Total Endothelial Nitric Oxide Synthase Research Articles

Physical activity alleviates obesity-associated mesenteric arterial endothelial dysfunction: Role of adiponectin receptor

Introduction: A strong association between cardiovascular disease and obesity has been reported. However, the role of adiponectin in the effect of physical activity on mesenteric circulation and its underlying mechanism has been unknown. We investigated the protective effect of voluntary wheel running (EX) on endothelial function in the mesenteric artery of obese mice and its underlying mechanisms. Methods: C57BL/6J male mice were randomly divided into four groups: (1) control low-fat diet (LF), (2) LF diet with free access to a voluntary running wheel (LF-EX), (3) high-fat diet (HF; 45% of calories from fat), and (4) HF-EX. The protein expressions of total-endothelial nitric oxide synthase (t-eNOS), adiponectin receptors 1 and 2, AMPK, Ob (leptin), inflammatory markers, and proteins regulating apoptosis were quantified by Western blot analysis. Statistical comparisons between groups were performed with two-way ANOVA with Fisher’s LSD test. Results: The protein expressions of t-eNOS, adiponectin receptors 1 and 2, and p-AMPK in HF were lower compared to LF, but EX increased the protein levels ( P < 0.05). Ob in HF was higher compared to LF, but EX decreased it ( P < 0.05). IL-1β, TNF-α, and Caspase-1 in HF were higher compared to LF, but EX decreased the protein levels ( P < 0.05). There was no difference in expressions of AMPK, CHOP, Bcl-2, and GADD153 between groups. Conclusion: Voluntary wheel running alleviates e-NOS-mediated endothelial dysfunction in the mesenteric artery of obese mice possibly via increased adiponectin receptors and decreased inflammation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dipeptidyl peptidase 4 inhibition rescues PKA-eNOS signaling and suppresses aortic hypercontractility in male rats with heart failure

AimsVascular dysfunction and elevated circulating dipeptidyl peptidase 4 (DPP4) activity are both reported to be involved in the progression of heart failure (HF). While the cardiac benefits of DPP4 inhibitors (DPP4i) have been extensively studied, little is known about the effects of DPP4i on vascular dysfunction in nondiabetic HF. This study tested the hypothesis that vildagliptin (DPP4i) mitigates aortic hyperreactivity in male HF rats. Materials and methodsMale Wistar rats were subjected to left ventricle (LV) radiofrequency ablation to HF induction or sham operation (SO). Six weeks after surgery, radiofrequency-ablated rats who developed HF were treated with vildagliptin (120 mg⸱kg−1⸱day−1) or vehicle for 4 weeks. Thoracic aorta reactivity, dihydroethidium fluorescence, immunoblotting experiments, and enzyme-linked immunosorbent assays were performed. Key findingsDPP4i ameliorated the hypercontractility of HF aortas to the α-adrenoceptor agonist phenylephrine towards SO levels. In HF, the reduced endothelium and nitric oxide (NO) anticontractile effect on phenylephrine response was restored by DPP4i. At the molecular level, this vasoprotective effect of DPP4i was accompanied by (i) reduced oxidative stress and NADPH oxidase 2 (Nox2) expression, (ii) enhanced total endothelial nitric oxide synthase (eNOS) expression and phosphorylation at Ser1177, and (iii) increased PKA activation, which acts upstream of eNOS. Additionally, DPP4i restored the higher serum angiotensin II concentration towards SO. SignificanceOur data demonstrate that DPP4i ameliorates aortic hypercontractility, most likely by enhancing NO bioavailability, showing that the DPP4i-induced cardioprotection in male HF may arise from effects not only in the heart but also in conductance arteries.

Cardioprotective Actions of a Glucagon-like Peptide-1 Receptor Agonist on Hearts Donated After Circulatory Death.

Background Heart transplantation with a donation after circulatory death (DCD) heart is complicated by substantial organ ischemia and ischemia-reperfusion injury. Exenatide, a glucagon-like peptide-1 receptor agonist, manifests protection against cardiac ischemia-reperfusion injury in other settings. Here we evaluate the effects of exenatide on DCD hearts in juvenile pigs. Methods and Results DCD hearts with 15-minutes of global warm ischemia after circulatory arrest were reperfused ex vivo and switched to working mode. Treatment with concentration 5-nmol exenatide was given during reperfusion. DCD hearts treated with exenatide showed higher myocardial oxygen consumption (exenatide [n=7] versus controls [n=7], over 60-120 minutes of reperfusion, P<0.001) and lower cardiac troponin-I release (27.94±11.17 versus 42.25±11.80 mmol/L, P=0.04) during reperfusion compared with controls. In working mode, exenatide-treated hearts showed better diastolic function (dp/dt min: -3644±620 versus -2193±610 mm Hg/s, P<0.001; Tau: 15.62±1.78 versus 24.59±7.35 milliseconds, P=0.02; lateral e' velocity: 11.27± 1.46 versus 7.19±2.96, P=0.01), as well as lower venous lactate levels (3.17±0.75 versus 5.17±1.44 mmol/L, P=0.01) compared with controls. Higher levels of activated endothelial nitric oxide synthase (phosphorylated to total endothelial nitric oxide synthase levels: 2.71±1.16 versus 1.37±0.35, P=0.02) with less histological evidence of endothelial damage (von Willebrand factor expression: 0.024±0.007 versus 0.331±0.302, pixel/μm, P=0.04) was also observed with exenatide treatment versus controls. Conclusions Acute treatment of DCD hearts with exenatide limits myocardial and endothelial injury and improves donor cardiac function.

