Stable End Products Of Nitric Oxide Research Articles

Significance of Nitric Oxide Level in Giardiasis.

Giardiasis is one of the most prevalent intestinal protozoa infections in humans. Nowadays, nitric oxide (NO) is known to be involved in the immune system against Giardia intestinalis. Therefore, the aim of the present study was to evaluate the level of NO in individuals with giardiasis in comparison to normal subjects. This descriptive study was conducted among 49 Giadia positive and 39 age and gender matched healthy volunteers. Examination of stool samples was done by wet mount technique and formol-ether concentration method. Serum samples were obtained for laboratory examination. NO production was quantified by measuring nitrite, a stable end product of NO, using the Griess reaction based on ELISA method. By using the standard curve in Excel program, the concentration of NO2- in samples was obtained. Finally, all data were analyzed using SPSS version 17. Values obtained from NO assays were placed into 4 groups: ≤ 10 (decline), 10.01 - 15 (normal), 15.01 - 25 (increase), and more than 25 µM (sharp increase). The mean level of NO in patients with G. intestinalis was 32.19 ± 2.15 µM and in people without G. intestinalis was 17.1 ± 1.33 µM. Eight point two percent of patients with Giardiasis were in normal range, but 2%, 20.4%, and 69.4% were in decline, increase, and sharp increase ranges, respectively. In group 2 (without infection), 17.9% were in normal range, and 20.5%, 51.3%, and 10.3% were in decline, increase, and sharp increase ranges, respectively. There was a statistical difference in nitric oxide levels between positive and negative groups with a 95% confidence interval. (p-value = 0.001). In our study, the number of people who showed a sharp increase in NO levels was significantly higher in individuals with giardiasis as compared to the control group, and patients infected with giardiasis showed significant increase in NO levels. Therefore, we suggest that further studies are required to understand the exact function of NO in the immune system against giardiasis in humans. It will be important to offer a new therapeutic target for eliminating G. intestinalis.

Beneficial effects of melatonin on serum nitric oxide, homocysteine, and ADMA levels in fructose-fed rats

Context: Melatonin, a pineal hormone and a potent antioxidant, has important roles in metabolic regulation.Objective: This study investigated serum asymmetric dimethylarginine (ADMA), homocysteine (Hcy), nitric oxide (NO) levels, known to be reliable markers of cardiovascular diseases, and determined possible protective effects of melatonin in fructose-fed rats.Materials and methods: Sprague–Dawley rats were divided into four groups: control, fructose, melatonin, and fructose plus melatonin. Metabolic syndrome was induced in rats by 20% (w/v) fructose solution in tap water, and melatonin was administered at the dose of 20 mg/kg bw per day by oral gavage. After 8 weeks, serum lipids, glucose, insulin, ADMA, Hcy, and NOx (the stable end products of NO) levels were quantified.Results: Fructose administration caused a statistically significant increase in systolic blood pressure (SBP), serum insulin, triglycerides, and very low-density lipoprotein (VLDL)–cholesterol levels compared with the control group and the metabolic syndrome model was successfully demonstrated. In comparison with the control group, fructose caused a significant increase in serum ADMA, Hcy, and NOx levels. Melatonin counteracted the changes in SBP, serum ADMA, and Hcy levels found in rats both alone and administered with fructose.Discussion and conclusion: These results show that high fructose consumption leads to elevated SBP, atherogenic lipid profile, increased serum ADMA, and Hcy levels and melatonin treatment has beneficial effects on these biochemical parameters in rats. Melatonin might be beneficial for the prevention and/or treatment of the cardiovascular complications of metabolic syndrome not only by reducing the well-known risk factors of the disease but also by diminishing blood ADMA and Hcy levels.

