Sulfane Sulfur Level Research Articles

Visualization of Sulfane Sulfur in Plants with a Near-Infrared Fluorescent Probe.

Sulfane sulfur species are an important type of reactive sulfur species. These compounds have unique reactivity to attach reversibly to other sulfur atoms and exhibit regulatory effects in diverse biological systems. Recent studies have suggested that sulfane sulfurs are involved in signal transduction processes of hydrogen sulfide (H2S). The development of probes for selective, rapid, and sensitive detection of sulfane sulfur is of great significance for studying their physiological and pathological roles in biological systems, especially in plant systems for which physiological research has lagged behind. However, so far there is still a lack of sufficient chemical tools for directly tracking and measuring sulfane sulfur in biological systems, and in particular, the detection of sulfane sulfur in living plant tissues is still challenging. Herein, we report a near-infrared fluorescent probe, SSNIP, for the selective imaging of sulfane sulfur. SSNIP is capable of detecting sulfane sulfur at physiological concentrations in both aqueous buffer and living human cells. Then, with SSNIP, we demonstrate the fluorescent monitoring of endogenous sulfane sulfur in plant tissues such as Arabidopsis thaliana roots for the first time. Furthermore, the application of SSNIP in evaluating the level of sulfane sulfur in Arabidopsis thaliana roots at different growth stages is performed. The results show that the level of sulfane sulfur in Arabidopsis thaliana roots correlates well with their growth stages, which suggests that sulfane sulfurs might act as actual signaling molecules to promote plant growth and root elongation. In addition, it reveals potential applications for the biological and pathological studies of sulfane sulfur, especially in plant physiology.

Inhibition of Human Neuroblastoma Cell Proliferation by N-acetyl-L-cysteine as a Result of Increased Sulfane Sulfur Level.

In various cancer cells, the level of sulfane sulfur-containing compounds is decreased compared to normal cells. In the present study the effect of N-acetyl-L-cysteine (NAC), which acts as a precursor of H2S synthesis, on the human neuroblastoma SH-SY5Y cell proliferation, the activity of 3-mercaptopyruvate sulfurtransferase (MPST), and the level of sulfane sulfur were investigated. SH-SY5Y cells were treated with NAC, while untreated cells were used as the control. The toxicity of NAC on the cells was studied by the LDH cytotoxicity assay; cell proliferation was examined by the MTT method. MPST activity and sulfane sulfur level were also analyzed in the NAC-treated cells. The addition of NAC to the medium, in non-cytotoxic concentrations, resulted in inhibition of the SH-SY5Y cell proliferation after 48 h of culture. The MPST activity and the level of sulfane sulfur-containing compounds were also elevated under the same culture conditions. The antiproliferative activity of NAC in the SH-SY5Y cells was associated with an increase in the MPST activity and consequently with an increase in the intracellular level of sulfane sulfur in these cells.

Colonic Indole And Hydrogen Sulfide, Gut Bacterial Metabolites, Affect Portal Blood Pressure in Healthy And Cirrhotic Rats

Liver cirrhosis is a leading cause of portal hypertension, and is often accompanied by systemic hypotension. Accumulating evidence suggests that gut bacteria may affect hemodynamics, however, the mechanisms are not clear. We investigated the effect of colon‐administered gut bacteria metabolites on portal blood pressure (PBP), portal blood flow (PBF) and systemic arterial blood pressure (ABP) in healthy (controls) and cirrhotic rats (CRH).10‐week‐old, male, Sprague Dawley rats were maintained either on tap water (controls) or water solution of thioacetamide for 18 weeks to induce liver cirrhosis (CRH). PBP, PBF and ABP were measured in anaesthetized rats at baseline and after the intracolonic administration of either a vehicle, indole, or Na2S, a hydrogen sulfide (H2S) donor into the colon.CRH showed significantly higher PBP but lower ABP than controls. The intracolonic administration of indole increased portal blood level of indole, and peripheral blood level of indoxyl sulfate, a liver metabolite of indole. Rats treated with Na2S showed increased portal blood levels of thiosulfate and sulfane sulfur, products of H2S oxidation. The intracolonic administration of vehicle did not affect hemodynamic parameters. In controls intracolonic H2S increased PBP but decreased PBF and ABP. In contrast, intracolonic indole increased both BPB and PBF, whereas did not affect significantly ABP. In comparison to controls, CRH showed significantly greater hemodynamic responses to H2S but not to indole. Cirrhotic livers had a significantly higher concentration of H2S but lower expression of rhodanese, an enzyme converting H2S to sulfate.Colon‐administered indole and H2S increase portal blood pressure via distinct hemodynamic mechanisms. Indole increases, whereas H2S decreases portal blood flow. Indole and H2S signaling in the gut‐liver axis may be involved in the control of portal blood pressure and in the etiology of portal hypertension. Further studies on the effects of gut bacterial metabolites on portal circulation are needed.Support or Funding InformationThis work was supported by the National Science Centre, Poland grant no. UMO‐2016/22/E/NZ5/00647This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Total sulfane sulfur bioavailability reflects ethnic and gender disparities in cardiovascular disease

