Plasma Nitrite Levels Research Articles

Effects of electroconvulsive therapy in the systemic inflammatory balance of patients with severe mental disorder.

There is a great interest in the role of the immune system and the inflammatory balance as key mechanisms involved in the pathophysiology of severe mental disorders. Previous studies have indicated that electroconvulsive therapy (ECT) produces changes in certain inflammatory mediators or in the immune system response. This study aimed to explore the effects of ECT on the nuclear transcription factor κB (NFκB) pathway, a main regulatory pathway of the inflammatory/immune response. Thirty subjects with a severe mental disorder receiving treatment with ECT in our center were included. Thirteen systemic biomarkers related to the NFκB pathway were analyzed right before and 2 h after a single ECT session. An ECT session significantly decreased the expression of NFκB (P = 0.035) and of the inducible nitric oxide synthase (P = 0.012), and the plasma levels of nitrites (P = 0.027), prostaglandin E2 (P = 0.049), and 15-deoxy-PGJ2 (P < 0.001). Decrease in plasmatic levels of nitrites was greater in females than in males (P = 0.021). A positive correlation between the ECT stimulus load and changes in the expression of NFkB was found (P = 0.036). Thiobarbituric acid reactive substance levels were decreased in treatment responders and increased in non-responders (P = 0.047). Our study shows the effects that a single session of ECT produces on a canonical regulatory pathway of the inflammatory/innate immune system and the inflammatory balance. These biomarkers could be useful as treatment response targets and could help to clarify the biological basis of ECT action. These findings warrant greater attention in future investigations and in the translational significance of these data.

N-Pyrazoloyl and N-thiopheneacetyl hydrazone of isatin exhibited potent anti-inflammatory and anti-nociceptive properties through suppression of NF-κB, MAPK and oxidative stress signaling in animal models of inflammation.

Hydrazide derivatives constitute an important class of compounds for new drug development as they are reported to possess good anti-inflammatory and analgesic activity. The present study was aimed to investigate the role of newly synthesized hydrazide derivatives N-pyrazoloyl hydrazone of isatin (PHI) and N-thiopheneacetyl hydrazone of isatin (THI) in acute and chronic inflammatory pain models induced by carrageenan and complete Freud's adjuvant (CFA). PHI and THI (0.1, 1 and 10mg/kg) pretreatments were provided intraperitoneally to male BALB/c mice prior to inflammatory inducers. Behavioral responses to inflammation and pain were evaluated by assessment of paw edema, mechanical allodynia, mechanical and thermal hyperalgesia. Cytokines production and NF-κB levels were evaluated by ELISA. Western blot analysis was performed for the detection of IκBα, p38, JNK and ERK. Hematoxylin and eosin (H&E) staining and radiographic analysis were performed to evaluate the effect of PHI and THI treatment on bone and soft tissues. Oxidative stress was determined by reduced glutathione, glutathione-S-transferase and catalase assays. Evans blue dye was used to monitor vascular protein leakage. PHI and THI dose dependently (0.1, 1 and 10mg/kg) reduced inflammation and pain in mice, however, the dose of 10mg/kg exhibited significant activity. The anti-inflammatory and analgesic effects were attributed to suppression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) productionlevels. PHI and THI significantly blocked CFA-induced activation of NF-κB and MAPK signaling pathways. Oxidative stress and plasma nitrite levels were reduced remarkably. The PHI and THI (10mg/kg) treatment did not exhibit any apparent toxicity on the liver, kidney, muscles strength, and motor co-ordination in mice. Both PHI and THI possess significant anti-inflammatory and analgesic activity via inhibition of inflammatory mediators.

Endothelial nitric oxide synthase gene polymorphisms modulate the risk of squamous cell carcinoma of head and neck in north Indian population