Nitric oxide production by polymorphonuclear leucocytes in infected cystic fibrosis sputum consumes oxygen

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is characterized by persisting mucoid biofilms in hypoxic endobronchial mucus. These biofilms are surrounded by numerous polymorphonuclear leucocytes (PMNs), which consume a major part of present molecular oxygen (O(2)) due to production of superoxide (O(2)(-)). In this study, we show that the PMNs also consume O(2) for production of nitric oxide (NO) by the nitric oxide synthases (NOS) in the infected endobronchial mucus. Fresh expectorated sputum samples (n = 28) from chronically infected CF patients (n = 22) were analysed by quantifying and visualizing the NO production. NO production was detected by optode measurements combined with fluorescence microscopy, flow cytometry and spectrophotometry. Inhibition of nitric oxide synthases (NOS) with N(G) -monomethyl-L-arginine (L-NMMA) resulted in reduced O(2) consumption (P < 0·0008, n = 8) and a lower fraction of cells with fluorescence from the NO-indicator 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) (P < 0·002, n = 8). PMNs stained with DAF-FM and the superoxide indicator hydroethidine (HE) and host cells with inducible NOS (iNOS) were identified in the sputum. In addition, the production of the stable end-products of NO in CF sputum was correlated with the concentration of PMNs; NO(3)(-) (P < 0·04, r = 0·66, n = 10) and NO(2)(-) (P< 0·006, r = 0·78, n = 11). The present study suggests that besides consumption of O(2) for production of reactive oxygen species, the PMNs in CF sputum also consume O(2) for production of NO.

High glucose enhances permeability of human pulmonary microvascular endothelial cells by lipopolysaccharide stimulation in vitro and effect of DDAH/NOS/NO imbalance on its pathogenesis

To investigate the damage to endothelial cells incubated in high concentration of glucose challenged by lipopolysaccharide (LPS), and the likely mechanisms of injury. Human pulmonary microvascular endothelial cells (PMVECs) were divided into the following groups: normal glucose group (NG), normal glucose + LPS stimulation group (NGL), high glucose stimulation group (HG), and high glucose + LPS stimulation group (HGL). The cells were incubated with normal glucose (5.5 mmol/L, contained 10% calf serum) or high glucose (33 mmol/L) for 5 days to form a monolayer of cells before LPS stimulation (10 mg/L) for 24 hours. The microfilaments (F-actin) were investigated by immuno-fluorescence, and the number and size change in fenestrae were examined by scanning electron microscopy. The permeability of vascular endothelial cell was assessed by trans-PMVEC horseradish peroxidase (HRP) flux. Western blotting was used to determine the expressions of dimethylarginine dimethylaminohydrolase 2 (DDAH2), inducible nitricoxide synthase (iNOS) and endothelial nitricoxide synthase (eNOS). Nitric oxide (NO) was assessed by Griess method. When stimulated with LPS, cells incubated with high glucose showed obvious microfilament rearrangement, a larger average diameter and increased number of F-actin, as well as higher HRP permeability on the hyperglycemic PMVECs compared with PMVECs cultured with normal glucose [(53.62±6.70)% vs. (23.63±3.92)%, P<0.01]. Furthermore, high glucose down-regulated DDAH2 expression (arbitrary units, AU, 0.33±0.08 vs. 0.77±0.14 , P<0.01) and up-regulated LPS-stimulated iNOS production (1.40±0.29 vs. 1.04±0.09, P<0.01), as well as increased LPS-stimulated nitrite/nitrate and stable NO end products compared with normal (20.36±2.25 μmol/L vs. 7.99±0.33 μmol/L, P<0.01) and reduction of eNOS levels was observed (0.67±0.09 vs. 0.91±0.17, P<0.05). It demonstrated that, in vitro high glucose deteriorate LPS-stimulated F-actin rearrangement and hyperpermeability of an endothelial monolayer, and the worsened imbalance of the NO pathway may lead to endothelial damage in microcirculation.

