Involvement of oxidation-sensitive mechanisms in the cardiovascular effects of hypercholesterolemia

Copper homeostasis and pregnancy complications: a comprehensive review

Pregnancy complications pose challenges for both pregnant women and obstetricians globally, with the pathogenesis of many remaining poorly understood. Recently coined as a mode of cell death, cuproptosis has been proposed but remains largely unexplored. This process involves copper overload, resulting in the accumulation of fatty acylated proteins and subsequent loss of iron-sulfur cluster proteins. This cascade induces proteotoxic stress, leading to cell death. In recent years, studies have indicated a connection between abnormal copper metabolism and several pregnancy-related diseases, including maternal placental dysplasia, gestational diabetes mellitus (GDM), gestational hypertension (PIH), preterm birth or abortion, as well as conditions in offspring such as intrauterine growth restriction (IUGR), allergic disease, Menkes disease, and Wilson's disease. Investigating the mechanism of cuproptosis and abnormal copper metabolism in these pregnancy-related diseases emerges as a critical research area. This article provides a concise review of cuproptosis mechanisms and emphasizes the association between abnormal copper metabolism and pregnancy-related diseases. Nevertheless, the doubtful viewpoints were also discussed.

The role of exercise in improving hyperlipidemia-renal injuries induced by a high-fat diet: a literature review

A diet that is high in sugar and fat is a precursor to various chronic diseases, especially hyperlipidemia. Patients with hyperlipidemia have increased levels of plasma free fatty acids and an ectopic accumulation of lipids. The kidney is one of the main organs affected by this disease and, recently, there have been more studies conducted on renal injury caused by hyperlipidemia. The main pathological mechanism is closely related to renal lipotoxicity. However, in different kidney cells, the reaction mechanism varies due to the different affinities of the lipid receptors. At present, it is believed that in addition to lipotoxicity, hyperlipidemia induced-renal injury is also closely related to oxidative stress, endoplasmic reticulum stress, and inflammatory reactions, which are the result of multiple factors. Exercise plays an important role in the prevention of various chronic diseases and recently emerging researches indicated its positive effects to renal injury caused by hyperlipidemia. However, there are few studies summarizing the effects of exercise on this disease and the specific mechanisms need to be further explored. This article summarizes the mechanisms of hyperlipidemia induced-renal injury at the cellular level and discusses the ways in which exercise may regulate it. The results provide theoretical support and novel approaches for identifying the intervention target to treat hyperlipidemia induced-renal injury.

A Systematic Review and Meta-Analysis of the Effect of Statins on Glutathione Peroxidase, Superoxide Dismutase, and Catalase

Statins may exert protective effects against oxidative stress by upregulating specific antioxidant mechanisms. We conducted a systematic review and meta-analysis of the effect of statins on three key antioxidant enzymes: glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase. The electronic databases PubMed, Web of Science, and Scopus were searched from inception to July 2021. The risk of bias was assessed with the Joanna Briggs Institute Critical Appraisal Checklist and certainty of evidence was assessed using the GRADE framework. In 15 studies, reporting 17 treatment arms in 773 patients (mean age 53 years, 54% males), statins significantly increased the concentrations of both GPx (standardized mean difference, SMD = 0.80, 95% confidence interval, CI 0.13 to 1.46, p = 0.018; high certainty of evidence) and SOD (SMD = 1.54, 95% CI 0.71 to 2.36, p < 0.001; high certainty of evidence), but not catalase (SMD = −0.16, 95% CI −0.51 to 0.20, p = 0.394; very low certainty of evidence). The pooled SMD values were not altered in sensitivity analysis. There was no publication bias. In conclusion, statin treatment significantly increases the circulating concentrations of GPx and SOD, suggesting an antioxidant effect of these agents (PROSPERO registration number: CRD42021271589).

Redox regulation of hemodynamics response to diadenosine tetraphosphate an agonist of P2 receptors and renal function in diet-induced hypercholesterolemic rats

Hypercholesterolemia and oxidative stress may lead to disturbances in the renal microvasculature in response to vasoactive agents, including P2 receptors (P2R) agonists. We investigated the renal microvascular response to diadenosine tetraphosphate (Ap₄A), an agonist of P2R, in diet‐induced hypercholesteremic rats over 28 days, supplemented in the last 10 days with tempol (2 mM) or DL‐buthionine‐(S,R)‐sulfoximine (BSO, 20 mM) in the drinking water. Using laser Doppler flowmetry, renal blood perfusion in the cortex and medulla (CBP, MBP) was measured during the infusion of Ap₄A. This induced a biphasic response in the CBP: a phase of rapid decrease was followed by one of rapid increase extended for 30 min in both the normocholesterolemic and hypercholesterolemic rats. The phase of decreased CBP was not affected by tempol or BSO in either group. Early and extended increases in CBP were prevented by tempol in the hypercholesterolemia rats, while, in the normocholesterolemic rats, only the extended increase in CBP was affected by tempol; BSO prevented extended increase in CBP in normocholesterolemic rats. MBP response is not affected by hypercholesterolemia. The hypercholesterolemic rats were characterized by increased urinary albumin and 8‐isoPGF_2α excretion. Moreover, BSO increased the urinary excretion of nephrin in the hypercholesterolemic rats but, similar to tempol, did not affect the excretion of albumin in their urine. The results suggest the important role of redox balance in the extracellular nucleotide regulation of the renal vasculature and glomerular injury in hypercholesterolemia.

Epigenetic-based therapy in allogenic hematopoietic stem cell transplantation: Novel opportunities for personalized treatment

Current management of patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) lacks immunosuppressant drugs able to block the host immune response toward the graft antigens. Novel treatments may include epigenetic compounds (epidrugs) some of which have been yet approved by the Food and Drugs Administration for the treatment of specific blood malignancies. The most investigated in clinical trials for allo-HSCT are DNA demethylating agents (DNMTi), such as azacitidine (Vidaza) and decitabine (Dacogen) as well as histone deacetylases inhibitors (HDACi), such as vorinostat (Zolinza) and panobinostat (Farydak). Indeed, azacitidine monotherapy before allo-HSCT may reduce the conventional chemotherapy-related complications, whereas it may reduce relapse risk and death after allo-HSCT. Besides, a decitabine-containing conditioning regimen could protect against graft versus host disease (GVHD) and respiratory infections after allo-HSCT. Regarding HDACi, the addition of vorinostat and panobinostat to the conditioning regimen after allo-HSCT seems to reduce the incidence of acute GVHD. Furthermore, panobinostat alone or in combination with low-dose decitabine may reduce the relapse rate in high-risk patients with acute myeloid leukemia patients after allo-HSCT. We discuss the phase 1 and 2 clinical trials evaluating the possible beneficial effects of repurposing specific epidrugs which may guide personalized therapy in the setting of allo-HSCT.

