Vascular Tissue Levels Research Articles

Lower Extremity Arterial Disease in Type 2 Diabetes Mellitus: Metformin Inhibits Femoral Artery Ultrastructural Alterations as well as Vascular Tissue Levels of AGEs/ET-1 Axis-Mediated Inflammation and Modulation of Vascular iNOS and eNOS Expression

Lower extremity arterial disease (LEAD) is a major risk factor for amputation in diabetic patients. The advanced glycation end products (AGEs)/endothelin-1 (ET-1)/nitric oxide synthase (NOS) axis-mediated femoral artery injury with and without metformin has not been previously investigated. Type 2 diabetes mellitus (T2DM) was established in rats, with another group of rats treated for two weeks with 200 mg/kg metformin, before being induced with T2DM. The latter cohort were continued on metformin until they were sacrificed at week 12. Femoral artery injury was established in the diabetic group as demonstrated by substantial alterations to the femoral artery ultrastructure, which importantly were ameliorated by metformin. In addition, diabetes caused a significant (p < 0.0001) upregulation of vascular tissue levels of AGEs, ET-1, and iNOS, as well as high blood levels of glycated haemoglobin, TNF-α, and dyslipidemia. All of these parameters were also significantly inhibited by metformin. Moreover, metformin treatment augmented arterial eNOS expression which had been inhibited by diabetes progression. Furthermore, a significant correlation was observed between femoral artery endothelial tissue damage and glycemia, AGEs, ET-1, TNF-α, and dyslipidemia. Thus, in a rat model of T2DM-induced LEAD, an association between femoral artery tissue damage and the AGEs/ET-1/inflammation/NOS/dyslipidemia axis was demonstrated, with metformin treatment demonstrating beneficial vascular protective effects.

Effects of lipopolysaccharide stimulation during pregnancy on kidneys and blood vessels in offspring rats

Objective: To investigate the effect of lipopolysaccharide (LPS) inflammatory stimulation during pregnancy on offspring rats. Methods 20 SD pregnant rats were randomly divided into control and LPS groups, with 10 rats in each group. Rats in LPS group received intraperitoneal injection of LPS 0.79 mg/kg on the Days 8th, 10th, and 12th of gestation, and rats in control group received intraperitoneal injection of the same volume of sterile saline. The blood pressure of offspring rats was measured once every two weeks from 8 weeks of age to 16 weeks of age. Protein expression of NF-κB and NOX2 was detected by immunohistochemistry. ROS and NO levels in vascular tissues were observed by staining with DHE and DAF-2DA cular tissues were observed by staining with DHE and DAF-2DA fluorescent probes, respectively. Results At 8, 10, 12, 14 and 16 weeks of age,the systolic blood pressure of offspring in the LPS group was higher than that of the control group at the same age (P< 0.01).The urine volume and urinary sodium excretion rate of the LPS group were significantly lower than those of the control group (P < 0.05), while the urine creatinine and urine protein were not statistically significant as compared with those of the control group. Compared with the control group, the expression of NF-κB, NOX2, Ang II in thoracic aorta, and ROS in mesenteric artery were higher in LPS group. However, mesenteric artery NO expression was lower (P < 0.01) Conclusion LPS inflammatory stimulation during pregnancy causes kidneys inflammation and increased oxidative stress in blood vessels in offspring rats.

Enhanced Contribution of Orai Channels to Contractility of Human Penile Smooth Muscle in Erectile Dysfunction