BackgroundNitric oxide (NO) is found to have both tumour promoting and inhibiting properties. Nitric oxide (NO) is synthesized by three isoforms of nitric oxide synthase (NOS) enzymes and endothelial NOS (eNOS) is one of them. Polymorphisms in eNOS 894G > T (rs1799983) and eNOS intron 4a/b geneS could modulate the risk for developing SCCHN by regulating the level of nitric oxide. ObjectiveIn this study we evaluated the association of eNOS 894G > T (rs1799983) and intron 4a/b polymorphisms with the plasma nitrite level and the risk of Squamous cell carcinoma of the head and neck (SCCHN). Materials and methodsA total of 352 subjects were genotyped for the above said polymorphisms. Genotypes were correlated with plasma nitrite level of study subjects. ResultsCompared to GG homozygote of 894G > T polymorphism a significantly increased risk of SCCHN was observed with TT homozygote (p = 0.03, OR = 2.72, 95% CI 1.14–6.50). In comparison to carrier of ‘b’ allele, ‘a’ allele carrier for intron 4a/b polymorphism were at increased risk to develop high stage diseases (p = 0.00, OR 8.67 and 95% CI 3.76–19.99). The haplotype bT constituted from 894G > T and intron 4a/b polymorphisms also showed association with increased susceptibility for SCCHN (p = 0.038 OR = 1.66, 95% CI 1.03–2.63). Plasma nitrite level was significantly higher in cases compared to control (p = 0.047). The level of plasma nitrite was also higher in individuals with TT genotype compared to those with GG genotype (p = 0.012 in SCCHN cases and 0.088 in control).Conclusions: Our results suggest that eNOS 894G > T and intron 4a/b polymorphisms influence the risk of SCCHN and, eNOS 894G > T polymorphism modulate the risk of disease by modulating plasma nitrite level.

The association of family history of hypertension and overweight induced early impairment in markers of oxidative stress and in heart rate variability

Considering the high prevalence of hypertension worldwide and the changes in lifestyle, the understanding of the mechanisms involved in the genesis of hypertension are important to reach more precise interventions. Our objective was to evaluate cardiovascular, autonomic and oxidative stress parameters in individuals with family history of hypertension (FH) with or without overweight. We performed a cross‐sectional study and selected 65 healthy sedentary men (24.08 ± 5.84 years) distributed into 4 groups: negative FH eutrophic (FNE, n=18) or with overweight (FNO, n=19) and positive FH eutrophic (FHE, n=17) or with overweight (FHO, n=17). The heart rate variability (HRV) was analyzed at rest by spectral analysis. The oxidative stress markers were evaluated in plasma. A positive correlation between levels LDL and WC/HC ratio was demonstrated (r: 0.54 p = 0.003) in FHE and FHO groups. We observed an increase in diastolic blood pressure in the FHO and FNO groups in relation to the FNE and FHE groups (p = 0.010). When we evaluated the cardiac sympathetic modulation (LF‐PI), we observed a significant increase in the FNO and FHO groups when compared to the FNE group (p = 0.0001). Furthermore, the FHO (2.30 ± 0.8) and FHE groups (2.52 ± 1) presented higher cardiac sympato‐vagal balance (LF/HF) compared to FNO (1.85 ± 0.67) and FNE groups (2.01 ± 0.84) (p =0.04). We observed an increase in systemic hydrogen peroxide concentration in the FHO group when compared to the other groups (p=0.003). Moreover, there was an increase in NADPH oxidase in plasma in FNO and FHO groups in relation the FNE and FHE groups (p = 0.04). In addition, there was an increase in plasma nitrite levels in FHO group compared to FNO, FNE and FHE groups (p=0.01). In conclusion our findings demonstrated that despite young and apparently healthy, the group with overweight and FH showed early impairment in HRV and in markers of oxidative stress. In addition, this group presented all dysfunctions observed in the presence of these risk factors alone, which may be associated with increased cardiovascular risk and target organ damage in this population.Support or Funding InformationUNINOVE, CNPq, CAPES, FAPESP.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Augmented Endothelial Specific Cationic Amino Acid Transporter‐1 Expression Prevents Renal Fibrosis and Inflammation and Loss of Renal Function in Heart Failure

