Action Of Carbon Monoxide Research Articles

Level of knowledge about carbon monoxide poisoning and its prevention among students of the Medical School of the Universidad Abierta Interamericana of the city of Rosario (Argentina) in the year 2023

Introduction: Carbon monoxide (CO) poisoning is a medical emergency that, if not adequately treated, can cause neurological sequelae and even death of the patient. However, its recognition is difficult due to the fact that CO is a colorless and odorless gas and that its symptoms are non-specific and can be confused with other pathologies.Objective: To describe the level of knowledge about CO poisoning and its prevention among students in the 1st, 2nd, 3rd and 4th YEAR (1st four-month period) of the Medical School of the Universidad Abierta Interamericana (UAI) - Rosario campus in the year 2023.Materials and methods: Quantitative, observational, descriptive, cross-sectional and retrospective study. It was carried out at the UAI Rosario campus. The population consisted of students in their 1st, 2nd, 3rd and 4th year, all of them in their 1st four-month period of the UAI Medical School. The sampling was non-probabilistic by convenience. The data collection instrument consisted of an anonymous, voluntary and self-administered survey consisting of 24 questions aimed at identifying the knowledge of medical students regarding CO poisoning, its causes, symptoms, action and prevention. The variables were analyzed through absolute and relative percentage frequencies and summarized through measures of central position: mean, and measures of dispersion: standard deviation.Results: A total of 85 students were surveyed, of whom 66% were female and 34% male, with a mean age of 26.43 ± 5.86 years (min: 18; max: 43). 36% were in their first year of high school. Thirty-six percent were in their second year of medical school, 26% in their fourth year, 20% in their third year and 18% in their first year. The mean score was 13.87 ± 4.07 points (min. 5; max. 22). Fifty-six percent of the medical students surveyed presented a medium level of knowledge about CO poisoning, 32% a high level and 12% a low level.Conclusions: 56% of the surveyed medical students presented a medium level of knowledge about the causes, symptoms, methods of action and prevention of CO poisoning. Among the symptoms of CO poisoning recognized by the students were headache, fainting, nausea, vomiting, fatigue, blurred vision, confusion and difficulty breathing.

Carbon monoxide-releasing molecule-2 ameliorates postresuscitation myocardial dysfunction in rat via mitochondrial-mediated apoptosis pathway and the regulation of mitochondrial dynamics

Mitochondrial dysfunction plays a significant role in the development of postresuscitation myocardial dysfunction (PRMD). Endogenous carbon monoxide (CO) has obvious protective effects on cardiomyocytes and that mitochondria are considered to be the main targets of CO action. This study aimed to investigate whether exogenous CO (carbon monoxide releasing molecule 2, CORM-2) could protect against PRMD, and improve cardiac function in rats via the mitochondria pathway. Forty male Sprague-Dawley rats were randomly divided into five groups: sham group, model cardiopulmonary resuscitation (CPR) group, CORM-2 treatment group, inactivated CORM-2 group, and DMSO (Dimethyl sulfoxide, CORM-2 vehicle) group. Excluding the sham group, all groups underwent CPR 4 min after cardiac arrest (CA), animals in every group underwent surgery for catheter insertion before the CA-CPR. In the treatment groups, CORM-2 and inactivated CORM-2 (both 4 mg/kg, dissolved in 2% dimethyl sulfoxide and diluted in normal saline) were intraperitoneally injected 12 h before CPR was started. In the sham, model CPR, and vehicle groups, animals were administered normal saline or vehicle as appropriate. The results demonstrated that the mitochondrial ultrastructure abnormalities in CORM-2 group was less severe than CPR rats. CORM-2 alleviated myocardial contractile and diastolic dysfunction after CPR, decreased caspase-3 and caspase-9 expression in myocardial tissues, and meanwhile suppressed cytochrome c release from mitochondria. Furthermore, CORM-2 lessen the production of reactive oxygen species (ROS) and increased myocardial mitochondrial respiratory complex IV enzyme activity after CPR. Dynamin-related protein 1（Drp1) was significantly less expressed in CORM-2 group with high expression of mitofusion-2 (Mfn2), suggesting that CORM-2 can promote mitochondrial fusion and reduce mitochondrial fission. Collectively, we provide the evidence that CORM-2 effectively relieved myocardial injury after CPR in rats, protected myocardial mitochondria, and preserved cardiac function after resuscitation. The proposed mechanisms of action were improved mitochondrial respiratory function, maintained mitochondrial dynamics balance, and suppressed the mitochondrial-mediated apoptosis.