Hydrogen sulfide (H2S) has emerged as an important physiological and pathophysiological signaling molecule in the cardiovascular system influencing vascular tone, cytoprotective responses, redox reactions, vascular adaptation, and mitochondrial respiration. However, bioavailable levels of H2S in its various biochemical metabolite forms during clinical cardiovascular disease remain poorly understood. We performed a case-controlled study to quantify and compare the bioavailability of various biochemical forms of H2S in patients with and without cardiovascular disease (CVD). In our study, we used the reverse-phase high performance liquid chromatography monobromobimane assay to analytically measure bioavailable pools of H2S. Single nucleotide polymorphisms (SNPs) were also identified using DNA Pyrosequencing. We found that plasma acid labile sulfide levels were significantly reduced in Caucasian females with CVD compared with those without the disease. Conversely, plasma bound sulfane sulfur levels were significantly reduced in Caucasian males with CVD compared with those without the disease. Surprisingly, gender differences of H2S bioavailability were not observed in African Americans, although H2S bioavailability was significantly lower overall in this ethnic group compared to Caucasians. We also performed SNP analysis of H2S synthesizing enzymes and found a significant increase in cystathionine gamma-lyase (CTH) 1364 G-T allele frequency in patients with CVD compared to controls. Lastly, plasma H2S bioavailability was found to be predictive for cardiovascular disease in Caucasian subjects as determined by receiver operator characteristic analysis. These findings reveal that plasma H2S bioavailability could be considered a biomarker for CVD in an ethnic and gender manner. Cystathionine gamma-lyase 1346 G-T SNP might also contribute to the risk of cardiovascular disease development.

Imaging and evaluation of sulfane sulfur in acute brain ischemia using a mitochondria-targeted near-infrared fluorescent probe.

Ischemia is a pathological condition owing to the deficiency of blood supply to a limited area of tissue. Ischemia can induce burst production of reactive oxygen species and lead to oxidative damage. As a family member of reactive sulfur species, sulfane sulfur plays important physiological roles in many biological events including synthesis of cofactors, modulation of enzyme activities, sulfuration of tRNA, and especially regulation of the intracellular redox state. We hypothesize that the endogenous level of sulfane sulfur will be adjusted to deal with ischemia-induced oxidative damage. Therefore, the bioimaging of sulfane sulfur real-time changes during ischemia is important for better understanding its physiological processes. Herein, we describe the development of a mitochondria-targeted fluorescent probe Mito-SH that allowed for selective and sensitive detection of sulfane sulfur. Mito-SH is designed on the basis of the tautomerization of sulfane sulfur to thiosulfoxide, which ensures its high selectivity and sensitivity. A lipophilic triphenylphosphonium cation is selected as the mitochondria-targeted moiety, which can precisely navigate Mito-SH into mitochondria. The emission profile of azo-BODIPY fluorophore locates at the near-infrared region, which deeply penetrates tissue and effectively avoids the interference of biological background. Mito-SH exhibits the desirable combination of selectivity, sensitivity and excellent fluorescence response upon reaction with sulfane sulfur in cells. By employing Mito-SH, we evaluate the real-time sulfane sulfur dynamic changes under oxygen-glucose deprivation. Finally, Mito-SH has been successfully used for imaging sulfane sulfur changes caused by acute ischemia in mice.