S-27-5: DELETION OF AT1A RECEPTORS IN THE PROXIMAL TUBULES AUGMENTS NATRIURETIC RESPONSE TO ATRIAL NATRIURETIC PEPTIDE VIA NPR/CGMP/NO SIGNALING

Objective: The proximal tubules of the kidney play a critical role in maintaining normal body salt and fluid balance and blood pressure homeostasis in part by interactions between two key vasoactive hormone receptors. In the proximal tubules, angiotensin II (Ang II) binds and activate AT1a receptors to stimulate proximal tubule Na+ reabsorption, whereas atrial natriuretic peptide (ANP) binds and activates NPRA receptors to inhibit Ang II-induced proximal tubule Na+ reabsorption. These two vasoactive systems play important counteracting roles in the proximal tubules to control proximal tubule Na+ reabsorption in the kidney and maintain blood pressure homeostasis. However, it is not known whether the hypotensive and natriuretic responses to ANP may be augmented by deletion of AT1 (AT1a) receptors selectively in the proximal tubules of the kidney. Design and Methods: The present study used a novel mouse model with proximal tubule-specific knockout of AT1a receptors in the kidney, PT-Agtr1a -/-, to test the hypothesis that deletion of AT1a receptors selectively in the proximal tubules indeed augments the hypotensive and natriuretic responses to ANP. Four groups (n = 9–12 per group) of adult male wild-type and PT-Agtr1a -/- mice were infused without (served as time controls) or with ANP via osmotic minipump (10 ng/min, i.p.) continuously for 2 weeks. Results: Basal blood pressure was about 16 ± 3 mmHg lower (P &lt; 0.01), fractional proximal tubule Na+ reabsorption was significantly lower (P &lt; 0.05), whereas 24 h urinary Na+ excretion was significantly higher in PT-Agtr1a -/- mice (P &lt; 0.01), compared with age-matched wild-type mice. ANP infusion significantly decreased blood pressure and increased the natriuretic response in PT-Agtr1a -/- mice further by inhibiting proximal tubule Na+ reabsorption, compared with wild-type controls (P &lt; 0.01). The augmented hypotensive and natriuretic responses to ANP infusion in PT-Agtr1a -/- mice was associated with increased plasma and kidney cGMP levels (P &lt; 0.01), kidney cortical NPRA and NPRC mRNA expression (P &lt; 0.05), total endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS proteins (P &lt; 0.01), and urinary nitric oxide (NO) excretion (P &lt; 0.01), respectively. Conclusions: Taken together, the results of the present study provide further new insights into the important physiological roles for intratubular Ang II/AT1a and ANP/NPRA in the proximal tubules to regulate proximal tubule Na+ reabsorption and help maintain blood pressure homeostasis. Supported by 2R01DK067299-10A1, 2R01DK102429-03A1, and 1 R01DK123144-01.

Canagliflozin Improves Myocardial Perfusion, Fibrosis, and Function in a Swine Model of Chronic Myocardial Ischemia.