Downregulation of Vascular Hemeoxygenase-1 Leads to Vasculopathy in Systemic Sclerosis.

Systemic sclerosis (SSc) is a terminal disease characterized by vasculopathy, tissue fibrosis, and autoimmunity. Although the exact etiology of SSc remains unknown, endothelial dysfunction, oxidative stress, and calcium handling dysregulation have been associated with a large number of SSc-related complications such as neointima formation, vasculogenesis, pulmonary arterial hypertension, impaired angiogenesis, and cardiac arrhythmias. Hemeoxygenase-1 (HO-1) is an antioxidant enzyme involved in multiple biological actions in the cardiovascular system including vascular tone, angiogenesis, cellular proliferation, apoptosis, and oxidative stress. The aim of this work was to investigate the physiological role of HO-1 and its relevance in the cardiovascular complications occurring in SSc. We found that, in early phases of SSc, the expression of HO-1 in dermal fibroblast is lower compared to those isolated from healthy control individuals. This is particularly relevant as reduction of the HO-1/CO signaling pathway is associated with endothelial dysfunction and vasculopathy. We show evidence of the role of HO-1/carbon monoxide (CO) signaling pathway in calcium handling. Using an in vitro model of pulmonary arterial hypertension (PAH) we investigated the role of HO-1 in Ca2+ mobilization from intracellular stores. Our results indicate that HO-1 regulates calcium release from intracellular stores of human pulmonary arterial endothelial cells. We interrogated the activity of HO-1 in angiogenesis using an organotypic co-culture of fibroblast-endothelial cell. Inhibition of HO-1 significantly reduced the ability of endothelial cells to form tubules. We further investigated if this could be associated with cell motility or migration of endothelial cells into the extracellular matrix synthesized by fibroblasts. By mean of holographic imaging, we studied the morphological and functional features of endothelial cells in the presence of an HO-1 activator and selective inhibitors. Our results demonstrate that inhibition of HO-1 significantly reduces cell proliferation and cell motility (migration) of cultured endothelial cells, whilst activation of HO-1 does not modify either morphology, proliferation or motility. In addition, we investigated the actions of CO on the Kv7.1 (KCQN1) channel current, an important component of the cardiac action potential repolarization. Using electrophysiology (whole-cell patch-clamp in a recombinant system overexpressing the KCQN1 channel), we assessed the regulation of KCQN1 by CO. CORM-2, a CO donor, significantly reduced the Kv7.1 current, suggesting that HO-1/CO signaling may play a role in the modulation of the cardiac action potential via regulation of this ion channel. In summary, our results indicate a clear link between: 1) downregulation of HO-1/CO signaling; and 2) pathophysiological processes occurring in early phases of SSc, such as calcium homeostasis dysregulation, impaired angiogenesis and cardiac arrhythmias. A better understanding of the canonical actions (mainly due to the biological actions of CO), and non-canonical actions of HO-1, as well as the interaction of HO-1/CO signaling with other gasotransmitters in SSc will contribute to the development of novel therapeutic approaches.

Carbon monoxide: mechanism of toxic action, pathogenesis and clinical manifestations of acute intoxication