Increased Nitric Oxide and Vascular Endothelial Growth Factor Levels in the Aqueous Humor of Patients with Coats' Disease

To determine the aqueous humor levels of nitric oxide (NO) and vascular endothelial growth factor (VEGF) in the eyes of patients with Coats' disease and study the correlation between these levels. Samples of aqueous humor were obtained from 7 patients with Coats' disease and 15 age-matched patients with congenital cataracts as controls. Nitrite and nitrate (NOx), the stable end products of NO, were detected by the Griess reaction, and VEGF levels were assessed by enzyme-linked immunosorbent assay. The aqueous humor NOx and VEGF levels were elevated in the eyes of patients with Coats' disease compared with those of controls (P=0.001 and P<0.001, respectively). The median NOx level was 55.2 μM (range, 23.0-75.3 μM) in the Coats' disease group and 18.8 μM (range, 8.7-36.2 μM) in the control group. The median VEGF level was 731.7 pg/mL (range, 288.3-1364.3 pg/mL) in the Coats' disease group and 33.3 pg/mL (range, 9.0-96.8 pg/mL) in the control group. No correlation was observed between the aqueous humor concentrations of NOx and VEGF. NOx and VEGF are increased but not related in the aqueous humor samples of patients with Coats' disease. NO and VEGF may play roles in the pathogenesis of Coats' disease. Further studies are needed to clearly elucidate the relationship among VEGF, NO, and other cytokines in Coats' disease.

Retinal nitric oxide and malonyldialdehyde levels following photodynamic therapy

Background:To determine the retinal nitric oxide (NO) and malonyldialdehyde (MDA) levels following photodynamic therapy (PDT).Materials and Methods:Seven Dutch-belted rabbits received dextrose, while seven others received 2 mg/kg verteporfin infusion over a period of 15 minutes in a dim-lit room. Irradiation to a 1.5 mm diameter intact chorioretinal area in the right eye of verteporfin-infused rabbits, was started 5 minutes after the end of infusion. Three groups were control (dextrose infusion), infusion with verteporfin (left eyes were not irradiated), and irradiation after verteporfin injection (right eyes were irradiated). On the fifth day of the experiment, the eyes were enucleated. The retinas were subsequently frozen and homogenized. Nitrite, a stable end-product of NO and MDA, was measured using the spectrophotometer. Protein concentrations were measured by the Lowry method. Tissue NO and MDA levels were expressed as μmol/gprt and nmol/mgprt, respectively.Results:The mean retinal NO and MDA levels of the control, infusion, and irradiation groups were 24.67 ± 6.66, 0.11 ± 0.02; 45.90 ± 15.52, 0.21 ± 0.09; and 84.43 ± 14.96 μmol/gprt, 0.58 ± 0.14 nmol/mgprt, respectively. The mean retinal NO levels were significantly elevated in the infusion and irradiation groups compared with the control group (P:0.004; P:0.001). The mean retinal MDA levels were significantly elevated in the infusion and irradiation groups compared to the control one (P:0.026; P:0.001). Also the mean retinal NO and MDA levels in the irradiation group were found to be significantly higher than the infusion group (P:0.018; P:0.018).Conclusion:Not only PDT, but also verteporfin infusion alone resulted in NO and MDA level increments in the retina, which might be toxic.

Nitric Oxide, Ammonia, and CRP Levels in Cirrhotic Patients With Hepatic Encephalopathy

Comparison of nitric oxide (NO) levels in cirrhotic patients with and without hepatic encephalopathy (HE), evaluation of possible correlation between HE and other clinical or laboratory characteristics, and estimation of utilization of NO levels in clinical practice. HE is a neuropsychiatric complication of cirrhosis. The exact pathogenetic mechanisms underlying the presence of HE are not known. However, dysfunction of the NO pathway and ammonia detoxification are thought to play a major role. Sixty-seven cirrhotic patients, 36 (53.7%) without HE, and 31 (46.3%) with HE were included in the study. Eighteen healthy individuals were used as control group. Clinical and laboratory data, including ammonia and stable end products of NO using Griess reaction, were collected. NOx levels were statistically significantly higher in cirrhotic patients (225.5 μmol/L) than in control group [(67.94 μmol/L) (P=0.000)]. NOx levels were, also, statistically significantly higher in patients with HE compared with patients without HE (324.67 μmol/L vs. 141.96 μmol/L, P=0.000). Significant correlation between the presence of HE and NOx, ammonia, C-reactive protein, albumin, Model for End-Stage Liver Disease score, and Child-Pugh classification revealed. NOx levels also correlated with severity of HE. NOx and ammonia are independent factors predicting HE according to regression analysis. Diagnostic accuracy for the diagnosis of HE using a combination of NOx and ammonia was superior compared with standalone NOx or ammonia utilization. NOx levels are correlated with the presence and severity of HE. NOx levels determination, in addition to ammonia levels, could contribute in diagnosis of HE.