INTRODUCTIONIt is now well established that impaired renal function associated with heart failure (HF) increases morbidity and mortality in HF patients. There are no effective treatments to rescue renal function in HF and the precise mechanisms that drive renal injury in HF remain elusive. Transport of L‐arginine via cationic amino acid transporter‐1 (CAT‐1) influences renal nitric oxide bioavailability. We hypothesised that impaired L‐arginine transport via CAT‐1 is central to the development of renal dysfunction in HF.METHODSAdult male 18–26 week old wild‐type mice (WT), transgenic mice with dilated cardiomyopathy (DCM) and double transgenic mice with DCM and endothelial‐specific overexpression of CAT1 (HFCAT‐1) were used (n=8 per group). Transgenic mice with dilated cardiomyopathy (DCM) have cardiac specific overexpression of Mammalian sterile 20‐like kinase‐1 (Mst1) which leads to apoptosis and DCM. The double transgenic HFCAT‐1 mouse model has endothelial specific overexpression of CAT1 driven by the Tie‐2 promotor and cardiac specific overexpression of Mst1. Cardiac and renal function were assessed via echocardiography and via calculating the albumin to creatinine ratio, respectively. Fibrosis was assessed via Masson's trichrome staining. Renal inflammation was assessed via expression of pro‐ and anti‐inflammatory gene expression. Plasma nitrate and nitrite levels were assessed via ELISA. Isolated renal cells from WT mice (n=3) were incubated with CAT1 antisense (2.5 μM) or its scrambled oligonucleotide for a period of 4‐h and then CAT1, collagen III and collagen IV expression were measured by PCR.RESULTSExpression of renal CAT1 was less in DCM mice (by 21%) compared to WT mice (P=0.04) and this was restored in HFCAT1 mice. Urinary albumin/creatinine ratio was greater in DCM mice (by 72%) compared to WT (P=0.04). Urinary albumin/creatinine ratio was normalized in HFCAT1 mice. Renal mRNA expression of Il6 was less in HFCAT‐1 mice than DCM mice (P=0.03). Renal mRNA expression of Il10 was 57% less in DCM mice than in WT mice and this was restored in HFCAT‐1 mice (P&lt;0.05). Renal mRNA expression of Pai1 was greater in DCM mice (by 42%), but not HFCAT‐1 mice, compared to WT mice (P=0.01). Tubulointerstitial and glomerular fibrosis were 89% and 76% greater respectively in DCM mice than in WT mice (P&lt;0.05). Tubulointerstitial and glomerular fibrosis were normalized in HFCAT‐1 mice. CAT1 antisense reduced the expression of CAT1 mRNA in isolated renal cells by 46% and collagen III expression in these cells was 8 fold greater compared to control. Ejection fraction was 33% less in DCM mice than in WT (P&lt;0.01) and this was not restored in HFCAT1 mice (P=0.24).CONCLUSIONRestoration of endothelial specific CAT1 expression normalizes renal inflammation and fibrosis and prevents the loss of GFR in experimental HF.Support or Funding InformationNHMRC Program grant (DK) and Baker Heart and Diabetes Institute Early Career Grant (NR)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Hydroxyurea Augments Nitric Oxide Bioavailability in Humanized Sickle Cell Mice

Sickle cell disease (SCD) is an inherited hemoglobinopathy that affects millions of people across the world. Despite advancements in disease management, sickle cell nephropathy (SCN), a major contributor to mortality and morbidity in patients, has limited therapeutic options. Only one of two FDA‐approved therapies for the treatment of SCD, hydroxyurea (HU) has been shown to improve renal injury but the mechanism is elusive. Studies have shown that many of the therapeutic benefits of HU may be due to its ability to improve nitric oxide (NO) bioavailability. Thus, we hypothesized that HU treatment would improve NO bioavailability in the humanized sickle cell mouse. Male 12‐week old sickle (HbSS) and genetic control (HbAA) mice were treated with HU or vehicle for two weeks before renal and systemic NO bioavailability as well as renal injury were assessed. Vehicle treated HbSS mice exhibited significant renal injury compared to vehicle treated HbAA mice, indicated by increased proteinuria (4.7 ± 0.6 vs. 2.2 ± 0.3 mg/day, respectively, p=0.002), elevated plasma endothelin‐1 (ET‐1) (1.6 ± 0.1 vs. 0.9 ± 0.1 pg/ml, respectively, p&lt;0.001), and reduced urine concentrating ability (1380 ± 89 vs. 2481 ± 93 mOsmol/kg, respectively, p&lt; 0.0001). HU treatment reduced renal injury in HbSS mice indicated by reduced proteinuria (2.3 ± 0.3 vs.4.7 ± 0.6 mg/day, respectively, p&lt;0.01) and lower plasma ET‐1 levels (1.2 ± 0.1 vs. 1.6 ±0.1 pg/ml, respectively, p=0.04). While HU treatment improved urine concentrating ability, this effect was not statistically significant (1623 ± 73 vs.1380 ± 89 mOsmol/kg, respectively, p=0.05). Vehicle treated HbSS mice showed signs of impaired systemic NO bioavailability compared to HbAA mice, indicated by elevated plasma arginase activity (347 ± 48 vs. 52.9 ± 4.6 units/L, respectively, p&lt;0.001). NO bioavailability impairments were improved with HU treatment as seen by reduced plasma arginase activity (150 ± 33 vs. 347±48 units/L, respectively, p=0.01) and increased plasma nitrite levels (1.1 ± 0.3 vs. 0.04 ± 0.02 mM, respectively, p=0.01) compared to HbSS vehicle treated mice. Renal vessels isolated from HbSS mice also had elevated nitric oxide synthase 3 (NOS3) expression (2.5 ± 0.4 vs.1.0 ± 0.1 arbitrary units (A.U.), respectively, p=0.04) compared to vehicle treated HbAA mice detected by Western blot analysis. HU treatment did not alter renal vascular NOS3 expression (0.9 ± 0.2 vs. 1.0 ± 0.1 A.U., respectively, p=0.94), however, renal vascular arginase 2 expression was reduced by HU (0.07± 0.01 vs. 1.0 ± 0.1 A.U., respectively, p&lt;0.0001). These data support the hypothesis that HU treatment augments renal and systemic NO bioavailability possibly via reducing arginase activity as a potential mechanism for the improvement on renal injury seen in sickle cell mice with HU.Support or Funding InformationSupport provided by an APS Porter Fellowship to CT, American Society of Nephrology Ben J. Lipps Research Fellowship for MK, F31 DK111067 to RS, T32 GM109780 to LSD, and a U01 HL117684 to JSP, CD, and DMP.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Does endurance training improve red blood cell aging and hemorheology in moderate-trained healthy individuals?