Introduction. Carbon monoxide (CO) remains one of the most common causes of acute poisoning and death, both in everyday life and in emergency situations, especially in fires.Material and methods. The paper summarizes information about the regulatory effects, mechanisms of toxic action, pathogenesis and clinical picture of intoxication, as well as predictors of the severity of CO poisoning.Results. The main mechanism of the toxic effect of CO is due to its ability to bind to the protohemal iron of hemoglobin (Hb) to form carboxyhemoglobin (HbCO). The toxicity of CO may also be enhanced by impaired functions of the myoglobin of the myocardium and skeletal muscles, mitochondrial cytochrome oxidase, and iron-containing enzymes of the antioxidant system. The leading link in the pathogenesis of acute CO intoxication is a violation of the oxygen transport function of hemoglobin and the associated development of hemic and tissue hypoxia. CO-induced cell and tissue damage due to the induction of mitochondrial dysfunction, oxidative stress, free radical hyperproduction, lipid peroxidation, inflammation, and apoptosis also play a role in the pathogenesis of intoxication.Conclusion. The mechanism of toxic action of CO, associated primarily with the formation of carboxyhemoglobin and the development of hypoxia, determines the clinical manifestations of acute intoxication, which depend on the concentration of CO and the duration of exposure, but are almost always associated with the central nervous system and cardiovascular system.

Distinct Pharmacological Properties of Gaseous CO and CO-Releasing Molecule in Human Platelets.

Carbon monoxide (CO)—gaseous or released by CO-RMs—both possess antiplatelet properties; however, it remains uncertain whether the mechanisms involved are the same. Here, we characterise the involvement of soluble guanylate cyclase (sGC) in the effects of CO—delivered by gaseous CO–saturated buffer (COG) and generated by CORM-A1—on platelet aggregation and energy metabolism, as well as on vasodilatation in aorta, using light transmission aggregometry, Seahorse XFe technique, and wire myography, respectively. ODQ completely prevented the inhibitory effect of COG on platelet aggregation, but did not modify antiplatelet effect of CORM-A1. In turn, COG did not affect, whereas CORM-A1 substantially inhibited energy metabolism in platelets. Even though activation of sGC by BAY 41-2272 or BAY 58-2667 inhibited significantly platelet aggregation, their effects on energy metabolism in platelets were absent or weak and could not contribute to antiplatelet effects of sGC activation. In contrast, vasodilatation of murine aortic rings, induced either by COG or CORM-A1, was dependent on sGC. We conclude that the source (COG vs. CORM-A1) and kinetics (rapid vs. slow) of CO delivery represent key determinants of the mechanism of antiplatelet action of CO, involving either impairment of energy metabolism or activation of sGG.

Carbon monoxide-triggered health effects: the important role of the inflammasome and its possible crosstalk with autophagy and exosomes.

Carbon monoxide (CO) has long been known as a "silent killer" because of its ability to bind hemoglobin (Hb), leading to reduced oxygen carrying capacity of Hb, which is the main cause of CO poisoning (COP) in humans. Emerging studies suggest that mitochondria is a key target of CO action that can impact key biological processes, including apoptosis, cellular proliferation, inflammation, and autophagy. Despite its toxicity at high concentrations, CO also exhibits cyto- and tissue-protective effects at low concentrations in animal models of organ injury and disease. Specifically, CO modulates the production of pro- or anti-inflammatory cytokines and mediators by regulating the NLRP3 inflammasome. Given that human diseases are strongly associated with inflammation, a deep understanding of the exact mechanism is helpful for treatment. Autophagic factors and inflammasomes interact in various situations, including inflammatory disease, and exosomes might function as the bridge between the inflammasome and autophagy activation. Thus, the interplay among autophagy, mitochondrial dysfunction, exosomes, and the inflammasome may play pivotal roles in the health effects of CO. In this review, we summarize the latest research on the beneficial and toxic effects of CO and their underlying mechanisms, focusing on the important role of the inflammasome and its possible crosstalk with autophagy and exosomes. This knowledge may lead to the development of new therapies for inflammation-related diseases and is essential for the development of new therapeutic strategies and biomarkers of COP.

Efficient technology for the extraction of non-ferrous metals from liquid production waste

The results of the study of Cu(II) to Cu(I) reduction process in chloride-sulfate solutions under the action of carbon monoxide at atmospheric pressure in the presence of palladium chloride(II) acting as catalyst are reported. This process is described by general equation: 2Cu2+ +2SO2-4 +2Cl +CO+H O- 2 →Pd(II) 2CuCl+CO +2H +2SO2 + 2-4 . It has been shown product mix in the sediment obtained hydrocarbonyl process. Thus, the recovery process Cu(II) → Cu(I) with the action of CO is catalyzed by Pd(II) in the initial stage, and then develops in an autocatalytic mode with the subsequent redox decomposition intermediate. As a reducing agent serve ligand molecules of CO which are in activated state: CO+HO=CO +2H +2e2 2 + .

