scholarly journals The energetic cost of NNT-dependent ROS removal

2020 ◽  
Vol 295 (48) ◽  
pp. 16217-16218
Author(s):  
Nina Kaludercic ◽  
Fabio Di Lisa
Keyword(s):  
Reactive Oxygen Species ◽  
Oxygen Consumption ◽  
Cell Injury ◽  
Atp Synthesis ◽  
Energetic Cost ◽  
Oxygen Species ◽  
Oxygen Utilization ◽  
Mitochondrial Oxygen Consumption ◽  
High Nutrient ◽  
Ros Formation

Under conditions of high nutrient availability and low ATP synthesis, mitochondria generate reactive oxygen species (ROS) that must be removed to avoid cell injury. Among the enzymes involved in this scavenging process, peroxidases play a crucial role, using NADPH provided mostly by nicotinamide nucleotide transhydrogenase (NNT). However, scarce information is available on how and to what extent ROS formation is linked to mitochondrial oxygen consumption. A new study by Smith et al. shows that NNT activity maintains low ROS levels by means of a fine modulation of mitochondrial oxygen utilization.

scholarly journals Why is cyanide acutely lethal at very low doses?

2019 ◽  
Author(s):  
Kelath Murali Manoj
Keyword(s):  
Reactive Oxygen Species ◽  
Oxygen Consumption ◽  
Oxygen Transport ◽  
Atp Synthesis ◽  
Low Doses ◽  
Oxygen Species ◽  
Mitochondrial Cytochrome ◽  
Futile Cycles ◽  
New Hypothesis ◽  
Mitochondrial Cytochrome Oxidase

Cyanide is conventionally perceived as a binder of heme-Fe centers, disrupting oxygen transport by blood hemoglobin and mitochondrial cytochrome oxidase function. This explanation of toxicity would require millimolar (g/Kg dosage) concentration of cyanide, whereas it is lethal even at micromolar (mg/Kg dosage) ranges. It is long known that oxygen consumption by cells leads to the production of diffusible reactive oxygen species (DROS). Recently, DROS mediated catalytic/metabolic roles were proposed as a physiological source of heat and phosphorylation of ADP within mitochondria. In this purview, it is hypothesized herein that cyanide uses the catalytic DROS via futile cycles, stopping ATP-synthesis and thus killing cells. A quantitative mechanistic perspective delineating the old and new explanations is provided herein. Further, experimental modalities and predictable outcomes are detailed to test the new hypothesis.

scholarly journals TRPM2 Non-Selective Cation Channels in Liver Injury Mediated by Reactive Oxygen Species

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1243
Author(s):  
Eunus S. Ali ◽  
Grigori Y. Rychkov ◽  
Greg J. Barritt
Keyword(s):  
Reactive Oxygen Species ◽  
Liver Injury ◽  
Cell Injury ◽  
Ischemia Reperfusion ◽  
Reactive Oxygen ◽  
Cell Types ◽  
Chronic Liver ◽  
Oxygen Species ◽  
Alcoholic Fatty Liver ◽  
Trpm2 Channels

TRPM2 channels admit Ca2+ and Na+ across the plasma membrane and release Ca2+ and Zn2+ from lysosomes. Channel activation is initiated by reactive oxygen species (ROS), leading to a subsequent increase in ADP-ribose and the binding of ADP-ribose to an allosteric site in the cytosolic NUDT9 homology domain. In many animal cell types, Ca2+ entry via TRPM2 channels mediates ROS-initiated cell injury and death. The aim of this review is to summarise the current knowledge of the roles of TRPM2 and Ca2+ in the initiation and progression of chronic liver diseases and acute liver injury. Studies to date provide evidence that TRPM2-mediated Ca2+ entry contributes to drug-induced liver toxicity, ischemia–reperfusion injury, and the progression of non-alcoholic fatty liver disease to cirrhosis, fibrosis, and hepatocellular carcinoma. Of particular current interest are the steps involved in the activation of TRPM2 in hepatocytes following an increase in ROS, the downstream pathways activated by the resultant increase in intracellular Ca2+, and the chronology of these events. An apparent contradiction exists between these roles of TRPM2 and the role identified for ROS-activated TRPM2 in heart muscle and in some other cell types in promoting Ca2+-activated mitochondrial ATP synthesis and cell survival. Inhibition of TRPM2 by curcumin and other “natural” compounds offers an attractive strategy for inhibiting ROS-induced liver cell injury. In conclusion, while it has been established that ROS-initiated activation of TRPM2 contributes to both acute and chronic liver injury, considerable further research is needed to elucidate the mechanisms involved, and the conditions under which pharmacological inhibition of TRPM2 can be an effective clinical strategy to reduce ROS-initiated liver injury.

scholarly journals CYP450 Mediates Reactive Oxygen Species Production in a Mouse Model of β-Thalassemia through an Increase in 20-HETE Activity