Background Sodium-glucose cotransporter-2 inhibitors are cardioprotective independent of glucose control, as demonstrated in animal models of acute myocardial ischemia and clinical trials. The functional and molecular mechanisms of these benefits in the setting of chronic myocardial ischemia are poorly defined. The purpose of this study is to determine the effects of canagliflozin therapy on myocardial perfusion, fibrosis, and function in a large animal model of chronic myocardial ischemia. Methods and Results Yorkshire swine underwent placement of an ameroid constrictor to the left circumflex artery to induce chronic myocardial ischemia. Two weeks later, pigs received either no drug (n=8) or 300 mg sodium-glucose cotransporter-2 inhibitor canagliflozin orally, daily (n=8). Treatment continued for 5 weeks, followed by hemodynamic measurements, harvest, and tissue analysis. Canagliflozin therapy was associated with increased stroke volume and stroke work and decreased left ventricular stiffness compared with controls. The canagliflozin group had improved perfusion to ischemic myocardium compared with controls, without differences in arteriolar or capillary density. Canagliflozin was associated with decreased interstitial and perivascular fibrosis in chronically ischemic tissue, with reduced Jak/STAT (Janus kinase/signal transducer and activator of transcription) signaling compared with controls. In ischemic myocardium of the canagliflozin group, there was increased expression and activation of adenosine monophosphate-activated protein kinase, decreased activation of endothelial nitric oxide synthase, and unchanged total endothelial nitric oxide synthase. Canagliflozin therapy reduced total protein oxidation and increased expression of mitochondrial antioxidant superoxide dismutase 2 compared with controls. Conclusions In the setting of chronic myocardial ischemia, canagliflozin therapy improves myocardial function and perfusion to ischemic territory, without changes in collateralization. Attenuation of fibrosis via reduced Jak/STAT signaling, activation of adenosine monophosphate-activated protein kinase, and antioxidant signaling may contribute to these effects.

Protocatechualdehyde restores endothelial dysfunction in streptozotocin-induced diabetic rats.

BackgroundThe present study was conducted with the aim of clarifying the effects of protocatechualdehyde (PCA) on the endothelial function in streptozotocin (STZ)-induced diabetic rats.MethodsSprague Dawley (SD) rats were intraperitoneally injected with STZ (single dose of 60 mg/kg). Diabetic model rats were given PCA (25 mg/kg/day) via gavage feeding for 6 weeks. Vascular function was studied; superoxide anion and nitrotyrosine levels were assessed; and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase as well as total superoxide dismutase (SOD) activity were detected. Protein expression of phosphorylated endothelial nitric oxide synthase (P-eNOS), total endothelial nitric oxide synthase (T-eNOS), p22phox, p47phox and Cu/Zn-SOD were measured by Western blot analysis.ResultsPCA treatment significantly ameliorated the impairment of acetylcholine- evoked endothelium-dependent relaxation, with no obvious effects observed on the blood glucose or body weight in the STZ-induced diabetic rats. Expression levels of aortic P-eNOS/T-eNOS and endothelial nitric oxide synthase (eNOS) activity were decreased in STZ-induced diabetic rats while they remained unchanged in PCA-treated rats. However, PCA treatment improved oxidative inactivation of nitric oxide (NO) and decreased the levels of superoxide anion and nitrotyrosine in the aorta of STZ-induced diabetic rats; these were achieved by reducing the level of nitrotyrosine and down-regulating p47phox and p22phox expression, as well as up-regulating Cu/Zn-SOD protein expression. Consistently, the effects observed were associated with a decrease in NADPH oxidase activity and an increase in total SOD activity.ConclusionsOur results indicate that the administration of PCA may be protective against oxidative stress and may restore endothelial function by improving vascular NO oxidative inactivation in diabetic condition.

Effects of High Fat Versus Normal Diet on Extracellular Vesicle-Induced Angiogenesis in a Swine Model of Chronic Myocardial Ischemia.

BackgroundMesenchymal stem cell–derived extracellular vesicles (EVs) promote angiogenesis in the ischemic myocardium. This study examines the difference in vascular density, myocardial perfusion, molecular signaling, and gene expression between normal diet (ND) and high fat diet (HFD) groups at baseline and following intramyocardial injection of EVs.Methods and ResultsIntact male Yorkshire swine fed either an ND (n=17) or HFD (n=14) underwent placement of an ameroid constrictor on the left circumflex coronary artery. Subsequently, animals received either intramyocardial injection of vehicle‐saline as controls; (ND‐controls n=7, HFD‐controls, n=6) or EVs; (ND‐EVs n=10, HFD‐EVs n=8) into the ischemic territory. Five weeks later, myocardial function, perfusion, vascular density, cell signaling, and gene expression were examined. EVs improved indices of myocardial contractile function, myocardial perfusion, and arteriogenesis in both dietary cohorts. Interestingly, quantification of alpha smooth muscle actin demonstrated higher basal arteriolar density in HFD swine compared with their ND counterparts; whereas EVs were associated with increased CD31‐labeled endothelial cell density only in the ND tissue, which approached significance. Levels of total endothelial nitric oxide synthase, FOXO1 (forkhead box protein O1) , transforming growth factor‐β, phosphorylated VEGFR2 (vascular endothelial growth factor receptor 2), and phosphorylated MAPK ERK1/ERK2 (mitogen‐activated protein kinase) were higher in ischemic myocardial lysates from ND‐controls compared with HFD‐controls. Conversely, HFD‐control tissue showed increased expression of phosphorylated endothelial nitric oxide synthase, phosphorylated FOXO1, VEGFR2, and MAPK ERK1/ERK2 with respect to ND‐controls. Preliminary gene expression studies indicate differential modulation of transcriptional activity by EVs between the 2 dietary cohorts.ConclusionsHFD produces a profound metabolic disorder that dysregulates the molecular mechanisms of collateral vessel formation in the ischemic myocardium, which may hinder the therapeutic angiogenic effects of EVs.