Carbon monoxide-releasing molecules inhibit the cystic fibrosis transmembrane conductance regulator Cl- channel.

The gasotransmitter carbon monoxide (CO) regulates fluid and electrolyte movements across epithelial tissues. However, its action on anion channels is incompletely understood. Here, we investigate the direct action of CO on the cystic fibrosis transmembrane conductance regulator (CFTR) by applying CO-releasing molecules (CO-RMs) to the intracellular side of excised inside-out membrane patches from cells heterologously expressing wild-type human CFTR. Addition of increasing concentrations of tricarbonyldichlororuthenium(II) dimer (CORM-2) (1-300 μM) inhibited CFTR channel activity, whereas the control RuCl3 (100 μM) was without effect. CORM-2 predominantly inhibited CFTR by decreasing the frequency of channel openings and, hence, open probability (Po). But, it also reduced current flow through open channels with very fast kinetics, particularly at elevated concentrations. By contrast, the chemically distinct CO-releasing molecule CORM-3 inhibited CFTR by decreasing Po without altering current flow through open channels. Neither depolarizing the membrane voltage nor raising the ATP concentration on the intracellular side of the membrane affected CFTR inhibition by CORM-2. Interestingly, CFTR inhibition by CORM-2, but not by CFTRinh-172, was prevented by prior enhancement of channel activity by the clinically approved CFTR potentiator ivacaftor. Similarly, when added after CORM-2, ivacaftor completely relieved CFTR inhibition. In conclusion, CORM-2 has complex effects on wild-type human CFTR consistent with allosteric inhibition and open-channel blockade. Inhibition of CFTR by CO-releasing molecules suggests that CO regulates CFTR activity and that the gasotransmitter has tissue-specific effects on epithelial ion transport. The action of ivacaftor on CFTR Cl- channels inhibited by CO potentially expands the drug's clinical utility.

Assessment of the impact on the health of the population of emissions from rolling production of a metallurgical plant

Introduction.Th e development of the metallurgical industry in Novokuznetsk, Kemerovo region, has led to a diffi cult environmental situation. Determining the relationship between exposure to atmospheric emissions and the health of the population based on the risk assessment methodology is an urgent hygiene issue.The aim of the studyis to assess the risk of health problems from emissions from rolling production of a metallurgical plant.Materials and methods. We used data from the volume of maximum permissible emissions of the enterprise. Calculations of maximum single and average annual concentrations of pollutants were carried out using the program “ECOcenter-Standard”. Public health risks were calculated and compared with acceptable values. Th e work also determined the values of risk levels taking into account background concentrations.Results.Priority pollutants were identifi ed: diiron trioxide, nitrogen dioxide, nitrogen oxide, sulfur dioxide, carbon monoxide, benz(a)pyrene. Th e maximum one-time and average annual concentrations of substances at the selected calculation points were determined, and the maximum permissible concentration of diiron trioxide was found to be exceeded. Immediate action risk levels are zero. The highest risk levels of chronic intoxication, expressed as a percentage of a unit, are observed from exposure to diiron trioxide (0.004-0.043) and nitrogen dioxide (0.001-0.012). The maximum total level of risks of chronic intoxication (0.012) is observed at the point of exposure to concentrations #3 from the infl uence of nitrogen dioxide, which is due to the close location of pollution sources. The carcinogenic risk from exposure to benz(a)pyrene ranges from 1×10-8 to 9×10-8 (as a fraction of a unit). The combined values of carcinogenic risk and immediate action risk are below the acceptable risk level. In seven points of exposure to concentrations, the total risk of chronic intoxication exceeds the acceptable level by 1.10-3.45 times.The greatest risk of immediate action, taking into account background concentrations, is observed from the action of carbon monoxide and benz(a)pyrene. Th e carcinogenic risk exceeds the acceptable level by 6-12 times. The risk of chronic intoxication, taking into account the background, exceeds an acceptable level. Th e highest total risk levels are typical for the Kuznetsky district of Novokuznetsk. Conclusions. Atmospheric emissions fr om rolling mill production contribute to air pollution in the city, increasing the risk of chronic intoxication.