Exercise reduces hyperlipidemia-induced kidney damage in apolipoprotein E-deficient mice

Hyperlipidemia is a risk factor of kidney damage that can lead to chronic kidney disease. Studies have shown that exercise reduces kidney damage; however, the specific mechanisms underlying the protective effects of exercise remain unclear. For 12 weeks, 8-week-old male apolipoprotein E-deficient (ApoE^-/-) mice were randomly divided into four treatment groups (n=7/group) as follows: Mice fed a normal diet (ND group); mice fed a ND and exercised (ND + E group); mice fed a high-fat diet (HD group); and mice fed a HD and exercised (HD + E group). Exercise training consisted of swimming for 40 min, 5 days/week. Metabolic parameters, such as low-density lipoprotein-cholesterol, total cholesterol and creatinine levels were higher in the ApoE^-/- HD mice compared with those in the ApoE^-/- HD + E mice. Serum levels of glutathione peroxidase and superoxide dismutase were significantly decreased in the HD group compared with those in the HD + E group. Significant pathological changes were observed in the HD + E group compared with in the HD group. Immunohistochemistry and immunoblotting revealed increased levels of oxidative stress (nuclear factor erythroid-2-related factor 2) and fibrosis (Smad3 and TGF-β) markers in the ApoE^-/- HD group; however, the expression levels of these markers were significantly decreased in the ApoE^-/- HD + E group. Furthermore, NF-κB expression in the HD + E group was significantly lower compared with that in the HD group. These results suggested that exercise may exert protective effects against kidney damage caused by hyperlipidemia.

A Comorbidity Model of Myocardial Ischemia/Reperfusion Injury and Hypercholesterolemia in Rat Cardiac Myocyte Cultures

Introduction

The use of comorbidity models is crucial in cardioprotective drug development. Hypercholesterolemia causes endothelial and myocardial dysfunction, as well as aggravates ischemia/reperfusion (I/R)-induced myocardial injury. Endogenous cardioprotective mechanisms against I/R are impaired in hyperlipidemic and hyperglycemic in vivo animal models. Therefore, our aim was to develop a medium throughput comorbidity cell-based test system of myocardial I/R injury, hypercholesterolemia and hyperglycemia that mimics comorbidity conditions.

Methods

Cardiac myocytes isolated from neonatal or adult rat hearts were cultured in control or in three different hypercholesterolemic media with increasing cholesterol content (hiChol) or hiChol + hyperglycemic medium, respectively. Each group was then subjected to simulated ischemia/reperfusion (SI/R) or corresponding normoxic condition, respectively. Cholesterol uptake was tested by Filipin staining in neonatal cardiac myocytes. Cell viability, total cell count and oxidative stress, i.e., total reactive oxygen species (ROS) and superoxide level were measured by fluorescent assays.

Results

Neonatal cardiac myocytes took up cholesterol from the different hiChol media at a concentration-dependent manner. In normoxia, viability of hiChol neonatal cardiac myocytes was not significantly changed, however, superoxide levels were increased as compared to vehicle. After SI/R, the viability of hiChol neonatal cardiac myocytes was decreased and total ROS level was increased as compared to vehicle. HiChol combined with hyperglycemia further aggravated cell death and oxidative stress in normoxic as well as in SI/R conditions. Viability of hiChol adult cardiac myocytes was significantly decreased and superoxide level was increased in normoxia and these changes were further aggravated by SI/R. HiChol combined with hyperglycemia further aggravated cell death, however level of oxidative stress increased only in normoxic condition.

Conclusion

HiChol rat cardiac myocytes showed reduction of cell viability and increased oxidative stress, which were further aggravated by SI/R and with additional hyperglycemia. This is the first demonstration that the combination of the current hypercholesterolemic medium and SI/R in cardiac myocytes mimics the cardiac pathology of the comorbid heart with I/R and hypercholesterolemia.

Lycopene-Rich Extract from Red Guava (Psidium guajava L.) Decreases Plasma Triglycerides and Improves Oxidative Stress Biomarkers on Experimentally-Induced Dyslipidemia in Hamsters

This work assessed the effects of a 28-day treatment with lycopene-rich extract (LRE) from red guava fruit (Psidium guajava L.) on the lipid profile and oxidative stress in an experimental model of dyslipidemia. Male hamsters (116.5 ± 2.16 g) were fed with the AIN 93G diet containing casein (20%), coconut fat (13.5%) and cholesterol (0.1%). The animals were divided into four groups: normolipidemic control (standard feed; NC, n = 7); hypercholesterolemic control (HC, n = 7); LRE 25 mg/kg/day (LRE-25, n = 7) and LRE 50 mg/kg/day (LRE-50, n = 9). After treatment, plasma concentrations of triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL) cholesterol (LDL-c), high-density lipoprotein (HDL) cholesterol (HDL-c), malondialdehyde (MDA-p) and myeloperoxidase (MPO), as well as erythrocytic superoxide dismutase (SOD-e) and the atherogenic index, were determined. Malondialdehyde (MDA-h), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD-h) levels were assessed. Feed intake (FI) and weight gain (WG) were also determined. The LRE-25 group presented significantly lower TG levels and atherogenic index than did the HC group (p < 0.05). Both LRE-25 and LRE-50 groups presented lower levels of MDA-p and MPO than did the HC group (p < 0.05). LRE demonstrated a promising effect against dyslipidemia and oxidative stress.