Impact of interval versus steady state exercise on nitric oxide production in patients with left ventricular dysfunction

Aim — The aim of the present study was to assess the impact of the interval exercise training (IET) vs. steady state exercise training (SSET) on nitric oxide production, through changes of circulating blood markers of endothelial function, including stable end-products of nitric oxide (NOx) and S-nitrosothiols (RSNOs) in patients with left ventricular dysfunction (LVD).Patients and methods — The impact of the IET vs. SSET on NOx and RSNOs production was assessed in a total of 31 (25 male, 6 female) patients with LVD (ejection fraction < 40%), who were admitted to our residential rehabilitation centre. Patients were randomised into an IET group (n = 18; 15 min interval exercise sessions, 2 times daily) and an SSET group (n = 13; 5-10 min steady state exercise sessions, 2 times daily), and exercised every day over a period of 3 weeks.The modified Saville-Griess method was used to determine NOx and RSNOs concentrations.Results — A significant increase was observed both for NOx (P < 0.05) and RSNOs (P < 0.001) in the IET group, as well as for RSNOs in the SSET group (P < 0.001). Both training methods were observed to significantly improve exercise capacity, as demonstrated for increased workload (P < 0.001 and P < 0.05 for the IET and SSET groups, respectively) and duration (P < 0.001 and P < 0.01 for the IET and SSET groups, respectively) of the exercise stress test at the end of the study.Conclusion — The results of the present study have demonstrated an increased nitric oxide production and improved exercise capacity in patients with left ventricular dysfunction, who were engaged in an interval exercise programme for three weeks, and clearly indicated an advantage of interval compared to steady state training method for cardiovascular rehabilitation.

The Relationship Between Brachial Artery Flow-Mediated Dilation and Plasma Levels of Nitrite/Nitrate (NOx)

Brachial artery flow-mediated dilation (FMD) is a bio assay that is predominantly dependent on endothelium-derived nitric oxide (NO). Because of the difficulty in the direct assessment of NO in humans, estimation of NO production from endothelial cells has been performed by quantifying the stable NO end products (nitrite and nitrate; NOx) in plasma as an alternative measure. However, plasma NOx can reflect NO production from sources other than the endothelium and may not reflect endothelial function. PURPOSE: To determine the relation between brachial FMD and plasma levels of NOx. METHODS: Brachial artery FMD was assessed non-invasively using high-resolution ultrasound in thirty six young men and women (23 ± 3 yr; 18M/18F). Brachial FMD was expressed as an absolute (?mm) and as a percent increase from baseline (FMD%). Since the amount of dilation depends on the hyperemic flow stimulus, all measurements of FMD were normalized (norm s-1) to the mean shear rate. Blood samples were collected from an indwelling venous catheter in the forearm following an overnight fast and a 36 hour low nitrate diet. Plasma blood samples were used to determine levels of NOx. Bivariate correlation analyses (Pearson) were performed to determine relations between NOx and brachial FMD (%, mm, and norm s-1). RESULTS: There was a significant relation between brachial FMD% and plasma NOx (r= 0.53, p≤ 0.001). The significant relationship was maintained when the brachial dilation was expressed as δmm (r= 0.51, p ≤ 0.002) and when it was normalized (s-1) to the mean shear rate (r= 0.50, p ≤ 0.002). CONCLUSION: This study demonstrates a close relation between FMD in the brachial artery and plasma levels of NOx in young healthy men and women. This relationship suggests that brachial FMD and plasma NOx may be used either together or alone as markers of peripheral endothelial function.