Heme is required for carbon monoxide activation of mitochondrial BKCa channel

Carbon monoxide (CO) is an endogenously synthesized gaseous mediator and is involved in the regulation of numerous physiological processes. Mitochondria, in which hemoproteins are abundant, are among the targets for CO action. Large-conductance calcium-activated (mitoBKCa) channels in the inner mitochondrial membrane share multiple biophysical similarities with the BKCa channels of the plasma membrane and could be a potential target for CO. To test this hypothesis, the activity of the mitoBKCa channels in human astrocytoma U-87 MG cell mitochondria was assessed with the patch-clamp technique. The effects of CO-releasing molecules (CORMs), such as CORM-2, CORM-401, and CORM-A1, were compared to the application of a CO-saturated solution to the mitoBKCa channels in membrane patches. The applied CORMs showed pleiotropic effects including channel inhibition, while the CO-containing solution did not significantly modulate channel activity. Interestingly, CO applied to the mitoBKCa channels, which were inhibited by exogenously added heme, stimulated the channel. To summarize, our findings indicate a requirement of heme binding to the mitoBKCa channel for channel modulation by CO and suggest that CORMs might have complex unspecific effects on mitoBKCa channels.

Carbon monoxide released by CORM-A1 prevents yeast cell death via autophagy stimulation.

Autophagy is an autodigestive process, promoting cytoprotection by the elimination of dysfunctional organelles, misfolded proteins and toxic aggregates. Carbon monoxide (CO) is an endogenous gasotransmitter that under low concentrations prevents cell death and inflammation. For the first time, the role of autophagy in CO-mediated cytoprotection against oxidative stress was evaluated in the model yeast Saccharomyces cerevisiae. The boron-based CO-releasing molecule, CORM-A1, was used to deliver CO. CORM-A1 partially prevented oxidative stress-induced cell death in yeast. Likewise, CORM-A1 activated autophagy under basal physiological conditions, which were assessed by autophagic flux and the expression of mCherry-Atg8 or GFP-Atg8. Inhibition of autophagy by knocking out key autophagic genes in yeast (ATG8 or ATG11) blocked CORM-A1 cytoprotective effect, indicating the critical role of autophagy in CO-induced cytoprotection. The CO-mediated cytoprotection via autophagy induction observed in yeast was validated in primary cultures of astrocytes, a well-characterized model for CO's cytoprotective functions. As in yeast, CORM-A1 prevented oxidative stress-induced cell death in an autophagy-dependent manner in astrocytes. Overall, our data support the cytoprotective action of CO against oxidative stress. CO promotes cytoprotection in yeast via autophagy, opening new possibilities for the study of molecular mechanisms of CO's biological functions using this powerful eukaryotic model.

INTRODUCTION TO FORENSICS - APPLICATION OF NATURAL SCIENCES

A well-known forensic material used in forensic technique is carbon monoxide on environment. In literature an important element that makes it difficult to assess the circumstances of fatal poisoning is the individual way of reacting the body to the action of carbon monoxide. Often staying in the same conditions cause that some people are poisoned while others alive. ''Introduction to forensics - application of natural sciences '' is a scientific presentation in order to disseminate preventive methods. The policy on environment is undoubtedly a theme to these important research methods. In order to analyze in the written work that toxic gas in strictly defined cases are the base of evidence. Empirical studies on the example of environmental protection included: quantitative analysis based on the Legalis Legal Information System, directions, noticeable tendencies in described scope, results of empirical research. Toxic gases on environment are used in the evaluation of the material for palynological analyze. The study took into account the analysis of the most suitable places on the body or clothing for taking palynological samples. The analysis covered whether the forensic traces of carbon dioxide recorded on the surface of the body or clothing, reflect the composition of vegetation occurring in the area of research and whether they can be used to mark the time of the event. The obtained results indicate that traces of carbon dioxide may be useful in determining the time of the event in practice in forensic science.

Hydrogen Sulfide: A Therapeutic Option in Systemic Sclerosis.