Effect of hypercholesterolaemia on myocardial function, ischaemia-reperfusion injury and cardioprotection by preconditioning, postconditioning and remote conditioning

Hypercholesterolaemia is considered to be a principle risk factor for cardiovascular disease, having direct negative effects on the myocardium itself, in addition to the development of atherosclerosis. Since hypercholesterolaemia affects the global cardiac gene expression profile, among many other factors, it results in increased myocardial oxidative stress, mitochondrial dysfunction and inflammation triggered apoptosis, all of which may account for myocardial dysfunction and increased susceptibility of the myocardium to infarction. In addition, numerous experimental and clinical studies have revealed that hyperlcholesterolaemia may interfere with the cardioprotective potential of conditioning mechanisms. Although not fully elucidated, the underlying mechanisms for the lost cardioprotection in hypercholesterolaemic animals have been reported to involve dysregulation of the endothelial NOS-cGMP, reperfusion injury salvage kinase, peroxynitrite-MMP2 signalling pathways, modulation of ATP-sensitive potassium channels and apoptotic pathways. In this review article, we summarize the current knowledge on the effect of hypercholesterolaemia on the non-ischaemic and ischaemic heart as well as on the cardioprotection induced by drugs or ischaemic preconditioning, postconditioning and remote conditioning. Future perspectives concerning the mechanisms and the design of preclinical and clinical trials are highlighted.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Mouse models of atherosclerosis: a historical perspective and recent advances

Atherosclerosis represents a significant cause of morbidity and mortality in both the developed and developing countries. Animal models of atherosclerosis have served as valuable tools for providing insights on its aetiology, pathophysiology and complications. They can be used for invasive interrogation of physiological function and provide a platform for testing the efficacy and safety of different pharmacological therapies. Compared to studies using human subjects, animal models have the advantages of being easier to manage, with controllable diet and environmental risk factors. Moreover, pathophysiological changes can be induced either genetically or pharmacologically to study the harmful effects of these interventions. There is no single ideal animal model, as different systems are suitable for different research objectives. A good understanding of the similarities and differences to humans enables effective extrapolation of data for translational application. In this article, we will examine the different mouse models for the study and elucidation of the pathophysiological mechanisms underlying atherosclerosis. We also review recent advances in the field, such as the role of oxidative stress in promoting endoplasmic reticulum stress, mitochondrial dysfunction and mitochondrial DNA damage, which can result in vascular inflammation and atherosclerosis. Finally, novel therapeutic approaches to reduce vascular damage caused by chronic inflammation using microRNA and nano-medicine technology, are discussed.

Anti-HMG-CoA Reductase, Antioxidant, and Anti-Inflammatory Activities of Amaranthus viridis Leaf Extract as a Potential Treatment for Hypercholesterolemia

Inflammation and oxidative stress are believed to contribute to the pathology of several chronic diseases including hypercholesterolemia (elevated levels of cholesterol in blood) and atherosclerosis. HMG-CoA reductase inhibitors of plant origin are needed as synthetic drugs, such as statins, which are known to cause adverse effects on the liver and muscles. Amaranthus viridis (A. viridis) has been used from ancient times for its supposedly medically beneficial properties. In the current study, different parts of A. viridis (leaf, stem, and seed) were evaluated for potential anti-HMG-CoA reductase, antioxidant, and anti-inflammatory activities. The putative HMG-CoA reductase inhibitory activity of A. viridis extracts at different concentrations was determined spectrophotometrically by NADPH oxidation, using HMG-CoA as substrate. A. viridis leaf extract revealed the highest HMG-CoA reductase inhibitory effect at about 71%, with noncompetitive inhibition in Lineweaver-Burk plot analysis. The leaf extract showed good inhibition of hydroperoxides, 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), and ferric ion radicals in various concentrations. A. viridis leaf extract was proven to be an effective inhibitor of hyaluronidase, lipoxygenase, and xanthine oxidase enzymes. The experimental data suggest that A. viridis leaf extract is a source of potent antioxidant and anti-inflammatory agent and may modulate cholesterol metabolism by inhibition of HMG-CoA reductase.

Protective role of phytosterol esters in combating oxidative hepatocellular injury in hypercholesterolemic rats

The aim of the present study is to evaluate the effect of eicosapentaenoic acid-docosahexaenoic acid (EPA-DHA) rich sterol ester and A-linolenic Acid (ALA) rich sterol ester on the atherogenic disturbances in hypercholesterolemic atherogenic animals. Six groups of male Wistar rats were employed in this study, wherein five groups were fed with a high cholesterol diet (stock diet supplemented with 1% cholesterol) for 30 days, among which, two groups of rats were also treated with EPA-DHA rich sterol ester in two doses (25 and 50 mg/rat/day, oral gavage) and two groups were treated with ALA rich sterol ester also in two doses (25 and 50 mg/rat/day, oral gavage). The remaining one group served as control. Abnormal increases in the levels of malondialdehyde, as well as depressed antioxidants status, were observed in hepatic tissue of hypercholesterolemic control group. Hypercholesterolemia induced abnormal elevation in the activities of marker enzymes in liver (aspartate transaminase, alanine transaminase and alkaline phosphatase) and was accompanied by increased hepatic cholesterol level and altered fatty changes in the histology of liver. These changes were restored partially in the groups administered with lower doses (25 mg/rat/day) of sterol esters. However, the higher doses (50 mg/rat/day) of sterol esters almost ameliorated the hypercholesterolemic-oxidative changes in the hypercholesterolemic rats. The results of this study present oxidative injury induced by hypercholesterolemic diet and administration of the treatment with higher doses of sterol esters afforded sound protection against lipemic-oxidative injury.

Sitagliptin ameliorates the progression of atherosclerosis via down regulation of the inflammatory and oxidative pathways

Back ground:

Atherosclerosis is the major cause of death. The most common risk factors are hyperlipidemia, diabetes, and other factors like chronic infection and inflammation.

Objective:

This study was undertaken to assess the effect of sitagliptin on atherosclerosis via interfering with inflammatory and oxidative pathways.

Materials and Methods:

A total of 18 local domestic male rabbits were included in this study. The animals were randomly divided into three groups (6 rabbits in each group): Group I normal were fed with chow (oxiod) diet for 12 weeks. Group II were fed with 1% cholesterol enriched diet for 12 weeks. Group III rabbits fed with cholesterol enriched diet for 6 weeks, and then continued on cholesterol enriched diet and treated with sitagliptin 125 mg/kg/day orally for the next 6 weeks. Blood samples were collected at the start of the study, at 6 weeks of the study and then at the end of treatment to measure serum lipids profile, hsCRP and TNFα. At end of the study, the aorta was removed for measurement of MDA, glutathione and, aortic intima-media thickness.

