibition of MCPs could potentially be a therapeutic target in hypertensive cardiomyopathy.

Myocardial microvascular function during acute coronary artery stenosis: effect of hypertension and hypercholesterolaemia

AIMS

Coronary collateral arteries (CCA) reduce cardiovascular events. We tested the hypothesis that new microvessels that proliferate in early atherosclerosis may be associated with myocardial protection during acute subtotal coronary artery obstruction (CAO).

METHODS AND RESULTS

Acute left anterior descending CAO was induced by a balloon catheter in pigs after 12 weeks of high-cholesterol (HC) diet, renovascular hypertension (HTN), or normal control. Cardiac structure, myocardial perfusion, and functional response to iv adenosine and CAO were studied in vivo using electron beam computed tomography (CT). The intra-myocardial microvessels were subsequently evaluated ex vivo using micro-CT, and myocardial expression of growth factors using immunoblotting. Basal myocardial perfusion and microvascular permeability were similar among the groups, whereas their responses to adenosine were attenuated in HC and HTN. A significant decline in myocardial perfusion in normal pigs during acute CAO was attenuated in HC and abolished in HTN. CAO also elicited an increase in normal anterior wall microvascular permeability (+202 +/- 59%, P < 0.05), which was attenuated in HC and HTN (+55 +/- 9 and +31 +/- 8%, respectively, P < 0.05 vs. normal). Microvascular (<200 microm) spatial density was significantly elevated in HC and HTN, accompanied by increased myocardial growth factor expression.

CONCLUSION

This study demonstrates that early exposure to the cardiovascular risk factors HC and HTN protects the heart from decreases in myocardial perfusion during acute subtotal CAO. This protective effect is associated with and potentially mediated by pre-emptive development of intra-myocardial microvessels that might serve as recruitable CCA.

Oxidative stress mediates cardiac fibrosis by enhancing transforming growth factor-beta1 in hypertensive rats

Cardiac fibrosis represented as perivascular/interstial fibrosis occurs in patients with hypertension. Oxidative stress has been demonstrated to contribute to such structural remodeling. The underlying mechanisms, however, remain to be elucidated. Herein, we tested the hypothesis that oxidative stress mediates cardiac fibrogenesis by stimulating transforming growth factor (TGF)-beta1 expression, which in turn triggers a series of fibrogenic responses. Sprague-Dawley rats were treated with angiotensin (Ang)II (9 microg/h s) for 4 weeks with/without co-treatment of combined antioxidants, apocynin, and tempol (120 mg/kg/day each, oral). Untreated rats served as controls. Appearance of cardiac oxidative stress and its potential effect on the expression of TGF-beta1, population of myofibroblasts, collagen synthesis/degradation, and fibrosis in hearts were examined. Chronic AngII infusion elevated systemic blood pressure (210 +/- 5 mmHg). Extensive perivascular and interstitial fibrosis was found in both ventricles, which were co-localized with oxidative stress represented as upregulated NADPH oxidase (gp91(phox) subunit) expression. Co-treatment with antioxidants led to: (1) markedly decreased cardiac gp91(phox); (2) significantly attenuated gene expression of TGF-beta1, type-I collagen, and tissue inhibitors of matrix metalloproteinase (TIMP)-I/II in the heart; (3) largely reduced population of myofibroblasts at sites of fibrosis; (4) significantly reduced cardiac collagen volume; (5) and partially suppressed blood pressure (190 +/- 4 mmHg). Thus, cardiac oxidative stress promotes the development of cardiac fibrosis by upregulating TGF-beta1 expression, which subsequently enhances cardiac collagen synthesis and suppresses collagen degradation in hypertensive rats.

Microcirculation and oxidative stress

The microcirculation is a complex and integrated system, transporting oxygen and nutrients to the cells. The key component of this system is the endothelium, contributing to the local balance between pro and anti-inflammatory mediators, hemostatic balance, as well as vascular permeability and cell proliferation. A constant shear stress maintains vascular endothelium homeostasis while perturbed shear stress leads to changes in secretion of vasodilator and vasoconstrictor agents. Increased oxidative stress is a major pathogenetic mechanism of endothelial dysfunction by decreasing NO bioavailability, promoting inflammation and participating in activation of intracellular signals cascade, so influencing ion channels activation, signal transduction pathways, cytoskeleton remodelling, intercellular communication and ultimately gene expression. Targeting the microvascular inflammation and oxidative stress is a fascinating approach for novel therapies in order to decrease morbidity and mortality of chronic and acute diseases.