Systemic sclerosis (SSc) is a lethal disease that is characterized by auto-immunity, vascular injury, and progressive fibrosis of multiple organ systems. Despite the fact that the exact etiology of SSc remains unknown, oxidative stress has been associated with a large range of SSc-related complications. In addition to the well-known detrimental properties of reactive oxygen species (ROS), gasotransmitters (e.g., nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S)) are also thought to play an important role in SSc. Accordingly, the diverse physiologic actions of NO and CO and their role in SSc have been previously studied. Recently, multiple studies have also shown the importance of the third gasotransmitter H2S in both vascular physiology and pathophysiology. Interestingly, homocysteine (which is converted into H2S through the transsulfuration pathway) is often found to be elevated in SSc patients; suggesting defects in the transsulfuration pathway. Hydrogen sulfide, which is known to have several effects, including a strong antioxidant and vasodilator effect, could potentially play a prominent role in the initiation and progression of vasculopathy. A better understanding of the actions of gasotransmitters, like H2S, in the development of SSc-related vasculopathy, could help to create early interventions to attenuate the disease course. This paper will review the role of H2S in vascular (patho-)physiology and potential disturbances in SSc. Moreover, current data from experimental animal studies will be reviewed. Lastly, we will evaluate potential interventional strategies.

Gas Signaling Molecules and Mitochondrial Potassium Channels.

Recently, gaseous signaling molecules, such as carbon monoxide (CO), nitric oxide (NO), and hydrogen sulfide (H2S), which were previously considered to be highly toxic, have been of increasing interest due to their beneficial effects at low concentrations. These so-called gasotransmitters affect many cellular processes, such as apoptosis, proliferation, cytoprotection, oxygen sensing, ATP synthesis, and cellular respiration. It is thought that mitochondria, specifically their respiratory complexes, constitute an important target for these gases. On the other hand, increasing evidence of a cytoprotective role for mitochondrial potassium channels provides motivation for the analysis of the role of gasotransmitters in the regulation of channel function. A number of potassium channels have been shown to exhibit activity within the inner mitochondrial membrane, including ATP-sensitive potassium channels, Ca2+-activated potassium channels, voltage-gated Kv potassium channels, and TWIK-related acid-sensitive K+ channel 3 (TASK-3). The effects of these channels include the regulation of mitochondrial respiration and membrane potential. Additionally, they may modulate the synthesis of reactive oxygen species within mitochondria. The opening of mitochondrial potassium channels is believed to induce cytoprotection, while channel inhibition may facilitate cell death. The molecular mechanisms underlying the action of gasotransmitters are complex. In this review, we focus on the molecular mechanisms underlying the action of H2S, NO, and CO on potassium channels present within mitochondria.

Carbon Monoxide and Cyanide Poisoning in the Burned Pregnant Patient: An Indication for Hyperbaric Oxygen Therapy.

Carbon monoxide (CO) is a small molecule poison released as a product of incomplete combustion. Carbon monoxide binds hemoglobin, reducing oxygen delivery. This effect is exacerbated in the burned pregnant patient by fetal hemoglobin that binds CO 2.5- to 3-fold stronger than maternal hemoglobin. With no signature clinical symptom, diagnosis depends on patient injury history, elevated carboxyhemoglobin levels, and alterations in mental status. The standard of care for treatment of CO intoxication is 100% normobaric oxygen, which decreases the half-life of CO in the bloodstream from 5 hours to 1 hour. Hyperbaric oxygen (HBO2) is a useful adjunct to rapidly reduce the half-life of CO to 20 minutes and the incidence of delayed neurologic sequelae. Because of the slow disassociation of CO from hemoglobin in the fetus, there is a far stronger indication for HBO2 in the burned pregnant patient than in other burn patient populations.Cyanide intoxication is often a comorbid disease with CO in inhalation injury from an enclosed fire, but may be the predominant toxin. It acts synergistically with CO to effectively lower the lethal doses of both cyanide and CO. Diagnosis is best made in the presence of high lactate levels, carboxyhemoglobin concentrations greater than 10%, injury history of smoke inhalation from an enclosed fire, and alterations in consciousness. While treatment with hydroxocobalamin is the standard of care and has the effect of reducing concomitant CO toxicity, data indicate cyanide may also be displaced by HBO2.Carbon monoxide and cyanide poisoning presents potential complications impacting care. This review addresses the mechanism of action, presentation, diagnosis, and treatment of CO and cyanide poisonings in the burned pregnant patient and the use of HBO2 therapy.