A possible mechanism of inhibition of U87MG and SH-SY5Y cancer cell proliferation by diallyl trisulfide and other aspects of its activity

The study was conducted to elucidate the mechanism of antiproliferative and antioxidative action of diallyl trisulfide (DATS), a garlic-derived organosulfur compound. Changes in the l-cysteine desulfuration, and the levels of cystathionine and non-protein thiols in DATS-treated human glioblastoma (U87MG) and neuroblastoma (SH-SY5Y) cells were investigated. The inhibition of proliferation of the investigated cells by DATS was correlated with an increase in the inactivated form of Bcl-2. In U87MG cells, an increased level of sulfane sulfur and an increased activity of 3-mercaptopyruvate sulfurtransferase (MPST) and rhodanese, the enzymes involved in sulfane sulfur generation and transfer, suggest that DATS can function as a donor of sulfane sulfur atom, transferred by sulfurtransferases, to sulfhydryl groups of cysteine residues of Bcl-2 and in this way lower the level of active form of Bcl-2 by S-sulfuration. Diallyl trisulfide antioxidative effects result from an increased level of cystathionine, a precursor of cysteine, and an increased glutathione level. MPST and rhodanese, the level of which is increased in the presence of DATS, can serve as antioxidant proteins.

Hydrogen sulfide generation from l-cysteine in the human glioblastoma-astrocytoma U-87 MG and neuroblastoma SHSY5Y cell lines.

Hydrogen sulfide (H2S) is endogenously synthesized from l-cysteine in reactions catalyzed by cystathionine beta-synthase (CBS, EC 4.2.1.22) and gamma-cystathionase (CSE, EC 4.4.1.1). The role of 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) in H2S generation is also considered; it could be important for tissues with low CTH activity, e.g. cells of the nervous system. The expression and activity of CBS, CTH, and MPST were detected in the human glioblastoma-astrocytoma (U-87 MG) and neuroblastoma (SHSY5Y) cell lines. In both cell lines, the expression and activity of MPST were the highest among the investigated enzymes, suggesting its possible role in the generation of H2S. The RP-HPLC method was used to determine the concentration of cystathionine and alpha-ketobutyrate, products of the CBS- and CTH-catalyzed reactions. The difference in cystathionine levels between cell homogenates treated with totally CTH-inhibiting concentrations of dl-propargylglycine and without the inhibitor was used to evaluate the activity of CBS. The higher expression and activity of CBS, CTH and MPST in the neuroblastoma cells were associated with more intensive generation of H2S in the presence of 2 mM cysteine. A threefold higher level of sulfane sulfur, a potential source of hydrogen sulfide, was detected in the astrocytoma cells in comparison to the neuroblastoma cells.

Lipoic Acid as a Possible Pharmacological Source of Hydrogen Sulfide/Sulfane Sulfur.

The aim of the present study was to verify whether lipoic acid (LA) itself is a source of H2S and sulfane sulfur. It was investigated in vitro non-enzymatically and enzymatically (in the presence of rat tissue homogenate). The results indicate that both H2S and sulfane sulfur are formed from LA non-enzymatically in the presence of environmental light. These results suggest that H2S is the first product of non-enzymatic light-dependent decomposition of LA that is, probably, next oxidized to sulfane sulfur-containing compound(s). The study performed in the presence of rat liver and kidney homogenate revealed an increase of H2S level in samples containing LA and its reduced form dihydrolipoic acid (DHLA). It was accompanied by a decrease in sulfane sulfur level. It seems that, in these conditions, DHLA acts as a reducing agent that releases H2S from an endogenous pool of sulfane sulfur compounds present in tissues. Simultaneously, it means that exogenous LA cannot be a direct donor of H2S/sulfane sulfur in animal tissues. The present study is an initial approach to the question whether LA itself is a donor of H2S/sulfane sulfur.

Similar effect of sodium nitroprusside and acetylsalicylic acid on antioxidant system improvement in mouse liver but not in the brain

