ascorbic-acid and Reperfusion-Injury

Ischemia/reperfusion (I/R) injury plays a pivotal role in the development of graft dysfunction and allograft rejection after transplantation. Excessive free radical production and massive consumption of endogenous antioxidants are common mechanisms underlying I/R injury and are implicated in posttransplant organ damage and reduced graft viability. Ascorbic Acid (AA) is an essential micronutrient involved in several biological processes, from antioxidative response to the modulation of apoptosis and inflammation. These properties, combined to the safety profile, low cost, and ease of administration and measurement, make AA a potential bullet for reducing I/R damage in the setting of solid organ transplantation. Although multiple preclinical and clinical studies have been performed to investigate the effectiveness of AA administration in reducing I/R injury during transplantation, its therapeutic potential remains controversial as well as the optimal dosage, timing, and combination with other antioxidants. In this review, we summarize the AA modulated metabolic pathways, focusing on its potential role in the treatment of solid organ (kidney, liver, lung, heart, and pancreas) transplantation.

Topics: Antioxidants; Apoptosis; Ascorbic Acid; Humans; Organ Transplantation; Reperfusion Injury

Percutaneous coronary intervention (PCI) has long remained the gold standard therapy to restore coronary blood flow after acute myocardial infarction (AMI). However, this procedure leads to the development of increased production of reactive oxygen species (ROS) that can exacerbate the damage caused by AMI, particularly during the reperfusion phase. Numerous attempts based on antioxidant treatments, aimed to reduce the oxidative injury of cardiac tissue, have failed in achieving an effective therapy for these patients. Among these studies, results derived from the use of vitamin C (Vit C) have been inconclusive so far, likely due to suboptimal study designs, misinterpretations, and the erroneous conclusions of clinical trials. Nevertheless, recent clinical trials have shown that the intravenous infusion of Vit C prior to PCI-reduced cardiac injury biomarkers, as well as inflammatory biomarkers and ROS production. In addition, improvements of functional parameters, such as left ventricular ejection fraction (LVEF) and telediastolic left ventricular volume, showed a trend but had an inconclusive association with Vit C. Therefore, it seems reasonable that these beneficial effects could be further enhanced by the association with other antioxidant agents. Indeed, the complexity and the multifactorial nature of the mechanism of injury occurring in AMI demands multitarget agents to reach an enhancement of the expected cardioprotection, a paradigm needing to be demonstrated. The present review provides data supporting the view that an intravenous infusion containing combined safe antioxidants could be a suitable strategy to reduce cardiac injury, thus improving the clinical outcome, life quality, and life expectancy of patients subjected to PCI following AMI.

Topics: Acetylcysteine; Animals; Antioxidants; Ascorbic Acid; Biomarkers; Deferoxamine; Dose-Response Relationship, Drug; Drug Synergism; Female; Humans; Male; Myocardial Infarction; Oxidative Stress; Percutaneous Coronary Intervention; Polyphenols; Protective Agents; Reactive Oxygen Species; Reperfusion Injury; Signal Transduction; Stroke Volume; Tocopherols; Ventricular Function, Left

Liver ischemia-reperfusion injury (IRI) is a phenomenon inherent to hepatic surgery that severely compromises the organ functionality, whose underlying mechanisms involve cellular and molecular interrelated processes leading to the development of an excessive inflammatory response. Liver resident cells and those recruited in response to injury generate pro-inflammatory signals such as reactive oxygen species, cytokines, chemokines, proteases and lipid mediators that contribute to hepatocellular necrosis and apoptosis. Besides, dying hepatocytes release damage-associated molecular patterns that actívate inflammasomes to further stimulate inflammatory responses leading to massive cell death. Since liver IRI is a complication of hepatic surgery in man, extensive preclinical studies have assessed potential protective strategies, including the supplementation with natural compounds, with the objective to downregulate nuclear factor-κB functioning, the main effector of inflammatory responses. This can be accomplished by either the activation of peroxisome proliferator-activated receptor-α, G protein-coupled receptor 120 or antioxidant signaling pathways, the synthesis of specific pro-resolving mediators, downregulation of Toll-like receptor 4 activity or additional contributory mechanisms that are beginning to be understood. The latter aspect is a crucial issue to be accomplished in preclinical studies, in order to establish adequate conditions for the supplementation with natural products before major liver surgeries in man involving warm IR, such as hepatic trauma or resection of large intrahepatic tumors.

Topics: Animals; Ascorbic Acid; Biological Products; Fatty Acids, Unsaturated; Humans; Liver; Phenylethyl Alcohol; Reperfusion Injury; Vitamin E; Vitamins

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2018. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2018 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901 .

Topics: Acute Coronary Syndrome; Administration, Intravenous; Ascorbic Acid; Ascorbic Acid Deficiency; Humans; Reperfusion Injury; Time Factors; Vitamins

This narrative review summarizes the role of vitamin C in mitigating oxidative injury-induced microcirculatory impairment and associated organ failure in ischemia/reperfusion or sepsis. Preclinical studies show that high-dose vitamin C can prevent or restore microcirculatory flow impairment by inhibiting activation of nicotinamide adenine dinucleotide phosphate-oxidase and inducible nitric oxide synthase, augmenting tetrahydrobiopterin, preventing uncoupling of oxidative phosphorylation, and decreasing the formation of superoxide and peroxynitrite, and by directly scavenging superoxide. Vitamin C can additionally restore vascular responsiveness to vasoconstrictors, preserve endothelial barrier by maintaining cyclic guanylate phosphatase and occludin phosphorylation and preventing apoptosis. Finally, high-dose vitamin C can augment antibacterial defense. These protective effects against overwhelming oxidative stress due to ischemia/reperfusion, sepsis or burn seems to mitigate organ injury and dysfunction, and promote recovery after cardiac revascularization and in critically ill patients, in the latter partially in combination with other antioxidants. Of note, several questions remain to be solved, including optimal dose, timing and combination of vitamin C with other antioxidants. The combination obviously offers a synergistic effect and seems reasonable during sustained critical illness. High-dose vitamin C, however, provides a cheap, strong and multifaceted antioxidant, especially robust for resuscitation of the circulation. Vitamin C given as early as possible after the injurious event, or before if feasible, seems most effective. The latter could be considered at the start of cardiac surgery, organ transplant or major gastrointestinal surgery. Preoperative supplementation should consider the inhibiting effect of vitamin C on ischemic preconditioning. In critically ill patients, future research should focus on the use of short-term high-dose intravenous vitamin C as a resuscitation drug, to intervene as early as possible in the oxidant cascade in order to optimize macrocirculation and microcirculation and limit cellular injury.

Topics: Animals; Antioxidants; Ascorbic Acid; Capillary Permeability; Critical Care; Endothelium, Vascular; Heart; Humans; Microcirculation; Multiple Organ Failure; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Sepsis; Vitamins

Low-dose irradiation induces various stimulating effects, especially activation of the biological defense system including antioxidative and immune functions. Oxidative stress induced by reactive oxygen species (ROS) can cause cell damage and death and can induce many types of diseases. This paper reviews new insights into inhibition of ROS-related diseases with low-dose irradiation or radon inhalation. X-irradiation (0.5 Gy) before or after carbon tetrachloride (CCl4) treatment inhibits hepatopathy in mice. X-irradiation (0.5 Gy) before ischemia-reperfusion injury or cold-induced brain injury also inhibits edema. These findings suggest that low-dose X-irradiation has antioxidative effects due to blocking the damage induced by free radicals or ROS. Moreover, radon inhalation increases superoxide dismutase activity in many organs and inhibits CCl4-induced hepatic and renal damage and streptozotocin-induced type I diabetes. These findings suggest that radon inhalation also has antioxidative effects. This antioxidative effect against CCl4-induced hepatopathy is comparable to treatment with ascorbic acid (vitamin C) at a dose of 500 mg/kg weight, or α-tocopherol (vitamin E) treatment at a dose of 300 mg/kg weight, and is due to activation of antioxidative functions. In addition, radon inhalation inhibits carrageenan-induced inflammatory paw edema, suggesting that radon inhalation has anti-inflammatory effects. Furthermore, radon inhalation inhibits formalin-induced inflammatory pain and chronic constriction injury-induced neuropathic pain, suggesting that radon inhalation relieves pain. Thus, low-dose irradiation very likely activates the defense systems in the body, and therefore, contributes to preventing or reducing ROS-related injuries, which are thought to involve peroxidation.

Topics: Administration, Inhalation; Animals; Antioxidants; Ascorbic Acid; Brain; Carbon Tetrachloride; Carrageenan; Edema; Free Radicals; Gases; Inflammation; Mice; Radon; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase; Vitamin E; X-Rays

The role of oxidative stress in ischaemic heart disease has been thoroughly investigated in humans. Increased levels of ROS (reactive oxygen species) and RNS (reactive nitrogen species) have been demonstrated during ischaemia and post-ischaemic reperfusion in humans. Depending on their concentrations, these reactive species can act either as benevolent molecules that promote cell survival (at low-to-moderate concentrations) or can induce irreversible cellular damage and death (at high concentrations). Although high ROS levels can induce NF-κB (nuclear factor κB) activation, inflammation, apoptosis or necrosis, low-to-moderate levels can enhance the antioxidant response, via Nrf2 (nuclear factor-erythroid 2-related factor 2) activation. However, a clear definition of these concentration thresholds remains to be established. Although a number of experimental studies have demonstrated that oxidative stress plays a major role in heart ischaemia/reperfusion pathophysiology, controlled clinical trials have failed to prove the efficacy of antioxidants in acute or long-term treatments of ischaemic heart disease. Oral doses of vitamin C are not sufficient to promote ROS scavenging and only down-regulate their production via NADPH oxidase, a biological effect shared by vitamin E to abrogate oxidative stress. However, infusion of vitamin C at doses high enough to achieve plasma levels of 10 mmol/l should prevent superoxide production and the pathophysiological cascade of deleterious heart effects. In turn, n-3 PUFA (polyunsaturated fatty acid) exposure leads to enhanced activity of antioxidant enzymes. In the present review, we present evidence to support the molecular basis for a novel pharmacological strategy using these antioxidant vitamins plus n-3 PUFAs for cardioprotection in clinical settings, such as post-operative atrial fibrillation, percutaneous coronary intervention following acute myocardial infarction and other events that are associated with ischaemia/reperfusion.