Combination of hyperglycaemia and hyperlipidaemia induces endothelial dysfunction: Role of the endothelin and nitric oxide systems.

Endothelial dysfunction (ED) is a key feature of diabetes and is a major cause of diabetic vasculopathy. Diabetic patients who also exhibit hyperlipidaemia suffer from accelerated vascular complications. While the deleterious effects of high glucose levels (HG) and hyperlipidaemia alone on ED are well established, the effects of combined hyperlipidaemia and HG have not been thoroughly studied. Therefore, the current study examines whether HG and hyperlipidaemia exert synergistic ED, and explores the mechanisms underlying this phenomenon. We applied multi‐disciplinary approaches including cultured HUVECs and HMEC‐1 as well as knockout mice CByJ.129S7(B6)‐Ldlrtm1Her/J (LDLR−/−) to investigate the mechanisms underlying combined HG and hyperlipidaemia‐induced ED. Incremental doses of glucose in the presence or absence of OxLDL were added to HUVECs and HMEC‐1. After 5 days, the status of nitric oxide (NO) and endothelin (ET)‐1 systems as well as their signal transduction were assessed using Western blot, ELISA and immunoreactive staining. The effects of chronic combination of HG and hyperlipidaemia on endothelial integrity and function as well as alterations in circulatory NO and ET‐1 systems were examined in knockout mice LDLR−/− and their wild‐type. HUVEC cells exposed to HG and OxLDL displayed enhanced ET‐1 production, more than HG or OxLDL when added alone. Overproduction of ET‐1 stems from up‐regulation of endothelin converting enzyme (ECE)‐1 as observed under these conditions. In contrast, combination of HG and OxLDL dramatically decreased both total endothelial NO synthase (eNOS) by 60%, and activated eNOS (peNOS) by 80%. Moreover, NRF2 decreased by 42% and its active form (pNRF2) by 56%, as compared to baseline. Likewise, ETB levels decreased by 64% from baseline on endothelial cells. Furthermore, diabetic LDLR−/− mice displayed a higher blood pressure, plasma triglycerides, cholesterol, ET‐1 and NO2/NO3 levels, when compared with normoglycemic LDLR−/− and BALB mice. Combined hyperglycaemia and hyperlipidaemia activates the ET system and attenuates the nitric oxide system with the Nrf2 signalling pathway. These findings suggest that perturbations in these paracrine systems may contribute to ED.

Acute Tetrahydrobiopterin Improves Endothelial Function in Patients With COPD

Cardiovascular diseases represent a hallmark characteristic in COPD, and endothelial dysfunction has been observed in these patients. Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide (NO) synthesis and a regulator of endothelial function. The goal of this study was to test the hypothesis that a single dose of BH4 would improve endothelial function in patients with COPD via an increase in NO bioavailability. Seventeen patients with COPD completed a randomized, double-blind, placebo (PLC)-controlled, crossover trial with an acute dose of either BH4 (Kuvan; BioMarin Pharmaceutical Inc) or PLC. Flow-mediated dilation (FMD), a bioassay of endothelial function, was completed prior to and 3h following each treatment. Phospho- and total endothelial NO synthase (NOS3) protein was evaluated after incubating endothelial cells with plasma from the patients prior to and following treatment. Fifteen demographically matched control subjects were tested at baseline for case control comparisons. Treatment with BH4 significantly (P≤ .004) increased FMD, improving endothelial function in patients compared to control values (P≥ .327). BH4 increased (P= .013) the ratio of phospho-NOS3 to total NOS3 protein. No changes in FMD (P≥ .776) or the protein ratio (P= .536) were observed following PLC. An acute dose of BH4 was able to improve endothelial function in patients with COPD to values similar to control subjects. The improvement in endothelial function was accompanied by an increase in NOS3 phosphorylation. BH4 may represent a potential novel therapy to improve endothelial function and reduce cardiovascular disease risk in patients with COPD. ClinicalTrials.gov; No.: NCT01398943; URL: www.clinicaltrials.gov.

Loss of Female Sex Hormones Exacerbates Cerebrovascular and Cognitive Dysfunction in Aortic Banded Miniswine Through a Neuropeptide Y-Ca2+-Activated Potassium Channel-Nitric Oxide Mediated Mechanism.