BackgroundThe aim of the present study was to analyze the relative antioxidant effects of acetylsalicylic acid (ASA) and sodium nitroprusside (SNP) in mouse liver and brain. MethodsThe activity of rhodanese, 3-mercaptopyruvate sulfurtransferase (MPST) and γ-cystathionase (CSE), functioning as antioxidant proteins and capable of producing H2S, was investigated in mouse liver and brain after intraperitoneal once a day administration of sodium nitroprusside (5 mg/kg body weight) or acetylsalicylic acid (500 mg/kg body weight) continued for 5 days. The tissues were homogenized and then the obtained supernatants were used for further determinations. At the same time, the levels of sulfane sulfur, reduced and oxidized glutathione, cysteine, cystine, and cystathionine were also studied in these tissues. ResultsBoth ASA and SNP show a statistically significant increase of sulfurtransferases activities in liver. The mechanism of action of sodium nitroprusside appears to consist in liberation of nitric oxide (NO), an important signaling molecule in the mammalian body. SNP also releases cyanide ions, which are converted in the liver to thiocyanate by the enzyme rhodanese and/or MPST and/or γ-cystathionase – the activities of all the enzymes were elevated in reaction to SNP. The action of γ-cystathionase is dependent upon converting cystathionine to cysteine, a precursor of the major cellular antioxidant, glutathione. Under oxidizing conditions, an increase in cystathionine β-synthase activity might indirectly result in an increase in the antioxidant glutathione level; this was reflected by the increased GSH/GSSG ratio in the liver, but not in the brain, where a trace activity of γ-cystathionase is normally detected. ConclusionThe results of the present investigations show that ASA and SNP may stimulate the GSH-dependent antioxidant system and protect liver cells from oxidative stress. An increased activity of the H2S-producing enzymes and the increased GSH/GSSG ratio may lead to an elevated level of H2S, a molecule with antioxidant properties. A similar effect was not observed in the brain. In case of both sodium nitroprusside and aspirin administration, homeostasis of sulfane sulfur level was noted in both the liver and brain.

The Effects of Different Garlic-Derived Allyl Sulfides on Anaerobic Sulfur Metabolism in the Mouse Kidney.

Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are major oil-soluble organosulfur compounds of garlic responsible for most of its pharmacological effects. The present study investigated the influence of repeated intraperitoneally (ip) administration of DAS, DADS and DATS on the total level of sulfane sulfur, bound sulfur (S-sulfhydration) and hydrogen sulfide (H2S) and on the activity of enzymes, which catalyze sulfane sulfur formation and transfer from a donor to an acceptor in the normal mouse kidney, i.e., γ-cystathionase (CSE) and rhodanese (TST). The activity of aldehyde dehydrogenase (ALDH), which is a redox-sensitive protein, containing an –SH group in its catalytic center, was also determined. The obtained results indicated that all tested compounds significantly increased the activity of TST. Moreover, DADS and DATS increased the total sulfane sulfur level and CSE activity in the normal mouse kidney. ALDH activity was inhibited in the kidney after DATS administration. The results indicated also that none of the studied allyl sulfides affected the level of bound sulfur or H2S. Thus, it can be concluded that garlic-derived DADS and DATS can be a source of sulfane sulfur for renal cells but they are not connected with persulfide formation.

Intracolonic hydrogen sulfide lowers blood pressure in rats

Research suggests that hydrogen sulfide (H2S) is an important biological mediator involved in various physiological processes including the regulation of arterial blood pressure (BP). Although H2S is abundant in the colon, the effects of gut-derived H2S on the circulatory system have not yet been investigated. We studied the effects of intracolonic administration of Na2S, a H2S donor, on systemic hemodynamics. Hemodynamics were recorded in anesthetized, normotensive Wistar Kyoto and spontaneously hypertensive rats at baseline and after intracolonic injection of either saline (controls) or Na2S·9H2O saline solution at a dose range of 10–300 mg/kg of BW. The H2S donor produced a significant, dose-dependent decrease in mean arterial blood pressure (MABP), which lasted several times longer than previously reported after parenteral infusions (>90 min). The effect was more pronounced in hypertensive than in normotensive rats. The Na2S-induced decrease in MABP was reduced by pretreatment with glibenclamide, an inhibitor of ATP-sensitive potassium-channels. Na2S did not affect mesenteric vein blood flow. Rats treated with Na2S showed increased portal blood levels of thiosulfate and sulfane sulfur, products of H2S oxidation. In contrast, rats treated with neomycin, an antibiotic, showed significantly decreased levels of thiosulfate and sulfane sulfur, and a tendency for greater hypotensive response to Na2S. The H2S donor decreased heart rate but did not affect ECG morphology and QTc interval. In conclusion the gut-derived H2S may contribute to the control of BP and may be one of the links between gut microbiota and hypertension. Furthermore, gut-derived H2S may be a therapeutic target in hypertension.

Hydrogen Sulfide Levels and Nuclear Factor-Erythroid 2-Related Factor 2 (NRF2) Activity Are Attenuated in the Setting of Critical Limb Ischemia (CLI).

BackgroundCystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase are endogenous enzymatic sources of hydrogen sulfide (H2S). Functions of H2S are mediated by several targets including ion channels and signaling proteins. Nuclear factor-erythroid 2-related factor 2 is responsible for the expression of antioxidant response element–regulated genes and is known to be upregulated by H2S. We examined the levels of H2S, H2S-producing enzymes, and nuclear factor-erythroid 2-related factor 2 activation status in skeletal muscle obtained from critical limb ischemia (CLI) patients.Methods and ResultsGastrocnemius tissues were attained postamputation from human CLI and healthy control patients. We found mRNA and protein levels of cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase were significantly decreased in skeletal muscle of CLI patients as compared to control. H2S and sulfane sulfur levels were significantly decreased in skeletal muscle of CLI patients. We also observed significant reductions in nuclear factor-erythroid 2-related factor 2 activation as well as antioxidant proteins, such as Cu, Zn-superoxide dismutase, catalase, and glutathione peroxidase in skeletal muscle of CLI patients. Biomarkers of oxidative stress, such as malondialdehyde and protein carbonyl formation, were significantly increased in skeletal muscle of CLI patients as compared to healthy controls.ConclusionsThe data demonstrate that H2S bioavailability and nuclear factor-erythroid 2-related factor 2 activation are both attenuated in CLI tissues concomitant with significantly increased oxidative stress. Reductions in the activity of H2S-producing enzymes may contribute to the pathogenesis of CLI.

Is development of high-grade gliomas sulfur-dependent?

We characterized γ-cystathionase, rhodanese and 3-mercaptopyruvate sulfurtransferase activities in various regions of human brain (the cortex, thalamus, hypothalamus, hippocampus, cerebellum and subcortical nuclei) and human gliomas with II to IV grade of malignancy (according to the WHO classification). The human brain regions, as compared to human liver, showed low γ-cystathionase activity. The activity of rhodanese was also much lower and it did not vary significantly between the investigated brain regions. The activity of 3-mercaptopyruvate sulfurtransferase was the highest in the thalamus, hypothalamus and subcortical nuclei and essentially the same level of sulfane sulfur was found in all the investigated brain regions. The investigations demonstrated that the level of sulfane sulfur in gliomas with the highest grades was high in comparison to various human brain regions, and was correlated with a decreased activity of γ-cystathionase, 3-mercaptopyruvate sulfurtransferase and rhodanese. This can suggest sulfane sulfur accumulation and points to its importance for malignant cell proliferation and tumor growth. In gliomas with the highest grades of malignancy, despite decreased levels of total free cysteine and total free glutathione, a high ratio of GSH/GSSG was maintained, which is important for the process of malignant cells proliferation. A high level of sulfane sulfur and high GSH/GSSG ratio could result in the elevated hydrogen sulfide levels. Because of the disappearance of γ-cystathionase activity in high-grade gliomas, it seems to be possible that 3-mercaptopyruvate sulfurtransferase could participate in hydrogen sulfide production. The results confirm sulfur dependence of malignant brain tumors.

Sodium thiosulfate attenuates acute lung injury in mice.

Acute lung injury is characterized by neutrophilic inflammation and increased lung permeability. Thiosulfate is a stable metabolite of hydrogen sulfide, a gaseous mediator that exerts antiinflammatory effects. Although sodium thiosulfate (STS) has been used as an antidote, the effect of STS on acute lung injury is unknown. The authors assessed the effects of STS on mice lung and vascular endothelial cells subjected to acute inflammation. Lung injury was assessed in mice challenged with intratracheal lipopolysaccharide or subjected to cecal ligation and puncture with or without STS. Effects of STS on endothelial permeability and the production of inflammatory cytokines and reactive oxygen species were examined in cultured endothelial cells incubated with lipopolysaccharide or tumor necrosis factor-α. Levels of sulfide and sulfane sulfur were measured using novel fluorescence probes. STS inhibited lipopolysaccharide-induced production of cytokines (interleukin-6 [pg/ml]; 313±164, lipopolysaccharide; 79±27, lipopolysaccharide+STS [n=10]), lung permeability, histologic lung injury, and nuclear factor-κB activation in the lung. STS also prevented up-regulation of interleukin-6 in the mouse lung subjected to cecal ligation and puncture. In endothelial cells, STS increased intracellular levels of sulfide and sulfane sulfur and inhibited lipopolysaccharide or tumor necrosis factor-α-induced production of cytokines and reactive oxygen species. The beneficial effects of STS were associated with attenuation of the lipopolysaccharide-induced nuclear factor-κB activation through the inhibition of tumor necrosis factor receptor-associated factor 6 ubiquitination. STS exerts robust antiinflammatory effects in mice lung and vascular endothelium. The results suggest a therapeutic potential of STS in acute lung injury.