ObjectiveTo examine the impact of a 6-week endurance training on red blood cell (RBC) aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations. MethodsA total of 31 participants (17 females and 14 males) performed a 6-week moderate training protocol (three 1-h running sessions per week at 70% of maximal heart rate). Blood was sampled before and after the training. RBCs from each participant were fractioned according to density and age into 4 RBC subfractions. Subfractions were examined for changes of RBC properties, including aging distribution, RBC deformability, RBC microparticles, and phosphatidylserine concentrations. RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism. ResultsAerobic performance, peak oxygen consumption, ventilatory thresholds, velocity at the aerobic–anaerobic threshold, and lactate at exhaustion improved after training. The relative amount of both young RBCs and old RBCs increased, and the amount of the main RBC fraction decreased. Phosphatidylserine externalization and RBC-derived microparticles decreased. Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs (p < 0.001). Nitrite decreased in total (p = 0.001), young (p < 0.001), main (p < 0.001), and old (p = 0.020) aged RBCs and in plasma (p = 0.002), but not in very old RBCs. ConclusionThese results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced, which might support oxygen supply in the microcirculation.

ANTIDEPRESSANT-LIKE ACTIVITY OF FLOWERS OF TECOMELLA UNDULATA IN MICE SUBJECTED TO CHRONIC UNPREDICTABLE MILD STRESS

Objective: Flowers of Tecomella undulata have been reported to be a rich source of flavonoids such as rutin and quercetin. The present study was designed to evaluate the effect of ethanol extract of flowers of T. undulata on chronic unpredictable mild stress (CUMS)-induced depression in Swiss young male albino mice.Methods: The mice were subjected to CUMS for 21 successive days. Ethanol extract of the flowers (50, 100, and 200 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) per se was administered for 21 successive days to separate groups of unstressed and stressed mice. Tail suspension test (TST) and sucrose preference test were used to evaluate the effect of the extract on depression-like behavior in mice.Results: Extract of flowers of T. undulata (100 and 200 mg/kg) significantly decreased immobility period of stressed mice in TST, indicating significant antidepressant-like activity of the extract. Stress-induced reduced sucrose preference was significantly restored by the extract. There was no significant effect on locomotor activity of mice by the extract and fluoxetine. The extract significantly reversed stress-induced increase in brain malondialdehyde levels; plasma nitrite and corticosterone levels; and also significantly reversed the stress-induced decrease in reduced glutathione and catalase levels. There was no significant effect of the extract on brain MAO-A activity in both unstressed and stressed mice.Conclusion: These results indicated that ethanol extract of flowers of T. undulata showed significant antidepressant-like activity in mice subjected to CUMS, probably through alleviation of oxidative stress and decrease in plasma corticosterone levels.

