ReviewMethods of quantitative analysis of the nitric oxide metabolites nitrite and nitrate in human biological fluids

Monooxygenase System and NO Metabolism in Liver Microsomes of Rats with Toxic Hepatitis and the Effect of Sesquiterpene Lactones

We analyzed changes in activities of enzymes of phases I and II of xenobiotic biotransformation and parameters of NO metabolism in liver microsomes of rats with toxic CCl₄-induced hepatitis after a 14-day course of sesquiterpene lactones from Artemisia leucodes (10 mg/kg). It was found that toxic hepatitis was associated with significant inhibition of NADPH-cytochrome c-reductase, benzo(a)pyrene hydroxylase, and NADPH-diaphorase, reduced cytochrome P-450 content, and enhanced induction of nitrate/nitrite reductase with accumulation of NO metabolites in the liver. Administration of sesquiterpene lactones stimulated activity of the studied components of the cytochrome P-450 system and promoted recovery of the NOergic system components; the effects were most pronounced in 7 and 14 days after treatment.

Metabotropic glutamate receptors and nitric oxide in dopaminergic neurotoxicity

Dopaminergic neurotoxicity is characterized by damage and death of dopaminergic neurons. Parkinson's disease (PD) is a neurodegenerative disorder that primarily involves the loss of dopaminergic neurons in the substantia nigra. Therefore, the study of the mechanisms, as well as the search for new targets for the prevention and treatment of neurodegenerative diseases, is an important focus of modern neuroscience. PD is primarily caused by dysfunction of dopaminergic neurons; however, other neurotransmitter systems are also involved. Research reports have indicated that the glutamatergic system is involved in different pathological conditions, including dopaminergic neurotoxicity. Over the last two decades, the important functional interplay between dopaminergic and glutamatergic systems has stimulated interest in the possible role of metabotropic glutamate receptors (mGluRs) in the development of extrapyramidal disorders. However, the specific mechanisms driving these processes are presently unclear. The participation of the universal neuronal messenger nitric oxide (NO) in the mechanisms of dopaminergic neurotoxicity has attracted increased attention. The current paper aims to review the involvement of mGluRs and the contribution of NO to dopaminergic neurotoxicity. More precisely, we focused on studies conducted on the rotenone-induced PD model. This review is also an outline of our own results obtained using the method of electron paramagnetic resonance, which allows quantitation of NO radicals in brain structures.

Synthesis and pharmacological evaluation of pomalidomide derivatives useful for sickle cell disease treatment

Fetal hemoglobin (HbF) induction constitutes a valuable and validated approach to treat the symptoms of sickle cell disease (SCD). Here, we synthesized pomalidomide-nitric oxide (NO) donor derivatives (3a-f) and evaluated their suitability as novel HbF inducers. All compounds demonstrated different capacities of releasing NO, ranging 0.3-30.3%. Compound 3d was the most effective HbF inducer for CD34+ cells, exhibiting an effect similar to that of hydroxyurea. We investigated the mode of action of compound 3d for HbF induction by studying the in vitro alterations in the levels of transcription factors (BCL11A, IKAROS, and LRF), inhibition of histone deacetylase enzymes (HDAC-1 and HDAC-2), and measurement of cGMP levels. Additionally, compound 3d exhibited a potent anti-inflammatory effect similar to that of pomalidomide by reducing the TNF-α levels in human mononuclear cells treated with lipopolysaccharides up to 58.6%. Chemical hydrolysis studies revealed that compound 3d was stable at pH 7.4 up to 24 h. These results suggest that compound 3d is a novel HbF inducer prototype with the potential to treat SCD symptoms.

Kolaviron stimulates glucose uptake with concomitant modulation of metabolic activities implicated in neurodegeneration in isolated rat brain, without perturbation of tissue ultrastructural morphology

Reduced glucose uptake usually occurs in type 2 diabetes due to down-regulation of brain glucose transporters. The potential of kolaviron, a biflavonoid from Garcinia kola to stimulate glucose uptake and suppress glucose-induced oxidative toxicity were investigated in rat brain. Its molecular interactions with the target proteins were investigated in silico. Kolaviron was incubated with excised rat brain in the presence of glucose for 2 h, with metformin serving as a positive control. Kolaviron caused a significant (p < 0.05) increase in glucose uptake, glutathione level, superoxide dismutase, catalase, ATPase, ENTPDase and 5'-nucleotidase activities, while concomitantly depleting malondialdehyde level, acetylcholinesterase and butyrylcholinesterase activities compared to brains incubated with glucose only. Electron microscopy (SEM and TEM) analysis revealed kolaviron had little or no effect on the ultrastructural morphology of brain tissues as evidenced by the intact dendritic and neuronal network, blood vessels, mitochondria, synaptic vesicles, and pre-synaptic membrane. SEM-EDX analysis revealed a restorative effect of glucose-induced alteration in brain elemental concentrations, with total depletion of aluminum and zinc. MTT analysis revealed kolaviron had no cytotoxic effect on HT-22 cells. Molecular docking revealed a potent interaction between kolaviron and catalase at the SER114 and MET350 residues, with a binding energy of 12 kcal/mol. Taken together, these results portray the potential of kolaviron to stimulate glucose uptake while concomitantly coffering a neuroprotective effect.

High-Throughput Griess Assay of Nitrite and Nitrate in Plasma and Red Blood Cells for Human Physiology Studies under Extreme Conditions

The metabolism of nitric oxide plays an increasingly interesting role in the physiological response of the human body to extreme environmental conditions, such as underwater, in an extremely cold climate, and at low oxygen concentrations. Field studies need the development of analytical methods to measure nitrite and nitrate in plasma and red blood cells with high requirements of accuracy, precision, and sensitivity. An optimized spectrophotometric Griess method for nitrite–nitrate affords sensitivity in the low millimolar range and precision within ±2 μM for both nitrite and nitrate, requiring 100 μL of scarcely available plasma sample or less than 50 μL of red blood cells. A scheduled time-efficient procedure affords measurement of as many as 80 blood samples, with combined nitrite and nitrate measurement in plasma and red blood cells. Performance and usefulness were tested in pilot studies that use blood fractions deriving from subjects who dwelt in an Antarctica scientific station and on breath-holding and scuba divers who performed training at sea and in a land-based deep pool facility. The method demonstrated adequate to measure low basal concentrations of nitrite and high production of nitrate as a consequence of water column pressure-triggered vasodilatation in deep-water divers.

Strawberry fruit (Fragaria x ananassa Romina) juice attenuates oxidative imbalance with concomitant modulation of metabolic indices linked to male infertility in testicular oxidative injury

This study investigated the protective properties of strawberry fruit on testicular oxidative injury. Oxidative injury was induced in vitro in testicular tissue homogenates by incubation with ferrous sulphate (FeSO₄ ) in the presence and absence of strawberry fruit extract (SFE) for 30 min at 37˚C, with gallic acid serving as the standard antioxidant drug. Induction of oxidative injury significantly reduced glutathione, cholesterol and triglyceride levels; and inhibited SOD, catalase and ENTPDase activities when compared to normal control. It also led to exacerbated nitric oxide, malondialdehyde, LDL-cholesterol levels, acetylcholinesterase, ATPase and lipase activities. These effects were, however, reversed following treatment with SFE when compared to the untreated control, except for cholesterol and triglyceride levels. Additionally, the induction of the oxidative injury led to alterations in testicular lipid metabolites that were accompanied by the activation of α-linolenic acid and linoleic acid metabolic pathways. While SFE treatment had no significant impact on the altered metabolites, it repressed pathways for mitochondrial beta-oxidation of long-chain saturated fatty acids and plasmalogen synthesis. High-performance liquid chromatography analysis of SFE revealed the presence of rutin, caffeic acid, p-coumarin and cinnamic acid. These data imply the protective potentials of strawberry fruits against testicular oxidative injury.

Endothelial Nitric Oxide Production and Antioxidant Response in Breath-Hold Diving: Genetic Predisposition or Environment Related?

Introduction

Nitric oxide (NO) is an essential signaling molecule modulating the endothelial adaptation during breath-hold diving (BH-diving). This study aimed to investigate changes in NO derivatives (NOx) and total antioxidant capacity (TAC), searching for correlations with different environmental and hyperbaric exposure.

Materials and methods

Blood samples were obtained from 50 breath-hold divers (BH-divers) before, and 30 and 60 min after the end of training sessions performed both in a swimming pool or the sea. Samples were tested for NOx and TAC differences in different groups related to their hyperbaric exposure, experience, and additional genetic polymorphism.

Results

We found statistically significant differences in NOx plasma concentration during the follow-up (decrease at T30 and increase at T60) compared with the pre-dive values. At T30, we found a significantly lower decrease of NOx in subjects with a higher diving experience, but no difference was detected between the swimming pool and Sea. No significant difference was found in TAC levels, as well as between NOx and TAC levels and the genetic variants.

Conclusion

These data showed how NO consumption in BH-diving is significantly lower in the expert group, indicating a possible training-related adaptation process. Data confirm a significant NO use during BH-diving, compatible with the well-known BH-diving related circulatory adaptation suggesting that the reduction in NOx 30 min after diving can be ascribed to the lower NO availability in the first few minutes after the dives. Expert BH-divers suffered higher oxidative stress. A preliminary genetic investigation seems to indicate a less significant influence of genetic predisposition.