Results:

Sitagliptin results in a significant reduction (p < 0.05) in serum level of total cholesterol (TC), triglycerides (TG), high sensitive C-reactive protein (hsCRP) and TNFα with a significant increase (p < 0.05) in serum HDL level. There was a significant reduction (p < 0.05) in aortic MDA, in comparison to the untreated control group. Furthermore, sitagliptin causes significant increment (p < 0.05) in aortic GSH in comparison to induced untreated group. Regarding histopathological results, sitagliptin results in a significant reduction (p < 0.05) in atherosclerotic lesions in comparison to the induced untreated group and significant reduction in aortic intima-media thickness (p < 0.05).

Conclusion:

Sitagliptin reduced atherosclerosis progression in hyperlipidemic rabbit via its effect on lipid parameters and interfering with inflammatory and oxidative stress.

Maternal lipids at mid-pregnancy and the risk of preterm delivery

OBJECTIVE

This study examined associations between maternal lipid levels at mid-pregnancy and preterm delivery, medically indicated or spontaneous.

DESIGN

Prospective cohort study.

SETTING

Women were recruited from 52 clinics in five Michigan, USA communities (1998-2004).

POPULATION

Pregnant women were enrolled at 15-27 weeks' gestation and followed to delivery (n=3019).

METHODS

A single blood sample was obtained at study enrollment. Blood lipids, i.e. total cholesterol (TC), high-density lipoprotein (HDLc), low-density lipoprotein (LDLc) cholesterol, and triglycerides (TG), were measured on a sub-cohort (n=1309).

MAIN OUTCOME MEASURES

There were 221 spontaneous, 100 medically indicated preterm deliveries and 988 term deliveries. Polytomous logistic regression models examined relationships among cholesterol levels (Low: <10(th) percentile, Referent: 10(th) -<70(th) percentile, High: ≥70(th) percentile), quartiles of TG (Referent: first quartile) and delivery outcome (Referent: term).

RESULTS

Odds of medically indicated preterm delivery were increased among women with low TC (adjusted odds ratio (aOR)=2.04, 95% confidence interval (CI): 1.12, 3.72), low HDLc (aOR=1.89, 95%CI: 1.04, 3.42) or low LDLc (aOR=1.96, 95%CI: 1.09, 3.54). Odds of spontaneous preterm delivery were increased among women with high TC (aOR=1.51, 95%CI: 1.06, 2.15), high LDLc (aOR=1.42, 95%CI: 0.99, 2.04) or high TG (aOR=1.90, 95%CI: 1.21, 2.97 and aOR=1.72, 95%CI: 1.06, 2.78 for third and fourth quartiles, respectively).

CONCLUSIONS

Extremely low TC, HDLc, and LDLc were associated with a modest increase in risk of medically indicated preterm delivery, whereas high TC, LDLc and TG modestly increased the risk of spontaneous preterm delivery. Further research is needed to uncover explanations for these associations and to identify optimal ranges for maternal lipids.

Hypercholesterolemia promotes early renal dysfunction in apolipoprotein E-deficient mice

Background

Aging and dyslipidemia are processes which can lead to deleterious consequences to renal function. Therefore, the aim of this study was to determine the effects of both hypercholesterolemia and aging on renal function in mice.

Methods

Male hypercholesterolemic apolipoprotein E-deficient mice (ApoE, n = 13) and age-matched C57BL/6 control mice (C57, n = 15) were studied at 2 (young) and 8 (adult) month-old. At each time point, animals were placed in metabolic cages for 24 hours to urine volume and urinary creatinine quantification. Blood samples were collected for serum cholesterol, urea and creatinine measurements. Glomerular filtration rate (GFR) was estimated through creatinine clearance determination. Mesangial expansion was evaluated by Periodic Acid Schiff staining, renal fibrosis was determined through Masson's trichrome staining and neuronal nitric oxide synthase (nNOS) expression in the kidney was performed by Western Blotting. To statistical analysis two-way ANOVA followed by Fisher's post hoc test was used.

Results

Total plasma cholesterol was increased about 5-fold in ApoE mice at both time points compared to C57 animals. At 2-month-old, GFR was already markedly reduced in ApoE compared to C57 mice (187 ± 28 vs 358 ± 92 μL/min, p < 0.05). Adult C57 (-77%) and ApoE (-50%) mice also presented a significant reduction of GFR. In addition, serum urea was significantly increased in young ApoE animals compared to C57 mice (11 ± 1.3 vs 7 ± 0.9 mmol/L, p < 0.01). A significant mesangial expansion was observed at 2-month old ApoE mice compared to C57 mice (35 ± 0.6 vs 30 ± 0.9%, respectively, p < 0.05), which was aggravated at 8-month old animals (40 ± 3 and 35 ± 3%, respectively). Tubulointersticial fibrosis was augmented at both young (17 ± 2%, p < 0.05) and adult (20 ± 1%, p < 0.05) ApoE mice compared to respective C57 age controls (8 ± 1 and 12 ± 2%, respectively). The expression of nNOS was markedly reduced in a time-dependent manner in both strains.

Conclusions

These data show that both hypercholesterolemia and aging contribute to the loss of renal function in mice.

Mechanisms of tissue injury in renal artery stenosis: ischemia and beyond

Renal injury distal to an atherosclerotic renovascular obstruction reflects multiple intrinsic factors producing parenchymal tissue injury. Atherosclerotic disease pathways superimposed on renal arterial obstruction may aggravate damage to the kidney and other target organs, and some of the factors activated by renal artery stenosis may in turn accelerate the progression of atherosclerosis. This cross-talk is mediated through amplified activation of renin-angiotensin system, oxidative stress, inflammation, and fibrosis-pathways notoriously involved in renal disease progression. Oxidation of lipids also accelerates the development of fibrosis in the stenotic kidney by amplifying profibrotic mechanisms and disrupting tissue remodeling. The extent to which actual ischemia modulates injury in the stenotic kidney has been controversial, partly because the decrease in renal oxygen consumption usually parallels a decrease in renal blood flow, and because renal vein oxygen pressure in the affected kidney is not decreased. However, recent data using novel methodologies demonstrate that intra-renal oxygenation is heterogeneously affected in different regions of the kidney. Activation of such local injury within the kidney may lead to renal dysfunction and structural injury, and ultimately unfavorable and irreversible renal outcomes. Identification of specific pathways producing progressive renal injury may enable development of targeted interventions to block these pathways and preserve the stenotic kidney.