Central Nervous System Dysfunction after Noncardiac Surgery and Anesthesia in the Elderly

Central Nervous System Dysfunction after Noncardiac Surgery and Anesthesia in the Elderly

Nitric Oxide Produced in Response to Engagement of β2 Integrins on Human Neutrophils Activates the Monomeric GTPases Rap1 and Rap2 and Promotes Adhesion

We found that engagement of beta2 integrins on human neutrophils increased the levels of GTP-bound Rap1 and Rap2. Also, the activation of Rap1 was blocked by PP1, SU6656, LY294002, GF109203X, or BAPTA-AM, which indicates that the downstream signaling events in Rap1 activation involve Src tyrosine kinases, phosphoinositide 3-kinase, protein kinase C, and release of calcium. Surprisingly, the beta2 integrin-induced activation of Rap2 was not regulated by any of the signaling pathways mentioned above. However, we identified nitric oxide as the signaling molecule involved in beta2 integrin-induced activation of Rap1 and Rap2. This was illustrated by the fact that engagement of beta2 integrins increased the production of nitrite, a stable end-product of nitric oxide. Furthermore, pretreatment of neutrophils with Nomega-monomethyl-L-arginine, or 1400W, which are inhibitors of inducible nitric-oxide synthase, blocked beta2 integrin-induced activation of Rap1 and Rap2. Similarly, Rp-8pCPT-cGMPS, an inhibitor of cGMP-dependent serine/threonine kinases, also blunted the beta2 integrin-induced activation of Rap GTPases. Also nitric oxide production and its downstream activation of cGMP-dependent serine/threonine kinases were essential for proper neutrophil adhesion by beta2 integrins. Thus, we made the novel findings that beta2 integrin engagement on human neutrophils triggers production of nitric oxide and its downstream signaling is essential for activation of Rap GTPases and neutrophil adhesion.

The effects of dexfenfluramine administration on brain serotonin immunoreactivity and lipid peroxidation in mice

Obesity continues to be an increasing health problem in worldwide and antiobesity drugs have commonly been used by obese patients. During the use of anorectic drugs, the antioxidant defense may be affected, especially by reactive oxygen species. It was decided to investigate the effects of dexfenfluramine on body weight, daily food intake, brain thiobarbituric acid-reactive substances (TBARS), glutathione (GSH) and nitric oxide (NO) levels, and 5-HT immunoreactivity. Mice were divided into two groups each containing 8 Swiss Albino adult (6 months) mice. Group 1, untreated, was used as a control; group 2 was treated with dexfenfluramine 0.4 mg/kg per day intraperitoneally for 7 days. Brain TBARS and GSH levels were assayed spectrophotometrically. The stable end-products of NO, nitrite and nitrate, were analyzed spectrophotometrically. Brain tissue 5-HT immunoreactivity was observed using an immunohistochemical method. There were significant decreases in body weight in the dexfenfluramine group (p < 0.05). Although brain GSH and NO(x) levels decreased significantly, brain TBARS levels increased in the dexfenfluramine group (p < 0.05). Brain 5-HT immunoreactivity also increased in the dexfenfluramine-treated group compared to control. In conclusion, our findings show that dexfenfluramine is effective in achieving weight loss and also increases lipid peroxidation in mouse brain.

Vascular endothelium-derived factors and arterial stiffness in strength- and endurance-trained men