ANTIDEPRESSANT-LIKE ACTIVITY OF FLOWERS OF TECOMELLA UNDULATA IN MICE SUBJECTED TO CHRONIC UNPREDICTABLE MILD STRESS

Objective: Flowers of Tecomella undulata have been reported to be a rich source of flavonoids such as rutin and quercetin. The present study was designed to evaluate the effect of ethanol extract of flowers of T. undulata on chronic unpredictable mild stress (CUMS)-induced depression in Swiss young male albino mice.Methods: The mice were subjected to CUMS for 21 successive days. Ethanol extract of the flowers (50, 100, and 200 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) per se was administered for 21 successive days to separate groups of unstressed and stressed mice. Tail suspension test (TST) and sucrose preference test were used to evaluate the effect of the extract on depression-like behavior in mice.Results: Extract of flowers of T. undulata (100 and 200 mg/kg) significantly decreased immobility period of stressed mice in TST, indicating significant antidepressant-like activity of the extract. Stress-induced reduced sucrose preference was significantly restored by the extract. There was no significant effect on locomotor activity of mice by the extract and fluoxetine. The extract significantly reversed stress-induced increase in brain malondialdehyde levels; plasma nitrite and corticosterone levels; and also significantly reversed the stress-induced decrease in reduced glutathione and catalase levels. There was no significant effect of the extract on brain MAO-A activity in both unstressed and stressed mice.Conclusion: These results indicated that ethanol extract of flowers of T. undulata showed significant antidepressant-like activity in mice subjected to CUMS, probably through alleviation of oxidative stress and decrease in plasma corticosterone levels.

The effects of incremental whole beetroot consumption on plasma nitrate and nitrite levels and blood pressure in young and old subjects

The effects of incremental whole beetroot consumption on plasma nitrate and nitrite levels and blood pressure in young and old subjects

Intervention mechanism of repeated oral GABA administration on anxiety-like behaviors induced by emotional stress in rats

The purpose of this study was to investigate the effects and mechanism of repeated oral administration of gamma-aminobutyric acid (GABA) on anxiety-like behaviors induced by emotional stress. Male Sprague-Dawley rats were randomly divided into five groups (8 rats each): control, emotional stress model, three emotional stress + GABA-treated groups (0.5, 1, 2 mg/kg). The rats were given empty water bottles after the training of drinking water to induce emotional stress. Each group was treated with saline or different doses of GABA respectively for 21 consecutive days. Then open field and elevated plus maze were used to assess anxiety-like behaviors. Both frontal cortex and plasma NO metabolites nitrate and nitrite (NOx) levels were determined spectrophotometrically. Results showed that oral administration of GABA significantly reversed the stress-induced anxiety-like negative responses dose-dependently. The frontal cortex NOx levels were lower in stressed rats than in control group (P < 0.05), but higher in 2 mg/kg GABA-treated group than stress model group (P < 0.05). On the other hand, NOx levels in plasma showed a gradual decline trend. Collectively, these results suggest that short repeated oral administration of GABA has an anxiolytic-like effect possibly via preventing NO reduction caused by stress and improving availability of NO in the frontal cortex.

Exercise-Induced Cardioprotection via eNOS: A Putative Role of Red Blood Cell Signaling.

Moderate exercise training is a key aspect of primary and secondary prevention strategies. Shear-induced upregulation of eNOS activity and function in the vascular endothelium is considered as one of the main molecular mechanisms of exercise-induced protection against myocardial ischemia/ reperfusion (I/R) injury. It has been reported that levels of plasma nitrite, which are largely dependent on eNOS activity, were increased in healthy subjects after acute exercise, while this increase was abolished in coronary artery disease (CAD) patients. Our group and others demonstrated that RBCs contain a functional eNOS, which contributes to systemic nitrite homeostasis and to cardioprotection; moreover, expression and activity of red cell eNOS are decreased in CAD patients and significantly correlated with flow-mediated dilation, a diagnostic marker of endothelial function. Therefore, in addition to vascular eNOS, also red cell eNOS (or in more general terms NO metabolic activity of RBCs) may play a role in exercise-dependent changes of NO-bioavailability. In this review, we will focus on what is known and what is unknown about the role of RBCs in exercise-dependent cardioprotection with emphasis on RBC signaling and red cell eNOS. In detail, we will discuss the effects and molecular mechanisms of shear stress and exercise training on RBC signaling and function, review how these changes may influence blood rheology and systemic hemodynamics and highlight the potential role of red cell eNOS-mediated cardiovascular protection induced by physical activity against myocardial injury in animal and human studies and in clinical settings.

The effects of LXR agonist GW3965 on vascular reactivity and inflammation in hypertensive rat aorta