Carbon monoxide in lung cell physiology and disease.

Carbon monoxide (CO) is an endogenously produced gas that has gained recognition as a biological signal transduction effector with properties similar, but not identical, to that of nitric oxide (NO). CO, which binds primarily to heme iron, may activate the hemoprotein guanylate cyclase, although with lower potency than NO. Furthermore, CO can modulate the activities of several cellular signaling molecules such as p38 MAPK, ERK1/2, JNK, Akt, NF-κB, and others. Emerging studies suggest that mitochondria, the energy-generating organelle of cells, represent a key target of CO action in eukaryotes. Dose-dependent modulation of mitochondrial function by CO can result in alteration of mitochondrial membrane potential, mitochondrial reactive oxygen species production, release of proapoptotic and proinflammatory mediators, as well as the inhibition of respiration at high concentration. CO, through modulation of signaling pathways, can impact key biological processes including autophagy, mitochondrial biogenesis, programmed cell death (apoptosis), cellular proliferation, inflammation, and innate immune responses. Inhaled CO is widely known as an inhalation hazard due to its rapid complexation with hemoglobin, resulting in impaired oxygen delivery to tissues and hypoxemia. Despite systemic and cellular toxicity at high concentrations, CO has demonstrated cyto- and tissue-protective effects at low concentration in animal models of organ injury and disease. These include models of acute lung injury (e.g., hyperoxia, hypoxia, ischemia-reperfusion, mechanical ventilation, bleomycin) and sepsis. The success of CO as a candidate therapeutic in preclinical models suggests potential clinical application in inflammatory and proliferative disorders, which is currently under evaluation in clinical trials.

CO-independent modification of K+ channels by tricarbonyldichlororuthenium(II) dimer (CORM-2)

Although toxic when inhaled in high concentrations, the gas carbon monoxide (CO) is endogenously produced in mammals, and various beneficial effects are reported. For potential medicinal applications and studying the molecular processes underlying the pharmacological action of CO, so-called CO-releasing molecules (CORMs), such as tricabonyldichlororuthenium(II) dimer (CORM-2), have been developed and widely used. Yet, it is not readily discriminated whether an observed effect of a CORM is caused by the released CO gas, the CORM itself, or any of its intermediate or final breakdown products. Focusing on Ca2+- and voltage-dependent K+ channels (KCa1.1) and voltage-gated K+ channels (Kv1.5, Kv11.1) relevant for cardiac safety pharmacology, we demonstrate that, in most cases, the functional impacts of CORM-2 on these channels are not mediated by CO. Instead, when dissolved in aqueous solutions, CORM-2 has the propensity of forming Ru(CO)2 adducts, preferentially to histidine residues, as demonstrated with synthetic peptides using mass-spectrometry analysis. For KCa1.1 channels we show that H365 and H394 in the cytosolic gating ring structure are affected by CORM-2. For Kv11.1 channels (hERG1) the extracellularly accessible histidines H578 and H587 are CORM-2 targets. The strong CO-independent action of CORM-2 on Kv11.1 and Kv1.5 channels can be completely abolished when CORM-2 is applied in the presence of an excess of free histidine or human serum albumin; cysteine and methionine are further potential targets. Off-site effects similar to those reported here for CORM-2 are found for CORM-3, another ruthenium-based CORM, but are diminished when using iron-based CORM-S1 and absent for manganese-based CORM-EDE1.