Role of renal cortical neovascularization in experimental hypercholesterolemia

Hypercholesterolemia induces renal inflammation and neovascularization, associated with renal endothelial dysfunction and injury. Neovascularization might conceivably represent a defense mechanism to sustain renal perfusion. Therefore, the present study was designed to test the hypothesis that preventing neovascularization using thalidomide, a potent anti-inflammatory and antiangiogenic agent, would impair basal renal hemodynamics in experimental hypercholesterolemia. Single-kidney function and hemodynamic responses to endothelium-dependent challenge were assessed in pigs after 12 weeks of hypercholesterolemia, hypercholesterolemia chronically supplemented with thalidomide (4 mg/kg per day), and normal controls. Renal microvascular architecture was then studied ex vivo using 3D microcomputed tomography imaging and inflammation, angiogenesis, and oxidative stress explored in renal tissue. The density of larger microvessels (200 to 500 microm) was selectively decreased in hypercholesterolemia plus thalidomide and accompanied by a decreased fraction of angiogenic, integrin beta(3)-positive microvessels (9.9%+/-0.9% versus 25.5%+/-1.7%; P<0.05 versus hypercholesterolemia), implying decreased angiogenic activity. Furthermore, thalidomide increased renal expression of endothelial NO synthase and decreased tumor necrosis factor-alpha and renal inflammation but did not decrease oxidative stress. Thalidomide also decreased basal renal blood flow and glomerular filtration rate but normalized the blunted renal hemodynamic responses in hypercholesterolemia. Attenuated inflammation and pathological angiogenesis achieved in hypercholesterolemia by thalidomide are accompanied by restoration of renovascular endothelial function but decreased basal renal hemodynamics. This study, therefore, suggests that neovascularization in the hypercholesterolemic kidney is a compensatory mechanism that sustains basal renal vascular function.

Endothelial function and hypertension

PURPOSE OF REVIEW

Endothelial dysfunction, in particular a reduced vascular availability of endothelium-derived nitric oxide, has been analysed in numerous experimental and clinical studies as a potential mechanism mediating the adverse vascular effects of hypertension. This paper outlines some notable studies in this dynamic field published recently.

RECENT FINDINGS

The understanding of mechanisms underlying endothelial dysfunction in hypertension has been substantially advanced recently. Increased oxidant stress is thought to represent a major mechanism leading to reduced vascular availability of endothelium-derived nitric oxide. Vascular nicotinamide adenine dinucleotide phosphate oxidases, uncoupled nitric oxide synthase and xanthine oxidase have been identified as major sources of reactive oxygen species in hypertension. Endothelial dysfunction has been implicated in the macrovascular complications of hypertension, such as stroke or myocardial infarction, coronary microvascular dysfunction and increased arterial stiffness, probably at least partly resulting from loss of the antiatherogenic and vasculoprotective effects of endothelium-derived nitric oxide.

SUMMARY

Recent research on endothelial dysfunction supports its clinical significance in hypertension, and has led to important insights into the pathophysiology of the disease. These observations suggest that targeting endothelial dysfunction, in particular reduced nitric oxide availability, would exert beneficial effects in hypertensive patients. This concept needs further evaluation in clinical studies.

Antioxidant vitamins induce angiogenesis in the normal pig kidney

The effects of chronic supplementation with antioxidant vitamins on angiogenesis are controversial. The aim of the present study was to evaluate in kidneys of normal pigs the effect of chronic supplementation with vitamins E and C, at doses that are effective in reducing oxidative stress and attenuating angiogenesis under pathological conditions. Domestic pigs were randomized to receive a 12-wk normal diet without ( n = 6) or with antioxidant vitamins supplementation (1g/day vitamin C, 100 IU·kg−1·day−1 vitamin E; n = 6). Electron beam computed tomography (CT) was used to evaluate renal cortical vascular function in vivo, and micro-CT was to assess the spatial density and average diameter of cortical microvessels (diameter <500 μm) ex vivo. Oxidative stress and expressions of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor (HIF)-1α were evaluated in renal tissue. The effects of increasing concentrations of the same vitamins on redox status and angiogenesis were also evaluated in human umbilical vascular endothelial cells (HUVEC). Compared with normal pigs, the density of cortical transmural microvessels was significantly greater in vitamin-supplemented pigs (149.0 ± 11.7 vs. 333.8 ± 48.1 vessel/cm2, P < 0.05), whereas the cortical perfusion response to ACh was impaired. This was accompanied by a significant increase in tissue oxidative stress and levels of VEGF and HIF-1α. A low dose of antioxidant decreased, whereas a high dose increased, HUVEC oxidative stress and angiogenesis, which was partly mediated by hydrogen peroxide. Antioxidant vitamin supplementation can increase tissue oxidative redox and microvascular proliferation in the normal kidney, probably due to a biphasic effect that depends on basal redox balance.

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia

Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia (HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic (HC) pigs can be detected using the novel X-ray contrast agent OsO(4) and three-dimensional micro-computed tomography (CT). Two groups of pigs were studied after they were fed a normal or an HC (2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO(4) solution, and cardiac samples (6-mum-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO(4) accumulation were determined. Leakage of OsO(4) from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO(4) enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO(4) in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO(4) as a contrast agent in micro-CT allows three-dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.