BackgroundPostmenopausal women represent the largest cohort of patients with heart failure with preserved ejection fraction, and vascular dementia represents the most common form of dementia in patients with heart failure with preserved ejection fraction. Therefore, we tested the hypotheses that the combination of cardiac pressure overload (aortic banding [AB]) and the loss of female sex hormones (ovariectomy [OVX]) impairs cerebrovascular control and spatial memory.Methods and ResultsFemale Yucatan miniswine were separated into 4 groups (n=7 per group): (1) control, (2) AB, (3) OVX, and (4) AB‐OVX. Pigs underwent OVX and AB at 7 and 8 months of age, respectively. At 14 months, cerebral blood flow velocity and spatial memory (spatial hole‐board task) were lower in the OVX groups (P<0.05), with significant impairments in the AB‐OVX group (P<0.05). Resting carotid artery β stiffness and vascular resistance during central hypovolemia were increased in the AB‐OVX group (P<0.05), and blood flow recovery after central hypovolemia was reduced in both OVX groups (P<0.05). Isolated pial artery (pressure myography) vasoconstriction to neuropeptide Y was greatest in the AB‐OVX group (P<0.05), and vasodilation to the Ca2+‐activated potassium channel α‐subunit agonist NS‐1619 was impaired in both AB groups (P<0.05). The ratio of phosphorylated endothelial nitric oxide synthase:total endothelial nitric oxide synthase was depressed and Ca2+‐activated potassium channel α‐subunit protein was increased in AB groups (P<0.05).ConclusionsMechanistically, impaired cerebral blood flow control in experimental heart failure may be the result of heightened neuropeptide Y–induced vasoconstriction along with reduced vasodilation associated with decreased Ca2+‐activated potassium channel function and impaired nitric oxide signaling, the effects of which are exacerbated in the absence of female sex hormones.

Metabolites of flavonoid compounds preserve indices of endothelial cell nitric oxide bioavailability under glucotoxic conditions

We hypothesized that metabolites of dietary flavonoids attenuate impairments in nitric oxide (NO) bioavailability evoked by glucotoxic conditions mimicking Type 1 or 2 diabetes. To test this, human aortic endothelial cells were treated with either vehicle control, quercetin-3-O-glucoronide, piceatannol or 3-(3-hydroxyphenyl)propionoic acid for 24 h. These are metabolites of quercetin, resveratrol and proanthocyanidin, respectively. Next, cells were exposed to control (5 mM) or high (25 mM) glucose conditions for 48 h, followed by insulin treatment (100 nM, 10 min) to stimulate NO production. In control glucose conditions NO production, phosphorylated to total endothelial nitric oxide synthase (p-eNOSser1177: eNOS), and phosphorylated to total Akt (p-AktSer473: Akt) were all increased by insulin stimulation. This response was abolished during high glucose conditions. Pretreatment of cells with flavonoid metabolites prior to high glucose challenge preserved insulin stimulated increases in NO production, p-AktSer473: Akt and p-eNOSSer1177: eNOS. These effects may be secondary to oxidative stress as pretreatment with all flavonoid metabolites prevented elevations in reactive oxygen and nitrogen species in response to high glucose. These data support the hypothesis that beneficial effects of flavonoids on endothelial cell function in the context of glucotoxicity, at least in part, are secondary to their metabolites.

Melatonin Attenuates Pulmonary Hypertension in Chronically Hypoxic Rats.

Chronic hypoxia induces pulmonary hypertension and vascular remodeling, which are clinically relevant to patients with chronic obstructive pulmonary disease (COPD) associated with a decreased level of nitric oxide (NO). Oxidative stress and inflammation play important roles in the pathophysiological processes in COPD. We examined the hypothesis that daily administration of melatonin (10 mg/kg) mitigates the pulmonary hypertension and vascular remodeling in chronically hypoxic rats. The right ventricular systolic pressure (RVSP) and the thickness of pulmonary arteriolar wall were measured from normoxic control, vehicle- and melatonin-treated hypoxic rats exposed to 10% O2 for 14 days. Levels of markers for oxidative stress (malondialdhyde) and inflammation (tumor necrosis factor-α (TNFα), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2)) and the expressions of total endothelial NO synthase (eNOS) and phosphorylated eNOS at serine1177 (ser1177) were determined in the lung tissue. We found that the RVSP and the thickness of the arteriolar wall were significantly increased in the vehicle-treated hypoxic animals with elevated levels of malondialdhyde and mRNA expressions of the inflammatory mediators, when compared with the normoxic control. In addition, the phosphorylated eNOS (ser1177) level was significantly decreased, despite an increased eNOS expression in the vehicle-treated hypoxic group. Melatonin treatment significantly attenuated the levels of RVSP, thickness of the arteriolar wall, oxidative and inflammatory markers in the hypoxic animals with a marked increase in the eNOS phosphorylation in the lung. These results suggest that melatonin attenuates pulmonary hypertension by antagonizing the oxidative injury and restoration of NO production.