Topics: Apoptosis; Ascorbic Acid; Cardiotonic Agents; Fatty Acids, Omega-3; Humans; Models, Biological; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Vitamin E

As a non-toxic endogenous antioxidant, the semi-essential amino acid taurine is a potential attenuator of oxidative damage such as that produced by ischaemia-reperfusion injury. Ischaemia-reperfusion injury is a well established if paradoxical phenomenon whereby ischaemic tissue, doomed to necrosis if it is not reperfused, is actually further damaged by oxidative attack when perfusion is restored. This paper is a review of the literature concerning therapeutic strategies in ischaemia-reperfusion injury, including non-pharmacological and pharmacological interventions. There is consistent experimental evidence of an important role of taurine in ischaemia-reperfusion injury, with a clinical role emerging in human trials of taurine administered prior to coronary artery bypass grafting and heart valve surgery.

Topics: Animals; Antioxidants; Ascorbic Acid; Clinical Trials as Topic; Disease Models, Animal; Free Radical Scavengers; Free Radicals; Humans; Ischemic Preconditioning; Lipid Peroxidation; Reperfusion Injury; Taurine; Vitamin E

Dehydroascorbic acid (DHA) is abundant in the human diet and also is generated from vitamin C (ascorbic acid, AA) in the lumen of the gastrointestinal tract. DHA is absorbed from the lumen of the small intestine and reduced to AA, which subsequently circulates in the blood. Utilization of AA as an antioxidant and enzyme cofactor causes its oxidation to DHA in extracellular fluid and cells. DHA has an important role in many cell types because it can be used to regenerate AA. Both physiological (e.g. insulin, insulin-like growth factor I, cyclic AMP) and pathological (e.g. oxidative stress, diabetes, sepsis) factors alter the transport and metabolic mechanisms responsible for this DHA recycling.

Topics: Animals; Ascorbic Acid; Biological Transport; Dehydroascorbic Acid; Diabetes Mellitus; Humans; Inflammation; Oxidation-Reduction; Reperfusion Injury; Sepsis

Oxidative stress, favoring disease progression by a rapid degeneration of endothelial cell function is deeply involved in Systemic Sclerosis (SSc) pathogenesis. Raynaud's phenomenon (RP), present in 90% of patients with SSc, provoking frequent daily episodes of hypoxia-reperfusion injury, produces several episodes of free radicals-mediated endothelial derangement. These events results in a positive feedback effect of luminal narrowing and ischemia and therefore to the birth of a vicious cycle of oxygen free radicals (OFR) generation, leading to endothelial damage, intimal thickening and fibrosis. Thus ischemia and reperfusion are two criticals events that may induce oxidative stress and inactivation of antioxidant enzymes. In RP and SSc, a reduced concentration of ascorbic acid, alpha-tocopherol and beta-carotene as well as low values of Selenium have been reported. This antioxidative potential deficiency increases the propensity to oxidative stress. favoring the development of injury mediated by OFR. We reviewed several antioxidant compounds, aiming at their capacity of reverting endothelial dysfunction and damage, scavenging lipid peroxidation and reducing multiple episodes of hypoxia-reperfusion injury. In order to interrupt SSc vicious cycle, we propose a main strategy for SSc treatment by a supplementation of antioxidants and different kind of drugs with antioxidant property, such as Lazaroids, Resveratrol, Melatonin and Probucol.

Topics: Antioxidants; Ascorbic Acid; beta Carotene; Endothelium, Vascular; Humans; In Vitro Techniques; Melatonin; Nitric Oxide; Oxidative Stress; Pregnatrienes; Probucol; Raynaud Disease; Reactive Oxygen Species; Reperfusion Injury; Resveratrol; Scleroderma, Systemic; Selenium; Stilbenes; Vitamin E

Involvement of oxygen free radicals in ischemia-/reperfusion injury is based on measurement of increased products of lipid peroxidation after organ ischemia and restoration of blood flow during surgical operations and reperfusion of organ transplants. In cardiology inverse epidemiological correlations between plasma vitamin E levels and mortality due to ischemic heart disease, as well as beneficial effects of vitamin E on experimentally induced oxidative damage to the heart support the hypothesis, that vitamin E might have a protective role against myocardial ischemia-/reperfusion injury. In abdominal surgery efficiency of free radical scavengers has been intensively studied on animal models of hepatic ischemia and reperfusion. Examination of free radical scavengers and adenosine metabolites in liver tissue during hepatic ischemia revealed that vitamin E and glutathione levels as well as hepatic adenosine triphosphate levels are decreased during hepatic ischemia and reperfusion. The beneficial effects of alpha-tocopherol on hepatic viability and survival rate after ischemia and reperfusion demonstrated in these studies will be of great importance concerning further studies in organ preservation. In clinical kidney transplantation prevention of lipid peroxidation and improvement in kidney viability and function was demonstrated after infusion of a multivitamin cocktail in a prospective randomised study.

Topics: Antioxidants; Ascorbic Acid; beta Carotene; Humans; Reperfusion Injury; Vitamin A; Vitamin E; Vitamins

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Chromans; Corpus Striatum; Hippocampus; Ischemic Attack, Transient; Male; Neurons; Rats; Rats, Wistar; Reperfusion Injury; Structure-Activity Relationship

In summary, much evidence supports the formation of toxic oxygen metabolites in ischemic reperfused tissue. Tissues are equipped with both an intracellular and extracellular antioxidant defense system. The defense system can also be divided into enzymatic and nonenzymatic defenses. Important components of a nonenzymatic antioxidant include alpha-tocopherol, ascorbic acid, and beta-carotene as well as other compounds that can react with radicals to form less reactive products such as sulfur-containing amino acids. Extracellular fluid comprises a second line of defense against oxidant injury. These extracellular antioxidants include ceruloplasmin, albumin, transferrin, haptoglobin, and uric acid. The oxidant injury can potentially occur during ischemia and reperfusion due to (1) an excess production of oxygen free radicals, (2) a decrease in antioxidant defenses, or (3) both. Because antioxidants function by removing the toxic oxygen metabolites, they are generally highly effective in reducing ischemia-reperfusion injury.

Topics: Animals; Antioxidants; Ascorbic Acid; beta Carotene; Carotenoids; Free Radicals; Humans; Ischemia; Oxidants; Reperfusion Injury; Vitamin E

Despite a realisation that antioxidants will not delay ageing in healthy older people, there is increasing scientific interest in the role of free radical oxidants in a number of diseases associated with older age. For most of these diseases there is suggestive theoretical and laboratory evidence but not confirmatory clinical evidence. Free radical damage seems likely to be significant in the pathophysiology of atherosclerosis, ischaemia-reperfusion injury, Parkinson's disease, cataract, some cancers and rheumatoid arthritis. Evidence to suggest a protective effect from antioxidant vitamins exists for ischaemic heart disease, cataract and some cancers. Attempts to influence the outcome of other diseases such as ischaemia-reperfusion injury, Parkinson's disease and rheumatoid arthritis have so far failed to achieve positive results. Research interest in the field is increasing although hampered by methodological difficulties and the limited financial return for drug companies. In the meantime there seems no reason to discourage older people who wish to ingest extra vitamin E and vitamin C. A diet with adequate vegetables and fruits should provide sufficient beta carotene.

Topics: Aged; Aging; Animals; Antioxidants; Arteriosclerosis; Ascorbic Acid; Cataract; Diet; Free Radicals; Humans; Parkinson Disease; Reactive Oxygen Species; Reperfusion Injury; Vitamin A; Vitamin E

Topics: Administration, Intravenous; Adult; Antioxidants; Ascorbic Acid; Endothelium, Vascular; Female; Humans; Male; Oxidative Stress; Radial Artery; Regional Blood Flow; Reperfusion Injury; Smoking; Time Factors; Upper Extremity; Vasodilation

It has been reported that hyperglycemia following hypoglycemia produces an ischemia-reperfusion-like effect in type 1 diabetes. In this study the possibility that GLP-1 has a protective effect on this phenomenon has been tested.. 15 type 1 diabetic patients underwent to five experiments: a period of two hours of hypoglycemia followed by two hours of normo-glycemia or hyperglycemia with the concomitant infusion of GLP-1 or vitamin C or both. At baseline, after 2 and 4 hours, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2alpha, sCAM-1a, IL-6 and flow mediated vasodilation were measured.. After 2 h of hypoglycemia, flow mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine and IL-6 significantly increased. While recovering with normoglycemia was accompanied by a significant improvement of endothelial dysfunction, oxidative stress and inflammation, a period of hyperglycemia after hypoglycemia worsens all these parameters. These effects were counterbalanced by GLP-1 and better by vitamin C, while the simultaneous infusion of both almost completely abolished the effect of hyperglycemia post hypoglycemia.. This study shows that GLP-1 infusion, during induced hyperglycemia post hypoglycemia, reduces the generation of oxidative stress and inflammation, improving the endothelial dysfunction, in type 1 diabetes. Furthermore, the data support that vitamin C and GLP-1 may have an additive protective effect in such condition.

Topics: Adult; Antioxidants; Ascorbic Acid; Biomarkers; Blood Glucose; Diabetes Mellitus, Type 1; Dinoprost; Female; Glucagon-Like Peptide 1; Humans; Hyperglycemia; Hypoglycemia; Hypoglycemic Agents; Inflammation; Inflammation Mediators; Infusions, Parenteral; Intercellular Adhesion Molecule-1; Interleukin-6; Male; Oxidative Stress; Reperfusion Injury; Time Factors; Treatment Outcome; Tyrosine; Vasodilation; Young Adult

Oxidative stress due to ischemia/reperfusion injury increases systemic inflammation and impairs immune defenses. Much interest has developed for the administration of antioxidant substrates in surgical patients. The purpose of this study was to perform a pilot evaluation of the impact of a carbohydrate- containing preconditioning oral nutritional supplement (pONS) enriched with glutamine, antioxidants, and green tea extract on postoperative oxidative stress.. We performed a double-blind placebo-controlled randomized clinical trial, involving 36 cancer patients undergoing pancreaticoduodenectomy. Patients were randomized to receive either pONS or placebo twice the day before surgery and once 3 hours before surgery. Total endogenous antioxidant capacity (TEAC), plasma levels of vitamin C, vitamin E, selenium, zinc, F2-isoprostanes, and C-reactive protein were measured at baseline and on postoperative day (POD) 1, 3, and 7.. At surgery, the mean gastric residual volume (mL) was 54.2 in the pONS group versus 51.3 in the placebo group (P = NS). On POD 1 plasma levels of vitamin C (P = 0.001), selenium (P = 0.07), and zinc (P = 0.06) were higher in the pONS group compared to placebo. TEAC was improved on POD 1, 3, and 7 in the pONS group compared to placebo (P = 0.01). No difference was found in plasma C-reactive protein levels after surgery in both groups.. Perioperative pONS administration positively affected plasma vitamin C levels and improved TEAC shortly after surgery, but did not reduce oxidative stress and systemic inflammation markers.