Ocimum tenuiflorum mitigates iron-induced testicular toxicity via modulation of redox imbalance, cholinergic and purinergic dysfunctions, and glucose metabolizing enzymes activities

Oxidative stress is a primary culprit in the pathophysiology of infertility conditions in males. This study investigated the effects of Ocimum tenuiflorum on redox imbalance, cholinergic and purinergic dysfunctions and glucose dysmetabolism in oxidative-mediated testicular toxicity using in vitro, ex vivo and in silico models. Induction of oxidative testicular injury was carried out by incubating normal testicular tissue with 0.1 mM FeSO₄ and treated by co-incubating with different concentrations of O. tenuiflorum infusion for 30 min at 37°C. O. tenuiflorum displayed significant ferric reducing power activity while scavenging DPPH and hydroxyl (OH˙) free radicals in vitro. Oxidative testicular injury significantly reduced the glutathione level and superoxide dismutase and catalase activities with concomitant elevation of malondialdehyde and nitric oxide levels and acetylcholinesterase, ATPase, fructose-1,6-bisphosphatase and glycogen phosphorylase (GlyP) activities. Incubation with the infusion significantly reversed these levels and activities. The phytochemical constituent of the infusion was detected by gas chromatography-mass spectroscopy analysis and revealed favourable binding energies when docked with some of the studied proteins. These results suggest O. tenuiflorum exerts a protective effect against Fe²⁺ induced testicular toxicity via mitigation of redox imbalance while modulating metabolic dysfunctions linked to male infertility.

L-leucine stimulation of glucose uptake and utilization involves modulation of glucose - lipid metabolic switch and improved bioenergetic homeostasis in isolated rat psoas muscle ex vivo

The antidiabetic effect of l-leucine has been attributed to its modulatory effect on glucose uptake and lipid metabolism in muscles. However, there is a dearth on its effect on glucose metabolism in muscles. Thus, the present study investigated the effect of l-leucine - stimulated glucose uptake on glucose metabolism, dysregulated lipid metabolic pathways, redox and bioenergetic homeostasis, and proteolysis in isolated psoas muscle from Sprague Dawley male rats. Isolated psoas muscles were incubated with l-leucine (30-240 μg/mL) in the presence of 11.1 mMol glucose at 37 ˚C for 2 h. Muscles incubated in only glucose served as the control, while muscles not incubated in l-leucine and/or glucose served as the normal control. Metformin (6.04 mM) was used as the standard antidiabetic drug. Incubation with l-leucine caused a significant increase in muscle glucose uptake, with an elevation of glutathione levels, superoxide dismutase, catalase, E-NTPDase and 5'nucleotidase activities. It also led to the depletion of malondialdehyde and nitric oxide levels, ATPase, chymotrypsin, acetylcholinesterase, glycogen phosphorylase, glucose-6-phosphatase, fructose-1,6-bisphosphatase and lipase activities. There was an alteration in lipid metabolites, with concomitant activation of glycerolipid metabolism, fatty acid metabolism, and fatty acid elongation in mitochondria in the glucose-incubated muscle (negative control). Incubation with l-leucine reversed these alterations, and concomitantly deactivated the pathways. These results indicate that l-leucine-enhanced muscle glucose uptake involves improved redox and bioenergetic homeostasis, with concomitant suppressed proteolytic, glycogenolytic and gluconeogenetic activities, while modulating glucose - lipid metabolic switch.

The Role of Poly-Herbal Extract in Sodium Chloride-Induced Oxidative Stress and Hyperlipidemia in Male Wistar Rats

Consistent consumption of high salt diet (HSD) has been associated with increased cellular generation of free radicals, which has been implicated in the derangement of some vital organs and etiology of cardiovascular disorders. This study was designed to investigate the combined effect of some commonly employed medicinal plants on serum lipid profile and antioxidant status of aorta, kidney, and liver of high salt diet-fed animals. Out of the total fifty male Wistar rats obtained, fifteen were used for acute toxicity study, while the remaining thirty-five were divided into 5 groups of 7 animals each. Group 1 and 2 animals were fed normal rat chow (NRC) and 16% high salt diet (HSD) only, respectively. Animals in groups 3, 4 and 5 were fed 16% HSD with 800, 400, and 200 mg/kg bw poly-herbal extract (PHE), respectively, once for 28 consecutive days. Serum low-density lipoprotein (LDL), triacylglycerol (TG), total cholesterol (TC) and high-density lipoprotein (HDL), malondialdehyde, nitric oxide, catalase, superoxide dismutase, glutathione peroxidase, glutathione concentration, and activities were assessed in the aorta, kidney, and liver. Poly-herbal extract (p < 0.05) significantly reduced malondialdehyde and nitric oxide concentrations and also increased antioxidant enzymes and glutathione activity. Elevated serum TG, TC, LDL, and TC content in HSD-fed animals were significantly (p < 0.05) reduced to normal in PHE-treated rats while HDL was significantly elevated (p < 0.05) in a concentration-dependent manner in PHE treated animals. Feeding with PHE attenuated high-salt diet imposed derangement in serum lipid profile and antioxidant status in the organs of the experimental rats.

Remote effects and biodistribution of pulmonary instilled silver nanoparticles in mice

Silver nanoparticles (AgNPs) are the most commonly used nanoparticles (NPs) owing to their anti-microbial properties, and the pulmonary system provides a major portal of entry for these NPs used in aerosolized products. AgNPs have the potential to cause pulmonary toxicity, cross the alveolar-capillary barrier, and distribute to remote organs following pulmonary exposure. The mechanism underlying the effects of AgNPs, secondary to lung exposure, on the major organs including liver, spleen, kidney and brain, however, is still not completely understood. The aim of this study was to analyze the organ toxicity and distribution of pulmonary exposure to single dose of 5 mg/kg AgNPs (10 nm) with varying coatings (polyvinylpyrrolidone and citrate), at different time points (1 and 7 days), in Balb/C mice. Silver ions (Ag⁺) were used as ionic control. Histological evidence of inflammation was observed in lungs for both types of AgNPs. Markers of inflammation including tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) were significantly increased in lung, brain and liver in AgNPs exposed animals. Ag⁺ ions caused significant increase of TNF-α and IL-6 in the spleen and kidney. Significant increase of reduced glutathione, nitric oxide, and 8-isoprostane was observed in most of the organs investigated. Furthermore, AgNPs induced DNA damage and apoptosis in the lung, liver and brain. The biodistribution showed that, AgNPs were distributed mainly in the spleen, liver, lung and little in kidney and brain. Comparatively, reduced amount of Ag was detected in most organs 7 days after exposure, except for AgAc in the kidney and brain. In conclusion, pulmonary exposure to AgNPs caused oxidative stress markers, inflammation, DNA damage and biodistribution in remote organs. These findings provide a novel mechanistic insight into the pathophysiological effects and tissue distribution of lung exposure to AgNPs.

Caffeic Acid Protects against Iron-Induced Cardiotoxicity by Suppressing Angiotensin-Converting Enzyme Activity and Modulating Lipid Spectrum, Gluconeogenesis and Nucleotide Hydrolyzing Enzyme Activities

The protective effects of caffeic acid on angiotensin-converting enzyme (ACE) and purinergic enzyme activities, as well as gluconeogenesis was investigated in iron-induced cardiotoxicity. Cardiotoxicity was induced in heart tissues harvested from healthy male SD rats by 0.1 mM FeSO4. Treatment was carried out by co-incubating hearts tissues with caffeic acid and 0.1 mM FeSO4. Cardiotoxicity induction significantly (p < 0.05) depleted GSH level, SOD, catalase, and ENTPDase activities, with concomitant elevation of the levels of malondialdehyde (MDA), nitric oxide, ACE, ATPase, glycogen phosphorylase, glucose 6-phosphatase, fructose 6-biphsophatase, and lipase activities. There was significant (p < 0.05) reversion in these levels and activities on treatment with caffeic acid. Caffeic acid also caused depletion in cardiac levels of cholesterol, triglyceride, LDL-c, while elevating HDL-c level. Our results suggest the protective effect of caffeic acid against iron-mediated cardiotoxicity as indicated by its ability to suppress oxidative imbalance and ACE activity, while concomitantly modulating nucleotide hydrolysis and metabolic switch.

Monocytes from preeclamptic women previously treated with silibinin attenuate oxidative stress in human endothelial cells

Objective: To investigate whether the supernatant from monocytes of preeclamptic and normotensive pregnant women, cultured in vitro with silibinin, can modulate oxidative stress in HUVEC.Methods: Concentrations of IL-1β, IL-10, and TNF-α in monocyte culture supernatants were determined by ELISA. HUVEC and their supernatant cultures were employed for determination of NO, nitrite and nitrate, lipid peroxidation, and hemeoxygenase-1 (HO-1).Results: HUVEC treatment with supernatant of preeclamptic monocytes cultured with silibinin produced increased levels of nitrite, reduced lipid peroxidation, and increased HO-1.Conclusion: Supernatant of monocytes from preeclamptic women induce oxidative stress in HUVEC which can be reduced by silibinin treatment.Abbreviations: DAF-FM^TM, Diaminofluorescein-FM; EDTA, Ethylenediaminetetraacetic acid; HO-1, heme oxygenase-1; HPLC, high-performance liquid chromatography; HUVEC, human umbilical vein endothelial cell; MDA, malondialdehyde; NO, nitric oxide; NT, normotensive; PE, preeclampsia; ROS, reactive oxygen species; Sb, silibinin.