BackgroundStore-operated calcium entry and its key players, stromal interaction molecule (STIM) and Orai calcium channels, have been proposed as emergent therapeutic targets in cardiovascular pathophysiology. We hypothesize alteration of STIM/Orai signaling in erectile dysfunction (ED). AimTo evaluate the contribution of STIM/Orai to human penile tissue contraction and to analyze the influence of ED on STIM/Orai signaling at functional and expression levels in human penile vascular tissues. MethodsHuman penile resistance arteries (HPRA) and human corpus cavernosum (HCC) were dissected from cavernosal specimens from 30 organ donors without history of ED (No ED) and from 48 patients with ED undergoing penile prosthesis insertion and functionally evaluated in wire myographs and organ chambers, respectively. Expression of STIM-1, Orai1, and Orai3 in HCC was localized and quantified by immunofluorescence. Main Outcome MeasuresThe main outcome measures are functional responses in HCC and HPRA and STIM/Orai channel protein expression in human cavernosal tissue. ResultsInhibition of Orai channels with YM-58483 (20 μM) significantly reduced norepinephrine–induced contractions in both HCC and HPRA from either No ED or ED subjects, but the effects were more marked in ED (−20.1 ± 5.9% vs −45.5 ± 13.2% and −15.9 ± 4.0% vs −31.4 ± 6.9% reduction in Emax to norepinephrine in HCC and HPRA, respectively). Thromboxane-induced contractions were reduced and neurogenic contractile and relaxant responses modulated by Orai inhibition in penile tissues from patients with ED. In fact, addition of YM-58483 concentration dependently relaxed precontracted HPRA and HCC. These relaxations were significantly more pronounced in tissues from patients with ED (EC50 7.5 vs 1.3 μM and 10.5 vs 1.3 μM, for HCC and HPRA, respectively). All HCC specimens displayed expression of STIM-1, Orai1, and Orai3. Significantly increased expression of Orai1 and Orai3 but not STIM-1 was observed in patients with ED. Clinical TranslationInhibition of enhanced Orai activity in human penile vascular tissue could facilitate erectile responses, alleviating ED. Strengths and LimitationsEnhanced STIM/Orai activity contribution to penile smooth muscle tone in ED is demonstrated at functional and structural levels in human tissues from a representative sample of patients with ED and in comparison with healthy tissue. We cannot differentiate the specific contribution of risk factors associated with ED to hyperactivity of the Orai system. ConclusionsOrai channels significantly contribute to human penile smooth muscle contraction. Orai contribution to penile smooth muscle tone is functionally enhanced in ED accompanied by increased expression of Orai channels in cavernosal tissue. Orai inhibition could be a potential therapeutic strategy to reduce penile smooth muscle contraction in ED.Sevilleja-Ortiz A, El Assar M, García-Rojo E, et al. Enhanced Contribution of Orai Channels to Contractility of Human Penile Smooth Muscle in Erectile Dysfunction. J Sex Med 2020;17:881–891.

Activation of 5-HT2 Receptors Reduces Inflammation in Vascular Tissue and Cholesterol Levels in High-Fat Diet-Fed Apolipoprotein E Knockout Mice

Coronary artery disease (CAD) is a progressive cardiovascular syndrome characterized by cholesterol-induced focal arterial lesions that impair oxygen delivery to the heart. As both innate and adaptive immune cells play critical roles in the formation and progression of arterial plaques and endothelial cell dysfunction, CAD is commonly viewed as a chronic inflammatory disorder. Our lab has previously discovered that 5-HT2A receptor activation with the 5-HT2 receptor selective agonist (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] has potent anti-inflammatory activity in both cell culture and whole animal models. Here we have examined the putative therapeutic effects of (R)-DOI in the ApoE−/− high fat model of cardiovascular disease. Subcutaneously implanted osmotic minipumps were used to infuse sustained low rates (0.15 μg / hr) of (R)-DOI∙HCl to mice fed a high-fat “Western” diet. (R)-DOI treated mice had significant reductions in expression levels of mRNA for inflammatory markers like Il6 in vascular tissue, normalized glucose homeostasis, and reduced circulating cholesterol levels. As cardiovascular disease is a leading cause of death both globally and in the Western world, activation of 5-HT2A receptors at sub-behavioral levels may represent a new strategy to treat inflammation-based cardiovascular disease.