Topics: Aged; Antioxidants; Ascorbic Acid; Common Bile Duct Neoplasms; Dietary Supplements; Double-Blind Method; Humans; Male; Middle Aged; Oxidative Stress; Pancreas; Pancreatic Neoplasms; Pancreaticoduodenectomy; Pilot Projects; Postoperative Complications; Preoperative Care; Reperfusion Injury; Selenium; Zinc

Damage and dysfunction of the vascular endothelium critically influence clinical outcomes after ischemia and reperfusion (I/R). Brief exposure to organic nitrates can protect the vascular endothelium from I/R injury via a mechanism that is similar to ischemic preconditioning and is independent of hemodynamic changes. The clinical relevance of these protective effects clearly depends on whether they can be sustained over time. Twenty-four healthy (age 25-32) male volunteers were randomized to receive 1) transdermal nitroglycerin (GTN; 0.6 mg/h) administered for 2 h on 1 day only, 2) transdermal GTN for 2 h/day for 7 days, or 3) continuous therapy with transdermal GTN for 7 days. Eight volunteers underwent continuous GTN therapy followed by intra-arterial infusion of the antioxidant vitamin C. Finally, five additional subjects underwent no therapy and served as controls. Endothelial function measurements were performed before and after induction of I/R of the arm. I/R caused a significant blunting of the flow responses to acetylcholine in the control group (P < 0.01 vs. before I/R). A single 2-h GTN dosage, given 24 h before I/R, prevented I/R-induced endothelial dysfunction [P = not significant (NS) vs. before I/R], but this protective effect was completely lost after 1 wk of GTN administration 2 h/day (P < 0.05 vs. before I/R; P = NS vs. control). In subjects who received continuous GTN, endothelial responses were blunted before I/R, and I/R did not cause further endothelial dysfunction. Finally, vitamin C normalized acetylcholine responses and prevented the loss of preconditioning associated with prolonged GTN. In a separate experimental model using isolated human endothelial cells, short-term incubation with GTN caused upregulation of heme oxygenase, an effect that was lost after prolonged GTN administration. Although a single administration of GTN is able to protect the endothelium from I/R-induced endothelial dysfunction, this protection is lost upon prolonged exposure, likely via an oxidative mechanism.

Topics: Acetylcholine; Administration, Cutaneous; Adult; Antioxidants; Ascorbic Acid; Dose-Response Relationship, Drug; Drug Tolerance; Endothelium, Vascular; Humans; Infusions, Intra-Arterial; Ischemic Preconditioning; Male; Nitroglycerin; Plethysmography; Reperfusion Injury; Vasodilator Agents

Ischemia-reperfusion (IR) injury causes tissue injury and endothelial dysfunction. There is evidence that oxidative stress plays an important role.. We tested if IR-induced endothelial dysfunction could be prevented by administration of the antioxidant vitamin C. Twenty-six healthy male subjects and eight male patients with peripheral arterial disease (PAD) were enrolled in this randomised placebo-controlled study. Forearm blood flow (FBF) measurements in response to the vasodilators acetylcholine (ACh; endothelium-dependent agonist) or nitroglycerin (NTG; endothelium-independent) were performed before and after forearm ischemia for 20 min. FBF responses were reassessed during reperfusion with intra-arterial co-administration of 24 mg/min vitamin C or placebo. In six volunteers responses to the NO-synthase inhibitor N-monomethyl-L-arginine (L-NMMA) were also assessed before and after ischemia with and without vitamin C.. ACh-induced vasodilation was blunted in subjects receiving placebo after reperfusion (p<0.05 versus baseline). Administration of vitamin C completely prevented impaired responsiveness. NTG-induced vasodilation was not affected by reperfusion or vitamin C. This finding was consistent in patients with PAD and impaired endothelial function, where local vitamin C infusion restored FBF reactivity to ACh before and after IR injury (p<0.05 versus baseline). Again, NTG-induced vasodilation was not affected. Blunted L-NMMA responses seen during reperfusion could be completely reversed by vitamin C.. Our data indicate that IR-induced vascular injury can be prevented by administration of antioxidants.

Topics: Adult; Antioxidants; Ascorbic Acid; Endothelium, Vascular; Enzyme Inhibitors; Forearm; Humans; Injections, Intra-Arterial; Male; Middle Aged; omega-N-Methylarginine; Oxidative Stress; Peripheral Vascular Diseases; Plethysmography; Regional Blood Flow; Reperfusion Injury; Vasodilation

Treatment with extracorporeal shock wave lithotripsy (ESWL), the preferred method of treating kidney stones <3 cm in size, has been shown to induce silent and often self-limiting acute and chronic lesions in the kidneys and adjacent organs. We conducted a randomized clinical trial to determine whether ESWL produces ischaemia and reperfusion injury in the kidneys and whether oral administration of antioxidants reduces the degree of short-term renal injury in patients treated with ESWL. The study included 120 patients with renal stones (1-3 cm in size) treated with ESWL. The patients were divided into three groups--patients in group A (n=39) served as a control group and were not given any antioxidants; patients in group B (n=41) were given two capsules of antioxidants "Nature Made R: " 2 h before ESWL, and 2 and 8 h after ESWL; and patients in group C (n=40) were given two capsules of the antioxidants 2 and 8 h after ESWL. Double 'J' stents were inserted in patients before treatment with ESWL. Blood and urine samples were obtained from all patients just before the start of treatment with ESWL, and at 2 and 24 h and on 7th and 28th day after ESWL. Serum levels of malondialdehyde (MDA), alpha-tocopherol, cholesterol, albumin and ascorbic acid, and alpha-tocopherol/cholesterol ratio were determined. Urinary levels of albumin and beta(2) microglobulin were also determined as measures of renal tubular injury. At 24 h after ESWL, patients given antioxidants (groups B + C) had significantly reduced mean serum concentration of MDA (P<0.001); higher levels of serum ascorbic acid (P<0.001) and serum albumin (P<0.001); lower alpha-tocopherol/cholesterol ratio, lower urinary albumin and beta(2 )microglobulin levels compared with patients who did not receive antioxidants (group A). These findings suggest that treatment with ESWL generates free radicals through ischaemic/reperfusion injury mechanism, and that oral administration of antioxidant may protect these patients from short term renal injury caused by ESWL.

Topics: Administration, Oral; Adult; alpha-Tocopherol; Antioxidants; Ascorbic Acid; beta 2-Microglobulin; Cholesterol; Dose-Response Relationship, Drug; Female; Free Radicals; Humans; Kidney; Kidney Calculi; Lithotripsy; Male; Malondialdehyde; Middle Aged; Reperfusion Injury; Serum Albumin

Intermittent claudication has proved to be a good in vivo model for ischaemia-reperfusion. For assessment of ischaemia-reperfusion damage, the known biochemical markers all have disadvantages with respect to sensitivity and interference with other physiological events. In this work, we studied the metabolic effects of ischaemia-reperfusion in patients with intermittent claudication, and the effects of vitamin C and E intervention, using both traditional biochemical measurements and 1H-NMR-based metabonomics on urine and plasma. The 1H-NMR spectra were subjected to multivariate modelling using principal components discriminant analysis, and the observed clusters were validated using joint deployment of univariate analysis of variance and Tukey-Kramer honestly significant difference (HSD) testing. The study involved 14 patients with intermittent claudication and three healthy volunteers, who were monitored during a walking test, before and after a vitamin C/E intervention, and after a washout period. The effect of exercise was only observable for a limited number of biochemical markers, whereas 1H NMR revealed an effect in line with anaerobic ATP production via glycolysis in exercising (ischaemic) muscle of the claudicants. Thus, the beneficial effect of vitamins C and E in claudicants was more pronounced when observed by metabonomics than by traditional biochemical markers. The main effect was more rapid recovery from exercise to resting state metabolism. Furthermore, after intervention, claudicants tended to have lower concentrations of lactate and glucose and several other citric acid cycle metabolites, whereas acetoacetate was increased. The observed metabolic changes in the plasma suggest that intake of vitamin C/E leads to increased muscle oxidative metabolism.

Topics: Aged; Antioxidants; Ascorbic Acid; Biomarkers; Blood Chemical Analysis; Exercise; F2-Isoprostanes; Female; Humans; Intermittent Claudication; Magnetic Resonance Imaging; Male; Metabolomics; Middle Aged; Reperfusion Injury; Urinalysis; Vitamin E

The cadaveric renal graft is exposed to ischaemic injury during preservation and to oxidative damage during reperfusion. Both these mechanisms are known to cause cell damage, which may impair graft function. Reperfusion injury (RPI) is mediated by reactive oxygen species (ROS). Ascorbic acid (AA) is a potent physiological extracellular scavenger of ROS. We perfused 31 renal grafts immediately before implantation with a solution of Euro-Collins containing 0.5 mg/ml of AA to diminish RPI. From every donor, the contralateral kidney served as a control. The control grafts were perfused with the same perfusion as those of the AA group, only without the AA substitution. We assessed the effect of AA by recording serum creatinine, creatinine clearance, initial graft function and early rejections. The incidence of delayed graft function (DGF) was 32% in the AA group, and 29% in the control group. Other parameters were also similar in both groups, except for the length of DGF, which showed a trend towards a shorter duration in the AA group. The pre-operative systemic AA concentration was significantly ( P=0.01) lower in the haemodialysis patients than in those on peritoneal dialysis. In conclusion, this clinical study could not demonstrate significant benefits of AA in renal transplantation.

Topics: Aged; Antioxidants; Ascorbic Acid; Graft Survival; Humans; Kidney; Kidney Transplantation; Middle Aged; Perfusion; Pilot Projects; Reperfusion Injury

Renal failure after lower torso ischemia is a serious problem, partly caused by hypotension and indirect reperfusion injury. This injury is partly due to the formation of oxygen free radicals by activated neutrophils. This injury results in albuminuria and renal function impairment. There are indications that free radical damage in indirect reperfusion injury can be diminished by administering extra antioxidants before and during reperfusion.. In this prospective randomised study we have looked at the influence of a multi-antioxidant supplementation on renal function in patients undergoing an elective open infrarenal abdominal aneurysm repair. The patients received either standard treatment (n=22) or standard treatment with additional antioxidants perioperatively (Allopurinol, vitamin E and C, N-acetylcysteine and mannitol). For renal function we have looked at the albumin/creatinine ratio in urine and 24 hr creatinine clearance.. Despite significantly increased serum total antioxidant capacity, the group receiving extra antioxidants showed no decrease in the albumin/creatinine ratio in urine. There was however a significantly higher creatinine clearance in this group at day 2.. The results indicate that the diminished renal function after infrarenal aneurysm repair may be influenced by antioxidant therapy.