Ferulic acid promotes muscle glucose uptake and modulate dysregulated redox balance and metabolic pathways in ferric-induced pancreatic oxidative injury

The antidiabetic properties of ferulic acid and its protective role against Fe²⁺ -induced oxidative pancreatic injury were investigated in this study using in vitro and ex vivo models. Induction of oxidative injury in the pancreas was achieved by incubating normal pancreatic tissue with 0.1 mM FeSO₄ and treated by co-incubating with different concentrations of ferulic acid for 30 min at 37°C. Ferulic acid inhibited the activities of α-glucosidase, α-amylase, and pancreatic lipase significantly (p < .05) and promoted glucose uptake in isolated rat psoas muscles. Induction of oxidative pancreatic injury caused significant (p < .05) depletion of glutathione (GSH) level, superoxide dismutase (SOD), and catalase activities, as well as elevation of malondialdehyde (MDA) and nitric oxide (NO) levels, acetylcholinesterase and chymotrypsin activities. Treatment of tissues with ferulic acid significantly (p < .05) reversed these levels and activities. LC-MS analysis of the extracted metabolites revealed 25% depletion of the normal metabolites with concomitant generation of m-Chlorohippuric acid, triglyceride, fructose 1,6-bisphosphate, and ganglioside GM1 in oxidative-injured pancreatic tissues. Treatment with ferulic acid restored uridine diphosphate glucuronic acid and adenosine tetraphosphate and generated P1,P4-Bis(5'-uridyl) tetraphosphate and L-Homocysteic acid, while totally inactivating oxidative-generated metabolites. Ferulic acid also inactivated oxidative-activated pathways, with concomitant reactivation of nucleotide sugars metabolism, starch and sucrose metabolism, and rostenedione metabolism, estrone metabolism, androgen and estrogen metabolism, porphyrin metabolism, and purine metabolism pathways. Taken together, our results indicate the antidiabetic and protective potential of ferulic acid as depicted by its ability to facilitate muscle glucose uptake, inhibit carbohydrate and lipid hydrolyzing enzymes, and modulate oxidative-mediated dysregulated metabolisms. PRACTICAL APPLICATIONS: There have been increasing concerns on the side effects associated with the use of synthetic antidiabetic drug, coupled with their expenses particularly in developing countries. This has necessitated continuous search for alternative treatments especially from natural products having less or no side effects and are readily available. Ferulic acid is among the common phenolics commonly found in fruits and vegetables. In this present study, ferulic acid was able to attenuate oxidative stress, cholinergic dysfunction, and proteolysis in oxidative pancreatic injury, as well as inhibit carbohydrate digesting enzymes. Thus, indicating the ability of the phenolic to protect against complications linked to diabetes. Crops rich in ferulic acid maybe beneficial in managing this disease.

Modulatory effect of ursolic acid on neurodegenerative activities in oxidative brain injury: An ex vivo study

Natural products-based antioxidants have been well reported for their therapeutic benefits in the treatment and management of neurodegenerative diseases. The neuroprotective effect of ursolic acid (UA) against oxidative injury was investigated in isolated rat brain. Induction of oxidative injury in isolated rat brains with 0.1 mM FeSO4 led to depleted levels of glutathione, superoxide dismutase, catalase, and ENTPDase activities, with concomitant exacerbation of malondialdehyde and nitric oxide levels, α-chymotrypsin, ATPase, and acetylcholinesterase activities. These levels and activities were significantly reversed following treatment of the brain tissues with UA. Molecular docking studies revealed strong molecular interactions between UA, catalase, and ATPase. Overall, these results indicate the neuroprotective effect of UA against oxidative injury in isolated rat brains as depicted by their ability to mitigate oxidative stress, purinergic, and cholinergic dysfunctions, with concomitant suppression of proteolytic activity. PRACTICAL APPLICATIONS: Neurodegenerative diseases are among the common diseases associated with aging and has been implicated as oxidative mediated. Natural products have received increasing recognition in their use as treatment remedy for various oxidative-mediated diseases including neurodegeneration. These natural products include plant secondary metabolites commonly known as phytochemicals. Ursolic acid is a phytochemical usually present in leafy vegetables and fruits. The present study describes the possible therapeutic mechanism of ursolic acid in the amelioration of complications linked to neurodegeneration in oxidative-mediated brain injury. These findings thus give insights into the use of natural products of plant origin in treating and managing neurodegenerative diseases, which may have little or no side effects.

Nitric Oxide and Oxidative Stress Changes at Depth in Breath-Hold Diving

Background

Several mechanisms allow humans to resist the extreme conditions encountered during breath-hold diving. Available nitric oxide (NO) is one of the major contributors to such complex adaptations at depth and oxidative stress is one of the major collateral effects of diving. Due to technical difficulties, these biomarkers have not so far been studied in vivo while at depth. The aim of this study is to investigate nitrate and nitrite (NOx) concentration, total antioxidant capacity (TAC) and lipid peroxidation (TBARS) before, during, and after repetitive breath-hold dives in healthy volunteers.

Materials and Methods

Blood plasma, obtained from 14 expert breath-hold divers, was tested for differences in NOx, TAC, and TBARS between pre-dive, bottom, surface, 30 and 60 min post-dive samples.

Results

We observed a statistically significant increase of NOx plasma concentration in the “bottom blood draw” as compared to the pre-dive condition while we did not find any difference in the following samples We found a statistically significant decrease in TAC at the bottom but the value returned to normality immediately after reaching the surface. We did not find any statistically significant difference in TBARS.

Discussion

The increased plasma NOx values found at the bottom were not observed at surface and post dive sampling (T0, T30, T60), showing a very rapid return to the pre-dive values. Also TAC values returned to pre- diving levels immediately after the end of hyperbaric exposure, probably as a consequence of the activation of endogenous antioxidant defenses. TBARS did not show any difference during the protocol.

Tetrahydrocannabinol-Rich Extracts From Cannabis Sativa L. Improve Glucose Consumption and Modulate Metabolic Complications Linked to Neurodegenerative Diseases in Isolated Rat Brains

Reduced brain glucose consumption arising from impaired glucose uptake and utilization has been linked to the pathogenesis and complications of neurodegenerative diseases. The ability of Cannabis sativa L. tetrahydrocannabinol (THC)-rich extracts to stimulate brain glucose uptake and utilization as well as its modulatory effect on gluconeogenesis, antioxidative, purinergic and cholinergic activities were investigated in isolated rats’ brains. C. sativa leaves were sequentially extracted to yield the hexane and dichloromethane extracts. The extracts were incubated at 37°C with freshly harvested brains in the presence of glucose for 2 h. The control consisted of incubation without the extracts, while brains without the extracts and glucose served as the normal control. Metformin was used as the standard drug. C. sativa extracts caused a significant (p < 0.05) increase in brain glucose uptake, with concomitant elevation of glutathione level, superoxide dismutase, catalase, and ecto-nucleoside triphosphate diphosphohydrolase activities compared to the controls. Incubation with C. sativa extracts also led to depletion in malondialdehyde and nitric oxide levels, acetylcholinesterase, butyrylcholinesterase, glucose 6-phosphatase and fructose-1,6-biphosphatase activities. GC-MS analysis of the extracts revealed the presence of THC. In silico analysis predicted THC to be permeable across the blood-brain-barrier. THC was also predicted to have an oral LD₅₀ and toxicity class values of 482 mg/kg and 4 respectively. These results indicate that C. sativa improves glucose consumption with concomitant suppression of oxidative stress and cholinergic dysfunction, and modulation of purinergic and gluconeogenic activities in brain tissues

Bioactive compounds of African star apple (Chrysophyllum albidum G. Don) and its modulatory effect on metabolic activities linked to type 2 diabetes in isolated rat psoas muscle

The infusion of Chrysophyllum albidum was investigated for its antidiabetic mechanism by studying its ability to promote glucose uptake and utilization as well as its modulatory effect on metabolic activities linked to type 2 diabetes in isolated psoas muscle. Isolated psoas muscle was incubated with different concentrations of the infusion in the presence of glucose at 37°C for 2 hr. The infusion improved muscle glucose uptake, with concomitant elevated muscular levels of glutathione, superoxide dismutase, catalase, and ectonucleotidase activities, while depleting malondialdehyde, nitric oxide, adenosine triphosphatase, acetylcholinesterase, glycogen phosphorylase, glucose 6-phosphatase, fructose-1,6-biphosphatase, and lipase activities. It also maintained muscular morphology, while increasing magnesium, calcium, and iron levels. The infusion inhibited α-glucosidase and α-amylase activities in vitro. LC-MS analysis of the infusion revealed the presence of phenolics. These results indicate that C. albidum may mediate antidiabetic activities by stimulating muscle glucose uptake and modulation of key metabolisms linked to diabetes. PRACTICAL APPLICATIONS: The African star apple is among the underutilized fruits consumed for nutritional and medicinal purposes in Western Africa. The fruits are usually wasted during its season leading to postharvest loss owing to poor utilization. The present study gives credence to its use in treating diabetes and its complications. Thus, the fruits can be utilized in the development of cheap and affordable nutraceuticals for the management of diabetes which has been reported for its high-cost treatment. Utilization of the fruits will also reduce its postharvest loss and improve its economic values.

Catechol protects against iron-mediated oxidative brain injury by restoring antioxidative metabolic pathways; and modulation of purinergic and cholinergic enzymes activities

OBJECTIVES

This study was aimed at investigating neuroprotective effect of catechol on redox imbalance, cholinergic dysfunctions, nucleotide hydrolysing enzymes activities, and dysregulated metabolic pathways in iron-mediated oxidative brain injury.