The adjustment of Prosopis tamarugo hydraulic architecture traits has a homeostatic effect over its performance under descent of phreatic level in the Atacama Desert

Prosopis tamarugo undergoes several modifications of its hydraulic architecture, which has a homeostatic effect on its performance under descent of phreatic level. Groundwater extraction for mining has generated a large area of descent of phreatic level in the Llamara Salt Flat, Atacama Desert, where Prosopis tamarugo lives as a strict phreatophyte. We study different hydraulic architecture traits of P. tamarugo after 12 years of exposure to a descent of phreatic level of ~ 11 m to assess its acclimation capacity. Under this condition, tree size was reduced making the structure of trees shrubbier. At branch level, leaf shedding increased Huber Value and theoretical leaf-specific hydraulic conductivity. At vascular tissue level, vessel composition decreased significantly due to an increase in vessel density and a slight decrease in mean vessel area. This meant that there were no differences of theoretical sapwood-specific hydraulic conductivity and wood density between conditions of descent of phreatic level. Although the theoretical hydraulic efficiency is high under descent of phreatic level, a lower midday water potential indicates other possible factors that may affect its performance (e.g., microclimate, daily loss of conductivity and a high root resistances). The above is consistent with a higher leaf mass per area of the remaining leaves, but no differences were observed in stomatal conductance, leaf 13C isotopic composition and predawn water potential between descent condition. While the adjustment of hydraulic architecture traits has a homeostatic effect on P. tamarugo performance, it is necessary to evaluate the limits of its resistance to contribute to its conservation in a context of intervention of its habit, mainly due to demographic growth and non-metallic mining.

Histone Variant H2A.Z Is Required for the Maintenance of Smooth Muscle Cell Identity as Revealed by Single-Cell Transcriptomics.

Histone variants endow chromatin with specific structures, and play essential roles in development and diseases. However, little is known about their roles in controlling cell identity in vascular diseases. Given the cell heterogeneity in atherosclerotic lesions, we applied single-cell RNA-Sequencing to analyze diseased human arteries, and identified histone variant H2A.Z as a key histone signature to maintain vascular smooth muscle cell (VSMC) identity. We show that H2A.Z occupies genomic regions near VSMC marker genes, and its occupancy is decreased in VSMCs undergoing dedifferentiation. Mechanistically, H2A.Z occupancy preferentially promotes nucleosome turnover, and facilitates the recruitment of SMAD3 and MED1, thereby activating VSMC marker gene expression. In addition, H2A.Z expression is dramatically reduced at both mRNA and protein levels in diseased human vascular tissues compared to those in normal arteries. Notably, in vivo overexpression of H2A.Z rescues injury-induced loss of VSMC identity and neointima formation. Together, our data introduce dynamic occupancy of a histone variant as a novel regulatory basis contributing to cell fate decisions, and imply H2A.Z as a potential intervention node for vascular diseases.

Effect of microRNA-26a on vascular endothelial cell injury caused by lower extremity ischemia-reperfusion injury through the AMPK pathway by targeting PFKFB3.

Vascular endothelial cell (VEC) dysfunction plays an important role in the ischemia-reperfusion injury (IRI)-related diseases, and microRNAs (miRNAs) are key factors during this process. We conducted this study to investigate whether miRNA-26a (miR-26a) has effect on the IRI-induced VEC injury via the AMPK pathway by targeting 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3). IRI rat models were successfully constructed by an abdominal incision. Additionally, the cultured VECs were further treated with miR-26a mimic or inhibitor, and si-PFKFB3. Both the reverse-transcription quantitative polymerase chain reaction and the western blot assay method were carried out to examine the expressions of PFKFB3, endothelial nitric oxide synthase (eNOS), and 5'-adenosine monophosphate-activated protein kinase (AMPK) α1, as well as the extent of the AMPK α1 phosphorylation levels in vascular tissues. Circulating endothelial cell (CEC), von Willebrand factor (VWF), thrombomodulin (TM), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), and endothelin (ET) were all measured. In the rat model of an IRI, a poorly expressed miR-26a and contrarily highly expressed PFKFB3 were identified in vascular tissues. In response to an overexpression of miR-26a or to the PFKFB3 gene silencing, decreased CEC number, TM, VWF, MDA, and ET contents, increased AMPK α1, and eNOS levels, as well as the extent of AMPK α1 phosphorylation coordinate with both increased SOD and NO contents based on the restoration of the AMPK pathway. Overexpression of the miR-26a or si-PFKFB3 provides an elevation in cell proliferation. Our study suggests that the miR-26a RNA alleviates lower extremity IRI-induced VEC injury in rats through the activation of the AMPK pathway by inhibiting PFKFB3.