Topics: Acetylcysteine; Aged; Albuminuria; Allopurinol; Antioxidants; Aortic Aneurysm, Abdominal; Ascorbic Acid; Female; Humans; Kidney Function Tests; Male; Mannitol; Prospective Studies; Renal Insufficiency; Reperfusion Injury; Vitamin E

The purpose of our study was to evaluate the clinical impact of reperfusion injury after normothermic ischemia during major liver resections and the effect of an intraoperative antioxidant infusion. This prospective randomized study comprised 50 patients; half of them (treatment group) were given an antioxidant infusion containing tocopherol and ascorbate immediately prior to reperfusion onset. Venous blood samples for the determination of MDA-TBARS (malondialdehyde-thiobarbituric acid reactive substances) by a HPLC-based test as a marker of lipid peroxidation were taken prior to ischemia, 30 min after reperfusion onset and at the end of the operation. In the control group there was a significant increase of MDA-TBARS (p = 0.001) at 30 min after reperfusion onset. At the end of the operation the values had returned to the initial level. The treatment group showed only a marginal increase (p-value for the difference between the two groups: 0.007). After exclusion of the patients with histologically proven advanced cirrhosis the increase in the control group (p < 0.001) and the difference between the increase in the two groups (p = 0.001) became more significant. Prothrombin time was also significantly better in the treatment group (p = 0.003). Postoperative complications such as prolonged liver failure, bleeding disorders and infections were seen more often in the control group. In our study MDA-TBARS was increased after liver ischemia, but in patients with advanced cirrhosis the effect was smaller or even absent. This increase and possible clinical consequences of reperfusion injury could be reduced by intraoperative administration of an antioxidant infusion.

Topics: Antioxidants; Ascorbic Acid; Humans; Lipid Peroxidation; Liver; Liver Cirrhosis; Malondialdehyde; Postoperative Complications; Prothrombin Time; Reperfusion Injury; Temperature; Thiobarbituric Acid Reactive Substances; Time Factors; Transaminases; Vitamin E

Testicular torsion is still an urgent surgical condition and without any treatment it can cause infertility. The main pathophysiology of testicular torsion ischaemic injury however; the main sequalae of detorsion is reperfusion injury. Furthermore; treatments to prevent ischemic reperfusion injury due to decreased blood flow are important to preserve testicular function.. Human chorionic gonadotropin β (β-hCG) is an anabolic hormone that supports steroidogenesis and spermatogenesis. Vitamin C (Vit-C) is one of the water-soluble vitamins and is also a potent antioxidant in ischemic damage. Moreover, it has protective effects by increasing blood and lymph flow in the testicles. The aim of this study is to investigate the effects of β-hCG, Vit-C and their combination on ischemic reperfusion injury occurring after surgical treatment of testicular torsion.. Animal research studies.. The study was performed on 25 male Wistar albino rats. The animals were divided equally into 5 groups. In the first group "Control Group," left orchiectomy was performed. In the second group "Sham Group," a 720° clockwise torsion was created and after 4 h of left testicular torsion it was detorsioned for 4 h and then left orchiectomy was performed. In the third group same procedure was applied with 30 mg vitamin C was administered via intraperitoneal route once a week for 3 weeks. In the fourth group after same surgical procedures 75 IU β-hCG was administered via intraperitoneal route once a week for 3 weeks. In the fifth group after 4 h left testicle torsion it was detorsioned for 4 h then, 75 IU β-hCG and vitamin C together were administered via intraperitoneal route once a week for 3 weeks. Left orchiectomy was performed after 3 weeks in the third, fourth and fifth groups. Specimens were evaluated histologically.. Testicular tissue histopathological evaluations were performed. A high histopathological stage indicates more testicular damage, and a low one was indicated less testicular damage. The average histopathological grade of vitamin C + β-hCG group was significantly higher than the average histopathological grade of the control, the sham group and vitamin C group. The average histopathological grade of the vitamin C group was significantly lower than the average histopathological grade of sham and β-hCG groups. The ratio of the testicular atrophy of the Vitamin C + β-hCG group (100%) was higher than sham (40%) and β-hCG (40%) groups with a significant difference. A significant statistical difference was found among all groups histopathological grades of testicular tissue.. In animals taking vitamin C, an improvement of histopathological findings and a significant decrease in histological stages has been provided. However, it was observed that the histological findings of β-hCG and β-hCG + vitamin C groups worsened. It was found that β-hCG increased oxidative damage in the testicles and this damage can be so severe that exceeding the capacity of potent antioxidants such as Vitamin C. We believe that β-hCG can be harmful to testicles exposed to oxidative damage.

Topics: Animals; Antioxidants; Ascorbic Acid; Humans; Ischemia; Male; Rats; Rats, Wistar; Reperfusion Injury; Spermatic Cord Torsion; Testicular Diseases; Testis; Vitamins

Cardiorenal syndrome (CRS) is a pathological link between the kidneys and heart, in which an insult in a kidney or heart leads the other organ to incur damage. CRS is classified into five subtypes, and type 3 (CRS3) is characterized by acute kidney injury as a precursor to subsequent cardiovascular changes. Mitochondrial dysfunction and oxidative and nitrosative stress have been reported in the pathophysiology of CRS3. It is known that vitamin C, an antioxidant, has proven protective capacity for cardiac, renal, and vascular endothelial tissues. Therefore, the present study aimed to assess whether vitamin C provides protection to heart and the kidneys in an in vivo CRS3 model. The unilateral renal ischemia and reperfusion (IR) protocol was performed for 60 min in the left kidney of adult mice, with and without vitamin C treatment, immediately after IR or 15 days after IR. Kidneys and hearts were subsequently collected, and the following analyses were conducted: renal morphometric evaluation, serum urea and creatinine levels, high-resolution respirometry, amperometry technique for NO measurement, gene expression of mitochondrial dynamic markers, and NOS. The analyses showed that the left kidney weight was reduced, urea and creatinine levels were increased, mitochondrial oxygen consumption was reduced, NO levels were elevated, and Mfn2 expression was reduced after 15 days of IR compared to the sham group. Oxygen consumption and NO levels in the heart were also reduced. The treatment with vitamin C preserved the left kidney weight, restored renal function, reduced NO levels, decreased iNOS expression, elevated constitutive NOS isoforms, and improved oxygen consumption. In the heart, oxygen consumption and NO levels were improved after vitamin C treatment, whereas the three NOS isoforms were overexpressed. These data indicate that vitamin C provides protection to the kidneys and some beneficial effects to the heart after IR, indicating it may be a preventive approach against cardiorenal insults.

Topics: Animals; Ascorbic Acid; Cardio-Renal Syndrome; Cell Respiration; Isoenzymes; Kidney; Male; Mice, Inbred C57BL; Mitochondria; Mitochondrial Dynamics; Models, Biological; Nitric Oxide; Nitric Oxide Synthase; Reperfusion Injury

Liver ischemia and reperfusion injury (IRI) is a major problem associated with liver surgery. This study is aimed to compare the preventive effect of an antioxidative nutrient-rich enteral diet (Ao diet) with an ordinal enteral diet (control diet) against liver IRI.. The Ao diet was an ordinary diet comprising polyphenols (catechin and proanthocyanidin) and enhanced levels of vitamins C and E. Male C57BL/6 mice were fed the Ao or control diet for 7 days before ischemic insult for 60 minutes, followed by reperfusion for 6 hours. The levels of inflammatory cytokines, chemokines, and antioxidant enzymes and oxidative stress were evaluated.. After 7 days of pretreatment with the Ao diet, the serum levels of vitamins C and E in mice were markedly elevated. The levels of serum aspartate aminotransferase and alanine aminotransferase, as well as the scores of liver necrosis caused by ischemia and reperfusion, were significantly lower in the Ao diet group than in the control diet group. The gene expression levels of inflammatory cytokines and chemokines, such as interleukin-6 and CXCL1, were significantly lower in the Ao diet group. In the liver, the levels of antioxidant enzymes superoxide dismutase 1 (SOD1) and SOD2 were significantly higher and the malondialdehyde levels were significantly lower in the Ao diet group. Cell adhesion molecule expression was significantly lower, and neutrophil and macrophage infiltration was less in the Ao diet group.. Antioxidative nutrient supplementation to an ordinary enteral diet may mitigate liver IRI by causing an antioxidant effect and suppressing inflammation.

Topics: Alanine Transaminase; Animals; Antioxidants; Ascorbic Acid; Aspartate Aminotransferases; Catechin; Diet; Digestive System Surgical Procedures; Enteral Nutrition; Food, Fortified; Ischemia; Liver; Liver Diseases; Male; Malondialdehyde; Mice, Inbred C57BL; Oxidative Stress; Plant Extracts; Proanthocyanidins; Reperfusion Injury; Superoxide Dismutase; Vitamin E

As a promising therapeutic treatment, ischemic postconditioning has recently received considerable attention. Although the neuroprotection effect of postconditioning has been observed, a reliable approach that can evaluate the neuroprotective efficiency of postconditioning treatment during the acute period after ischemia remains to be developed. This study investigates the dynamics of cortex ascorbic acid during the acute period of cerebral ischemia before and after ischemic postconditioning with an online electrochemical system (OECS). The cerebral ischemia/reperfusion injury and the neuronal functional outcome are evaluated with triphenyltetrazolium chloride staining, immunohistochemistry, and electrophysiological recording techniques. Electrochemical recording results show that cortex ascorbic acid sharply increases 10 min after middle cerebral artery occlusion and then reaches a plateau. After direct reperfusion following ischemia (i.e., without ischemic postconditioning), the cortex ascorbic acid further increases and then starts to decrease slowly at a time point of about 40 min after reperfusion. In striking contrast, the cortex ascorbic acid drops and recovers to its basal level after ischemic postconditioning followed by reperfusion. With the recovery of cortex ascorbic acid, ischemic postconditioning concomitantly promotes the recovery of neural function and reduces the oxidative damage. These results demonstrate that our OECS for monitoring cortex ascorbic acid can be used as a platform for evaluating the neuroprotective efficiency of ischemic postconditioning in the acute phase of cerebral ischemia, which is of great importance for screening proper postconditioning parameters for preventing ischemic damages.