Zofenopril Protects Against Myocardial Ischemia-Reperfusion Injury by Increasing Nitric Oxide and Hydrogen Sulfide Bioavailability.

BackgroundZofenopril, a sulfhydrylated angiotensin‐converting enzyme inhibitor (ACEI), reduces mortality and morbidity in infarcted patients to a greater extent than do other ACEIs. Zofenopril is a unique ACEI that has been shown to increase hydrogen sulfide (H2S) bioavailability and nitric oxide (NO) levels via bradykinin‐dependent signaling. Both H2S and NO exert cytoprotective and antioxidant effects. We examined zofenopril effects on H2S and NO bioavailability and cardiac damage in murine and swine models of myocardial ischemia/reperfusion (I/R) injury.Methods and ResultsZofenopril (10 mg/kg PO) was administered for 1, 8, and 24 hours to establish optimal dosing in mice. Myocardial and plasma H2S and NO levels were measured along with the levels of H2S and NO enzymes (cystathionine β‐synthase, cystathionine γ‐lyase, 3‐mercaptopyruvate sulfur transferase, and endothelial nitric oxide synthase). Mice received 8 hours of zofenopril or vehicle pretreatment followed by 45 minutes of ischemia and 24 hours of reperfusion. Pigs received placebo or zofenopril (30 mg/daily orally) 7 days before 75 minutes of ischemia and 48 hours of reperfusion. Zofenopril significantly augmented both plasma and myocardial H2S and NO levels in mice and plasma H2S (sulfane sulfur) in pigs. Cystathionine β‐synthase, cystathionine γ‐lyase, 3‐mercaptopyruvate sulfur transferase, and total endothelial nitric oxide synthase levels were unaltered, while phospho‐endothelial nitric oxide synthase1177 was significantly increased in mice. Pretreatment with zofenopril significantly reduced myocardial infarct size and cardiac troponin I levels after I/R injury in both mice and swine. Zofenopril also significantly preserved ischemic zone endocardial blood flow at reperfusion in pigs after I/R.ConclusionsZofenopril‐mediated cardioprotection during I/R is associated with an increase in H2S and NO signaling.

PPARγ affects nitric oxide in human umbilical vein endothelial cells exposed to Porphyromonas gingivalis

ObjectivePorphyromonas gingivalis induces nitric oxide (NO) synthesis in human umbilical vein endothelial cells (HUVECs). Peroxisome proliferator-activated receptor (PPARγ) has an anti-inflammation function, and its involvement in this NO induction process requires elucidation. Here, we focused on PPARγ expression in HUVECs exposed to P. gingivalis, and investigated its effects on NO synthesis. Materials and methodsHUVECs were time-dependently stimulated by P. gingivalis W83 for 0–24h. PPARγ expression was assessed at the mRNA and protein levels, and PPARγ activation was measured using dual-luciferase reporter assays. NO synthesis and NO synthase (NOS) expression in response to P. gingivalis were examined in HUVECs pretreated with representative PPARγ agonist (15-deoxy-Δ12,14-prostaglandin J2 10μM) or antagonist (GW9662 10μM). In addition, NO synthesis and NOS expression in the P. gingivalis infected and control groups were detected. ResultsThe PPARγ mRNA level in HUVECs increased after exposure to P. gingivalis for 1h and its protein level increased at 2h. Luciferase-induced PPARγ increased in P. gingivalis-exposed HUVECs. NO synthesis in the infected group at 4h, and in the PPARγ-activated group at 8h, was higher than that in controls. Inducible NOS increased in the infected and PPARγ-activated groups at 4 and 8h. The total endothelial NOS (eNOS) and phospho-eNOS levels were lower in the infected group than controls, but did not change in the PPARγ-activated group. ConclusionsActivated PPARγ induces NO generation through the NOS pathway in HUVECs exposed to P. gingivalis.

Effect of Interleukin-10 and Laminar Shear Stress on Endothelial Nitric Oxide Synthase and Nitric Oxide in African American Human Umbilical Vein Endothelial Cells.