Systems Pharmacology and Rational Polypharmacy: Nitric Oxide-Cyclic GMP Signaling Pathway as an Illustrative Example and Derivation of the General Case.

Impaired nitric oxide (NO˙)-cyclic guanosine 3', 5'-monophosphate (cGMP) signaling has been observed in many cardiovascular disorders, including heart failure and pulmonary arterial hypertension. There are several enzymatic determinants of cGMP levels in this pathway, including soluble guanylyl cyclase (sGC) itself, the NO˙-activated form of sGC, and phosphodiesterase(s) (PDE). Therapies for some of these disorders with PDE inhibitors have been successful at increasing cGMP levels in both cardiac and vascular tissues. However, at the systems level, it is not clear whether perturbation of PDE alone, under oxidative stress, is the best approach for increasing cGMP levels as compared with perturbation of other potential pathway targets, either alone or in combination. Here, we develop a model-based approach to perturbing this pathway, focusing on single reactions, pairs of reactions, or trios of reactions as targets, then monitoring the theoretical effects of these interventions on cGMP levels. Single perturbations of all reaction steps within this pathway demonstrated that three reaction steps, including the oxidation of sGC, NO˙ dissociation from sGC, and cGMP degradation by PDE, exerted a dominant influence on cGMP accumulation relative to other reaction steps. Furthermore, among all possible single, paired, and triple perturbations of this pathway, the combined perturbations of these three reaction steps had the greatest impact on cGMP accumulation. These computational findings were confirmed in cell-based experiments. We conclude that a combined perturbation of the oxidatively-impaired NO˙-cGMP signaling pathway is a better approach to the restoration of cGMP levels as compared with corresponding individual perturbations. This approach may also yield improved therapeutic responses in other complex pharmacologically amenable pathways.

Systems Biology Research into Cardiovascular Disease: Contributions of Lipidomics-based Approaches to Biomarker Discovery.

Atherosclerosis is a progressive inflammatory thickening of the arterial wall resulting from increased cellularity and the accumulation of lipids, cellular debris, and extracellular matrix. Conventional determinations of plasma lipoproteins have resulted in a wealth of clinical data documenting the correlation between low- and high-density lipoproteins (LDL and HDL) and cardiovascular disease (CVD) risk. Current mass spectrometry methodologies allow the detection and quantification of multiple molecular lipid species with various structural and functional roles. The opportunities provided by lipidomics for lipid-based biomarker discovery are prominent in disease diagnostics, monitoring of drug efficacy, and translational model development. For example, the analysis of human plasma samples assessing the effects of statins has shown correlative effects between the LDL/HDL ratio and sphingomyelin and phosphatidylcholine. Additionally, at the vascular tissue level, lipids from different classes are enriched in human plaques of coronary arteries and in the aortas of apolipoprotein E-deficient mice exposed to cigarette smoke, highlighting a set of lipid biomarkers for translational research. Molecular lipidomics will provide insights in which other lipids may play important roles in vascular disease progression and will serve as novel markers for preventive as well as therapeutic purposes.

Contrast Ultrasound Imaging Does Not Affect Heat Shock Protein 70 Expression in Cholesterol-Fed Rabbit Aorta.

Diagnostic ultrasound imaging is enhanced by the use of circulating microbubble contrast agents (UCAs), but the interactions between ultrasound, UCAs, and vascular tissue are not fully understood. We hypothesized that ultrasound with a UCA would stress the vascular tissue and increase levels of heat shock protein 70 (Hsp70), a cellular stress protein. Male New Zealand White rabbits (n = 32) were fed a standard chow diet (n = 4) or a 1% cholesterol, 10% fat, and 0.11% magnesium diet (n = 28). At 21 days, 24 rabbits on the cholesterol diet were either exposed to ultrasound (3.2-MHz f/3 transducer; 2.1 MPa; mechanical index, 1.17; 10 Hz pulse repetition frequency; 1.6 microseconds pulse duration; 2 minutes exposure duration at 4 sites along the aorta) with the UCA Definity (1× concentration, 1 mL/min; Lantheus Medical Imaging, North Billerica, MA) or sham exposed with a saline vehicle injection (n = 12 per group). Four rabbits on the cholesterol diet and 4 on the chow diet served as cage controls and were not exposed to ultrasound or restrained for blood sample collection. Animals were euthanized 24 hours after exposure, and aortas were quickly isolated and frozen in liquid nitrogen. Aorta lysates from the area of ultrasound exposure were analyzed for Hsp70 level by Western blot. Blood plasma was analyzed for cholesterol, Hsp70, and von Willebrand factor, a marker of endothelial function. Plasma total cholesterol levels increased to an average of 705 mg/dL. Ultrasound did not affect plasma von Willebrand factor, plasma Hsp70, or aorta Hsp70. Restraint increased Hsp70 (P < .001, analysis of variance). Restraint, but not ultrasound with the UCA or cholesterol feeding, significantly increased Hsp70.