Topics: Acute Disease; Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Disease Models, Animal; Electrophysiological Phenomena; Infarction, Middle Cerebral Artery; Ischemic Postconditioning; Male; Monitoring, Physiologic; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Stroke

An ischemia/reperfusion injury of rat's sciatic nerve was experimentally developed. In this model, we measured the in vivo production of superoxide radical, as a marker of oxidative stress and the occludin expression as an indicator of blood-nerve barrier function and we examined potential protective innervations against these abnormalities. Right sciatic nerves of the animals underwent 3 h of ischemia followed by 7 days of reperfusion and were divided into three groups: ischemic, pretreated with vitamin C in conjunction with vitamin E and treated with tissue plasminogen activator. Compared to measurements from left sciatic nerves used as sham, the ischemic group showed significantly increased superoxide radical and reduced expression of occludin in western blot and immunohistochemistry. No such differences were detected between sham and nerves in the vitamin or tissue plasminogen activator groups. It is suggested that the experimental ischemia/reperfusion model was suitable for studying the relationship between oxidative state and blood-nerve barrier. The reversion of abnormalities by the applied neuroprotective agents might prove to be a clinically important finding in view of the implication of vascular supply derangement in various neuropathies in humans.

Topics: Animals; Ascorbic Acid; Ischemia; Male; Neuroprotective Agents; Oxidative Stress; Rats, Wistar; Reperfusion Injury; Sciatic Nerve; Tissue Plasminogen Activator; Vitamin D

Topics: Ascorbic Acid; Heart Arrest; Humans; Renal Replacement Therapy; Reperfusion Injury

Parquetina nigrescens is a medicinal herb with recognized antioxidant properties and potential to alleviate conditions associated with oxidative stress, including gastric ulcers. We investigated the protective potential of methanol extract of Parquetina nigrescens (MEPN) against ischemia-reperfusion injury in the intestine of rats. Thirty (30) male Wistar albino rats were randomly assigned into five groups with Group I made up of control rats and Group II consisting of rats experimentally subjected to ischemia and reperfusion (IR) by clamping of the superior mesenteric artery (SMA) for 30 minutes and 45 minutes, respectively. Groups III and IV rats also had IR, but were initially pre-treated with MEPN at 500 mg/kg and 1000 mg/kg respectively, for seven days. Rats in Group V were also pre-treated with Vitamin C, for seven days, before induction of IR. The results showed marked reduction in intestinal epithelial lesions in groups treated with MEPN, compared to the IR group which had severe villi erosion, inflammatory cell infiltration and hemorrhages. There were significant increases in Malondialdehyde (MDA) and significant reductions in reduced glutathione (GSH) and Glutathione S-transferase (GST) activity with IR injury, while pre-treatment with either MEPN or Vitamin C prevented these effects. Increases in Glutathione peroxidase (GPX), Catalase (CAT) and Superoxide dismutase (SOD) with IR provided evidence for adaptive responses to oxidative injury during IR and preservation of enzyme activity by MEPN and Vitamin C. Taken together, Parquetina nigrescens provided considerable alleviation of intestinal injury produced by IR, at values much as effective as that offered by Vitamin C.

Topics: Animals; Antioxidants; Ascorbic Acid; Catalase; Cryptolepis; Disease Models, Animal; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Intestinal Diseases; Male; Malondialdehyde; Methanol; Oxidative Stress; Plant Extracts; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase

One of the major events in ischemia-reperfusion (I/R)-induced heart injury in cardiac transplantation is the generation of reactive oxygen species. We hypothesized that a novel preservation solution called SBI-SEIIKU II (SS-II) contains 3 antioxidant reagents: L-cysteine, glycine, ascorbic acid/ascorbic acid-2-phosphate magnesium, which can block the generation of reactive oxygen species to result in a prolongation of the cold storage time via attenuating I/R injury.. C57BL/6CrSlc(B6) mice underwent syngeneic mice heterotopic heart transplantation, and the animals were derived into 3 groups: recipients with nonpreserved grafts (control group), recipients with grafts preserved in histidine-tryptophan-ketoglutarate (HTK) for 24 and 48 hours (HTK group), and recipients with grafts preserved in SS-II for 24 and 48 hours (SS-II group).. After 48 hours of preservation, there were no grafts that survived in the HTK group; however, the SS-II group had a high survival rate. After 24 hours of preservation, SS-II decreased the oxidative damage, myocardial apoptosis, and the infiltration of macrophages and neutrophils in the cardiac grafts in the early phase and suppressed the development of myocardial fibrosis in long-term grafts compared with HTK.. The SS-II prolongs the acceptable cold storage time and protects the myocardium from I/R injury via inhibiting oxidative stress-associated damage. We believe that this novel preservation solution may be simple and safe for use in the clinical transplantation field.

Topics: Animals; Antioxidants; Apoptosis; Ascorbic Acid; Cold Temperature; Cryopreservation; Cysteine; Glycine; Graft Survival; Heart; Heart Injuries; Heart Transplantation; Heme Oxygenase-1; Macrophages; Magnesium; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mitochondria; Myocardium; Neutrophils; Organ Preservation; Organ Preservation Solutions; Organophosphorus Compounds; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Time Factors

Topics: Animals; Antioxidants; Ascorbic Acid; Humans; Lung; Lung Transplantation; Organ Preservation Solutions; Oxidative Stress; Perfusion; Potassium Channels; Protein Kinase C; Reperfusion Injury; Signal Transduction; Tissue Preservation

How to provide effective prevention and treatment of myocardial ischemia/reperfusion (I/R) injury and study of the mechanism underlying I/R injury are hotspots of current research. This study aimed to elucidate the effect and cardioprotective mechanism of vitamin C (VC) on myocardial I/R injury. Our study introduced two different I/R models: I/R in vitro and oxygen-glucose deprivation/recovery (OGD/R) in primary neonatal rat cardiac myocytes. We used the mitochondrial permeability transition pore (mPTP) opener lonidamine (LND) and the mitochondrial KATP (mitoKATP) channel inhibitor 5-hydroxydecanoate (5-HD) to analyze the underlying mechanisms. We found that post-treatment with VC decreased I/R injury in our models. Post-treatment with VC significantly decreased I/R-induced injury, attenuated apoptosis, and maintained the functional integrity of mitochondria via alleviation of Ca(2+) overload, reactive oxygen species burst, inhibition of the opening of mPTP, and prevention of mitochondrial membrane potential (ΔΨm) depolarization. VC post-treatment increased the phosphorylation of Akt and glycogen synthase kinase (GSK)-3β. The present results demonstrate that VC might protect the myocardium from I/R-induced injury by inhibiting the mPTP opening via activation of mitoKATP channels. VC mediates cardioprotection via activation of the phosphatidyl inositol 3-kinase (PI3K)-Akt signaling pathway. These findings may contribute toward the development of novel strategies for clinical cardioprotection against I/R injury.

Topics: Animals; Ascorbic Acid; Cardiotonic Agents; Decanoic Acids; Hydroxy Acids; Indazoles; Male; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocytes, Cardiac; Potassium Channels; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Recent evidences suggest that cerebral ischemia-reperfusion insult plays significant role in pathogenic diseases like Alzheimer's disease (AD) and other neurodegenerative diseases. Toxic reactive oxygen species (ROS) generated by induced oxidative stress in the episodes of cerebral ischemia-reperfusion (CIR) plays major role in neurodegeneration. As the prime source of ROS generation, neuronal mitochondria, the cellular energy metabolic centre experience severe damage because of CIR-induced oxidative stress. The process of mitochondrial dysfunction is accelerated by CIR that may pave the pathway for neurodegeneration in AD among aged individuals. Prevention of CIR injury may be a shunt in order to minimize the risk of dementia of Alzheimer's type in aged individuals. The use of chemical antioxidants in CIR is not suitable as the blood- brain barrier (BBB) doesn't allow the entry of molecules from blood circulation into the brain. Thus L-ascorbic acid loaded polylactide nanocapsules were prepared and fed orally to assess the role of nanocapsulated ascorbic acid (NAA) against CIR induced oxidative injury in mitochondrial region of rat brains. Mitochondrial injury was assessed by the extent of lipid peroxidation and in situ antioxidant enzyme status. The levels of cytochrome c (cyt c), cyclooxygenase- 2 (COX-2) and iNOS were determined. Results showed that in comparison to free ascorbic acid (AA), NAA exerted better protection to the brain mitochondria by preventing oxidative damage in ROS mediated CIR injury.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Brain Ischemia; Catalase; Disease Models, Animal; Female; Glutathione Peroxidase; Glutathione Reductase; Lipid Peroxidation; Mitochondria; Nanocapsules; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase

Renal ischemia/reperfusion injury (IRI) is a very common clinical event and usually leads to ischemic acute renal failure (ARF). In the present study, we investigated the protective role of vitamin C in renal function and renal arterial relaxation following ischemic injury.. IRI model in mice was used. Various biochemical parameters including nitric oxide (NO), reduced glutathione (GSH), total reactive oxygen species (ROS) level and superoxide dismutase (SOD) were examined. Doppler was used to investigate renal arterial resistance. The isolated renal arterial rings served for hypoxia/reoxygenation analysis. Acetylcholine (ACh) and sodium nitroprusside (SNP)-induced relaxations of isolated renal arterial rings were exerted.. Vitamin C supplementation preserved kidney morphology and renal function following IRI. It was shown that pretreatment with vitamin C for mice subjected to IRI significantly elevated renal NO and GSH levels after reperfusion. Meanwhile, vitamin C administration decreased resistance index of renal artery and ameliorated oxidative stress secondary to IRI. The total ROS level in renal artery was decreased whereas the renal arterial SOD expression was increased by vitamin C supplementation following IRI. Pretreatment with vitamin C significantly potentiated the ACh and SNP-induced relaxations in both control and hypoxic renal arterial rings.. Vitamin C protects kidney function and renal arterial reactivity against IRI. The protective role of vitamin C is linked to ROS, SOD, GSH and NO levels in renal ischemic injury.

Topics: Animals; Ascorbic Acid; Dietary Supplements; Glutathione; Kidney; Mice; Mice, Inbred C57BL; Nitric Oxide; Reactive Oxygen Species; Renal Artery; Reperfusion Injury; Superoxide Dismutase; Vascular Stiffness

To compare the protective efficacy of erdosteine and vitamins C and E against renal injury caused by hind limb ischemia-reperfusion (I/R).. Rats were split into 4 groups: group I as the control, group II as I/R, group III as I/R + erdosteine, and group IV as I/R + vitamins C and E. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) tissue levels were determined.. MDA levels were found comparable with the control group in groups II and III. However, they were considerably decreased in group IV when compared to group II (P < 0.01). Additionally, SOD, CAT, and GSH-Px activities were considerably (P < 0.05) decreased in group II. While CAT and GSH-Px activities were restored (P <0.01) by vitamin E and C treatment, SOD activity was not significantly affected. While GSH-Px activities were higher (P < 0.05) with erdosteine administration, SOD and CAT activities were unchanged.. The protective effect of vitamins C and E is higher than that of erdosteine treatment in reducing the oxidative stress after renal ischemia in this animal model.