African Americans have a predisposition to heightened systemic inflammation and a high prevalence of hypertension. The purpose of this study was to evaluate the influence of interleukin-10 (IL-10) and laminar shear stress (LSS) on African American endothelial cells by measuring total endothelial nitric oxide synthase (eNOS) protein expression and its phosphorylated form (p-eNOS) at Serine 1177, and nitric oxide (NO) levels, in response to IL-10 incubation and high physiological levels of LSS, used as an in vitro mimetic for aerobic exercise training (AEXT). Human umbilical vein endothelial cells (HUVEC) from an African American donor were cultured. The experimental conditions included Static, Static with IL-10 Incubation, LSS at 20 dynes/cm², and LSS at 20 dynes/cm² with IL-10 Incubation. Western blotting was used to measure eNOS and p-eNOS protein expression in the cells. A modified Griess assay was used to measure NO metabolites in the cell culture media. There were significant increases in p-eNOS, eNOS, and NO in the LSS at 20 dynes/cm² and LSS at 20 dynes/cm² with IL-10 Incubation experimental conditions when compared to the Static experimental condition. There were no other statistically significant differences demonstrating that IL-10 did not have an additive effect on eNOS activity in our study. The significant increases in p-eNOS, eNOS, and NO as a result of LSS in African American HUVECs suggest that AEXT may be a viable, nonpharmacologic method to improve vascular inflammation status and vasodilation, and thereby contribute to hypertension reduction in the African American population.

Endogenous angiotensin-(1-7)/Mas receptor/NO pathway mediates the cardioprotective effects of pacing postconditioning.

The aim of the present study was to investigate the role of the ANG-(1-7) receptor (Mas) and nitric oxide (NO) in pacing postconditiong (PPC)-mediated cardioprotection against ischemia-reperfusion injury. Cardiac contractility and hemodynamics were assessed using a modified Langendorff system, cardiac damage was assessed by measuring infarct size and creatinine kinase levels, and levels of phosphorylated and total endothelial NO synthase (eNOS) were determined by Western blot analysis. Isolated hearts were subjected to 30 min of regional ischemia, produced by fixed position ligation of the left anterior descending coronary artery, followed by 30 min of reperfusion (n = 6). Hearts were also subjected to PPC (three cycles of 30 s of left ventricular pacing alternated with 30 s of right atrial pacing) and/or treated during reperfusion with ANG-(1-7), N(G)-nitro-l-arginine methyl ester, or the Mas antagonist (d-Ala7)-ANG I/II (1-7). The PPC-mediated improvement in cardiac contractility and hemodyanamics, cardiac damage, and eNOS phosphorylation were significantly attenuated upon treatment with (d-Ala7)-ANG I/II (1-7) or N(G)-nitro-l-arginine methyl ester. Treatment with ANG-(1-7) improved cardiac function and reduced infarct size and creatinine kinase levels; however, the effects of ANG-(1-7) were not additive with PPC. In conclusion, these data provide novel insights into the cardioprotective mechanisms of PPC in that they involve the Mas receptor and eNOS and further suggest a potential therapeutic role for ANG-(1-7) in cardiac ischemic injury.

PP.14.20

Objective: Metabolic syndrome (MS) was the major risk factors for heart failure, initially manifesting as diastolic dysfunction. In this present study, the effects and the mechanisms of astragaloside IV (AST) were investigated on high fructose/high fat diet (HFFD) induced MS rats. Design and method: The rat MS model was established by feeding HFFD for 24 weeks. Rats were divided into four groups as normal control group, MS group, MS+AST 0.5 (0.5 mg/kg, i.p.) group and MS+AST 2 (2 mg/kg, i.p.) group. The hemodynamic and echocardiographic parameters were used to assess the left ventricular functions. Rat left ventricular tissue and plasma samples were collected for biochemical and molecular analysis. Results: Our HFFD fed rats had hypertriglyceridaemia, high blood glucose, hyperinsulinemia, elevated blood pressure, weight gain, and diastolic dysfunction. AST could improve diastolic dysfunction without any effect on systolic function in MS rats. In the present study, the experimental results showed that nitric oxide (NO) production and superoxide dismutase (SOD) level decreased while the level of malondialdehyde (MDA) increased in the left ventricular cardiomyocytes of MS rats. After treatment with AST in MS rats, cardiac MDA was attenuated as well as NO production and SOD level were dose-dependently improved. The highest dose of AST (2.0 mg/kg) increased cyclic guanosine monophosphate (cGMP) production in the myocardium. At the mean time, the total endothelial nitric oxide synthase (eNOS) and neuronal NOS (nNOS) expression had no significant changes. Compared with the normal control rats, eNOS dimer was decreased in HFFD induced MS rats. Both low and high dose AST treatments restored the eNOS dimer expression of myocardium in MS rats. Conclusions: The present study demonstrated that AST ameliorated the oxidative stress damage and metabolic abnormalities in HFFD induced MS rats. The antioxidant properties of AST and its protection function of the left ventricular diastolic function worked through the eNOS/NO/cGMP pathway.