METHODS

Oxidative injury was induced in brain tissues by incubating with 0.1 mm FeSO₄ and treated with different concentrations of catechol.

KEY FINDINGS

Catechol significantly elevated glutathione level, superoxide dismutase and catalase activities, while depleting malondialdehyde and nitric oxide levels. It also inhibited the activities of acetylcholinesterase, butyrylcholinesterase, and ATPase, with concomitant elevation of ENTPDase activity. GC-MS analysis revealed that treatment with catechol completely depleted oxidative-generated lipid metabolites. While LC-MS analysis revealed depletion of oxidative-generated metabolites in brain tissues treated with catechol, with concomitant restoration of oxidative-depleted metabolites. Catechol also led to reactivation of oxidative-inactivated taurine and hypotaurine, purine, glutathione, glycerophospholipid, nicotinate and nicotinamide, fructose and mannose, pyrimidine metabolisms and pentose phosphate pathways. Catechol was predicted in silico to be permeable across the blood-brain barrier with a predicted oral LD₅₀ value of 100 mg/kg and a toxicity class of 3.

CONCLUSION

These results suggest the neuroprotective effects of catechol in iron-mediated oxidative brain injury.

Caffeic acid improves glucose utilization and maintains tissue ultrastructural morphology while modulating metabolic activities implicated in neurodegenerative disorders in isolated rat brains

Impaired glucose utilization has been implicated in the pathophysiology of neurodegenerative diseases. The neuroprotective effect of caffeic acid (CA) was investigated in the isolated rat brain by determining its ability to promote glucose uptake, mitigate redox imbalance, modulate purinergic and cholinergic activities, elemental distribution, and maintain tissue morphology. Isolated rat brains were incubated for 2 hours with glucose, CA and glucose, and metformin and glucose. There was an increased glucose uptake, glutathione level, superoxide dismutase, and catalase activities in brain tissues incubated with CA compared to the controls. Incubation with CA also led to significantly decreased levels of malondialdehyde, nitric oxide, acetylcholinesterase, butyrylcholinesterase, and ATPase activities. Electron microscopy (scanning electron microscopy and transmission electron microscopy) analysis portrayed a maintenance of tissue ultrastructural morphology in 2CA-incubated tissues as indicated by the intact synaptic vesicles, blood vessels, dendritic and neuronal network, mitochondria, and presynaptic membrane. CA also restored altered elemental levels in brain tissues. These results indicate the stimulatory potential of CA on brain glucose utilization with simultaneous neuroprotective activities.

Transplanted Kidney Increases Nitric Oxide Formation With Metabolic Acidosis Reduction

OBJECTIVES

As a vasodilator, nitric oxide is considered to play a significant role in the homeostatic regulation of renal hemodynamics. To test the hypothesis that a kidney graft is capable of producing nitric oxide immediately after renal transplant surgery, we examined the possibility that it positively affects local metabolic acidosis.

MATERIALS AND METHODS

In kidney transplant recipients, we analyzed renal vein and central vein blood samples, which reflect local and systemic metabolic alterations, respectively. Samples were taken immediately after kidney recirculation (that is, the first blood passing through after clamps are released) and at 5, 15, and 30 minutes thereafter. Levels of nitric oxide metabolites (nitrites, nitrates, and their sum), malondialdehyde (an indicator of oxidative damages), and parameters of acid-base balance (pH level, actual excess base, hemoglobin, actual bicarbonate, partial pressure of carbon dioxide, partial pressure of oxygen) were analyzed. Living kidney donors (the recipients' parents) were controls.

RESULTS

In renal vein samples, nitrates and the sum of nitrites and nitrates were significantly higher than that shown in control (P < .001) and central vein (P < .05) samples, suggesting an immediate increase in nitric oxide production in the transplanted organ. Metabolic acidosis occurred in both the renal and central vein, indicated by decreased pH and actual bicarbonate level as well as by negative actual base excess level. Only in the renal vein was an increased nitrite and nitrate associated with a reduction of negative actual excess base, thereby suggesting a decrease in anion formation.

CONCLUSIONS

Transplanted kidneys increase nitric oxide production immediately after organ transplant surgery, which positively affects local metabolic acidosis. The mechanism for this effect is likely local circulation improvement.

Ferric-Induced Pancreatic Injury Involves Exacerbation of Cholinergic and Proteolytic Activities, and Dysregulation of Metabolic Pathways: Protective Effect of Caffeic Acid

The protective effect of caffeic acid on ferric-induced pancreatic injury was investigated using ex vivo and in silico models. Incubation of pancreatic tissues with Fe2+ led to significant depleted levels of glutathione (GSH) and SOD and catalase activities, with concomitant elevated levels of malondialdehyde (MDA) and nitric oxide (NO) and acetylcholinesterase and α-chymotrypsin activities. Treatment with caffeic acid led to significant reversion of these levels and activities. Molecular docking revealed a higher binding affinity of caffeic acid with acetylcholinesterase via hydrogen bonding, Pi-Pi stacking, and Van der Waals interactions. FTIR spectroscopy of pancreatic metabolite revealed little or no effect by caffeic acid on functional groups in ferric-induced injured pancreas. The LC-MS analysis of the metabolites revealed Fe2+ caused a 20% depletion of the normal metabolites, with concomitant generation of glyceraldehyde and 3,4-dihydroxymandelaldehyde. Treatment with caffeic acid led to the restoration of TG(22:4(7Z,10Z,13Z,16Z)/24:0/22:5(7Z,10Z,13Z,16Z,19Z)) and dTDP-D-glucose, while depleting glyceraldehyde as well as activating gluconeogenesis. These results indicate the ability of caffeic acid to protect against ferric toxicity by exacerbating antioxidative activities, with concomitant inhibition of MDA and NO levels while deactivating metabolic pathways linked to oxidative stress.

Following the Fate of Dye-Containing Liposomes In Vitro

The rather limited success of translation from basic research to clinical application has been highlighted as a major issue in the nanomedicine field. To identify the factors influencing the applicability of nanosystems as drug carriers and potential nanomedicine, we focused on following their fate through fluorescence-based assays, namely flow cytometry and imaging. These methods are often used to follow the nanocarrier internalization and targeting; however, the validity of the obtained results strictly depends on how much the nanosystem’s fate can be inferred from the fate of fluorescent dyes. To evaluate the parameters that affect the physicochemical and biological stability of the labeled nanosystems, we studied the versatility of two lipid dyes, TopFluor^®-PC and Cy5-DSPE, in conventional liposomes utilizing well-defined in vitro assays. Our results suggest that the dye can affect the major characteristics of the system, such as vesicle size and zeta-potential. However, a nanocarrier can also affect the dye properties. Medium, temperature, time, fluorophore localization and its concentration, as well as their interplay, affect the outcome of tracing experiments. Therefore, an in-depth characterization of the labeled nanosystem should be fundamental to understand the conditions that validate the results within the screening process in optimization of nanocarrier.

Dacryodes edulis (G. Don) H.J. Lam modulates glucose metabolism, cholinergic activities and Nrf2 expression, while suppressing oxidative stress and dyslipidemia in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Dacryodes edulis L. is an evergreen tree indigenous to western and eastern Africa which is utilized for nutritional and medicinal purposes. Folklorically, different parts of the tree are used in treating and managing diabetes and its complications.

AIMS

The antidiabetic effect of the butanol fraction of D. edulis ethanol extract (BFDE) was studied in fructose-streptozotocin induced type 2 diabetic rats.

METHODS

The ethanol extract was fractionated to yield the hexane, dichloromethane, ethyl acetate, butanol and aqueous fractions. The in vitro antidiabetic activities of the fractions were determined by their ability to inhibit α-glucosidase activity. BDFE was the most active and showed no cytotoxic effect while stimulating glucose uptake in 3T3-L1 adipocytes. Thus, selected for in vivo study. Diabetic rats were grouped into 4. The negative control group was administered water only, another group was treated with metformin (200 mg/kg bodyweight), while the other groups were administered BDFE at 150 and 300 mg/kg bodyweight respectively. Two other groups consisting of normal rats were given water and BFDE (300 mg/kg bodyweight) respectively, with the former serving as normal control. After 6 weeks of intervention, the rats were humanely sacrificed using appropriate anaesthesia.

RESULTS

Treatment with the fraction significantly (p < 0.05) reduced the blood glucose level of the diabetic rats, with concomitant increase in serum insulin secretion. It also caused significant (p < 0.05) elevation of reduced glutathione level, superoxide dismutase, catalase, α-amylase, and ATPase activities, with concomitant depletion in myeloperoxidase activity, NO and MDA levels of the serum and pancreas. The pancreatic morphology and β-cell function were significantly improved in BFDE-treated rats, with restoration of the pancreatic capillary networks. Treatment with BFDE significantly (p < 0.05) inhibited the activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose 6 phosphatase, and acetylcholinesterase, while suppressing the expression of Nrf2. HPLC analysis revealed the presence of gallic acid, vanillic acid, vanillin, and (-)-epicatechin in the fraction.

CONCLUSION

These results portray the antidiabetic and antioxidative properties of BFDE, which may be a synergistic consequence of the identified phenolics.