Topics: Animals; Antioxidants; Ascorbic Acid; Hindlimb; Kidney; Kidney Diseases; Lipid Peroxidation; Male; Oxidoreductases; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thioglycolates; Thiophenes; Vitamin E

Ex vivo lung perfusion (EVLP) has recently shown promise as a means of more accurately gauging the health of lung grafts and improving graft performance post-transplant. However, reperfusion of ischemic lung promotes the depletion of high-energy compounds and a progressive loss of normal mitochondrial function, and it remains unclear how and to what extent the EVLP approach contributes to this metabolic decline. Although ascorbate has been used to mitigate the effects of ischemia-reperfusion injury, the nature of its effects during EVLP are also not clear. To address these uncertainties, this study monitored the energy status of lungs during EVLP and after the administration of ascorbate using (31)P and hyperpolarized (13)C NMR (nuclear magnetic resonance). Our experiments demonstrated that the oxidative phosphorylation capacity and pyruvate dehydrogenase flux of lungs decline during ex vivo perfusion. The addition of ascorbate to the perfusate prolonged lung viability by 80% and increased the hyperpolarized (13)C bicarbonate signal by a factor of 2.7. The effect of ascorbate is apparently due not to its antioxidant quality but rather to its ability to energize cellular respiration given that it increased the lung's energy charge significantly, whereas other antioxidants (glutathione and α-lipoic acid) did not alter energy metabolism. During ascorbate administration, inhibition of mitochondrial complex I with rotenone depressed energy charge and shifted the metabolic state of the lung toward glycolysis; reenergizing the electron transport chain with TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) recovered metabolic activity. This indicates that ascorbate slows the decline of the ex vivo perfused lung's mitochondrial activity through an independent interaction with the electron transport chain complexes.

Topics: Animals; Antioxidants; Ascorbic Acid; Carbon Radioisotopes; Cell Respiration; Energy Metabolism; Glycolysis; Lung; Magnetic Resonance Imaging; Male; Mitochondria; Oxidation-Reduction; Oxidative Phosphorylation; Perfusion; Phosphorus Isotopes; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The aim of this study was to evaluate antioxidant and cytoprotective effects of iloprost and Vitamin C in a distant organ after abdominal aorta ischemia-reperfusion injury.. Twenty-eight New Zealand rabbits weighing 2,400-2,800 g were used for this study. The rabbits were divided into four equal groups. These groups are control group, sham group, iloprost group, and iloprost+vitamin C group. Suprarenal aorta was occluded with a vascular clamp. Following 30 minutes of ischemia, the vascular clamp was removed. Rabbits in group 3 received 10 ng/kg/min iloprost and those in group 4 received 10 ng/kg/min iloprost and 10 mg/kg vitamin C. At the end of the reperfusion period, the rabbits were sacrificed by a high intraperitoneal dose of xylazine+ketamine injection. Myocardial tissue samples were taken for electron microscopic analysis. We evaluated SOD, MDA and catalase in myocardial tissue samples.. Iloprost and iloprost+vitamin C groups significantly reduced the oxidative stress markers in tissue samples (p<0.05) and significantly decreased the myofibrillar injury and mitochondrial morphology changes in the myocardial tissue as shown with electron microscopy (p<0.05). Myocardial edema was significantly alleviated by iloprost and iloprost+vitamin C administration (p<0.05).. This study clearly showed that myocardial injury and edema occurred after ischemia-reperfusion of abdominal aorta and that groups administered with iloprost and iloprost+vitamin C showed an attenuation of ischemia-reperfusion injury in distant organs (Tab. 3, Fig. 4, Ref. 30).

Topics: Animals; Aorta, Abdominal; Ascorbic Acid; Drug Therapy, Combination; Iloprost; Myocardial Reperfusion Injury; Oxidative Stress; Platelet Aggregation Inhibitors; Rabbits; Reperfusion Injury; Vitamins

Free radicals are chemicals that play roles in the etio-pathogenesis of ischaemia-reperfusion injury. Various antioxidants have been used in an attempt to mitigate the damage induced by these chemicals. In the present study, the antioxidative effects of grape seed extract (proanthocyanidin), tomato extract (lycopene), and vitamin C (ascorbic acid) on a composite re-established-flow inferior epigastric artery based rectus abdominis muscle-skin flap model on which experimental ischaemia was induced were investigated. The rats have been administered antioxidants for 2 weeks prior to the surgery and for 2 more weeks thereafter. Macroscopic, histopathological, and biochemical analyses were carried out at the decision of the experiment. It was found that flap skin island necrosis was significantly reduced in the proanthocyanidin, lycopene, vitamin C groups (p < 0.001). Statistical analyses showed significant decreases in inflammation, oedema, congestion, and granulation tissue in the proanthocyanidin and lycopene groups compared to the vitamin C and control groups (p < 0.001). When the viability rates of fat and muscle tissues were examined, significant improvements were found in the proanthocyanidin and lycopene groups in comparison to the other groups (p < 0.001). Serum antioxidant capacity measurements revealed significant differences in the lycopene group compared to all other groups (p < 0.001). It is concluded that lycopene and proanthocyanidin are protective antioxidants in rat composite muscle-skin flap ischaemia-reperfusion models.

Topics: Animals; Antioxidants; Ascorbic Acid; Carotenoids; Composite Tissue Allografts; Grape Seed Extract; Lycopene; Male; Necrosis; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Surgical Flaps

Ascorbic acid (AA) is an established antioxidant and has been used for treatment of various disorders. Recent reports suggest that administration of AA increases the level of steroids such as progesterone in the body. The present study investigated the protective role of progesterone against ischemia-reperfusion-induced acute kidney injury (AKI) and possible involvement of progesterone receptors in AA-mediated renoprotection in rats.. The male rats were subjected to bilateral renal ischemia for 40 min followed by reperfusion for 24 h to induce AKI. The rats were treated with progesterone (5 and 10 mg/kg, intraperitoneally) and AA (500 mg/kg, intraperitoneally for 1, 2, and 5 d) before AKI. In separate groups, mifepristone, the progesterone receptor antagonist was administered to rats before progesterone (10 mg/kg) and AA treatment (5 d). Various parameters including creatinine clearance, serum urea, uric acid, potassium level, fractional excretion of sodium, lactate dehydrogenase, and microproteinuria were used to assess kidney injury. Moreover, renal tissues were subjected to quantification of oxidative stress and evaluation of histopathologic changes.. The exogenous administration of progesterone afforded protection against AKI in a dose-dependent manner that was abolished by mifepristone. The administration of AA for 1, 2, and 5 d induced significant increase in serum progesterone levels and afforded protection against AKI. The antioxidant and renoprotective effect of AA was abolished by prior treatment with mifepristone.. It is concluded that exogenous administration of progesterone exerts significant antioxidant and renoprotective effect. Moreover, the progesterone receptors find their explicit involvement in AA-mediated renoprotection against ischemia-reperfusion-induced AKI in rats.

Topics: Acute Kidney Injury; Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Dose-Response Relationship, Drug; Iron; Male; Oxidative Stress; Potassium; Progesterone; Rats; Receptors, Progesterone; Reperfusion Injury; Urea; Uric Acid

Endothelial dysfunction, manifesting as attenuated flow-mediated dilation (FMD), is clinically important. Antioxidants may prevent this dysfunction; however, the acute effects of oral administration in humans are unknown. Low flow-mediated constriction (L-FMC), a further parameter of endothelial health, is largely unstudied and the mechanisms for this response unclear.. Twelve healthy participants (five women and seven men) completed three test conditions: control; antioxidant cocktail (α-lipoic acid, vitamins C and E); and prostaglandin inhibitor ingestion (ibuprofen). Ultrasound measurements of brachial artery responses were assessed throughout 5 min of forearm ischemia and 3 min after. Subsequently, an ischemia-reperfusion injury was induced by a 20-min upper arm occlusion. Further, vascular function protocols were completed at 15, 30, and 45 min of recovery.. Endothelial dysfunction was evident in all conditions. FMD was attenuated at 15 min after ischemia-reperfusion injury (Pre: 6.24 ± 0.58%; Post15: 0.24 ± 0.75%; mean ± SD, P < 0.05), but recovered by 45 min. Antioxidant administration did not preserve FMD compared with control (P > 0.05). The magnitude of L-FMC was augmented at 15 min (Pre: 1.44 ± 0.27%; Post15: 3.75 ± 1.73%; P < 0.05) and recovered by 45 min. Ibuprofen administration produced the largest constrictive response (Pre: -1.13 ± 1.71%; Post15: -5.57 ± 3.82%; time × condition interaction: P < 0.05).. Results demonstrate ischemia-reperfusion injury causes endothelial dysfunction and acute oral antioxidant supplementation fails to reduce its magnitude. Our results also suggest that a lack of shear stress during occlusion combined with suppression of prostaglandin synthesis magnifies L-FMC, possibly due to augmented endothelin-1 expression.

Topics: Adult; Antioxidants; Ascorbic Acid; Blood Flow Velocity; Brachial Artery; Endothelium, Vascular; Female; Forearm; Forearm Injuries; Hemodynamics; Humans; Ibuprofen; Male; Prostaglandin Antagonists; Prostaglandins; Reperfusion Injury; Thioctic Acid; Ultrasonography; Vasodilation; Vitamin E; Young Adult

The use of vitamin C against different diseases has been controversially and emotionally discussed since Linus Pauling published his cancer studies. In vitro and animal studies showed promising results and explained the impact of vitamin C, particularly in cases with endothelial dysfunction. Indeed, studies (reviewed in this issue of Critical Care by Oudemans-van Straaten and colleagues) using high-dose vitamin C and the parenteral route of application seem to be more successful than oral vitamin C delivery.