Abstract 236: Carbon Monoxide Mediated Changes in Macrophages are Regulated by Vagal Activation

Introduction: Carbon monoxide (CO) has potent vasoproective effects in vivo through changes in macrophage (MΦ) function. Because of these marked changes, we examined the vagal cholinergic anti-inflammatory pathway in regulating the actions of inhaled CO. We previously showed that vagotomy inhibited the ability of inhaled CO to prevent intimal hyperplasia following arterial injury in rats. We now hypothesize that the anti-inflammatory effects of inhaled CO can be blocked through pharmacologic vagal inhibition. Methods: Sprague-Dawley rats (3 rats/group) were treated with inhaled CO (250 parts per million) for 1 hr or remained in room air. Some were injected with atropine (0.05 mg/kg SQ) 1 hr prior to and just prior to inhaled CO treatment. Peritoneal macrophages (MΦ) were collected 1 hr after CO treatment or comparable time period in control rats and were cultured overnight under standard conditions. Media from these cells were collected for Western blot analysis for high mobility box group 1 (HMGB1) and VEGF. Results: MΦ isolated from CO treated rats released increased levels of HMGB1 and VEGF into the media compared to MΦs from air treated rats (1.7 and 4 fold increase, respectively; Fig.). These molecules mediate the proendothelial actions of inhaled CO. MΦs isolated from atropine treated rats showed a mild reduction of HMGB1 and VEGF secretion. In contrast, MΦ from atropine and CO treated rats showed a significant inhibition of HMGB1 release (P<0.01 vs. all other treatment groups) and a trend toward significance in the reduction in VEGF release (Fig.). Conclusions: Inhaled CO activates vagal signaling to mediate changes in MΦ behavior. Inhibition of vagal signaling with atropine blocked the changes in MΦ induced by inhaled CO, confirming the importance of the vagus nerve in mediating the vasoprotective actions of CO. These findings suggest the potential ability to reproduce the therapeutic actions of CO through pharmacologic vagal stimulation.

Mechanistic insight into the heme-independent interplay between iron and carbon monoxide in CFTR and Slo1 BKCa channels.

Ion channels have been extensively reported as effectors of carbon monoxide (CO). However, the mechanisms of heme-independent CO action are still not known. Because most ion channels are heterologously expressed on human embryonic kidney cells that are cultured in Fe3+-containing media, CO may act as a small and strong iron chelator to disrupt a putative iron bridge in ion channels and thus to tune their activity. In this review CFTR and Slo1 BKCa channels are employed to discuss the possible heme-independent interplay between iron and CO. Our recent studies demonstrated a high-affinity Fe3+ site at the interface between the regulatory domain and intracellular loop 3 of CFTR. Because the binding of Fe3+ to CFTR prevents channel opening, the stimulatory effect of CO on the Cl- and HCO3- currents across the apical membrane of rat distal colon may be due to the release of inhibitive Fe3+ by CO. In contrast, CO repeatedly stimulates the human Slo1 BKCa channel opening, possibly by binding to an unknown iron site, because cyanide prohibits this heme-independent CO stimulation. Here, in silico research on recent structural data of the slo1 BKCa channels indicates two putative binuclear Fe2+-binding motifs in the gating ring in which CO may compete with protein residues to bind to either Fe2+ bowl to disrupt the Fe2+ bridge but not to release Fe2+ from the channel. Thus, these two new regulation models of CO, with iron releasing from and retaining in the ion channel, may have significant and extensive implications for other metalloproteins.

Role of Gasotransmitters in Oxidative Stresses, Neuroinflammation, and Neuronal Repair.

To date, three main gasotransmitters, that is, hydrogen sulfide (H2S), carbon monoxide (CO), and nitric oxide (NO), have been discovered to play major bodily physiological roles. These gasotransmitters have multiple functional roles in the body including physiologic and pathologic functions with respect to the cellular or tissue quantities of these gases. Gasotransmitters were originally known to have only detrimental and noxious effects in the body but that notion has much changed with years; vast studies demonstrated that these gasotransmitters are precisely involved in the normal physiological functioning of the body. From neuromodulation, oxidative stress subjugation, and cardiovascular tone regulation to immunomodulation, these gases perform critical roles, which, should they deviate from the norm, can trigger the genesis of a number of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). The purpose of this review is to discuss at great length physical and chemical properties and physiological actions of H2S, NO, and CO as well as shedding light on recently researched molecular targets. We particularly put emphasis on the roles in neuronal inflammation and neurodegeneration and neuronal repair.