Arginine uptake is attenuated, through post-translational regulation of cationic amino acid transporter-1, in hyperlipidemic rats

Endothelial cell dysfunction (ECD) is a common feature of hypercholesterolemia. Defective nitric oxide (NO) generation due to decreased endothelial nitric oxide synthase (eNOS) activity is a crucial parameter characterizing ECD. L-arginine is the sole precursor for NO biosynthesis. Among several transporters that mediate L-arginine uptake, cationic amino acid transporter-1 (CAT-1) acts as a specific arginine transporter for eNOS. Our hypothesis implies that CAT-1 is a major determinant of eNOS activity in hypercholesterolemia. We studied aortic arginine uptake, CAT-1 and CAT-2 mRNA expression, and CAT-1, and PKC alpha protein in: (a) control, untreated animals (CTL), (b) rats fed with 4% cholesterol+1% cholate and 2% corn oil for 6 weeks (CHOL) and (c) rats with hypercholesterolemia treated orally with either atorvastatin (CHOL+ATORVA, 20mg/kg BW/day) or arginine 1% (CHOL+ARG) in the drinking water (modalities which have been shown to enhance CAT-1 activity and improve endothelial function). Serum cholesterol levels significantly increased in cholesterol fed animals, an increase which was blocked by atorvastatin (CTL: 66.8+/-15, CHOL: 133.9+/-22, CHOL+ARG: 128.2+/-20, CHOL+ATORVA: 77+/-15 mg/dl). Arginine transport was significantly decreased in CHOL. Treatment with neither arginine nor atorvastatin had an effect. Using RT-PCR, we found no change in aortic CAT-1 and CAT-2 mRNA expression in CHOL as well as following arginine or atorvastatin administration. The abundance of CAT-1 protein was significantly augmented in cholesterol fed rats and was not affected by arginine or atorvastatin. PKC alpha protein content, which was previously shown to regulate CAT-1 activity, increased significantly in CHOL and was neither affected by atorvastatin nor arginine. In conclusion, aortic arginine uptake is attenuated in hypercholesterolemia, through post-translational modulation of CAT-1 protein, possibly via upregulation of PKC alpha.

Pomegranate juice reduces oxidized low-density lipoprotein downregulation of endothelial nitric oxide synthase in human coronary endothelial cells

We examined the hypothesis that pomegranate juice (PJ) can revert the potent downregulation of the expression of endothelial nitric-oxide synthase (NOSIII) induced by oxidized low-density liporotein (oxLDL) in human coronary endothelial cells. Western blot and Northern blot analyses showed a significant decrease of NOSIII expression after a 24-h treatment with oxLDL. Accordingly, we observed a significant dose-dependent reduction in nitric oxide bioactivity represented by both basal and bradykinin-stimulated cellular cGMP accumulation. These phenomena were corrected significantly by the concomitant treatment with PJ. Our data suggest that PJ can exert beneficial effects on the evolution of clinical vascular complications, coronary heart disease, and atherogenesis in humans by enhancing the NOSIII bioactivity.

Therapeutic effects of concurrent autologous bone marrow cell infusion and metabolic intervention in ischemia-induced angiogenesis in the hypercholesterolemic mouse hindlimb

Lower-limb ischemia is a major health problem especially when associated to hypercholesterolemia. Because of the absence of effective treatment in the advanced stages of the disease, amputation is undertaken to alleviate unbearable symptoms. Since tissue ischemia and hypercholesterolemia are associated with an overwhelming generation of oxygen radicals, metabolic intervention with antioxidants and l-arginine can induce beneficial effects beyond those achieved by a novel therapeutic approach represented by the use of autologous bone marrow cells (BMCs). The protective effect of BMCs and vascular protection by metabolic cotreatment (1.0% vitamin E added to the chow, 0.05% vitamin C and 6% l-arginine added to the drinking water) were examined in ischemia-induced angiogenesis in the hypercholesterolemic mouse hindlimb. Intravenous BMC therapy improved blood flow and increased capillary densities. This beneficial effect was amplified by metabolic cotreatment, an intervention inducing vascular protection, at least in part, through the nitric oxide pathway, reduction of systemic oxidative stress and macrophage activation.

Oxidative renal injury and lipoprotein oxidation in hypercholesterolemic atherogenesis: Role of eicosapentaenoate-lipoate (EPA-LA) derivative

Hypercholesterolemia, an independent risk factor for increased oxidative renal injury, is associated with the formation of oxidized low-density lipoprotein. Production of reactive oxygen species and nitrogen species have been implicated in diet-induced hypercholesterolemia, principally as means of oxidising low-density lipoproteins. This in turn initiates the accumulation of cholesterol in macrophages, which sets key event in the initiation of atherosclerosis. The aim of the present work is to evaluate the effects of eicosapentaenoic acid (EPA), DL alpha-lipoic acid (LA) and eicosapentaenoate-lipoate derivative (EPA-LA) in controlling the atherogenic disturbances. Four groups of male Wistar rats were fed with a high cholesterol diet (rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days. Among them, 3 groups of rats were treated with either EPA (35 mg/kg body weight/day, oral gavage), LA (20 mg/kg body weight/day, oral gavage) or EPA-LA derivative (50 mg/kg body weight/day, oral gavage) from 16th day to 30th day of the experimental period. Abnormal increase in the levels of reactive oxygen species, 3-nitrotyrosine, malondialdehyde and protein carbonyl as well as an elevation in the activities of xanthine oxidase, lactate dehydrogenase, alkaline phosphatase and acid phosphatase was observed in renal tissue of HCD fed rats. HCD fed rats also showed an increased susceptibility of the apo B-containing lipoproteins to in vitro oxidation. These changes were restored partially in the EPA and LA administered groups. However, the combined derivative EPA-LA almost ameliorated the hypercholesterolemic-oxidative changes in the HCD fed rats.