Topics: Animals; Antioxidants; Ascorbic Acid; Humans; Oxidative Stress; Reperfusion Injury; Sepsis; Vitamins

The objective of the present study was to prepare a stable iv injectable formulation of ascorbic acid and α-tocopherol in preventing the cerebral ischemia. Different niosomal formulations were prepared by Span and Tween mixed with cholesterol. The physicochemical characteristics of niosomal formulations were evaluated in vitro. For in vivo evaluation, the rats were made ischemic by middle cerebral artery occlusion model for 30 min and the selected formulation was used for determining its neuroprotective effect against cerebral ischemia. Neuronal damage was evaluated by optical microscopy and transmission electron microscopy. The encapsulation efficiency of ascorbic acid was increased to more than 84% by remote loading method. The cholesterol content of the niosomes, the hydrophilicity potential of the encapsulated compounds, and the preparation method of niosomes were the main factors affecting the mean volume diameter of the prepared vesicles. High physical stability of the niosomes prepared from Span 40 and Span 60 was demonstrated due to negligible size change of vesicles during 6 months storage at 4-8(°)C. In vivo studies showed that ST60/Chol 35 : 35 : 30 niosomes had more neuroprotective effects against cerebral ischemic injuries in male rats than free ascorbic acid.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Chemistry, Pharmaceutical; Disease Models, Animal; Infarction, Middle Cerebral Artery; Liposomes; Male; Neurons; Particle Size; Rats, Wistar; Reperfusion Injury

There is an interaction between many cell types involved in the pathophysiology of ischemic acute renal failure. Nitric oxide (NO) precursors, especially l-arginine, may have protective effects on tissue ischemia/reperfusion injury (IRI); however, their molecular mechanisms are unclear. In the present study, the interaction between l-arginine, cyclo-oxygenase (COX)-2 and reactive oxygen species (ROS) in the pathogenesis of ischemic acute renal failure was investigated.. Ischemia/reperfusion injury model in rats was used and various biochemical parameters examined. The rat isolated aortic rings served as model for hypoxia/reoxygenation where endothelium dependent and independent relaxations were exerted.. Pre-treatment of rats subjected to IRI with l-arginine (125mg/kg) significantly reduced kidney MDA levels, elevated kidney SOD activity, GSH level and total NO levels at 24 and 48h after reperfusion. Kidney COX-2 level was only different in the l-arginine-treated group 48h after reperfusion compared to the IRI group. Pre-treatment with l-arginine (10(-2)M) alone or in combination with celecoxib significantly potentiated the acetylcholine (Ach)-induced relaxations in control and hypoxic rings. The effect of the combination was synergistic only in hypoxic rings. Addition of ascorbic acid to the celecoxib-arginine combination did not produce further potentiation. Sodium nitroprusside-induced relaxations in control and hypoxic rings were potentiated by l-arginine or celecoxib-arginine combination but not by ascorbic acid.. The protective effect of l-arginine may result from the interaction between NO and ROS and increased NO bioavailability. The protective effects of combined celecoxib and l-arginine against IRI could be attributed to their antioxidant activity which exceeded that of ascorbic acid.

Topics: Acetylcholine; Acute Kidney Injury; Animals; Antioxidants; Aorta; Arginine; Ascorbic Acid; Celecoxib; Cyclooxygenase 2; Drug Synergism; Kidney Function Tests; Nitric Oxide; Nitroprusside; Rats; Reactive Oxygen Species; Reperfusion Injury

Quantitative monitoring of the redox status is the foundation for redox-related treatment. The purpose of this study was to evaluate the reliability of a new depolarization curve method for plasma redox potential (ORP) monitoring.. Using the new method, we performed redox determinations for the first time under different sample-handling conditions, including redox titration experiments using KMnO4 and vitamin C and dynamic redox monitoring in burn patients. The relative ORP value (ΔORP) method (improved traditional method) was used as the reference.. The new method's better reliability, electrochemical specificity and practicability, and known group validity, which are closely associated with the redox-related pathological processes of severe burns, were confirmed. Furthermore, bidirectional change in the redox status in severe burn patients was also observed for the first time.. This simple, stable new method could be a better practical tool for making the dynamic monitoring of the redox status feasible and for providing useful quantitative information for the judgment of redox-related pathological process, thus improving corresponding individualized treatments that rely on quantitative adjustments to the redox status.

Topics: Abbreviated Injury Scale; Adult; Ascorbic Acid; Blood Chemical Analysis; Burns; Electrochemistry; Electrodes; Female; Humans; Male; Methemoglobin; Middle Aged; Monitoring, Physiologic; Oxidation-Reduction; Oxidative Stress; Potassium Permanganate; Reperfusion Injury; Reproducibility of Results; Sensitivity and Specificity; Sepsis; Shock; Uric Acid

Ischemic brain injury is a leading cause of sever neurological and neurobehavioral deficits and death. The hippocampus plays vital roles in learning and memory processes and it is impaired by ischemic insults. Cerebral ischemia/reperfusion leads to Oxidative stress damage impairing the hippocampus. Here we tested whether ascorbic acid and adenosine receptor played a neuroprotective role in a mouse brain ischemia model induced by common carotid arteries occlusion. Adult male mice were randomly assigned into nine experimental groups. The animals were subjected to ischemia by the ligation of common carotid arteries for 15 min. Drugs were injected intrapritoneally once daily for 7 days. Behavioral tests performed at day 14 and then mice were killed at day 21 and their brains were fixed for microscopic studies and some samples were prepared for western blot analysis. Western blot analysis utilized to evaluate the expression of apoptosis-related proteinsin the hippocampus. Short-term memory was assessed by shuttle-box test. Our findings revealed that administration of vitamin C and N6-cyclopentyladenosine (CPA) significantly attenuated ischemia-induced brain injury. Vitamin C and CPA administration increased the expression of anti-apoptotic protein Bcl-2 and decreased the expression of pro-apoptotic protein Bax in the ischemic mice. Ischemia caused short-term memory loss that was improved by vitamin c and CPA treatment. Our results demonstrate that treatment with vitamin C and adenosine receptor agonist attenuated cerebral ischemia/reperfusion-induced brain injury as a potential neuroprotective agent.

Topics: Adenosine; Adenosine A1 Receptor Agonists; Adenosine A1 Receptor Antagonists; Animals; Antioxidants; Ascorbic Acid; Avoidance Learning; bcl-2-Associated X Protein; Behavior, Animal; Blotting, Western; CA1 Region, Hippocampal; In Situ Nick-End Labeling; Male; Maze Learning; Memory, Short-Term; Mice; Neuroprotective Agents; Proto-Oncogene Proteins c-bcl-2; Receptors, Purinergic P1; Reperfusion Injury; Xanthines

Nitric oxide (NO) plays an important role in acute ischemic preconditioning (IPC). In addition to activating soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) signaling pathways, NO-mediated protein S-nitros(yl)ation (SNO) has been recently shown to play an essential role in cardioprotection against ischemia-reperfusion (I/R) injury. In our previous studies, we have shown that IPC-induced cardioprotection could be blocked by treatment with either N-nitro-L-arginine methyl ester (L-NAME, a constitutive NO synthase inhibitor) or ascorbate (a reducing agent to decompose SNO). To clarify NO-mediated sGC/cGMP/PKG-dependent or -independent (i.e., SNO) signaling involved in IPC-induced cardioprotection, mouse hearts were Langendorff-perfused in the dark to prevent SNO decomposition by light exposure. Treatment with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, a highly selective inhibitor of sGC) or KT5823 (a potent and selective inhibitor of PKG) did not abolish IPC-induced acute protection, suggesting that the sGC/cGMP/PKG signaling pathway does not play an important role in NO-mediated cardioprotective signaling during acute IPC. In addition, treatment with ODQ in IPC hearts provided an additional protective effect on functional recovery, in parallel with a higher SNO level in these ODQ+IPC hearts. In conclusion, these results suggest that the protective effect of NO is not related primarily to activation of the sGC/cGMP/PKG signaling pathway, but rather through SNO signaling in IPC-induced acute cardioprotection.

Topics: Animals; Ascorbic Acid; Carbazoles; Cells, Cultured; Cyclic GMP-Dependent Protein Kinases; Guanylate Cyclase; Ischemic Preconditioning, Myocardial; Male; Mice; Mice, Inbred C57BL; Myocardium; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitrosation; Organ Culture Techniques; Oxadiazoles; Quinoxalines; Reperfusion Injury; Signal Transduction

The early antecedents of cerebral palsy (CP) are unknown but are suspected to be due to hypoxia-ischemia (H-I). In our rabbit model of CP, the MRI biomarker, apparent diffusion coefficient (ADC) on diffusion-weighted imaging, predicted which fetuses will develop postnatal hypertonia. Surviving H-I fetuses experience reperfusion-reoxygenation but a subpopulation manifested a continued decline of ADC during early reperfusion-reoxygenation, which possibly represented greater brain injury (RepReOx). We hypothesized that oxidative stress in reperfusion-reoxygenation is a critical trigger for postnatal hypertonia. We investigated whether RepReOx predicted postnatal neurobehavior, indicated oxidative stress, and whether targeting antioxidants at RepReOx ameliorated motor deficits, which included testing of a new superoxide dismutase mimic (MnTnHex-2-PyP). Rabbit dams, 79% gestation (E25), were subjected to 40 min uterine ischemia. Fetal brain ADC was followed during H-I, immediate reperfusion-reoxygenation, and 4-72 h after H-I. Endpoints were postnatal neurological outcome at E32, ADC at end of H-I, ADC nadir during H-I and reperfusion-reoxygenation, and area under ADC curve during the first 20 min of reperfusion-reoxygenation. Antioxidants targeting RepReOx were administered before and/or after uterine ischemia. The new MRI-ADC biomarker for RepReOx improved prediction of postnatal hypertonia. Greater superoxide production, mitochondrial injury, and oligodendroglial loss occurred in fetal brains exhibiting RepReOx than in those without. The antioxidants, MnTnHex-2-PyP and Ascorbate and Trolox combination, significantly decreased postnatal motor deficits and extent of RepReOx. The etiological link between early injury and later motor deficits can thus be investigated by MRI, and allows us to distinguish between critical oxidative stress that causes motor deficits and noncritical oxidative stress that does not.

Topics: Age Factors; Animals; Animals, Newborn; Antioxidants; Ascorbic Acid; Benzimidazoles; Blood Flow Velocity; Brain; Brain Mapping; Carbocyanines; Chromans; Diffusion Magnetic Resonance Imaging; Disease Models, Animal; Embryo, Mammalian; Female; Flow Cytometry; Hypoxia-Ischemia, Brain; Ionophores; Laser-Doppler Flowmetry; Membrane Potential, Mitochondrial; Metalloporphyrins; Microvessels; Mitochondria; Movement Disorders; Muscle Hypertonia; O Antigens; Pregnancy; Rabbits; Reperfusion Injury; Superoxides; Time Factors; Valinomycin

An important component of postoperative management includes alleviation of hepatic ischemia-reperfusion (I/R) injury, which commonly results from liver surgery. EPC-K1 is a hydroxyl radical scavenger reported to have mitigating effects on I/R injury in many organs. This study evaluates the effects of EPC-K1 on hepatic I/R injury.. Rats were injected subcutaneously with either EPC-K1 (100 mg/kg) or saline. The hepatic artery and left branch of the portal vein were clamped for 45 min under general anesthesia. Indicators of liver function, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), and of liver tissue damage were evaluated after 6h and 24h of reperfusion. Serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and high-mobility group box 1 (HMGB1) protein were measured, and apoptosis was quantified via caspase 3/7 activity and TUNEL assay.. AST, ALT, and LDH levels increased significantly as a result of hepatic I/R injury, but were attenuated by EPC-K1 administration. Histologic findings revealed that normal structure of the hepatic parenchyma was maintained in rats pretreated with EPC-K1. TNF-α, IL-6, and HMGB1 levels rose significantly after reperfusion, together with activation of the inflammatory response. However, EPC-K1 administration suppressed levels of inflammatory markers and attenuated the inflammatory response. Moreover, EPC-K1 administration prevented apoptosis as determined by inhibition of caspase 3/7 activity and a decrease in apoptotic cells.. Results demonstrate that EPC-K1 inhibits the inflammatory response and suppresses apoptosis during hepatic I/R injury. This suggests that EPC-K1 has hepatoprotective effects, and may be a valuable and novel therapeutic agent in the clinical setting.

