ubiquinol and Reperfusion-Injury

Ischemia/reperfusion (IR) injury is a central component in the pathogenesis of several diseases and is a leading cause of morbidity and mortality in the western world. Subcellularly, mitochondrial dysfunction, characterized by depletion of ATP, calcium-induced opening of the mitochondrial permeability transition pore, and exacerbated reactive oxygen species (ROS) formation, plays an integral role in the progression of IR injury. Nitric oxide (NO) and more recently nitrite (NO(2)(-)) are known to modulate mitochondrial function, mediate cytoprotection after IR and have been implicated in the signaling of the highly protective ischemic preconditioning (IPC) program. Here, we review what is known about the role of NO and nitrite in cytoprotection after IR and consider the putative role of nitrite in IPC. Focus is placed on the potential cytoprotective mechanisms involving NO and nitrite-dependent modulation of mitochondrial function.

Topics: Animals; Cytochromes c; Cytoprotection; Glutathione; Humans; Ischemic Preconditioning; Mice; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Mitochondrial Proton-Translocating ATPases; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Protein Processing, Post-Translational; Reactive Oxygen Species; Reperfusion Injury; Signal Transduction; Ubiquinone

Mitochondria have long been known to play a critical role in maintaining the bioenergetic status of cells under physiological conditions. Mitochondria produce large amounts of free radicals, and mitochondrial oxidative damage can contribute to a range of degenerative conditions including cardiovascular diseases (CVDs). Although the molecular mechanisms responsible for mitochondrion-mediated disease processes are not correctly understood, oxidative stress seems to play an important role. Consequently, the selective inhibition of mitochondrial oxidative damage is an obvious therapeutic strategy. This review considers the process of CVD from a mitochondrial perspective and provides a summary of the following areas: reactive oxygen species (ROS) production and its role in pathophysiological processes such as CVD, currently available antioxidants and possible reasons for their efficacy and inefficacy in ameliorating oxidative stress-mediated diseases, and recent developments in mitochondria-targeted antioxidants that concentrate on the matrix-facing surface of the inner mitochondrial membrane. These mitochondrion-targeted antioxidants have been developed by conjugating the lipophilic triphenylphosphonium cation to antioxidant moieties such as ubiquinol. These compounds pass easily through biological membranes and, due to their positive charge, they accumulate several-hundred-fold within mitochondria. In this way they protect against mitochondrial oxidative damage and show potential as a future therapy for CVDs.

Topics: Antioxidants; Cardiovascular Diseases; Diabetes Mellitus; Endothelium, Vascular; Humans; Membrane Potentials; Mitochondria; Mitochondrial Diseases; Nitric Oxide; Organophosphorus Compounds; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Risk Factors; Ubiquinone

Topics: Animals; Antioxidants; Apoptosis; Astrocytes; bcl-2-Associated X Protein; bcl-Associated Death Protein; bcl-X Protein; Caspase 3; Cell Survival; Disease Models, Animal; Female; Gene Expression Regulation; Intraocular Pressure; Mice; Mice, Inbred C57BL; Microglia; Oxidative Stress; Phosphorylation; Reactive Oxygen Species; Reperfusion Injury; Retinal Degeneration; Retinal Ganglion Cells; Signal Transduction; Ubiquinone

Generation of toxic oxygen metabolites followed by oxidant- and inflammatory-mediated tissue injury plays a crucial role in the pathogenesis of ischemia and reperfusion (IR). Ubiquinol, the reduced form of coenzyme Q10, is recognized for its potent antioxidant and anti-inflammatory properties in biological membranes. The present study was established to examine the possible protective effect of ubiquinol against renal IR injury. Groups of male Wistar rats were assigned into sham, ubiquinol, IR (45-min bilateral renal ischemia followed by 24-h reperfusion), and ubiquinol+ IR (ubiquinol 300 mg/kg given orally for 7 consecutive days before IR induction). Renal morphology, function, oxidative stress, and inflammatory markers were evaluated at the end of reperfusion. IR caused renal dysfunction as shown by significant increases in blood urea nitrogen, plasma creatinine, and a decrease in creatinine clearance. Light and electron microscopic examinations exhibited severe tubular damages and abnormal mitochondrial structure. IR-induced renal injuries were associated with significant increases in malondialdehyde, nitric oxide, tumor necrosis factor-α, but decreases in antioxidant thiols and superoxide dismutase. Pretreatment with ubiquinol obviously attenuated all the changes caused by IR, whereas it had no considerable effect in the sham-operated rats. These findings indicate that supplementation of ubiquinol prior to IR incidence confers functional and morphological protection to the ischemic kidney by maintaining the redox balance and regulating the generation of inflammatory mediator. The outcomes suggest that ubiquinol may be a potential candidate to counteract organ dysfunction in conditions involving IR injury.

Topics: Animals; Antioxidants; Blood Urea Nitrogen; Dietary Supplements; Drug Evaluation, Preclinical; Ischemia; Kidney; Male; Malondialdehyde; Nitric Oxide; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Sulfhydryl Compounds; Superoxide Dismutase; Tumor Necrosis Factor-alpha; Ubiquinone

Haemorrhagic shock (HS) and fluid resuscitation can lead to increased reactive oxygen species (ROS), contributing to ischaemia-reperfusion injury and organ damage. Ubiquinol is a potent antioxidant that decreases ROS. This study examined the effects of ubiquinol administered with fluid resuscitation following controlled HS. Adult male Sprague-Dawley rats were randomly assigned to treatment [ubiquinol, 1 mg (100 g body weight)(-1)] or control groups. Rats were subjected to 60 min of HS by removing 40% of the total blood volume to a mean arterial pressure ∼45-55 mmHg. The animals were resuscitated with blood and lactated Ringer solution, with or without ubiquinol, and monitored for 120 min. At the end of the experiments, the rats were killed and the lungs, diaphragm, heart and kidneys harvested. Leucocytes were analysed for mitochondrial superoxide at baseline, end of shock and 120 min following fluid resuscitation using MitoSOX Red. Diaphragms were examined for hydrogen peroxide using dihydrofluorescein diacetate and confocal microscopy. The apoptosis in lungs, diaphragm, heart and kidneys was measured using fluorescence microscopy with acridine orange and ethidium bromide. Leucocyte mitochondrial superoxide levels were significantly lower in rats that received ubiquinol than in the control animals. Production of hydrogen peroxide and apoptosis were significantly reduced in the organs of rats treated with ubiquinol. These findings suggest that ubiquinol, administered with fluid resuscitation after HS, attenuates ROS production and apoptosis. Thus, ubiquinol is a potent antioxidant that may be used as a potential treatment to reduce organ injury following haemorrhagic events.

Topics: Animals; Antioxidants; Apoptosis; Diaphragm; Fluid Therapy; Heart; Hydrogen Peroxide; Kidney; Leukocytes; Lung; Male; Mitochondria; Myocardium; Rats, Sprague-Dawley; Reperfusion Injury; Resuscitation; Shock, Hemorrhagic; Superoxides; Ubiquinone