Protective effects of diltiazem against vascular endothelial cell injury induced by angiotensin-II and hypoxia

To provide pharmacological data for future clinical studies, this study investigated the protective effects of diltiazem on vascular endothelial cell (VEC) injury induced by angiotensin-II (AngII), hypoxia, and a combination of both treatments. The concentration of intracellular free calcium and the mitochondrial membrane potential in VEC were assessed as indicators of cell injury. An in vivo hypoxic animal model was used to test the protective effect of diltiazem on vascular endothelial tissues. Our study showed that AngII and hypoxia decreased the mitochondrial membrane potential in VEC, which was significantly inhibited by diltiazem. Diltiazem protected against VEC injury induced by the increased concentration of intracellular free calcium, which was associated with AngII and hypoxia. Diltiazem reduced the apoptosis of rat VEC under a sustained hypoxic condition. In addition, it reduced AngII and endothelin I levels in rat vascular endothelial tissues. Our study confirmed that AngII and hypoxia induced VEC injury by regulating the levels of mitochondrial membrane potential and intracellular free calcium. Diltiazem, a calcium channel blocker, protected VEC from AngII- and hypoxia-induced injury.

Effects of restraint and contrast ultrasound imaging on Hsp70 expression in cholesterol‐fed rabbit aorta (643.11)

Diagnostic ultrasound imaging (US) is enhanced by the use of circulating microbubble contrast agents (UCAs), but the interactions between US, UCAs, and vascular tissue are not well understood. We hypothesized that US with UCA would stress the vascular tissue and increase levels of Hsp70, a cellular stress protein. Male New Zealand White rabbits (n=32) were fed a standard chow diet (n=4) or a 1% cholesterol, 10% fat and 0.11% magnesium diet (n=28). At 21 days, 24 rabbits on cholesterol diet were either exposed to US (3.2 MHz f/3 transducer, 2.1 MPa, Mechanical Index=1.17, 10 Hz pulse repetition frequency, 1.6 µs pulse duration, 2 min exposure duration at 4 sites) using the UCA Definity (1x concentration, 1 mL/min) or sham exposed using a saline control (n=12 per group). Four rabbits on cholesterol diet and the four on chow diet served as cage controls, and were not exposed to ultrasound or restrained for blood sample collection. Animals were euthanized 24 hours after exposure and aortas quickly isolated and snap‐frozen in liquid nitrogen. Aorta lysates from the area of US exposure were analyzed for Hsp70 protein level by Western blot. Blood plasma was analyzed for cholesterol and von Willebrand Factor (vWF), a marker of endothelial function. Plasma total cholesterol levels increased to an average of 705 mg/dL. Restraint (p&lt;0.001 by ANOVA), but not US with UCA or cholesterol feeding, significantly increased Hsp70.Grant Funding Source: Supported by NIH R37EB002641 and the Beckman Institute Graduate Fellowship

Telomere shortening and increased oxidative stress are restricted to venous tissue in patients with varicose veins: A merely local disease?