Abstract 17514: Hydrogen Sulfide Levels and NRF2 Activity are Attenuated in the Setting of Critical Limb Ischemia (CLI)

Background: Cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST) are enzymatic sources of hydrogen sulfide (H2S). Functions of H2S are mediated by several targets including ion channels and signaling proteins. Nuclear factor-erythriod 2-related factor 2 (NRF2) is responsible for the expression of antioxidant response element (ARE)-regulated genes and is known to be upregulated by H2S. We examined the levels of H2S producing enzymes, H2S, and NRF2 activation status in skeletal muscle obtained from CLI patients. Methods: Gastrocnemius tissues were attained post amputation from human CLI and aged-matched control patients. Tissue H2S levels were measured using gas chromatography methods coupled with sulfur chemiluminescence. RT-qPCR, immunoblot, and electrophoretic mobility shift assay (EMSA) were used to analyze respective gene expression, protein levels, and DNA binding activity, respectively. Results: We found mRNA and protein levels of CSE, CBS, and 3-MST were significantly decreased in skeletal muscle of CLI (~2 fold, p < 0.05) patients as compared to control. H2S and sulfane sulfur levels were significantly decreased in skeletal muscle of CLI patients. We also observed significant reductions in NRF2 activation (2 fold, p < 0.05) as well as antioxidant proteins, such as CuZn-superoxide dismutase (2 fold, p < 0.05), catalase (2 fold, p < 0.05), and glutathione peroxidase (2 fold, p < 0.05) in skeletal muscle of CLI patients. Biomarkers of oxidative stress, such as malondialdehyde and protein carbonyl formation were significantly increased (2 fold, p < 0.05) in skeletal muscle of CLI patients as compared to age-matched controls. Conclusions: The data demonstrate that H2S bioavailability and NRF2 activation are both attenuated in CLI tissues concomitant with significantly increased oxidative stress. Reductions in the activity of H2S producing enzymes may contribute to the pathogenesis of CLI.

Alpha lipoic acid protects the heart against myocardial post ischemia–reperfusion arrhythmias via KATP channel activation in isolated rat hearts

The cardiovascular effects of alpha lipoic acid were evaluated in isolated rat hearts exposed to ischemia–reperfusion injury in vitro. Alpha-lipoic acid raised the level of sulfane sulfur playing an important role in the release of hydrogen sulfide. H2S was shown to prevent the post-reperfusion arrhythmias and to protect the cardiomyocytes from death caused by hypoxia. The activation of potassium ATP-sensitive channels (KATP channels) is one of the most important mechanisms of action of hydrogen sulfide in the cardiovascular system. The aim of this study was to investigate whether alpha lipoic acid can prevent the occurrence of post-reperfusion arrhythmias in vitro using a Langendorff model of ischemia–reperfusion in rats affecting the KATP channels. Alpha lipoic acid significantly improved post-reperfusion cardiac function (reducing incidence of arrhythmias), especially in a dose of 10−7M. These cardiovascular effects of this compound on the measured parameters were reversed by glibenclamide, a selective KATP blocker. Alpha lipoic acid increased the level of sulfane sulfur in the hearts. This may suggest that the positive effects caused by alpha lipoic acid in the cardiovascular system are not only related to its strong antioxidant activity, and the influence on the activity of such enzymes as aldehyde dehydrogenase 2, as previously suggested, but this compound can affect KATP channels. It is possible that this indirect effect of alpha lipoic acid is connected with changes in the release of sulfane sulfur and hydrogen sulfide.