Arterial stiffness is higher in strength-trained humans and lower in endurance-trained humans. However, the mechanisms underlying these different adaptations are unclear. Vascular endothelium-derived factors, such as endothelin-1 (ET-1) and nitric oxide (NO), play an important role in the regulation of vascular tonus. We hypothesized that endogenous ET-1 and NO participate in the adaptation of arterial stiffness in different types of exercise training. The purpose of this study was to investigate plasma ET-1 and NO concentrations and arterial stiffness in strength- and endurance-trained men. Young strength-trained athletes (SA; n = 11), endurance-trained athletes (EA; n = 12), and sedentary control men (C; n = 12) participated in this study. Maximal handgrip strength in SA and maximal oxygen uptake in EA were markedly greater than in C. Aortic pulse-wave velocity, which is an established index of arterial stiffness, was higher in SA and lower in EA than in C. Additionally, we measured systemic arterial compliance (SAC) using carotid artery applanation tonometry and Doppler echocardiography, because arterial stiffness is a primary determinant of the compliance. SAC was lower in SA and higher in EA compared with that in C. Plasma ET-1 concentrations were higher in SA compared with C and EA. We did not find significant differences in plasma NO concentrations (measured as the stable end product of NO, i.e., nitrite/nitrate). The relationships of plasma ET-1 concentrations to aortic pulse-wave velocity and SAC were linear. These results suggest that differences in endogenous ET-1 may partly participate in the mechanism underlying different adaptations of arterial stiffness in strength- and endurance-trained men.

L'exercice de sprint induit une augmentation des concentrations plasmatiques en dérivés de l'oxyde nitrique

Introduction Nitric oxide (NO) production increases during aerobic exercises. Different factors (shear stress, catecholamine and hypoxia) are well known to increase NO production and all of them are additionally involved during sprint exercise. Thus, the aim of this study was to explore plasma stable end products of NO response to a Wingate-test. Synthesis This study showed that sprint exercise induces a 25% increase in stable end products of NO in physically active subjects of both sexes. Conclusion The increase in stable end products of NO was lower than the increase reported during aerobic exercises. Moreover, this study failed to show any gender difference.

Plasma- and urine concentrations of nitrite/nitrate and cyclic Guanosinemonophosphate in intrauterine growth restricted and preeclamptic pregnancies

The Nitric Oxide (NO) system plays an important role in the establishment and maintenance of the feto-placental circulation. Research on the pathogenesis of preeclampsia in several studies has established the involvement of the NO-system in preeclampsia and fetal intrauterine growth restriction (IUGR). In the presented study we analyzed the urine and plasma concentrations of nitrite/nitrate, the stable endproducts of NO and its second messenger, cyclic Guanosinemonophosphate (cGMP) in normal, preeclamptic and IUGR pregnancies. In total 76 patients were investigated in a prospective study for repeated determination of plasma and urinary levels of nitrate/nitrite and cGMP: 49 patients with a normal course of pregnancy, 14 patients with fetal IUGR and 13 patients with preeclampsia were included into the study. Plasma and urine Nitrite/Nitrate-concentrations were determined using a Colorimetric Assay (Cayman Inc., USA), concentrations of the second messenger cGMP in plasma and urinary samples were determined with a J(125)-Radio-Immuno-Assay (ibl Inc., Germany). The Stat View Program (Abacus Concepts, Inc., Berkeley, CA, 1992-1998) was used for statistical analysis, a P value <0.05 was considered significant. Analyzing the data with the Kruskall-Wallis test a significance was reached for Plasma Nitrite/Nitrate (P=0.0236), plasma cGMP (P=0.004) and urinary nitrite/nitrate (P=0.032). No significance was seen for urinary cGMP (P=0.656). Comparing normal and preeclamptic and normal and IUGR pregnancies the following significant differences were seen (Mann-Whitney U test): In preeclamptic pregnancies urine nitrite/nitrate concentration was significantly lower compared to normal pregnancies (P=0.009) No significant difference between normal and preeclamptic pregnancies for plasma nitrite/nitrate (P=0.819) and plasma-cGMP (P=0.072) could be observed. In IUGR pregnancies plasma nitrite/nitrate and the plasma-cGMP concentrations were both significantly lower compared to normal pregnancies (P=0.0077 and 0.0066) in IUGR-pregnancies. No significance was reached when analyzing urine-Nitrite/Nitrate (P=0.7). Whereas in preeclampsia a reduced urinary nitrite/nitrate was analyzed, IUGR pregnancies showed reduced plasma nitrite/nitrate and cGMP. A reduced release of NO into the maternal circulation might lead to the presented findings and be involved in the pathogenesis of preeclampsia and fetal IUGR.