AimsLiver X receptors (LXRs) play an important role in the regulation of cholesterol, fatty acid and glucose metabolisms together with inflammatory processes. In the present study, the effects of LXR agonist GW3965 on vascular reactivity and expression of functional proteins in DOCA-Salt induced hypertension were examined. Main methodsHypertension was induced through unilateral nephrectomy and deoxycorticosterone-acetate (DOCA) injection (20 mg/kg, twice a week) for 6 weeks in male Wistar albino rats (8 weeks old). An LXR agonist GW3965 (10 mg/kg/day, i.p.) was administered to animals for last seven days. Key findingsGW3965 treatment reduced systolic blood pressures in hypertensive rats. Acetylcholine-induced endothelium-dependent and sodium nitroprusside-induced endothelium-independent vasorelaxations were decreased in hypertensive rats but not affected by GW3965. GW3965 treatment enhanced plasma nitrite levels in normotensive rats. KCl and phenylephrine (Phe)-induced vasocontractions were reduced in hypertensive groups and increased with GW3965 treatment. Decreased sarco/endoplasmic reticulum Ca2+-ATPase2 (SERCA2) expression in the hypertensive aorta was not changed by GW3965 treatment. Expression of inositoltrisphosphate receptor1 (IP3R1) was increased by GW3965 in normotensive animals. The nuclear factor kappaB (NF-κB) and tumor necrosis factor alpha (TNF-α) expressions were increased in hypertensive rats and reduced by GW3965 treatment. SignificanceThe results of study indicate that the LXR agonist, GW3965, exhibited a beneficial effect on increased blood pressure and improved hypertension-induced impairment in contractile activity of vessel and inflammatory markers in vascular tissue. Therefore, these effects of LXR agonists on vessel should be taken into account in experimental or therapeutic approaches to hypertension.

Effects of Beet Juice Supplementation on Monocrotaline-Induced Pulmonary Hypertension in Rats.

Recently, attention has been focused on the cardiovascular protective effects of beet juice (BJ) with high amounts of nitrate. In this study, we examined the effect of BJ supplementation in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). MCT (60 mg/kg) was subcutaneously administered to rats, and BJ (prepared by dissolving BJ powder at a concentration of 1 g/l or 10 g/l in drinking water) supplementation was started from the day of, 1 week before, and 2 weeks after MCT injection. Saline-injected rats given drinking water were used as controls. Low-dose BJ supplementation starting from the day of MCT injection exerted protective effects on the MCT-induced elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary arterial remodeling, without causing a significant increase in plasma nitrite plus nitrate (NOx) levels. On the other hand, such beneficial effects were not observed with high-dose BJ supplementation, although the NOx levels were slightly higher than those in the low-dose group. In addition, low-dose BJ supplementation starting from 1 week before MCT injection did not improve PH symptoms, as described above. Furthermore, low-dose BJ supplementation starting from 2 weeks after MCT injection was ineffective against functional and morphological alterations in pulmonary circulation associated with MCT-induced PH. Habitual ingestion of a suitable amount of BJ could be a potential option for preventing PH. However, beneficial effects cannot be expected when PH has developed to some degree.

Effects of Oral Supplementation With Nitrate-Rich Beetroot Juice in Patients With Pulmonary Arterial Hypertension—Results From BEET-PAH, an Exploratory Randomized, Double-Blind, Placebo-Controlled, Crossover Study

BackgroundThe nitrate–nitrite–nitric oxide (NO) pathway may represent a potential therapeutic target in patients with pulmonary arterial hypertension (PAH). We explored the effects of dietary nitrate supplementation, with the use of nitrate-rich beetroot juice (BRJ), in patients with PAH. Methods and ResultsWe prospectively studied 15 patients with PAH in an exploratory randomized, double-blind, placebo-controlled, crossover trial. The patients received nitrate-rich beetroot juice (∼16 mmol nitrate per day) and placebo in 2 treatment periods of 7 days each. The assessments included; exhaled NO and NO flow–independent parameters (alveolar NO and bronchial NO flux), plasma and salivary nitrate and nitrite, biomarkers and metabolites of the NO-system, N-terminal pro–B-type natriuretic peptide, echocardiography, ergospirometry, diffusing capacity of the lung for carbon monoxide, and the 6-minute walk test. Compared with placebo ingestion of BRJ resulted in increases in; fractional exhaled NO at all flow-rates, alveolar NO concentrations and bronchial NO flux, and plasma and salivary levels of nitrate and nitrite. Plasma ornithine levels decreased and indices of relative arginine availability increased after BRJ compared to placebo. A decrease in breathing frequency was observed during ergospirometry after BRJ. A tendency for an improvement in right ventricular function was observed after ingestion of BRJ. In addition a tendency for an increase in the peak power output to peak oxygen consumption ratio (W peak/VO2 peak) was observed, which became significant in patients reaching an increase of plasma nitrite >30% (responders). ConclusionsBRJ administered for 1 week increases pulmonary NO production and the relative arginine bioavailability in patients with PAH, compared with placebo. An increase in the W peak/VO2 peak ratio was observed after BRJ ingestion in plasma nitrite responders. These findings indicate that supplementation with inorganic nitrate increase NO synthase–independent NO production from the nitrate-nitrite-NO pathway.