Vanillin and vanillic acid modulate antioxidant defense system via amelioration of metabolic complications linked to Fe2+-induced brain tissues damage

The therapeutic effect of phenolics on neurodegenerative diseases has been attributed to their potent antioxidant properties. In the present study, the neuroprotective activities of vanillin and vanillic acid were investigated in Fe2+- induced oxidative toxicity in brain tissues by investigating their therapeutic effects on oxidative imbalance, cholinergic and nucleotide-hydrolyzing enzymes activities, dysregulated metabolic pathways. Their cytotoxicity was investigated in hippocampal neuronal cell lines (HT22). The reduced glutathione level, SOD and catalase activities were ameliorated in tissues treated with the phenolics, with concomitant depletion of malondialdehyde and nitric oxide levels. They inhibited acetylcholinesterase and butyrylcholinesterase activities, while concomitantly elevated ATPase activity. Treatment with vanillin led to restoration of oxidative-depleted metabolites and reactivation of the pentose phosphate and purine metabolism pathways, with concomitant activation of pathways for histidine and selenoamino metabolisms. While vanillic acid restored and reactivated oxidative-depleted metabolites and pathways but did not activate any additional pathway. Both phenolics portrayed good binding affinity for catalase, with vanillic acid having the higher binding energy of -7.0 kcal/mol. Both phenolics were not cytotoxic on HT22 cells, and their toxicity class were predicted to be 4. Only vanillin was predicted to be permeable across the blood brain barrier (BBB). These results insinuate that vanillin and vanillic acid confer a neuroprotective effect on oxidative brain damage, when vanillin being the most potent.

Imperatorin suppresses IL-1β-induced iNOS expression via inhibiting ERK-MAPK/AP1 signaling in primary human OA chondrocytes

Joint inflammation is a key player in the pathogenesis of osteoarthritis (OA). Imperatorin, a plant-derived small molecule has been reported to have anti-inflammatory properties; however, its effect on chondrocytes is not known. Here, we investigated the effects of Imperatorin on interleukin-1β (IL-1β) induced expression of inducible nitric oxide synthase (iNOS) and nitric oxide production in primary human OA chondrocytes and cartilage explants culture under pathological conditions and explored the associated signaling pathways. We pretreated chondrocytes or explants with Imperatorin (50 μM) followed by IL-1β (1 ng/ml), and the culture supernatant was used to determine the levels of nitrite production by Griess assay and chondrocytes were harvested to prepare cell lysate or RNA for gene expression analysis of iNOS by Western blot or qPCR and in explants by immunohistochemistry (IHC). Pretreatment of primary chondrocytes and cartilage explants with Imperatorin suppressed IL-1β induced expression of iNOS and NO production. Imperatorin blocked the IL-1β-induced phosphorylation of ERK-MAPK/AP1 signaling pathway to suppress iNOS expression. The role of ERK in the regulation of iNOS expression was verified by using ERK inhibitor. Interestingly, we also found that Imperatorin binds to iNOS protein and inhibits its activity in vitro. Our data demonstrated that Imperatorin possess strong anti-inflammatory activity and may be developed as a therapeutic agent for the management of OA.

Buddleja saligna Willd (Loganiaceae) inhibits angiotensin-converting enzyme activity in oxidative cardiopathy with concomitant modulation of nucleotide hydrolyzing enzymatic activities and dysregulated lipid metabolic pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Buddleja saligna Willd (Loganiaceae), mostly indigenous to South Africa is traditionally used in the treatment cardio-dysfunctional related ailments amongst other diseases.

AIMS

The cardio-protective effect of B. saligna was investigated in ferric-induced oxidative cardiopathy.

METHODS

Hearts harvested from healthy male SD rats were incubated with 0.1 mM FeSO₄ to induce oxidative damage and co-incubated with B. saligna extract. Reaction mixtures without the extract served as negative control, while tissues without the extract or standard antioxidant (gallic acid) and pro-oxidant served as the normal control. The tissues were analyzed for levels of glutathione, malondialdehyde, and nitric oxide as well as cholinergic, angiotensin-converting enzyme (ACE), lipase, and purinergic enzymes activities, lipid profiles, fatty acid metabolic pathways and metabolites.

RESULTS

Induction of oxidative damage significantly (p < 0.05) depleted the levels of GSH, SOD, catalase, and ENTPDase activities, while concomitantly elevating the levels of MDA, NO, ACE, acetylcholinesterase, lipase and ATPase activities. These levels and activities were significantly reversed on treatment with B. saligna. Treatment with B. saligna also led to depletion of cardiac cholesterol and LDL-c levels, while elevating triglyceride and HDL-c level. It also depleted oxidative-induced lipid metabolites with concomitant generation of thirteen other metabolites. B. saligna also inactivated oxidative-induced pathways for beta oxidation of very long chain fatty acids, glycerolipid metabolism, and fatty acid elongation in mitochondria.

CONCLUSION

These results suggest that B. saligna protects against ferric-induced oxidative cardiopathy by mitigating oxidative stress, while concomitantly inhibiting ACE, acetylcholinesterase and lipase activities, and modulating lipid spectrum and dysregulated metabolic pathways.

Antioxidant effect of endothelin-1 receptor antagonist protects the rat kidney against chronic injury induced by hypertension and hyperglycemia

ABSTRACT Hypertension and Diabetes mellitus are the two main causes of chronic kidney disease that culminate in the final stage of kidney disease. Since these two risk factors are common and can overlap, new approaches to prevent or treat them are needed. Macitentan (MAC) is a new non-selective antagonist of the endothelin-1 (ET-1) receptor. This study aimed to evaluate the effect of chronic blockade of ET-1 receptor with MAC on the alteration of renal function observed in hypertensive and hyperglycemic animals. Genetically hypertensive rats were divided into control hypertensive (HT-CTL) group, hypertensive and hyperglycemic (HT+DIAB) group, and hypertensive and hyperglycemic group that received 25 mg/kg macitentan (HT-DIAB+MAC25) via gavage for 60 days. Kidney function and parameters associated with oxidative and nitrosative stress were evaluated. Immunohistochemistry for neutrophil gelatinase-associated lipocalin (NGAL), ET-1, and catalase in the renal cortex was performed. The HT+DIAB group showed a decrease in kidney function and an increase in NGAL expression in the renal cortex, as well as an increase in oxidative stress. MAC treatment was associated with attenuated ET-1 and NGAL production and increases in antioxidant defense (catalase expression) and nitric oxide production. In addition, MAC prevented an increase in oxidant injury (as measured by urinary hydroperoxide and lipid peroxidation), thus improving renal function. Our results suggest that the antioxidant effect of the ET-1 receptor antagonist MAC is involved in the improvement of kidney function observed in hypertensive and hyperglycemic rats.

15N-labelled nitrite/nitrate tracer analysis by LC-MS/MS: Urinary and fecal excretion of nitrite/nitrate following oral administration to mice

Determination of the modulation of nitrite and nitrate levels in biological samples usually poses a major challenge, owing to their high background concentrations. To effectively investigate the variation of nitrite/nitrate in vivo, in this study, we developed a¹⁵N-labelled nitrite/nitrate tracer analysis using LC-MS/MS following the derivatization with 2,3-diaminonaphthalene. This method allows for the determination of ¹⁵N-labelled nitrite/nitrate as ¹⁵N-2,3-naphthotriazole (¹⁵N-NAT) that can efficiently differentiate newly introduced nitrite/nitrate from the background nitrite/nitrate in biological matrices. We also investigated the contribution of background ¹⁴N-NAT isotopomers to ¹⁵N-NAT, which has long been overlooked in the literature. Our results indicated that the contribution of background ¹⁴N-NAT isotopomers to ¹⁵N-NAT is significant. Such contribution is constant (~2.2% under positive ion mode and 1.1% under negative ion mode), and does not depend upon the concentration of ¹⁴N-NAT or the sample matrix measured. An equation has been therefore developed, for the first time, to correct the contribution of background ¹⁴N-NAT isotopomers to ¹⁵N-NAT. With the proposed ¹⁵N-labelled nitrite/nitrate tracer analysis, the amount and percentage distribution of ¹⁵NO₂^- and ¹⁵NO₃^-, both in urine and feces, after oral administration of ¹⁵N-labelled nitrite/nitrate are clearly demonstrated. The excretions of ¹⁵NO₂^- and ¹⁵NO₃^- were significantly increased with the increasing dose implying that the dietary nitrite/nitrate intake is an important source in urine/feces. The present method allows for the simple, reliable and accurate quantification of ¹⁵NO₂^- and ¹⁵NO₃^-, and it should also be useful to trace the biotransformation of nitrite and nitrate in vivo.

The antidiabetic properties of the hot water extract of kola nut (Cola nitida (Vent.) Schott & Endl.) in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida is amongst the evergreen plants native to West Africa used in the treatment of various ailments including diabetes.

AIM OF THE STUDY

This study aims to investigate the antidiabetic effects of the hot water extract of C. nitida seeds in type 2 diabetic rats.

METHODS

Type 2 diabetic rats were orally administered with low (150 mg/kg bw) and high (300 mg/kg bw) doses of the hot water extract for 6 wk and thereafter, blood glucose, insulin level, lipid profile, pancreatic β-cell function, perfusion and morphology, redox imbalance, glycolytic and cholinergic enzymes, as well as of caspase-3 and Nrf2 expressions were measured.