Shortened telomere length (TL) and oxidative stress have been described in several vascular disorders at both the tissue and circulating level. However, to our knowledge, there are no reports about TL associated with varicose vein (VV) disease. This paper aimed to evaluate, at the tissue and circulating level, TL and oxidative stress in VV disease, compared to the corresponding counterparts from abdominal aortic aneurysm (AAA) patients and control healthy subjects. TL was measured using quantitative fluorescence in situ hybridization (Q-FISH). Oxidative stress was evaluated by measuring the malondialdehyde (MDA) concentration by thiobarbituric acid reactive substance/s (TBARS) assay. At the vascular tissue level, VV patients had shortened TL and a high MDA concentration, similarly to AAA patients. Conversely, blood lymphocytes and epidermal cells from VV patients had a TL similar to healthy controls and significantly longer than the same cells from AAA patients. Moreover, the MDA concentration in plasma from VV patients was significantly lower than from the AAA group. Linear regression analysis showed a statistically significant inverse correlation between the blood lymphocyte TL and plasma MDA level. Our results suggest that, unlike AAA, telomere attrition in VV tissue is not a systemic phenomenon but it may be attributable to tissue microenvironment conditions and possibly to high local oxidative stress.

Elevated vascular γ‐butyrobetaine levels attenuate the development of high glucose‐induced endothelial dysfunction

The aim of the present study was to investigate the effects of vascular tissue levels of l-carnitine and its precursor, γ-butyrobetaine (GBB), on the development of endothelial dysfunction induced by 5μmol/L lysophosphatidylcholine (LPC), 10mmol/L triglycerides (TG) or a high glucose concentration (44mmol/L). Changes in vascular tissue levels of l-carnitine and GBB were induced by administration of l-carnitine (100mg/kg), mildronate (100mg/kg; an inhibitor of l-carnitine synthesis) or their combination to male Wistar rats for 2weeks. Treatment with l-carnitine elevated vascular tissue levels of l-carnitine, whereas administration of mildronate reduced l-carnitine levels and increased GBB levels. Experimental animals that received the combination of both drugs showed elevated tissue levels of GBB. The results from organ bath experiments demonstrated that increased GBB levels with preserved l-carnitine content in vascular tissues attenuated the development of endothelial dysfunction induced by high glucose. However, changes in vascular tissue l-carnitine and GBB levels had no impact on endothelial dysfunction induced by TG or LPC. The results demonstrate that increased levels of GBB with preserved l-carnitine content in vascular tissue attenuate the development of endothelial dysfunction induced by high glucose concentrations.

CGMP-Dependent Protein Kinase Contributes to Hydrogen Sulfide-Stimulated Vasorelaxation

A growing body of evidence suggests that hydrogen sulfide (H2S) is a signaling molecule in mammalian cells. In the cardiovascular system, H2S enhances vasodilation and angiogenesis. H2S-induced vasodilation is hypothesized to occur through ATP-sensitive potassium channels (KATP); however, we recently demonstrated that it also increases cGMP levels in tissues. Herein, we studied the involvement of cGMP-dependent protein kinase-I in H2S-induced vasorelaxation. The effect of H2S on vessel tone was studied in phenylephrine-contracted aortic rings with or without endothelium. cGMP levels were determined in cultured cells or isolated vessel by enzyme immunoassay. Pretreatment of aortic rings with sildenafil attenuated NaHS-induced relaxation, confirming previous findings that H2S is a phosphodiesterase inhibitor. In addition, vascular tissue levels of cGMP in cystathionine gamma lyase knockouts were lower than those in wild-type control mice. Treatment of aortic rings with NaHS, a fast releasing H2S donor, enhanced phosphorylation of vasodilator-stimulated phosphoprotein in a time-dependent manner, suggesting that cGMP-dependent protein kinase (PKG) is activated after exposure to H2S. Incubation of aortic rings with a PKG-I inhibitor (DT-2) attenuated NaHS-stimulated relaxation. Interestingly, vasodilatory responses to a slowly releasing H2S donor (GYY 4137) were unaffected by DT-2, suggesting that this donor dilates mouse aorta through PKG-independent pathways. Dilatory responses to NaHS and L-cysteine (a substrate for H2S production) were reduced in vessels of PKG-I knockout mice (PKG-I−/−). Moreover, glibenclamide inhibited NaHS-induced vasorelaxation in vessels from wild-type animals, but not PKG-I−/−, suggesting that there is a cross-talk between KATP and PKG. Our results confirm the role of cGMP in the vascular responses to NaHS and demonstrate that genetic deletion of PKG-I attenuates NaHS and L-cysteine-stimulated vasodilation.