The effect of lipoate on anaerobic cysteine metabolism in erythrocytes of patients treated with peritoneal dialysis

BackgroundThe studies aimed to evaluate the changes in cysteine sulfur metabolism in erythrocytes of end-stage renal failure (ESRF) patients treated with continuous ambulatory peritoneal dialysis (CAPD) caused by a one-month lipoate (LA) supplementation at a daily dose of 600mg. MethodsThe level of sulfane sulfur and activity of sulfurtransferases were determined in erythrocytes of CAPD patients and in the control group. ResultsThe sulfane sulfur level in erythrocytes of CAPD patients did not differ compared with healthy volunteers but LA supplementation increased the reactive sulfur concentration. LA elevated also cystathionase activity. ConclusionsLA supplementation in ESRF patients treated with CAPD increases the sulfane sulfur level which indicates the augmentation of its antioxidant and regulatory properties.

The effect of lipoic acid on cyanate toxicity in the rat heart

BackgroundCyanate is a uremic toxin formed principally via spontaneous urea biodegradation. Its active isoform, isocyanate, is capable of reaction with proteins by N and S carbamoylation, which influences their structure and function. Sulfurtransferases implicated in anaerobic cysteine transformation and cyanide detoxification belong to the enzymes possessing SH groups in their active centers. The present studies aimed to demonstrate the effect of cyanate and lipoic acid on the activity of these enzymes as well as on the level of antioxidants and prooxidants in the rat heart. MethodsWistar rats, which received intraperitoneal injections of cyanate and lipoic acid alone and in combination were sacrificed 2.5h after the first injection. The hearts were isolated and homogenized in phosphate buffer and next biochemical assays were performed comprising determination of the level of glutathione, malondialdehyde and sulfane sulfur and the activity of antioxidant enzymes as well as glutathione S-transferase and gamma glutamyl transferase. ResultsSulfurtransferases and glutathione S-transferase were deactivated by cyanate treatment. It was accompanied by the decreased level of glutathione and sulfane sulfur and the increased level of reactive oxygen species and malondialdehyde. In parallel, antioxidant enzymes: catalase, glutathione peroxidase and gamma glutamyl transferase were activated under such circumstances. Lipoic acid, administered in combination with cyanate prevented the decrease in the level of glutathione and reduction of a pool of sulfane sulfur-containing compounds, concomitantly preserving the activity of antioxidant enzymes. ConclusionsSince uremia, characterized by the elevated cyanate/isocyanate level, is accompanied by frequent cases of cardiovascular diseases, the addition of lipoic acid to the therapy seems promising in prophylaxis of heart diseases in uremic patients.

OP04 Microbiota regulation of host hydrogen sulfide bioavailability and metabolism

Hydrogen sulfide (H2S), generated through various endogenous enzymatic and nonenzymatic pathways, is emerging as a regulator of physiological and pathological events throughout the body. Bacteria in the gastrointestinal tract also produce significant amounts of H2S that regulates microflora growth and virulence responses. However, the impact of the microbiota on host global H2S bioavailability and metabolism remains unknown. To address this question, we examined H2S bioavailability in its various forms (free, acid labile, or bound sulfane sulfur), cystathionine γ-lyase (CSE) activity, and cysteine levels in tissues from germ-free versus conventionally housed mice. Free H2S levels were significantly reduced in plasma and gastrointestinal tissues of germ-free mice. Bound sulfane sulfur levels were decreased by 50–80% in germ-free mouse plasma and adipose and lung tissues. Tissue CSE activity was significantly reduced in many organs from germ-free mice, whereas tissue cysteine levels were significantly elevated compared to conventional mice. These data reveal that the microbiota profoundly regulates systemic bioavailability and metabolism of H2S.

Microbial regulation of host hydrogen sulfide bioavailability and metabolism

Hydrogen sulfide (H2S), generated through various endogenous enzymatic and nonenzymatic pathways, is emerging as a regulator of physiological and pathological events throughout the body. Bacteria in the gastrointestinal tract also produce significant amounts of H2S that regulates microflora growth and virulence responses. However, the impact of the microbiota on host global H2S bioavailability and metabolism remains unknown. To address this question, we examined H2S bioavailability in its various forms (free, acid labile, or bound sulfane sulfur), cystathionine γ-lyase (CSE) activity, and cysteine levels in tissues from germ-free versus conventionally housed mice. Free H2S levels were significantly reduced in plasma and gastrointestinal tissues of germ-free mice. Bound sulfane sulfur levels were decreased by 50–80% in germ-free mouse plasma and adipose and lung tissues. Tissue CSE activity was significantly reduced in many organs from germ-free mice, whereas tissue cysteine levels were significantly elevated compared to conventional mice. These data reveal that the microbiota profoundly regulates systemic bioavailability and metabolism of H2S.