Effect of Interleukin‐10 and Laminar Shear Stress on African American Human Umbilical Vein Endothelial Cells

African Americans (AA) have a predisposition to heightened systemic inflammation and a high prevalence of hypertension. The purpose of this study was to evaluate the influence of interleukin‐10 (IL‐10) and laminar shear stress (LSS) on AA endothelial cells by measuring total endothelial nitric oxide synthase (eNOS) protein expression and its activated, phosphorylated form (p‐eNOS) at Serine 1177, as well as nitric oxide (NO) levels, in response to IL‐10 incubation and high physiological levels of LSS, used as a mimetic for aerobic exercise training (AEXT). Human umbilical vein endothelial cells (HUVEC) from an AA donor were cultured. The experimental conditions included Static, Static with IL‐10 Incubation, LSS at 20 dynes/cm2, and LSS at 20 dynes/cm2 with IL‐10 Incubation. Western blotting was used to measure eNOS and p‐eNOS protein expression in the cells. A modified Griess assay was used to measure NO production in the cell culture media. There were significant increases in p‐eNOS, eNOS, and NO in the LSS at 20 dynes/cm2 and LSS at 20 dynes/cm2 with IL‐10 Incubation experimental conditions when compared to the Static experimental condition. There were no other statistically significant differences, demonstrating that IL‐10 did not have an additive effect on eNOS activity in the present study. The significant increases in p‐eNOS, eNOS, and NO as a result of LSS in AA HUVECs suggest that AEXT may be a viable, nonpharmacologic method to improve vascular inflammation status and vasodilation, and thereby contribute to reduction of hypertension in the AA population.AHA Scientist Development Grants 12SDG12070327NIH Grant RO1 [HL085497]

Double disruption of α2A- and α2C-adrenoceptors induces endothelial dysfunction in mouse small arteries: role of nitric oxide synthase uncoupling.

Knockout mice lacking both α2A- and α2C-adrenergic receptors (α2A/α2C-ARKO) provide a model for understanding the mechanisms underlying the deleterious effects of sympathetic hyperactivity on the cardiovascular system. Thus, in the present study we investigated the vascular reactivity of large and small arteries of α2A/α2C-ARKO mice. Aorta and mesenteric small arteries (MSAs) from 7-month-old male α2A/α2C-ARKO mice and congenic C57BL6/J mice (wild-type, WT) were studied. In the aorta, noradrenaline- and serotonin-induced contraction was similar between groups, but in MSAs there was an increase in agonist-induced contraction in α2A/α2C-ARKO compared with WT. The l-NAME effect was reduced in MSAs of α2A/α2C-ARKO mice compared with WT mice, as was basal NO evaluated by a 4,5-diaminofluorescein diacetate probe. Increased total endothelial nitric oxide synthase (eNOS) protein expression was observed in MSAs from α2A/α2C-ARKO mice, while the dimer/monomer ratio of eNOS was decreased. Mesenteric small arteries from α2A/α2C-ARKO mice showed an increase in ethidium bromide-positive nuclei, indicating oxidative stress, which was attenuated by incubation with l-NAME. The sympathetic hyperactivity present in α2A/α2C-ARKO mice alters vascular reactivity only in certain types of arteries. Moreover, after chronic sympathetic hyperactivity, uncoupling eNOS may be a significant source of superoxide anion and reduced NO bioavailability in small vessels, increasing the contractile tone.

The urea decomposition product cyanate promotes endothelial dysfunction.

The dramatic cardiovascular mortality of patients with chronic kidney disease is attributable in a significant proportion to endothelial dysfunction. Cyanate, a reactive species in equilibrium with urea, is formed in excess in chronic kidney disease. Cyanate is thought to have a causal role in promoting cardiovascular disease, but the underlying mechanisms remain unclear. Immunohistochemical analysis performed in the present study revealed that carbamylated epitopes associate mainly with endothelial cells in human atherosclerotic lesions. Cyanate treatment of human coronary artery endothelial cells reduced expression of endothelial nitric oxide synthase, and increased tissue factor and plasminogen activator inhibitor-1 expression. In mice, administration of cyanate, promoting protein carbamylation at levels observed in uremic patients, attenuated arterial vasorelaxation of aortic rings in response to acetylcholine without affecting the sodium nitroprusside-induced relaxation. Total endothelial nitric oxide synthase and nitric oxide production were significantly reduced in aortic tissue of cyanate-treated mice. This coincided with a marked increase of tissue factor and plasminogen activator inhibitor-1 protein levels in aortas of cyanate-treated mice. Thus, cyanate compromises endothelial functionality in vitro and in vivo. This may contribute to the dramatic cardiovascular risk of patients suffering from chronic kidney disease.