Simvastatin prevents coronary microvascular remodeling in renovascular hypertensive pigs

Patients with hypertension and chronic kidney disease are at risk for cardiovascular diseases, possibly related to inflammation. Statins have beneficial anti-inflammatory effects on vascular structure regardless of cholesterol reduction. It was hypothesized that alterations in myocardial microvascular structure in swine renovascular hypertension (RVH) would be improved by simvastatin treatment. Three groups of pigs were studied after 12 wk: normal (n = 7), RVH (n = 7), or RVH+simvastatin (RVH+S; 80 mg/d; n = 6). Left ventricular muscle mass and myocardial perfusion were determined in vivo using electron beam computed tomography, and myocardial samples then were scanned ex vivo using micro-computed tomography for measurement of the spatial density of myocardial microvessels (80 to 500 microm) in situ. Capillary density and myocardial expression of inflammatory and growth factors were determined in myocardial tissue. The effects of simvastatin on inflammation-induced tube formation were evaluated in vitro in human umbilical vein endothelial cells that were exposed to TNF-alpha. RVH and RVH+S had similarly increased arterial pressure and serum creatinine. However, left ventricular hypertrophy was prevented by simvastatin, and myocardial perfusion was increased. Compared with normal, RVH showed increased spatial density of microvessels (169.6 +/- 21 versus 107.7 +/- 15.2 vessels/cm(2); P < 0.05), which was decreased in RVH+S (72.5 +/- 14.9 vessels/cm(2)), whereas capillary density remained similar to normal. RVH also increased myocardial expression of inflammatory and growth factors, which were reversed by simvastatin. Furthermore, simvastatin attenuated TNF-alpha-induced angiogenesis in vitro. Simvastatin prevents myocardial microvascular remodeling and hypertrophy in experimental RVH independent of lipid lowering. This protective effect is partly mediated by blunted expression as well as angiogenic activity of inflammatory cytokines.

Tissue Inhibitor of Metalloproteinase-3 Deficiency Inhibits Blood Pressure Elevation and Myocardial Microvascular Remodeling Induced by Chronic Administration of N.OMEGA.-Nitro-L-Arginine Methyl Ester in Mice

Hypertension is a major risk factor for cardiovascular disease. Thus, prevention of hypertension and consequent organ damage is important for reducing its incidence. In the present study, we examined the involvement of tissue inhibitor of metalloproteinase-3 (Timp-3) in N(omega)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension and accompanying vascular remodeling in mice. L-NAME was orally administered to wild-type (WT) and Timp-3 knockout (KO) mice for 6 weeks, blood pressure was monitored, and histological changes in myocardial arteries were examined. After L-NAME administration, blood pressure was lower in Timp-3 KO mice than in WT mice. The coronary arteries of WT and Timp-3 KO mice were similar after L-NAME treatment and showed no differences compared to untreated control mice. However, cardiac microvessels differed histologically between WT and Timp-3 KO mice. Vascular walls were less thickened in Timp-3 KO than in WT mice, and fibrotic changes were significantly reduced in Timp-3 KO mice. Moreover, the L-NAME-induced production of reactive oxygen species in cardiac microvessels was lower in Timp-3 KO than in WT mice. These results indicate that Timp-3 plays an important role in L-NAME-induced hypertension and myocardial vascular remodeling. Our findings suggest that Timp-3 may be a novel therapeutic target for the treatment of hypertension and consequent organ damage.

Enhancement of endogenous defenses against ROS by supra-nutritional level of selenium is more safe and effective than antioxidant supplementation in reducing hypertensive target organ damage

Hypertension-induced target organ damage (TOD), is one of the leading causes of morbidity and mortality. Reactive oxygen species (ROS) play an important role in the pathogenesis and development of hypertension. It has been suggested that hypertension-induced TOD is related to the level of oxidative stress, but is in part independent of the level of blood pressure. Therefore, in addition to anti-hypertensive drug therapy, novel strategies against ROS, will provide additional benefits to patient with hypertension. Vitamin E has long been supplemented as an effective antioxidant. However, the potential hazardous effects of vitamin E supplementation as antioxidant revealed by recent studies make its clinical and routine use prudent. Therefore, novel approaches capable of enhancing endogenous system to defend against ROS are required. Here, we propose that enhancement of intrinsic defenses against ROS by supra-nutritional level of selenium is more safe and effective than antioxidant supplementation in reducing hypertensive target organ damage, owing to its role in activating and constitution of native vital proteins and/or enzymes against oxidative stress, and the fact that scarcity of selenium can not be supplemented by normal food, and potentially extra benefits by supra-normal intake.