Microvascular responses to hypercholesterolemia: the interactions between innate and adaptive immune responses

Hypercholesterolemia is recognized as one of the major risk factors in cardiovascular disease. It promotes the development of a proinflammatory phenotype in large vessels, in particular arteries, with disease. Cells of the innate and adaptive immune system are localized within atherosclerotic plaques and participate in the initiation and progression of plaque formation. It is now recognized that each segment of the microvasculature also experiences inflammation due to hypercholesterolemia, and that this occurs long before events in the large vessels. More recently, it is has been established that the innate and adaptive immune systems participate in the responses of postcapillary venules, and possibly arterioles, to elevated cholesterol levels, and that T lymphocytes may be one of the early cell types activated by hypercholesterolemia. These cells initiate a series of steps that lead to leukocyte accumulation in postcapillary venules and endothelial dysfunction in the arterioles. This review discusses the microvascular alterations induced by hypercholesterolemia, with particular attention paid to the roles of the innate and adaptive immune responses, and how these two systems may communicate to induce the microvascular inflammation.

Nitric oxide and atherosclerosis: an update

Nitric oxide (NO) is a molecule that has gained recognition as a crucial modulator of vascular disease. NO has a number of intracellular effects that lead to vasorelaxation, endothelial regeneration, inhibition of leukocyte chemotaxis, and platelet adhesion. Endothelium damage induced by atherosclerosis leads to the reduction in bioactivity of endothelial NO synthase (eNOS) with subsequent impaired release of NO together with a local enhanced degradation of NO by increased generation of reactive oxygen species with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Many commonly used vasculoprotective agents have their therapeutic actions through the production of NO. L-Arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. Finally, eNOS gene polymorphism might be an additional risk factor that may contribute to predict cardiovascular events. However, further studies are needed to understand the possible clinical implications of these correlations.

Protective role of eicosapentaenoate-lipoate (EPA-LA) derivative in combating oxidative hepatocellular injury in hypercholesterolemic atherogenesis

The aim of the present study is to evaluate the effect of eicosapentaenoic acid (EPA), dl-alpha-lipoic acid (LA) and eicosapentaenoate-lipoate (EPA-LA) derivative on the atherogenic disturbances in hypercholesterolemic atherogenic animals. Eight groups of male Wistar rats were employed in this study, wherein four groups were fed with a high cholesterol diet (rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days, among which, three groups of rats were also treated with either EPA (35 mg/kg body weight/day, oral gavage), LA (20 mg/kg body weight/day, oral gavage) or EPA-LA derivative (50 mg/kg body weight/day, oral gavage) commencing from 16th day of the experimental period. The remaining four groups served as control and EPA, LA and EPA-LA derivative treated drug controls. Abnormal increases in the levels of malondialdehyde, protein carbonyl and 8-hydroxy-2-deoxyguanosine, as well as depressed antioxidants status, were observed in hepatic tissue of HCD fed rats. HCD induced abnormal elevation in the activities of hepatic lactate dehydrogenase, aminotransferases and alkaline phosphatase (ALP) and was accompanied by increased hepatic cholesterol level and altered fatty changes in the histology of liver. These changes were restored partially in the EPA and LA administered groups. However, the combined derivative EPA-LA almost ameliorated the hypercholesterolemic-oxidative changes in the HCD fed rats. The results of this study present oxidative injury induced by hypercholesterolemic diet and administration of the combination treatment of EPA-LA afforded sound protection against lipemic-oxidative injury.

Attenuation of serum lipid abnormalities and cardiac oxidative stress by eicosapentaenoate-lipoate (EPA-LA) derivative in experimental hypercholesterolemia

BACKGROUND

Dietary cholesterol plays an important role in development of atherogenesis and cardiovascular disease. We explored the lipemic-oxidative injury in the hypercholesterolemic atherogenic animals. The effects of eicosapentaenoic acid (EPA), dl-alpha-lipoic acid (LA) and eicosapentaenoate-lipoate derivative (EPA-LA) were tested for their efficacy in controlling the atherogenic disturbances.

METHODS

Four groups of male Wistar rats were fed with a high cholesterol diet (rat chow supplemented with 4% cholesterol and 1% cholic acid; HCD) for 30 days. Of these groups, 3 groups of rats were treated with either EPA (oral gavage, 35 mg/kg body weight/day), LA (oral gavage, 20 mg/kg body weight/day) or EPA-LA derivative (oral gavage, 50 mg/kg body weight/day) from 16th day to 30th day of the experimental period.

RESULTS

HCD induced abnormal increase in lipid peroxidation and serum cholesterol, triglyceride, LDL and VLDL, and a decreased HDL concentration. Altered activity of cardiac and serum creatine kinase, accompanied by a depressed cardiac enzymatic and nonenzymatic antioxidants defense system were observed in HCD fed rats. These changes were partially restored in the EPA and LA treated groups, however, their combined derivative EPA-LA more effectively restored the altered parameters near to that of control (P<0.05).

CONCLUSION

Lipid abnormalities and oxidative injury were induced by a hypercholesterolemic diet. Administration of the combination treatment of EPA-LA afforded protection against the lipemic-oxidative injury.

Hyperlipidemia in children

Hyperlipidemia in children has emerged as an increasingly prevalent risk factor in children, concomitant with the worldwide epidemic of obesity. Hyperlipidemia can alter vascular endothelial function and impair some of its pro-fibrinolytic and anti-thrombotic regulatory properties, as well as initiate the atherosclerotic process. There are strong links between vascular changes and hyperlipidemia in children, both from pathologic and non-invasive assessment studies. More severe lipid abnormalities in children are related to primary familial dyslipidemias. Current recommendations for screening begin with assessment of family history for cardiovascular disease or events or parental hyperlipidemia. High-risk individuals merit more intensive investigation and intervention. While fat-restricted diets have been shown to be safe in children, lipid-lowering is modest. Those with more severe lipid abnormalities may meet criteria for drug therapy, and the statin agents commonly used in adults are increasingly being used in high-risk children, with similar efficacy and safety, although long-term concerns remain.