RESULTS

Treatment with the extract led to significant depletion of blood glucose, serum triglycerides, LDL-cholesterol, fructosamine, ALT, and uric acids, while elevating serum insulin and HDL-cholesterol levels. The infusion also significantly (p < 0.05) elevated GSH level, SOD, catalase, α-amylase, and ATPase activities, with concomitant depletion of myeloperoxidase enzyme activity, and NO and MDA levels in the serum and pancreas. Significantly (p < 0.05) improved pancreatic β-cell function and morphology were observed in rats treated with C. nitida, with restored pancreatic capillary networks. C. nitida inhibited the activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose 6 phosphatase, and acetylcholinesterase while downregulated the Nrf2 expression. NMR analysis of the extract revealed the presence of caffeine and theobromine. The molecular docking studies indicated that identified compounds displayed strong molecular interactions with caspase-3 and Nrf2.

CONCLUSION

These results insinuate the antidiabetic activities of C. nitida hot water extract and may be attributed to the NMR-identified compounds.

Detection and quantification of nitric oxide-derived oxidants in biological systems

The free radical nitric oxide (NO•) exerts biological effects through the direct and reversible interaction with specific targets (e.g. soluble guanylate cyclase) or through the generation of secondary species, many of which can oxidize, nitrosate or nitrate biomolecules. The NO•-derived reactive species are typically short-lived, and their preferential fates depend on kinetic and compartmentalization aspects. Their detection and quantification are technically challenging. In general, the strategies employed are based either on the detection of relatively stable end products or on the use of synthetic probes, and they are not always selective for a particular species. In this study, we describe the biologically relevant characteristics of the reactive species formed downstream from NO•, and we discuss the approaches currently available for the analysis of NO•, nitrogen dioxide (NO2•), dinitrogen trioxide (N2O3), nitroxyl (HNO), and peroxynitrite (ONOO-/ONOOH), as well as peroxynitrite-derived hydroxyl (HO•) and carbonate anion (CO3•-) radicals. We also discuss the biological origins of and analytical tools for detecting nitrite (NO2-), nitrate (NO3-), nitrosyl-metal complexes, S-nitrosothiols, and 3-nitrotyrosine. Moreover, we highlight state-of-the-art methods, alert readers to caveats of widely used techniques, and encourage retirement of approaches that have been supplanted by more reliable and selective tools for detecting and measuring NO•-derived oxidants. We emphasize that the use of appropriate analytical methods needs to be strongly grounded in a chemical and biochemical understanding of the species and mechanistic pathways involved.

Aortic Oxidative Stress, Inflammation and DNA Damage Following Pulmonary Exposure to Cerium Oxide Nanoparticles in a Rat Model of Vascular Injury

Pulmonary exposure to cerium oxide nanoparticles (CeO₂ NPs) can occur either at the workplace, or due to their release in the environment. Inhaled CeO₂ NPs are known to cross the alveolar–capillary barrier and reach various parts of the body, including the vasculature. The anticancer drug cisplatin (CP) causes vascular damage. However, the effects CeO₂ NPs on vascular homeostasis in a rat model of CP-induced vascular injury remain unclear. Here, we assessed the impact and underlying mechanism of pulmonary exposure to CeO₂ NPs on aorta in rats given a single intraperitoneal injection of cisplatin (CP, 6 mg/kg) to induce vascular damage. Six days later, the rats were intratracheally instilled with either CeO₂ NPs (1 mg/kg) or saline (control), and various variables were studied 24 h thereafter in the aortic tissue. The concentration of reduced glutathione and the activity of catalase were significantly increased in the CP + CeO₂ NPs group compared with both the CP + saline and the CeO₂ NPs groups. The activity of superoxide dismutase was significantly decreased in the CP + CeO₂ NPs group compared with both the CP + saline and CeO₂ NPs groups. The expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) by the nuclei of smooth muscles and endocardial cells assessed by immunohistochemistry was significantly augmented in CeO₂ NPs versus saline, in CP + saline versus saline, and in CP + CeO₂ NPs versus CeO₂ NPs. Moreover, the concentrations of total nitric oxide, lipid peroxidation and 8-hydroxy-2-deoxyguanosine were significantly elevated in the CP + CeO₂ NPs group compared with both the CP + saline and the CeO₂ NPs groups. Similarly, compared with both the CP + saline and CeO₂ NPs groups, the combination of CP and CeO₂ NPs significantly elevated the concentrations of interleukin-6 and tumour necrosis factor-α. Additionally, aortic DNA damage assessed by Comet assay was significantly increased in CeO₂ NPs compared with saline, and in CP + saline versus saline, and all these effects were significantly aggravated by the combination of CP and CeO₂ NPs. We conclude that pulmonary exposure to CeO₂ NPs aggravates vascular toxicity in animal model of vascular injury through mechanisms involving oxidative stress, Nrf2 expression, inflammation and DNA damage.

Raffia palm (Raphia hookeri G. Mann & H. Wendl) wine modulates glucose homeostasis by enhancing insulin secretion and inhibiting redox imbalance in a rat model of diabetes induced by high fructose diet and streptozotocin

ETHNOPHARMACOLOGICAL RELEVANCE

Raffia palm (Raphia hookeri) wine (RPW) is amongst the natural products from plants, utilized singly or in combination with other medicinal plants for the treatment of several ailments including Diabetes Mellitus (DM). However, there is a scientific dearth on its antidiabetic activity.

AIM

The antidiabetic effect of RPW and its possible mechanism of actions were investigated in diabetic rats.

METHODS

Four groups of male SD rats were first supplied with 10% fructose solution ad libitum for 2 weeks instead of drinking water followed by an intraperitonial injection of streptozotocin (40 mg/kg) to induce diabetes. Two diabetic groups were administered RPW at 150 and 300 mg/kg bodyweight (BW) respectively; a group was administered with metformin, while the other one was served as a negative control. Two groups of normal rats were administered with water and RPW (300 mg/kg BW) and served as normal control and normal toxicology group, respectively.

RESULTS

Five weeks treatment of RPW led to significant (p < 0.05) increase in serum insulin and HDL-c levels with concomitant reduction in blood glucose, fructosamine, ALT, uric acid, triglycerides and LDL-c levels in diabetic rats. Rats treated with RPW had elevated levels of GSH, SOD, catalase, ATPase and α-amylase activities, while reduced NO level and myeloperoxidase activity was observed in their serum and pancreatic tissues. RPW also improved pancreatic β-cell function and restored β- and acinar cells morphology, and capillary networks. The activities of glycogen phosphorylase, fructose 1,6 biphosphatase, glucose-6-phosphatase, and acetylcholinesterase were also inhibited in RPW-treated diabetic rats, with concomitant down regulation of Nrf2 gene expression.

CONCLUSION

The data of this study suggest that RPW modulates glucose homeostasis by enhancing insulin secretion as well as inhibiting redox imbalance in diabetic rats, which may be attributed to the synergetic effects of its phytochemical constituents as identified by GC-MS analysis.

Vernonia Amygdalina Del. stimulated glucose uptake in brain tissues enhances antioxidative activities; and modulates functional chemistry and dysregulated metabolic pathways

Brain glucose uptake is usually reduced in type 2 diabetes owing to downregulation of brain glucose transporters. The ability of Vernonia amygdalina to stimulate glucose uptake as well as ameliorate glucose-induced oxidative stress and proinflammation were investigated in rat brain. Hot infusion of V. amygdalina leaves was incubated with rat brain tissues for 2 h in the presence of glucose. Another incubation with glucose only, served as negative control while metformin served as positive control. Incubation of brain tissues with V. amygdalina led to significant (p < 0.05) increase in glucose uptake, reduced glutathione, nitric oxide and non-thiol proteins levels, superoxide dismutase, catalase and ATPase activities, while concomitantly decrease in myeloperoxidase activity and malondialdehyde level compared to the negative control. Incubation with glucose only, led to the development of nitrate, amide II and amide I functional groups which were removed on incubation with the infusion. LC-MS analysis revealed depletion of oxidative stress-induced 2-keto-glutaramic acid and cysteinyl-tyrosine metabolites in brain tissues, with concomitant generation of S-formylglutathione and adenosine tetraphosphate by the infusion. Pathway analysis of the metabolites revealed an activation of pyruvate metabolism pathway in the negative control, with the infusion reducing the intensity fold. LC-MS analysis of the infusion revealed the presence of l-serine, l-cysteine, l-proline, nicotinic acid, cumidine, salicylic acid, isoquinoline, 3-methyl-, and γ-octalactone. Except for l-serine, l-cysteine and l-proline, the other compounds were predicted to be permeable across the blood brain barrier. These results indicate the brain glucose uptake stimulatory and neuroprotective effect of V. amygdalina.

Circulating markers of nitric oxide homeostasis and cardiometabolic diseases: insights from population-based studies

Emerging data suggest that impaired nitric oxide (NO) homeostasis has a key role in development of cardiometabolic disorders. The association between circulating levels of NO metabolites, i.e. nitrate and nitrite (NOx), and risk of chronic diseases has not yet been fully clarified. This work aims to address epidemiologic aspects of NO metabolism and discusses different physiologic and pathophysiologic conditions influencing circulating NOx. Further, cross-sectional associations of serum NOx with metabolic disorders are described and along the way, potential short-term and long-term power of serum NOx for predicting cardiometabolic outcomes are reviewed. Results from population-based studies show that circulating NOx is affected by aging, smoking habits, pregnancy, menopause status, thyroid hormones, and various pathologic conditions including type 2 diabetes, insulin resistance, hypertension, and renal dysfunction. Lifestyle factors, especially dietary habits, but also smoking habits and the degree of physical activity influence NO homeostasis and the circulating levels of NOx. Elevated serum NOx, due to increased iNOS activity, is associated with increased incidence of metabolic syndrome, different obesity phenotypes, and cardiovascular events.