Coupling NOS to endothelial function and inflammation in cardiovascular disease

Nitric oxide synthases (NOS) regulate cardiovascular homeostasis through nitric oxide (NO) production, for example in the vascular endothelium. Loss of NO mediated endothelial function is a characteristic of cardiovascular disease states. However, deranged NOS function in is not reflected in loss of NOS enzyme protein, or absent NOS enzymatic activity. Rather, NOS uncoupling, mediated by loss of the co-factor tetrahydrobiopterin (BH4), generates ROS rather than NO, thus altering the signalling repertoire of NOS and contributing to cardiovascular pathophysiology. In the endothelium, transgenic mouse models have demonstrated that increasing endothelial cell BH4 is sufficient to rescue eNOS uncoupling, leading to beneficial effects on atherosclerotic plaque, remodelling after vascular injury and endothelial cell repopulation. However, in a clinical trial of oral BH4 therapy in patients with coronary artery disease, there was no beneficial effect on endothelial function, in part due to oxidation of the administered BH4. Oxidative loss of BH4 in cardiovascular diseases is related local and systemic inflammation. In coronary artery disease, increased markers of systemic inflammation are associated with increased plasma levels of BH4, but with reduced vascular tissue levels of BH4 and endothelial dysfunction. Acute inflammatory stimulus by vaccination rapid increases circulating BH4, but impairs endothelial function. Variants in the GCH1 gene, that regulates BH4 synthesis, are associated with altered responses to inflammatory stimulation and endothelial function. Future studies need to improve understanding of endothelial versus systemic BH4 regulation in inflammation, in order to identify and target new therapies that take advantage of BH4 dependent NOS regulation.

In Vivo Administration of an EET Agonist Rescues Diet‐ Induced Obesity and Associated Vascular and Adipose Tissue Abnormalities in SD Rats: Contributions of the Heme‐Heme Oxygenase System

Recent reports show interplay between EETs and the heme oxygenase (HO) system in attenuating adipogenesis in in vitro models, prompting an examination of the effects of treatment with an EET agonist on diet‐induced obesity and associated cardio‐metabolic dysfunction. Patho‐physiological effects of an EET agonist (NUDSA) were contrasted, in the absence and in the presence of SnMP (an HO inhibitor), in SD rats fed a high fat (58%, HF) or lean diet for 16 weeks. HF diet resulted in increased (p&lt;0.05) body weight (BW), inflammatory cytokines and decreased levels adiponectin in the plasma; along with reduced vascular and adipose tissue levels of EETs and HO‐1. Treatment with NUDSA not only reversed BW, serum adiponectin and vascular and adipose tissue levels of EETs and HO‐1, but also, decreased blood pressure, subcutaneous and visceral fat content and serum TNFα and IL‐6 in rats on HF diet. Aortic endothelial function, p‐eNOS expression and adipose tissue markers of energy homeostasis i.e. pAMPK, Sirt1 and FAS, impaired (p&lt;0.05) in rats on HF diet, were restored in animals treated with NUDSA. Prevention of these beneficial effects of NUDSA, in animals on HF diet and concurrently exposed to NUDSA and SnMP, support the role of EET‐HO interaction in mediating such effects. Taken together, our findings suggest that interplay of these two systems affords vascular and metabolic protection in diet induced obesity. NIH‐ HL034300

Role of Protein Kinase C-MAPK, Oxidative Stress and Inflammation Pathways in Diabetic Nephropathy