Effects of citrus leaf extract on aortic vascular reactivity in hypertensive rats fed repeatedly heated vegetable oil.

The prolonged intake of diet containing repeatedly heated vegetable oil can cause hypertension in the long run. In this study, the effects of citrus leaf extract (CLE) supplementation on vascular reactivity, plasma nitrite, and aortic structure in hypertensive rats were investigated by the consumption of repeatedly heated vegetable oil [corrected]. Male Sprague Dawley rats (n = 56) were divided into 7 groups corresponding to the respective diets. For 16 weeks, 1 group was given standard rat chow (control) while other groups were given diets containing 15% w/w of palm oil, fresh palm oil (FPO), palm oil heated 5 times (5HPO), and palm oil heated 10 times (10HPO), with or without the incorporation of 0.15% w/w CLE (FPO+CLE, 5HPO+CLE, or 10HPO+CLE). Plasma nitrite levels were measured before and at 16 weeks of treatment. After 16 weeks, the rats were sacrificed and aortae were harvested for measuring vascular reactivity and for microscopic study. CLE supplementation had significantly reduced the loss of plasma nitrite and attenuated the vasoconstriction response to phenylephrine in the 5HPO group but not in the 10HPO group. However, CLE had no significant effect on the vasorelaxation response to acetylcholine and sodium nitroprusside. The elastic lamellae of tunica media in 5HPO, 10HPO, and 10HPO+CLE groups appeared disorganised and disrupted. Obtained findings suggested that CLE was able to enhance nitric oxide bioavailability that might dampen the vasoconstriction effect of phenylephrine.

Hydrogen sulfide improves postischemic neoangiogenesis in the hind limb of cystathionine-β-synthase mutant mice via PPAR-γ/VEGF axis.

Neoangiogenesis is a fundamental process which helps to meet energy requirements, tissue growth, and wound healing. Although previous studies showed that Peroxisome proliferator‐activated receptor (PPAR‐γ) regulates neoangiogenesis via upregulation of vascular endothelial growth factor (VEGF), and both VEGF and PPAR‐γ expressions were inhibited during hyperhomocysteinemic (HHcy), whether these two processes could trigger pathological effects in skeletal muscle via compromising neoangiogenesis has not been studied yet. Unfortunately, there are no treatment options available to date for ameliorating HHcy‐mediated neoangiogenic defects. Hydrogen sulfide (H2S) is a novel gasotransmitter that can induce PPAR‐γ levels. However, patients with cystathionine‐β‐synthase (CBS) mutation(s) cannot produce a sufficient amount of H2S. We hypothesized that exogenous supplementation of H2S might improve HHcy‐mediated poor neoangiogenesis via the PPAR‐γ/VEGF axis. To examine this, we created a hind limb femoral artery ligation (FAL) in CBS +/− mouse model and treated them with GYY4137 (a long‐acting H2S donor compound) for 21 days. To evaluate neoangiogenesis, we used barium sulfate angiography and laser Doppler blood flow measurements in the ischemic hind limbs of experimental mice post‐FAL to assess blood flow. Proteins and mRNAs levels were studied by Western blots and qPCR analyses. HIF1‐α, VEGF, PPAR‐γ and p‐eNOS expressions were attenuated in skeletal muscle of CBS +/− mice after 21 days of FAL in comparison to wild‐type (WT) mice, that were improved via GYY4137 treatment. We also found that the collateral vessel density and blood flow were significantly reduced in post‐FAL CBS +/− mice compared to WT mice and these effects were ameliorated by GYY4137. Moreover, we found that plasma nitrite levels were decreased in post‐FAL CBS +/− mice compared to WT mice, which were mitigated by GYY4137 supplementation. These results suggest that HHcy can inhibit neoangiogenesis via antagonizing the angiogenic signal pathways encompassing PPAR‐γ/VEGF axis and that GYY4137 could serve as a potential therapeutic to alleviate the harmful metabolic effects of HHcy conditions.