2021 ◽  
Vol 22 (3) ◽  
pp. 1106
Author(s):  
Rayan Bou-Fakhredin ◽  
Batoul Dia ◽  
Hilda E. Ghadieh ◽  
Stefano Rivella ◽  
Maria Domenica Cappellini ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Mouse Model ◽  
Cell Injury ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Reactive Oxygen ◽  
Ros Generation ◽  
Oxygen Species ◽  
Species Production ◽  
Different Sources ◽  
Dependent Pathway

Oxidative damage by reactive oxygen species (ROS) is one of the main contributors to cell injury and tissue damage in thalassemia patients. Recent studies suggest that ROS generation in non-transfusion-dependent (NTDT) patients occurs as a result of iron overload. Among the different sources of ROS, the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family of enzymes and cytochrome P450 (CYP450) have been proposed to be major contributors for oxidative stress in several diseases. However, the sources of ROS in patients with NTDT remain poorly understood. In this study, Hbbth3/+ mice, a mouse model for β-thalassemia, were used. These mice exhibit an unchanged or decreased expression of the major NOX isoforms, NOX1, NOX2 and NOX4, when compared to their C57BL/6 control littermates. However, a significant increase in the protein synthesis of CYP4A and CYP4F was observed in the Hbbth3/+ mice when compared to the C57BL/6 control mice. These changes were paralleled by an increased production of 20-hydroxyeicosatetraenoic acid (20-HETE), a CYP4A and CYP4F metabolite. Furthermore, these changes corroborate with onset of ROS production concomitant with liver injury. To our knowledge, this is the first report indicating that CYP450 4A and 4F-induced 20-HETE production mediates reactive oxygen species overgeneration in Hbbth3/+ mice through an NADPH-dependent pathway.

scholarly journals Intradialytic granulocyte reactive oxygen species production: a prospective, crossover trial.

1993 ◽  
Vol 4 (2) ◽  
pp. 178-186 ◽  
Author(s):  
J Himmelfarb ◽  
K A Ault ◽  
D Holbrook ◽  
D A Leeber ◽  
R M Hakim
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Fold Increase ◽  
Ros Production ◽  
Oxygen Species ◽  
Susceptibility To Infection ◽  
Flow Cytometric ◽  
Ros Formation ◽  
Dialysis Membranes ◽  
Species Production

By the use of flow cytometric techniques, this prospective, randomized crossover study was designed to analyze intradialytic granulocyte reactive oxygen species (ROS) formation in whole blood with complement-activating and noncomplement-activating hollow fiber membranes. Dialysis with a complement-activating membrane resulted in a 6.5-fold increase in granulocyte hydrogen peroxide production 15 min after dialysis initiation and remained significantly elevated (P < 0.01) through the first 30 min with this membrane in comparison to both predialysis values and simultaneous values with a noncomplement-activating membrane. Further studies demonstrated that blood obtained at 15 min with a complement-activating membrane generated significantly less granulocyte ROS production in response to Staphylococcus aureus incubation than blood obtained either predialysis or at the same time in dialysis with a noncomplement-activating membrane. Both complement-activating and noncomplement-activating dialysis membranes caused slightly decreased granulocyte responsiveness to phorbol myristate acetate. It was concluded that hemodialysis with complement-activating membranes results in increased granulocyte ROS production and decreased responsiveness to S. aureus challenge during the dialysis procedure. These results document the potential role of ROS in hemodialysis-associated pathology and susceptibility to infection.

Hypoxia-induced reactive oxygen species formation in skeletal muscle

2007 ◽  
Vol 102 (6) ◽  
pp. 2379-2388 ◽  
Author(s):  
Thomas L. Clanton
Keyword(s):  
Reactive Oxygen Species ◽  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Cell Injury ◽  
Cell Function ◽  
Contractile Activity ◽  
Reactive Oxygen ◽  
Hypoxic Exposure ◽  
Ros Production ◽  
Oxygen Species

The existence of hypoxia-induced reactive oxygen species (ROS) production remains controversial. However, numerous observations with a variety of methods and in many cells and tissue types are supportive of this idea. Skeletal muscle appears to behave much like heart in that in the early stages of hypoxia there is a transient elevation in ROS, whereas in chronic exposure to very severe hypoxia there is evidence of ongoing oxidative stress. Important remaining questions that are addressed in this review include the following. Are there levels of Po2 in skeletal muscle, typical of physiological or mildly pathophysiological conditions, that are low enough to induce significant ROS production? Does the ROS associated with muscle contractile activity reflect imbalances in oxygen uptake and demand that drive the cell to a more reduced state? What are the possible molecular mechanisms by which ROS may be elevated in hypoxic skeletal muscle? Is the production of ROS in hypoxia of physiological significance, both with respect to cell signaling pathways promoting cell function and with respect to damaging effects of long-term exposure? Discussion of these and other topics leads to general conclusions that hypoxia-induced ROS may be a normal physiological response to imbalance in oxygen supply and demand or environmental stress and may play a yet undefined role in normal response mechanisms to these stimuli. However, in chronic and extreme hypoxic exposure, muscles may fail to maintain a normal redox homeostasis, resulting in cell injury or dysfunction.

Sign in / Sign up

Export Citation Format

Share Document