Effects of Proteasome Inhibition on the Kidney in Experimental Hypercholesterolemia

Hypercholesterolemia (HC) and atherosclerosis often accompany and aggravate renal disease. Proteasome inhibitors (PSI) can decrease proliferation and inflammation, likely by reducing activation of the proinflammatory NF-kappaB. However, chronic proteasome inhibition has never been demonstrated in the HC kidney. Four groups of pigs (n = 7 each) were studied after a 12-wk normal (N) or 2% HC diet alone or supplemented (N+PSI and HC+PSI) with MLN-273 (0.08 mg/kg subcutaneously twice weekly). Renal hemodynamics and function were quantified in vivo using electron-beam computed tomography at baseline and after vasodilator challenge using acetylcholine. Renal tissue was studied ex vivo using immunoblotting, PCR, and immunohistochemistry. Serum cholesterol was similarly elevated in HC and HC+PSI. Basal renal blood flow was similar among the groups, whereas GFR was decreased in both N+PSI and HC+PSI. The blunted renovascular and functional responses to acetylcholine in HC were normalized in HC+PSI (suggesting renal endothelial function improvement), which was accompanied by decreased renal endothelin, NF-kappaB, and augmented endothelial nitric oxide synthase expression. In parallel, HC+PSI animals also showed elevated NAD(P)H oxidase expression and circulating oxidized LDL, suggesting a potential for increased oxidative stress. This study shows that chronic PSI intervention in HC improves renal endothelial functional responses to challenge, possibly by modulating nitric oxide availability and endothelin. Furthermore, PSI may decrease intrarenal inflammation through modulation of the NF-kappaB pathway but may potentially increase oxidative stress, which warrants further investigation. This study may support a role for the ubiquitin/proteasome system in the kidney in HC and early atherosclerosis.

Novel features of nitric oxide, endothelial nitric oxide synthase, and atherosclerosis

There is a complex pathophysiologic scenario involving nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and the development of atherosclerosis and unstable atheroma. Endothelial damage induced by atherosclerosis leads to the reduction in bioactivity of eNOS with subsequent impaired release of NO. An important mechanism is local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals, with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Novel molecular approaches have resulted in the development of new strains of mice lacking eNOS. These experimental models will help to understand how to implement NO-based therapies against atherosclerosis. L-arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. The target or goal for new drugs should be the complete restoration of NO-mediated signaling pathways in atherosclerotic arteries.

Novel features of nitric oxide, endothelial nitric oxide synthase, and atherosclerosis

There is a complex pathophysiologic scenario involving nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and the development of atherosclerosis and unstable atheroma. Endothelial damage induced by atherosclerosis leads to the reduction in bioactivity of ENOS with subsequent impaired release of NO. An important mechanism is local enhanced degradation of NO by increased generation of reactive oxygen species and other free radicals, with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Novel molecular approaches have resulted in the development of new strains of mice lacking eNOS. These experimental models will help to understand how to implement NO-based therapies against atherosclerosis. L-arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. The target or goal for new drugs should be the complete restoration of NO-mediated signaling pathways in atherosclerotic arteries.

The beneficial effects of antioxidant supplementation in enteral feeding in critically ill patients: a prospective, randomized, double-blind, placebo-controlled trial

We investigated whether intervention with antioxidant vitamins C and E in enteral feeding influenced oxidative stress and clinical outcome in critically ill patients. Two-hundred-sixteen patients expected to require at least 10 days of enteral feeding completed the study. One-hundred-five patients received enteral feeding supplemented with antioxidants, and 111 control patients received an isocaloric formula. Plasma lipoperoxidation (by thiobarbituric acid reactive substances [TBARS] and prostaglandin F(2alpha) isoprostane levels), low-density lipoprotein (LDL) oxidizability, and LDL tocopherol content were determined at baseline and at the end of the 10-day period. The clinical 28-day outcome was also assessed. Plasma TBARS and isoprostanes were 5.33 +/- 1.26 nM/mL and 312 +/- 68 pg/mL, respectively, before treatment and 2.42 +/- 0.61 nM/mL and 198 +/- 42 pg/mL after intervention (P < 0.01 for both comparisons). Antioxidants improved LDL resistance to oxidative stress by approximately 30% (the lag time before treatment was 87 +/- 23 min and was 118 +/- 20 min after treatment; P < 0.04). There was a significantly reduced 28-day mortality after antioxidant intervention (45.7% in the antioxidant group and 67.5% in the regular-feeding group; P < 0.05). Isoprostanes may provide a sensitive biochemical marker for dose selection in studies involving antioxidants.

Long-term combined beneficial effects of physical training and metabolic treatment on atherosclerosis in hypercholesterolemic mice

The pathogenic mechanisms by which physical exercise influences atherosclerotic lesion formation remain poorly understood. Because vigorous physical training increases oxidative stress, this study tested the hypothesis that graduated and moderate physical exercise together with metabolic intervention (l-arginine and antioxidants) may contribute to increased vascular protection. Exercise training in mice was induced by graduated swimming. In hypercholesterolemic male mice on an atherogenic high-cholesterol diet, graduated and moderate exercise lowered plasma cholesterol and decreased atherosclerotic lesions compared with sedentary control mice. Antioxidants (1.0% vitamin E added to the chow and 0.05% vitamin C added to the drinking water) and l-arginine (6% in drinking water) supplementation to exercising hypercholesterolemic mice further and synergistically reduced atherosclerosis compared with untreated exercised mice. Arterial oxidation-specific epitopes and systemic oxidative stress were reduced by metabolic intervention. Graduated chronic exercise elicited an increase in production of nitric oxide through increased endothelial nitric oxide synthase expression and ameliorated scavenger activities. Thus, metabolic intervention with l-arginine and antioxidants together with graduated and moderate exercise training reduce atherosclerotic lesion formation.