Raffia palm (Raphia hookeri) wine extenuates redox imbalance and modulates activities of glycolytic and cholinergic enzymes in hyperglycemia-induced testicular injury in type 2 diabetic rats

This study investigated the effects of Raffia palm wine (RPW) on redox imbalance, glycolytic and cholinergic enzymes, and ATPase activities in hyperglycemia-induced oxidative testicular injury. Type 2 diabetes (T2D) was induced in male albino rats (Sprague-Dawley) by first administering 10% fructose solution for 14 days, before injecting with an intraperitoneal injection (40 mg/kg body weight) of streptozotocin. Raffia palm wine was administered to two diabetic groups at 150 and 300 mg/kg body weight (bw), when untreated diabetic group was used as a negative control, and metformin-fed group was served as a positive control. The rats were sacrificed after 5 weeks of treatment, and testes were harvested. Treatment with RPW led to lower levels of nitric oxide, malondialdehyde and myeloperoxidase activity, with concomitant elevation of reduced glutathione level, superoxide dismutase, catalase and ATPase activities. Raffia palm wine also inhibited glycogen phosphorylase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and acetylcholinesterase, while restoring the altered testicular morphology to near-normal. The results of this study suggest the therapeutic potentials of RPW against the effects of T2D on testicular functions and morphology. PRACTICAL APPLICATIONS: Diabetes mellitus is one of the fastest growing global epidemy, with most developing countries being at the receiving end owing to the cost of treatment. Testicular damage has been recognized as one of the complications of diabetes, and if left untreated will lead to erectile dysfunction followed by infertility. Raffia palm wine is among the common natural beverage in West Africa, which is utilized for both social and medicinal purposes. In this study, for the first time we showed its ability to protect diabetes-induced testicular injury in type 2 diabetic rats. This may be of great benefit in managing diabetes associated erectly dysfunction and male infertility, as Raffia palm wine is readily available in all seasons. This study will also improve the medicinal use of this wine, which may also indirectly improve its commercial benefit.

Gum Arabic Ameliorates Impaired Coagulation and Cardiotoxicity Induced by Water-Pipe Smoke Exposure in Mice

Water-pipe smoking (WPS) is prevalent in the East and elsewhere. WPS exposure is known to induce thrombosis and cardiovascular toxicity involving inflammation and oxidative stress. Here, we have investigated the effect of Gum Arabic (GA), a prebiotic with anti-oxidant, anti-inflammatory and cytoprotective properties, on WPS exposure (30 min/day for 1 month) on coagulation and cardiac homeostasis, and their possible underlying mechanisms in mice. Animals received either GA in drinking water (15%, w/v) or water only for the entire duration of study. GA significantly mitigated thrombosis in pial microvessels in vivo, platelet aggregation in vitro, and the shortening of prothrombin time induced by WPS exposure. The increase in plasma concentrations of fibrinogen, plasminogen activator inhibitor-1 and markers of lipid peroxidation, 8-isoprostane and malondialdehyde, induced by WPS were significantly reduced by GA administration. Moreover, WPS exposure induced a significant increase in systolic blood pressure and the concentrations of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin 1β in heart homogenates. GA significantly alleviated these effects, and prevented the decrease of reduced glutathione, catalase and total nitric oxide levels in heart homogenates. Immunohistochemical analysis of the hearts showed that WPS exposure increased nuclear factor erythroid-derived 2-like 2 (Nrf2) expressions by cardiac myocytes and endothelial cells, and these effects were potentiated by the combination of GA and WPS. WPS also increased DNA damage and cleaved caspase 3, and GA administration prevented these effects. Our data, obtained in experimental murine model of WPS exposure, show that GA ameliorates WPS-induced coagulation and cardiovascular inflammation, oxidative stress, DNA damage and apoptosis, through a mechanism involving Nrf2 activation.

Altered Venous Blood Nitric Oxide Levels at Depth and Related Bubble Formation During Scuba Diving

Introduction: Nitric oxide (NO) plays an important role in the physiology and pathophysiology of diving, and the related endothelial dysfunction and oxidative stress roles have been extensively investigated. However, most available data have been obtained before and after the dive, whilst, as far as we know, no data is available about what happens during the water immersion phase of dive. The scope of this study is to investigate the Nitrate and Nitrite (NO_X) concentration and the total plasma antioxidant capacity (TAC) before, during and after a single SCUBA dive in healthy scuba diving volunteers, as well as to look for evidence of a possible relationship with venous gas bubble formation. Materials and Methods: Plasma, obtained from blood of 15 expert SCUBA divers, 13 male and 2 female, was investigated for differences in NO_X and TAC values in different dive times. Differences in NO_X and TAC values in subjects previously known as "bubble resistant" (non-bubblers - NB) and "bubble prone" (Bubblers - B) were investigated. Results: We found a statistically significant increase of NO_X plasma concentration in the "bottom blood draw" and in the "safety stop blood draw" as compared to the basal pre diving condition. We did not find any difference in NO_X plasma concentration between the basal value and the post diving samples. We did not find any significant statistical difference in TAC in the bottom blood sample, while the safety-stop and the post-dive samples showed higher TAC values compared with the basal value. We did not find any difference in NO_X and TAC mean values between non-bubblers and Bubblers. Discussion: Our protocol, by including underwater blood drawing, allowed to monitor plasma NO_X changes occurred during diving activity, and not only by comparing pre and post diving values. It is particularly interesting to note that the increased NO_X values found at the bottom and at the safety stop were not observed at post dive sampling (T0, T30, T60), showing a very rapid return to the pre-dive values. In this preliminary study we did not find any relationship between bubble formation and changes in NO_X parameters and TAC response.

Double-Blind Clinical Trial of Arginine Supplementation in the Treatment of Adult Patients with Sickle Cell Anaemia

Background

Sickle cell anaemia (SCA) is the most prevalent monogenic disease in Brazil. In SCA, haemoglobin S (HbS) is formed, which modifies red blood cell morphology. Intravascular haemolysis occurs, in which free Hb and free radicals degrade nitric oxide (NO) and release arginase, which reduces arginine levels. Because arginine is a substrate for NO formation, this decrease leads to reduced NO (vasodilator) synthesis. SCA treatment uses hydroxyurea (HU) to maintain high foetal haemoglobin (HbF) levels and reduces HbS to avoid haemolytic episodes.

Objective

To analyse the efficacy of L-arginine as an adjuvant in the treatment of SCA patients.

Setting

The State Blood Centre of Ceará, Brazil.

Methods

This was a randomized double-blind clinical study of adults with SCA with continuous use of HU at the State Blood Centre of Ceará. The clinical study enrolled 25 patients receiving HU + L-arginine (500 mg) and 25 patients receiving HU + placebo. The treatment was carried out over four months. Laboratory tests were performed to determine the levels of the following: (1) complete blood count; (2) nitrite + nitrate; (3) HbF; and (4) reticulocytes. The clinical experiments were performed by a haematologist. The main outcome measures were nitrite and pain.

Results

Statistical analysis showed that the levels of NO were increased in the study group, and there was also a reduction in pain frequency using a pain frequency scale by day, week, and month. The levels of nitrite plus nitrate in the group receiving placebo plus HU did not change among the times evaluated (38.27 ± 17.27 mg/L, 39.49 ± 12.84 mg/L, 34.45 ± 11.25 mg/L, p >0.05), but in the patients who received supplementation with L-arginine plus HU, a significant increase in nitrite plus nitrate levels was observed between M0 and M4 (36.55 ± 20.23 mg/L versus 48.64 ± 20.63 mg/L, p =0.001) and M2 and M4 (35.71 ± 15.11 mg/L versus 48.64 ± 20.63 mg/L, p <0.001). It is important to note that the increase in nitrite plus nitrate levels occurred only in the fourth month of follow-up of patients in the treatment group, showing that at least 4 months of supplementation with L-arginine is necessary to show an increase in these metabolites in the serum.

Conclusion

The use of L-arginine as a coadjuvant in the treatment of sickle cell anaemia may function as a potential tool for pain relief, consequently improving the life of patients.

Higher-energy collision-induced dissociation for the quantification by liquid chromatography/tandem ion trap mass spectrometry of nitric oxide metabolites coming from S-nitroso-glutathione in an in vitro model of the intestinal barrier

RATIONALE

The potency of S-nitrosoglutathione (GSNO) as a nitric oxide (NO) donor to treat cardiovascular diseases (CVDs) has been highlighted in numerous studies. In order to study its bioavailability after oral administration, which represents the most convenient route for the chronic treatment of CVDs, it is essential to develop an analytical method permitting (i) the simultaneous measurement of GSNO metabolites, i.e. nitrite, S-nitrosothiols (RSNOs) and nitrate and (ii) to distinguish them from other sources (endogenous synthesis and diet).

METHODS

Exogenous GSNO was labeled with ¹⁵ N, and the GS¹⁵ NO metabolites after conversion into the nitrite ion were derivatized with 2,3-diaminonaphthalene. The resulting 2,3-naphthotriazole was quantified by liquid chromatography/tandem ion trap mass spectrometry (LC/ITMS/MS) in multiple reaction monitoring mode after Higher-energy Collision-induced Dissociation (HCD). Finally, the validated method was applied to an in vitro model of the intestinal barrier (monolayer of Caco-2 cells) to study GS¹⁵ NO intestinal permeability.