The role of nitrite in muscle function, susceptibility to contraction injury, and fatigability in sickle cell mice

Sickle cell disease (SCD) patients can have limited exercise capacity and muscle dysfunction characterized by decreased force, atrophy, microvascular abnormalities, fiber distribution changes, and skeletal muscle energetics abnormalities. Growing evidence suggests that in SCD there is alteration in nitric oxide (NO) availability/signaling and that nitrate/nitrite can serve as a NO reservoir and enhance muscle performance. Here, we examined effects of nitrite on muscle strength, exercise capacity, and on contractile properties of fast-(extensor digitorum longus, EDL) and slow-twitch (soleus) muscles in SCD mice. Compared to controls, homozygotes (sickling) had decreased grip strength, impaired wheel running performance, and decreased muscle mass of fast-twitch, but not slow-twitch muscle. Nitrite treatment yielded increases in nitrite plasma levels in controls, heterozygotes, and homozygotes but decreases in muscle nitrite levels in heterozygotes and homozygotes. Regardless of genotype, nitrite yielded increases in grip strength, which were coupled with increases in specific force in EDL, but not in soleus muscle. Further, nitrite increased EDL, but not soleus, fatigability in all genotypes. Conversely, in controls, nitrite decreased, whereas in homozygotes, it increased EDL susceptibility to contraction-induced injury. Interestingly, nitrite yielded no changes in distances ran on the running wheel. These differential effects of nitrite in fast- and slow-twitch muscles suggest that its ergogenic effects would be observed in high-intensity/short exercises as found with grip force increases but no changes on wheel running distances. Further, the differential effects of nitrite in homozygotes and control animals suggests that sickling mice, which have altered NO availability/signaling, handle nitrite differently than do control animals.

Association of plasma nitrite levels with obesity and metabolic syndrome in the Old Order Amish.

SummaryObjectivesPlasma nitrite is a metabolite of nitric oxide and reflects endogenous nitric oxide synthase (NOS) activity. Although plasma nitrites were previously linked with obesity and metabolic syndrome (MetS), the direction of association remains inconsistent, possibly due to sample heterogeneity. In a relatively homogeneous population, we hypothesized that nitrite levels will be positively associated with overweight/obesity and MetS.MethodsFasting nitrite levels were measured in 116 Old Order Amish (78% women). We performed age‐and‐sex‐adjusted ancovas to compare nitrite levels between three groups (a) overweight/obese(−)MetS(−), (b) overweight/obese(+)MetS(−) and (c) overweight/obese(+)MetS)(+). Multivariate linear regressions were conducted on nitrite associations with continuous metabolic variables, with successive adjustments for demographics, body mass index, C‐reactive protein and neopterin.ResultsNitrite levels were higher in the obese/overweight(+)MetS(+) group than in the other two groups (p < 0.001). Nitrites were positively associated with levels of triglycerides (p < 0.0001), total cholesterol (p = 0.048), high‐density lipoprotein/cholesterol ratio (p < 0.0001) and fasting glucose (p < 0.0001), and negatively correlated with high‐density lipoprotein‐cholesterol (p < 0.0001). These associations were robust to adjustments for body mass index and inflammatory markers.ConclusionFurther investigation of the connection between obesity/MetS and plasma nitrite levels may lead to novel dietary and pharmacological approaches that ultimately may contribute to reducing the increasing burden of obesity, MetS and cardiovascular morbidity and mortality.

Increased Plasma Nitrite and von Willebrand Factor Indicates Early Diagnosis of Vascular Diseases in Chemotherapy Treated Cancer Patients.

Chemotherapy induced cardiotoxicity leads to development of hypertension, conduction abnormalities, and congestive heart failure. However, there is no simple test to detect and assess cardiovascular risk in a chemotherapy treated cancer patient. The aim of the present study on cancer patients treated with (n = 66) and without (n = 66) chemotherapy is to identify indicators from plasma for vascular injury. The levels of plasma nitrite, asymmetric dimethyl arginine (ADMA), von Willebrand factor (vWF), cardiac troponins, lipid peroxidation (MDA), and lactate dehydrogenase (LDH) were estimated. An R package, namely, Optimal Cutpoints, and a machine learning method-support vector machine (SVM) were applied for identifying the indicators for cardiovascular damage. We observed a significant increase in nitrite (p < 0.001) and vWF (p < 0.001) level in chemotherapy treated patients compared to untreated cancer patients and healthy controls. An increased MDA and LDH activity from plasma in chemotherapy treated cancer patients was found. The R package analysis and SVM model developed using three indicators, namely, nitrite, vWF, and MDA, can distinguish cancer patients before and after chemotherapy with an accuracy of 87.8% and AUC value of 0.915. Serum collected from chemotherapy treated patients attenuates angiogenesis in chick embryo angiogenesis (CEA) assay and inhibits migration of human endothelial cells. Our work suggests that measurement of nitrite along with traditional endothelial marker vWF could be used as a diagnostic strategy for identifying susceptible patients to develop cardiovascular dysfunctions. The results of the present study offer clues for early diagnosis of subclinical vascular toxicity with minimally invasive procedure. Schematic representation of chemotherapy induced elevated plasma nitrite level in cancer patients.