Aortic glutathione metabolic status: time-dependent alterations in fat-fed rabbits

Little is known about the vascular metabolic status of glutathione (GSH), which is crucial in cell antioxidant protection, in experimental conditions like high-fat diet-induced atherosclerosis. This issue was, therefore, investigated in two groups of seven rabbits fed a 0.5% cholesterol-, 5% lard- and 5% peanut oil-enriched diet for 18 and 80 days, which, respectively, raised the plasma values of total cholesterol by factors of about 12 and 37, and those of triglycerides by factors of 3 and 13; rabbits fed a standard diet for the same periods served as controls. Total GSH and the activities of the GSH level-maintaining enzymes glutathione reductase (GSSG-Red), gamma-glutamylcysteine synthetase (gamma-GCS) and gamma-glutamyl transpeptidase (gamma-GT) were specifically assessed in the aortic tissue, which was also assayed for fluorescent damage products of lipid peroxidation (FDPL). Sudan red staining of the aortic intima surface was also performed in two other groups of six controls and six fat-fed rabbits. After 18 days of fat feeding, a significant decrement of aortic GSSG-Red activity, associated with gamma-GCS activation, increased GSH levels and normal gamma-GT activity, was observed; FDPL were only moderately enhanced, and atherosclerotic lesions did not occur. After 80 days of atherogenic diet, aortic GSH content was significantly decreased in concomitance with a marked depression of gamma-GT activity, while GSSG-Red and gamma-GCS activities were not significantly changed with respect to 18 days of fat feeding; FDPL underwent further considerable augmentation, and extensive Sudan red-stained atherosclerotic lesions were evident. Thus, short-term fat feeding induces gamma-GCS-dependent GSH biosynthesis of the rabbit aorta; prolonged high-fat intake and hyperlipidemic burden result instead in vascular gamma-GT dysfunction with GSH depletion, eventually favoring oxidative atherogenic effects.

Hypercholesterolemia promotes inflammation and microvascular dysfunction: role of nitric oxide and superoxide

Relatively brief periods (days) of hypercholesterolemia can exert profound effects on endothelium-dependent functions of the microcirculation, including dilation of arterioles, fluid filtration across capillaries, and regulation of leukocyte recruitment in postcapillary venules. Hypercholesterolemia appears to convert the normal anti-inflammatory phenotype of the microcirculation to a proinflammatory phenotype. This phenotypic change appears to result from a decline in nitric oxide (NO) bioavailability that results from a reduction in NO biosynthesis, inactivation of NO by superoxide (O(2)(*)(-)), or both. A consequence of the hypercholesterolemia-induced microvascular responses is an enhanced vulnerability of the microcirculation to the deleterious effects of ischemia and other inflammatory conditions. Hence, therapeutic strategies that are directed towards preventing the early microcirculatory dysfunction and inflammation caused by hypercholesterolemia may prove effective in reducing the high mortality associated with ischemic tissue diseases. Agents that act to maintain the normal balance between NO and reactive oxygen species (ROS) in vascular endothelial cells may prove particularly useful in this regard.

c-Myc oncoprotein: a dual pathogenic role in neoplasia and cardiovascular diseases?

A growing body of evidence indicates that c-Myc can play a pivotal role both in neoplasia and cardiovascular diseases. Indeed, alterations of the basal machinery of the cell and perturbations of c-Myc-dependent signaling network are involved in the pathogenesis of certain cardiovascular disorders. Down-regulation of c-Myc induced by intervention with antioxidants or by antisense technology may protect the integrity of the arterial wall as well as neoplastic tissues. Further intervention studies are necessary to investigate the effects of tissue-specific block of c-Myc overexpression in the development of cardiovascular diseases.

Oxidation-sensitive transcription factors and molecular mechanisms in the arterial wall

Adaptation to various forms of cellular stress involves signal transduction into the cytoplasm and subsequently into the cellular nucleus, and ultimately alteration of gene regulation and expression. Increased oxidative stress, which is associated with increased production of reactive oxygen species and other radical species, plays a pivotal role in vascular dysfunction and contributes substantially to the structural and functional changes leading to vascular disease progression. Activation of oxidation-sensitive transcription factors and molecular mechanisms can be triggered in the systemic, tissue, cellular, and molecular environments, thereby affecting a multitude of pathophysiological events involved in the pathogenesis of atherosclerosis and other vascular diseases. Radicals per se also participate in the pathophysiological vascular response to shear stress and injury. Among the oxidation-sensitive transcription factors, important roles have been ascribed to nuclear factor-kappaB, c-Myc, and the peroxisome proliferator-activated receptor family. Regulation of nuclear events has also been recently proposed to involve corepressor and coactivator molecules. Identification of the genes that are involved in these processes has been facilitated by recent development of microarray chip techniques, which allow simultaneous evaluation of differential gene expression. As many of the transcription factors or their interactions are redox-regulated, antioxidant intervention may affect their bioactivity.

Renal vascular function in hypercholesterolemia is preserved by chronic antioxidant supplementation

Hypercholesterolemia impairs systemic vascular reactivity in response to endothelium-dependent vasodilators, which may be mediated partly through increased formation of lipid peroxides. However, it is unclear whether these pathophysiological mechanisms play a role in renal vascular impairment in experimental hypercholesterolemia. Hence, pigs were studied after a 3-mo normal (n = 7) or high cholesterol (HC) (n = 7) diet, HC diet supplemented daily with antioxidant vitamins E (100 IU/kg) and C (1000 mg; HC+vitamins, n = 5), or normal diet supplemented with vitamins (N+vitamins, n = 5). Renal blood flow was measured with electron-beam computed tomography before and during infusion of acetylcholine (Ach). Endothelial function, endothelial and inducible nitric oxide synthase (NOS), and nitrotyrosine immunoreactivity were studied in renal arteries ex vivo. Despite similar cholesterol levels, LDL oxidizability (lag time, malondialdehyde, and relative electrophoretic mobility) was increased in pigs that were fed the HC diet but was significantly decreased in pigs that were fed the HC+vitamins diet. Renal blood flow response to Ach was blunted in pigs that were fed the HC diet but was preserved in pigs that were fed the HC+vitamins diet. Maximal relaxation to Ach was attenuated in pigs that were fed the HC diet compared with those that were fed the normal diet (51.5 +/- 6.4% versus 97.0 +/- 2.9%; P < 0.01) but was preserved in pigs that were fed the HC+vitamins diet (103.1 +/- 3.0%; P = 0.39) and N+vitamins diet (87.7 +/- 3.0%; P = 0.1), as were relaxation responses to calcium ionophore A23187. Vascular smooth-muscle relaxation to diethylamine was enhanced in endothelium-denuded HC vessel but was restored in pigs that were on the HC+vitamins regimen. In HC, immuno-reactivity of endothelial NOS was decreased, that of inducible NOS was increased, and both were preserved in pigs that were fed the HC+vitamins and N+vitamins diets, whereas nitrotyrosine was not detected. The present study demonstrates that antioxidant intervention in experimental HC reduces LDL oxidizability and preserves renal vascular responses to endothelium-dependent vasodilators. Therefore, this beneficial effect potentially can protect the kidney from hypercholesterolemia-induced damage.