Differences in the nitric oxide metabolism in streptozotocin-treated rats and children suffering from Type 1 diabetes

The relationship between diabetes mellitus Type 1 and nitric oxide (NO) synthesis was studied in multiple low-dose streptozotocin (STZ)-treated rats and diabetic children. The aim of our experimental work was to test the effect of hyperglycemic state on the level of urinary stable NO end products and on the expression of inducible nitric oxide synthase (NOS II) in white blood cells (WBC). It was also studied whether the measurements of these parameters were suitable to predict the presence of early diabetes before its onset. The occurrence of insulitis in streptozotocin-treated rats could not be clearly demonstrated. Urinary nitrite plus nitrate level significantly increased both in diabetic rats and in children compared to controls. However, the increase of the activity and the expression of inducible NOS II were only observed in rat white blood cells and this effect was prevented by insulin treatment. In human samples, less than 25% of children showed elevated NOS II expression in white blood cells without any correlation to the level of urinary NO end products and glycated hemoglobin in blood. Correlation was found only between the activity and expression of NOS II in white blood cells of patients whose white blood cells were positive for the presence of NOS II. Measurement of urinary nitrite plus nitrate content as well as the determination of NOS II expression of white blood cells in an early phase of diabetes are not suitable predictors in humans probably due to the basic differences in the mechanism of streptozotocin-induced rat and spontaneous human Type 1 diabetes.

Inhibitory Effects ofCentella asiaticaWater Extract and Asiaticoside on Inducible Nitric Oxide Synthase During Gastric Ulcer Healing in Rats

In this study, the effects of Centella asiatica water extract (CE) and its active constituent, asiaticoside (AC), on the expression and activity of inducible nitric oxide synthase (iNOS) during gastric ulcer healing in rats were investigated. CE was prepared from Centella asiatica dry plant and the concentration of AC in CE was quantitatively determined with the use of high performance liquid chromatography analysis. Different concentrations of CE (0.10 g/kg and 0.25 g/kg) and AC (5 mg/kg and 10 mg/kg) were orally administered to rats with acetic acid-induced gastric ulcers. They were found to reduce the size of the ulcers at days 1, 3 and 7 after ulcer induction in a dose-dependent manner, with a concomitant attenuation of iNOS activity and protein expression at the ulcer tissues. The levels of nitrite and nitrate (NO(X)-), the stable end-products of nitric oxide (NO), in the gastric ulcer tissues were also decreased. N-[3-(aminomethyl)benzyl]acetamidine (1400W), a highly selective inhibitor of iNOS, was found to produce similar but more potent inhibition on iNOS activity at a dose of 0.1 mg/kg. These findings indicate that CE and AC have an anti-inflammatory property that is brought about by inhibition of NO synthesis and thus facilitates ulcer healing.

Effect of tacrolimus and cyclosporine on renal microcirculation and nitric oxide production

Objectives Cyclosporine (CSA) and tacrolimus (TAC) frequently induce nephrotoxicity and similar pathologic changes. Acute CSA-induced nephrotoxicity has been reported to be mediated by activation of vasoconstrictors such as endothelin. The purpose of the present study was to investigate the acute effects of TAC and CSA on the renal microcirculation and upon a vasodilator such as nitric oxide (NO) production. Methods Renal blood flow (RBF) in the microcirculation was measured by a Laser Doppler flow meter in uninephrectomised rats. RBF, mean arterial pressure (MAP), and renal vascular resistance (RVR) were measured in the following groups: (a) TAC (0.1 to 2.0 mg/kg/h, n = 3∼6); CSA (20 and 50 mg/kg/h, n = 5); (b) L-NAME (10 mg/kg), an NO synthase inhibitor, 8 minutes prior to TAC (0.5 and 1.5 mg/kg/h, n = 5), or CSA (20 and 50 mg/kg/h, n = 5). Stable NO end-products, serum NO 2 and NO 3, were measured by the Griess method ( n = 5). Results None of the parameters were changed by TAC alone, whereas TAC with L-NAME significantly reduced RBF (−28 ± 7%) and increased RVR (46 ± 17%) in a dose-dependent manner. CSA alone significantly reduced RBF (−37 ± 6%) and increased RVR (69 ± 22%) without any changes in MAP. The effects of CSA were enhanced by L-NAME. Serum concentration of NO 2 + NO 3 was significantly reduced by both L-NAME alone and CSA (50 mg/kg) ( P < .05), while there were no changes with TAC (1.5 mg/kg). Conclusions Blockade of NO production enhance the vasoconstrictive effect of CSA, and unmasked such an effect of TAC. These results suggest that the nephrotoxicity of CSA and TAC may involve the NO system.