Diabetic nephropathy is the most common cause of end-stage renal disease. It is assumed that hyperglycemia is one of the major systemic risk factors for diabetic complications. Numerous hypotheses exist to enlighten the adverse effect of hyperglycemia. One of these hypotheses is the activation of the calcium- and phospholipid-dependent protein kinase C signaling pathway by hyperglycemia which subsequently mediates cellular response and affects gene expression and protein function to cause cellular dysfunction and damage. It is well known that the intracellular protein kinase C activation is achieved by the elevated diacylglycerol levels in vascular tissues as well as in nonvascular tissues. Besides diacylglycerol, oxidative stress has also been reported to induce prolonged activation of protein kinase C within cells through the reactive oxygen species. Activation of protein kinase C and oxidative stress have been associated with vascular alterations such as increases in permeability of endothelial cells, extracellular matrix synthesis, cell growth and apoptosis, angiogenesis, and cytokines activation and inhibition. These derangements in vascular cell homeostasis caused by the activation protein kinase C as well as oxidative stress are connected to the occurrence of pathologies affecting large vessel and small vessel complications. Accumulating evidences have also shown that the inflammation process is an essential pathogenetic mechanism in diabetic nephropathy. Therefore, modulation of this process is an important target for both metabolic and hemodynamic derangements in diabetic nephropathy. In this review, we will discusses the role of protein kinase C, oxidative stress and inflammation process and the signaling pathway in the pathogenesis of diabetic nephropathy.

EET agonist prevents adiposity and vascular dysfunction in rats fed a high fat diet via a decrease in Bach 1 and an increase in HO-1 levels

Recent reports have shown interplay between EETs (epoxides) and the heme oxygenase (HO) system in attenuating adipogenesis in cell culture models; prompting an examination of the effectiveness of EET agonist on obesity and associated cardio-metabolic dysfunction. Patho-physiological effects of an EET agonist (NUDSA) were contrasted in the absence and in the presence of stannous mesoporphyrin (an HO inhibitor) in SD rats fed a high fat (58%, HF) for 16 weeks. Animals on HF diet exhibited enhanced oxidative stress, increased levels of inflammatory cytokines and decreased levels of adiponectin along with reduced vascular and adipose tissue levels of EETs, HO-1; as compared to control rats (11% dietary fat). Treatment with NUDSA not only reversed serum adiponectin and vascular and adipose tissue levels of EETs and HO-1, but also, decreased blood pressure, subcutaneous and visceral fat content and serum TNFα and IL-6 levels in rats on HF diet. Aortic endothelial function, peNOS expression and adipose tissue markers of energy homeostasis i.e. pAMPK, Sirt1 and FAS, impaired in rats fed a HF diet, were restored in animals treated with this EET agonist. That NUDSA enhanced HO-1 expression, was accompanied by increase in p-GSK-3β and pAKT levels along with attenuation of adipose tissue levels of Bach 1 – the transcriptional suppresser of HO-1 expression. Prevention of these beneficial effects of NUDSA, in animals on HF diet and concurrently exposed to NUDSA and SnMP, supports the role of EET-HO interaction in mediating such effects. Taken together, our findings suggest that the EETs stimulate HO-1 expression via suppression of Bach 1 and interplay of these two systems affords vascular and metabolic protection in diet induced obesity.

Modulators of the Vascular Endothelin Receptor in Blood Pressure Regulation and Hypertension

Endothelin (ET) is one of the most investigated molecules in vascular biology. Since its discovery two decades ago, several ET isoforms, receptors, signaling pathways, agonists and antagonists have been identified. ET functions as a potent endothelium-derived vasoconstrictor, but could also play a role in vascular relaxation. In endothelial cells, preproET and big ET are cleaved by ET converting enzymes into ET-1, -2, -3 and -4. These ET isoforms bind with different affinities to ETA and ETB receptors in vascular smooth muscle (VSM), and in turn increase [Ca2+]i, protein kinase C and mitogen-activated protein kinase and other signaling pathways of VSM contraction and cell proliferation. ET also binds to endothelial ETB receptors and stimulates the release of nitric oxide, prostacyclin and endothelium-derived hyperpolarizing factor. ET, via endothelial ETB receptor, could also promote ET re-uptake and clearance. While the effects of ET on vascular reactivity and growth have been thoroughly examined, its role in the regulation of blood pressure and the pathogenesis of hypertension is not clearly established. Elevated plasma and vascular tissue levels of ET have been identified in saltsensitive hypertension and in moderate to severe hypertension, and ET receptor antagonists have been shown to reduce blood pressure to variable extents in these forms of hypertension. The development of new pharmacological and genetic tools could lead to more effective and specific modulators of the vascular ET system for treatment of hypertension and related cardiovascular disease. Keywords: Blood pressure, calcium, endothelium, nitric oxide, smooth muscle, Hypertension, ET Receptor-Mediated Signaling