RESULTS

A LC/ITMS/MS method based on an original transition (m/z 171 to 156) for sodium ¹⁵ N-nitrite, GS¹⁵ NO and sodium ¹⁵ N-nitrate measurements was validated, with recoveries of 100.8 ± 3.8, 98.0 ± 2.7 and 104.1 ± 3.3%, respectively. Intra- and inter-day variabilities were below 13.4 and 12.6%, and the limit of quantification reached 5 nM (signal over blank = 4). The permeability of labeled GS¹⁵ NO (10-100 μM) was evaluated by calculating its apparent permeability coefficient (P_app ).

CONCLUSIONS

A quantitative LC/ITMS/MS method using HCD was developed for the first time to selectively monitor GS¹⁵ NO metabolites. The assay allowed evaluation of GS¹⁵ NO intestinal permeability and situated this drug candidate within the middle permeability class according to FDA guidelines. In addition, the present method has opened the perspective of a more fundamental work aiming at studying the fragmentation mechanism leading to the ion at m/z 156 in HCD tandem mass spectrometry in the presence of acetonitrile.

Circulating nitric oxide metabolites and the risk of cardiometabolic outcomes: a prospective population-based study

Aim: This study was conducted to investigate whether serum NO metabolites (NOx) could predict the occurrence of type 2 diabetes (T2DM), hypertension (HTN) and metabolic syndrome (MetS). Methods: We measured serum NOx concentrations in the Tehran Lipid and Glucose Study participants (aged ≥19 years) and followed them for a median of 7.7 years for the incidence of outcomes. To determine the appropriate cut-off points of serum NOx for predicting clinical events, a random sampling method (50:50 ratio) was used for the population and for analysis, receiver operator characteristic curve was used. Multivariable Cox proportional hazard models were used to estimate the hazard ratios (HRs) with 95% confidence intervals (95% CIs) of T2DM, HTN and MetS in response to serum NOx values. Results: The optimal cut-off points of serum NOx levels for predicting T2DM, HTN and MetS were 26.5, 25.5 and 25.5 µmol/L, respectively. Participants with serum NOx levels ≥25.5 µmol/L had increased risk of MetS (HR = 1.31, 95% CI = 1.01-1.72). No evidence was found for any association of serum NOx with incidence of T2DM and HTN (HR = 1.03, 95% CI = 0.83-1.77 and HR = 1.09, 95% CI = 0.88-1.35). Conclusion: In this prospective population-based investigation, a higher circulating NOx was associated with development of MetS.

Measurement of nitrate and nitrite in biopsy-sized muscle samples using HPLC

Studies of rats have indicated that skeletal muscle plays a central role in whole-body nitrate ( NO3- )/nitrite ( NO2- )/nitric oxide (NO) metabolism. Extending these results to humans, however, is challenging due to the small size of needle biopsy samples. We therefore developed a method to precisely and accurately quantify NO3- and NO2- in biopsy-sized muscle samples. NO3- and NO2- were extracted from rat soleus samples using methanol combined with mechanical homogenization + ultrasound, bead beating, pulverization at liquid N₂ temperature or pulverization + 0.5% Triton X-100. After centrifugation to remove proteins, NO3- and NO2- were measured using HPLC. Mechanical homogenization + ultrasound resulted in the lowest NO3- content (62 ± 20 pmol/mg), with high variability [coefficient of variation (CV) >50%] across samples from the same muscle. The NO2- / NO3- ratio (0.019 ± 0.006) was also elevated, suggestive of NO3- reduction during tissue processing. Bead beating or pulverization yielded lower NO2- and slightly higher NO3- levels, but reproducibility was still poor. Pulverization + 0.5% Triton X-100 provided the highest NO3- content (124 ± 12 pmol/mg) and lowest NO2- / NO3- ratio (0.008 ± 0.001), with the least variability between duplicate samples (CV ~15%). These values are consistent with literature data from larger rat muscle samples analyzed using chemiluminescence. Samples were stable for at least 5 wk at -80°C, provided residual xanthine oxidoreductase activity was blocked using 0.1 mmol/l oxypurinol. We have developed a method capable of measuring NO3- and NO2- in <1 mg of muscle. This method should prove highly useful in investigating the role of skeletal muscle in NO3- / NO2- /NO metabolism in human health and disease. NEW & NOTEWORTHY Measurement of nitrate and especially nitrite in small, i.e., biopsy-sized, muscle samples is analytically challenging. We have developed a precise, accurate, and convenient method for doing so using an affordable commercial HPLC system.

Clerodendrum volubile inhibits key enzymes linked to type 2 diabetes but induces cytotoxicity in human embryonic kidney (HEK293) cells via exacerbated oxidative stress and proinflammation

The toxicity and safety associated with the use of medicinal plants remains a major concern. In this study, the antidiabetic properties of the dichloromethane (DCM) fraction of C. volubile leaves were investigated in vitro. Its cytotoxic effect and mechanism of toxicity were also investigated in Human Embryonic Kidney (HEK293) cells. The fraction was subjected to in vitro antioxidant assays using the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging and Ferric reducing antioxidant power (FRAP) protocols. Its enzyme-inhibitory properties were investigated on α-glucosidase and α-amylase activities. Gas Chromatography Mass Spectroscopy (GCMS) and Fourier Transform Infrared (FTIR) spectroscopic analysis were used to identify its phytoconstituents. Cytotoxicity was determined via MTT assay. The treated cells were assayed for reduced glutathione (GSH), non-protein thiol, nitric oxide and malondialdehyde (MDA) levels, as well as Superoxide Dismutase (SOD), catalase, myeloperoxidase and ATPase activities. Cell apoptosis and/or morphological changes were determined using the acridine orange and ethidium bromide (AO/EB) dual staining method. The fraction showed significant (p < 0.05) antioxidant and enzyme-inhibitory activity. It showed significant (p < 0.05) cytotoxic effect against HEK293 cells with concomitant depletion of antioxidative and elevation of proinflammatory biomarkers. Morphological changes were examined in the cells with an apoptotic index of 0.84. 1,1-Dodecanediol, diacetate was identified as the most predominant compound, while aromatics and amines as the most functional groups present in the fraction. These results suggest the antidiabetic and cytotoxic effects of C. volubile leaves. The toxicity can be attributed to induced oxidative stress and proinflammation with concomitant depletion of ATP leading to apoptosis of the cells.

Changes in plasma levels of nitric oxide metabolites and negative symptoms after 16-week minocycline treatment in patients with schizophrenia

OBJECTIVE

This study examined the effect of adjunctive minocycline on psychopathology and possibly relevant biomarkers in patients with schizophrenia.

METHOD

In a 16-week randomized, double-blind, placebo-controlled study, subjects received either minocycline (200mg per day) or placebo. Psychopathology was assessed using the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative Syndrome Scale (PANSS) at baseline and week 16. Plasma levels of tumor necrosis factor α (TNFα), interleukin-1 β (IL-1β) and nitric oxide metabolites were assessed at both time points.

RESULTS

Fifty-five patients completed the study (27 in the minocycline group, 28 in the placebo group). The minocycline group had significant decreases in the SANS total sore, the PANSS total score and the PANSS negative symptoms score at week 16 compared to the placebo group. In addition, the minocycline group had a significant decrease in plasma levels of nitric oxide metabolites, but no significant difference in changes in plasma levels of IL-1β or TNF-α, compared to the placebo group at week 16. Further, the more decrease in plasma levels of nitric oxide metabolites was associated with less improvement in negative symptoms.

CONCLUSION

The beneficial effect of adjunctive minocycline treatment on negative symptoms might be through mechanisms other than the nitric oxide pathway. The implications for future studies were discussed.

Effect of plasma sodium concentration on blood pressure regulators during hemodialysis: a randomized crossover study

Background

Intradialytic hypotension is a common complication of hemodialysis. The Hemocontrol biofeedback system, improving intradialytic hemodynamic stability, is associated with an initial transient increase in plasma sodium levels. Increases in sodium could affect blood pressure regulators.

Methods

We investigated whether Hemocontrol dialysis affects vasopressin and copeptin levels, endothelial function, and sympathetic activity in twenty-nine chronic hemodialysis patients. Each patient underwent one standard hemodialysis and one Hemocontrol hemodialysis. Plasma sodium, osmolality, nitrite and nitrate (NOx), endothelin-1, angiopoietins-1 and 2, and methemoglobin as measures of endothelial function, plasma catecholamines as indices of sympathetic activity and plasma vasopressin and copeptin levels were measured six times during each modality. Blood pressure, heart rate, blood volume, and heart rate variability were repeatedly monitored. Generalized Estimating Equations was used to compare the course of the parameters during the two treatment modalities.

Results

Plasma sodium and osmolality were significantly higher during the first two hours of Hemocontrol hemodialysis. Overall, mean arterial pressure (MAP) was higher during Hemocontrol dialysis. Neither the measures of endothelial function and sympathetic activity nor copeptin levels differed between the two dialysis modalities. In contrast, plasma vasopressin levels were significantly higher during the first half of Hemocontrol dialysis. The intradialytic course of vasopressin was associated with the course of MAP.

Conclusions

A transient intradialytic increase in plasma sodium did not affect indices of endothelial function or sympathetic activity compared with standard hemodialysis, but coincided with higher plasma vasopressin levels. The beneficial effect of higher intradialytic sodium levels on hemodynamic stability might be mediated by vasopressin.

Trial registration

ClinicalTrials.gov. Identifier: NCT03578510. Date of registration: July 5th, 2018. Retrospectively registered.