Moderate Aerobic Exercise Training Increases Basal Production of Nitric Oxide in Older Women

1085 PURPOSE: Vascular endothelial cells produce nitric oxide (NO), which is a potent vasodilator substance and has been proposed as having antiatherosclerotic property. Therefore, NO has been implicated in the regulation of vascular tonus and prevention of progression of atherosclerosis. On the other hand, NO activity reduces with aging. We previously reported that the plasma nitrite/nitrate (NOx: the stable end product of NO) concentration was significantly increased by an intense aerobic exercise training in healthy young humans. We hypothesized that lifestyle modification (e.g., even a moderate regular exercise training) can increase basal NO production in previously sedentary older humans. METHODS: We measured the plasma NOx concentration before and after a moderate aerobic exercise training (cycling on a leg ergometer at 80% ventilatory threshold for 30 min, 5 days/week) for 3 months in ten older women (63 ± 1 years old). Furthermore, we assessed the plasma concentration of cyclic guanosine monophosphate (cGMP), a second messenger of NO, in the same samples. RESULTS: The individual ventilatory threshold significantly increased after the 3-month exercise training. The systolic blood pressure and diastolic blood pressure at rest significantly decreased after the exercise training. These results suggest that the 3-month exercise training in the older women produced favorable physiological effects, i.e., effects of exercise training. The plasma concentration of NOx significantly increased by the exercise training, and the plasma concentration of cGMP also increased by the exercise training. CONCLUSIONS: The present study suggests that even a moderate regular aerobic-endurance exercise increases basal NO production in previously sedentary older humans, which may have beneficial effects (i.e., antihypertensive and antiatherosclerotic effects by endogenous NO) on the cardiovascular system.

Moderate Aerobic Exercise Training Increases Basal Production of Nitric Oxide in Older Women

1085 PURPOSE: Vascular endothelial cells produce nitric oxide (NO), which is a potent vasodilator substance and has been proposed as having antiatherosclerotic property. Therefore, NO has been implicated in the regulation of vascular tonus and prevention of progression of atherosclerosis. On the other hand, NO activity reduces with aging. We previously reported that the plasma nitrite/nitrate (NOx: the stable end product of NO) concentration was significantly increased by an intense aerobic exercise training in healthy young humans. We hypothesized that lifestyle modification (e.g., even a moderate regular exercise training) can increase basal NO production in previously sedentary older humans. METHODS: We measured the plasma NOx concentration before and after a moderate aerobic exercise training (cycling on a leg ergometer at 80% ventilatory threshold for 30 min, 5 days/week) for 3 months in ten older women (63 ± 1 years old). Furthermore, we assessed the plasma concentration of cyclic guanosine monophosphate (cGMP), a second messenger of NO, in the same samples. RESULTS: The individual ventilatory threshold significantly increased after the 3-month exercise training. The systolic blood pressure and diastolic blood pressure at rest significantly decreased after the exercise training. These results suggest that the 3-month exercise training in the older women produced favorable physiological effects, i.e., effects of exercise training. The plasma concentration of NOx significantly increased by the exercise training, and the plasma concentration of cGMP also increased by the exercise training. CONCLUSIONS: The present study suggests that even a moderate regular aerobic-endurance exercise increases basal NO production in previously sedentary older humans, which may have beneficial effects (i.e., antihypertensive and antiatherosclerotic effects by endogenous NO) on the cardiovascular system.