Topics: Alanine Transaminase; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Aspartate Aminotransferases; HMGB1 Protein; Inflammation; Injections, Subcutaneous; Interleukin-6; L-Lactate Dehydrogenase; Liver; Male; Models, Animal; Rats; Rats, Wistar; Reperfusion Injury; Tumor Necrosis Factor-alpha; Vitamin E

The Pringle maneuver is a surgical procedure to minimize hemorrhage during hepatectomy, which however, can induce production of reactive oxygen species causing remote organ injury. We sought to study the impact of the Pringle maneuver on cardiac function as well as the protective effects of L-ascorbic acid and α-tocopherol pretreatments.. Rats were divided into four study groups: L-ascorbic acid (60 mg/kg/d) or α-tocopherol (200 mg/kg/d), and surgical interventions (Sham-operated or liver ischemia-reperfusion [I/R]). Liver ischemia was performed by clamping the hepatic artery and portal vein for 30 minutes, followed by reperfusion by releasing the clamps for 2 hours. Cardiac function was evaluated by a high-fidelity pressure-volume catheter positioned in the left ventricle. Myocardial injury was assessed through plasma creatine kinase-MB (CKMB) and troponin I (cTnI). Cardiac lipid peroxidation and systemic hydroxyl radical levels were assessed by cardiac tissue malondialdehyde and plasma methylguanidine, respectively.. Cardiac function was significantly depressed in the I/R group, where plasma CKMB and cTnI were markedly increased (P < .05). L-ascorbic acid and α-tocopherol pretreatments improved cardiac function and significantly reduced cardiac injury (P < .05). L-ascorbic acid pretreatment demonstrated better heart protection than α-tocopherol, in terms of cTnI and CKMB (P < .05), but no significant difference in terms of cardiac functional improvement.. L-ascorbic acid and α-tocopherol pretreatment 3 days prior to the Pringle maneuver attenuated myocardial injury and protected cardiac function by scavenging hydroxyl radical and reducing lipid peroxidation. L-ascorbic acid demonstrated better protection than α-tocopherol.

Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; Biomarkers; Cardiac Catheterization; Creatine Kinase, MB Form; Disease Models, Animal; Heart Diseases; Hepatectomy; Hydroxyl Radical; Lipid Peroxidation; Liver Diseases; Malondialdehyde; Methylguanidine; Myocardial Contraction; Myocardium; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Time Factors; Troponin I; Ventricular Function, Left; Ventricular Pressure

Tetrahydrobiopterin has been shown to efficiently abrogate ischemia reperfusion injury (IRI). However, it is unclear, whether its beneficial action relies on cofactor activity of one of the five known tetrahydrobiopterin-dependent reactions or on its antioxidative capacity. We therefore compared tetrahydrobiopterin with the pterin derivate tetrahydroneopterin (similar biochemical properties, but no nitric oxide synthase cofactor activity) and the antioxidants vitamin C and 5-methyltetrahydrofolate. Donor mice were pretreated with tetrahydrobiopterin, tetrahydroneopterin, vitamin C, or 5-methyltetrahydrofolate. Pancreatic grafts were subjected to 16-h cold ischemia time and implanted in syngeneic recipients. Untreated and nontransplanted animals served as controls. Following 2-h reperfusion, microcirculation was analyzed by intravital fluorescence microscopy. Graft damage was assessed by histology and nitrotyrosine immunostaining, and tetrahydrobiopterin levels were determined by HPLC. Recipient survival served as ultimate readout. Prolonged cold ischemia time resulted in microcirculatory breakdown. Only tetrahydrobiopterin pretreatment succeeded to preserve the capillary net, whereas all other compounds showed no beneficial effects. Along with increased intragraft tetrahydrobiopterin levels during recovery and implantation, only tetrahydrobiopterin pretreatment led to significant reduction of IRI-related parenchymal damage enabling recipient survival. These results show a striking superiority of tetrahydrobiopterin in preventing lethal IRI compared with related compounds and suggest nitric oxide synthases as treatment target.

Topics: Animals; Antioxidants; Ascorbic Acid; Biopterins; Cold Ischemia; Immunohistochemistry; Ischemia; Liver; Male; Mice; Mice, Inbred C57BL; Microcirculation; Microscopy, Confocal; Nitric Oxide; Organ Preservation; Pancreas; Pancreas Transplantation; Reperfusion Injury; Tetrahydrofolates; Time Factors

Topics: Animals; Antioxidants; Ascorbic Acid; Reperfusion Injury; Vitamin E

The objective of this study was to investigate the effects of dopamine as vasodilator, vitamin C as an antioxidant and combined administration of them on ischaemia-reperfusion (I-R) injury following testicular torsion (TT). Thirty adult male rats were divided into six groups each containing five rats. Testicular ischaemia was achieved by twisting the left testis for 4 h. Group 1 was for determination of the basal values. Group 2 had 4 h TT. Group 3 had 4 h TT and was then treated with dopamine. Group 4 had 4 h TT and was then treated with vitamin C. Group 5 had 4 h TT and was then treated with dopamine and vitamin C. Group 6 was designed as a sham operated group. Testicular torsion caused a significant decrease in the percentage of spermatogenesis and seminiferous tubules diameters compared with the control and sham groups. Administration of dopamine, vitamin C and their combination increased above mentioned parameters and decreased serum malondialehyde levels significantly. However, vitamin C had better results than the other treatments (P < 0.05). In conclusion, a potent antioxidant like vitamin C was found to be more effective than increasing blood flow by a vasodilator like dopamine on improving I-R injury following TT.

Topics: Animals; Antioxidants; Ascorbic Acid; Dopamine; Drug Therapy, Combination; Male; Malondialdehyde; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Seminiferous Tubules; Spermatic Cord Torsion; Spermatogenesis; Vasodilator Agents

Acute kidney injury (AKI) occurs frequently in the intensive care unit. A primary cause is renal ischemia/reperfusion (I/R) injury, during which excess reactive oxygen species (ROS) are produced. ROS subsequently damage renal cells, leading to the development of AKI. Here, we investigated whether renal I/R injury could be attenuated by the antioxidant EPC-K1.. We divided male Wistar rats into the following three groups: (1) a renal I/R group, (2) an EPC-K1 + renal I/R group and (3) a control group. Rats were sacrificed 24 h after treatment (I/R or sham). To measure oxidative stress in renal tissue, histological examinations were performed and serum levels of blood urea nitrogen (BUN) and creatinine were measured. The antioxidant action of EPC-K1 was also evaluated in RAW264.7 cells stimulated with antimycin A.. Serum BUN and creatinine levels were elevated in the I/R group; however, this increase was significantly attenuated by EPC-K1 in the EPC-K1 + I/R group. Renal tissue injury was also significantly lower in the EPC-K1 + I/R group compared with the I/R group. In vitro experiments showed that EPC-K1 significantly attenuated the generation of ROS induced by antimycin A.. In our study, EPC-K1 was able to attenuate AKI due to renal I/R by reducing oxidative stress. These results suggest that EPC-K1 may be effective against various types of I/R injury.

Topics: Animals; Antioxidants; Ascorbic Acid; Biomarkers; Cell Line; Disease Models, Animal; Kidney; Kidney Diseases; Kidney Function Tests; Male; Malondialdehyde; Mice; Oxidative Stress; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Vitamin E

Oxidative stress may cause a loss of tetrahydrobiopterin (BH4), a co-factor of nitric oxide synthase (NOS), decrease the bioavailability of NO and aggravate ischemia/reperfusion (I/R) injury in diabetic heart. We hypothesized that ascorbic acid (AA) and N-acetyl cysteine (NAC) protect the diabetic heart from I/R injury by increasing BH4/dihydrobiopterin (BH2) ratio and inhibiting uncoupling of NOS. Diabetes mellitus was induced in rats by streptozotocin treatment, and the hearts were isolated and perfused. BH4 and BH4/BH2 ratio decreased in the diabetic heart associated with increased production of superoxide and nitrotyrosine (NT). Treatment with AA or NAC significantly increased BH4/BH2 ratio in the diabetic heart associated with decreased production of superoxide and NT and increased generation of nitrate plus nitrite (NOx). Pre-treatment with AA or NAC before 30 min ischemia followed by 120 min reperfusion improved left ventricular (LV) function and reduced infarct size in the diabetic but not non-diabetic hearts. The NOS inhibitor, L-NAME, inhibited the increase in the generation of superoxide, NT and NOx, but aggravated LV function and increased infarct size in the diabetic heart. L-NAME also abrogated the increase in NOx and improvement of LV function and the infarct size-limiting effect induced by AA or NAC in the diabetic heart. These results suggest that AA and NAC increase BH4/BH2 ratio and prevent NOS uncoupling in the diabetic heart. Resultant increase in the bioavailability of NO renders the diabetic heart toleratant to I/R injury.

Topics: Acetylcysteine; Animals; Ascorbic Acid; Biopterins; Diabetes Mellitus, Experimental; Disease Models, Animal; Male; Myocardial Reperfusion Injury; Myocardium; Nitric Oxide Synthase; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Drug Tolerance; Endothelium, Vascular; Heme Oxygenase-1; Humans; Ischemic Preconditioning; Nitrates; Nitroglycerin; Reperfusion Injury; Vasodilator Agents

Rat liver was subjected to two-thirds warm ischemia for 45 min and reperfusion (I/R) to evaluate the resulting oxidative stress. The plasma alanine aminotransferase and aspartate aminotransferase activities were significantly higher than those in the sham group 1.5-24 h after I/R, showing extensive liver cell death. The level of oxidative stress was compared between the ischemic and non-ischemic regions based on the change in antioxidative vitamins C and E. The vitamin C level was significantly decreased during I/R in both the ischemic and non-ischemic regions 0, 1.5, 3, 6, 12, and 24 h after the start of reperfusion, showing enhanced oxidative stress even in the non-ischemic lobules. This decrease of vitamin C in the ischemic region was significantly higher than that in the non-ischemic lobules, while the vitamin E content was decreased only in the ischemic lobes, demonstrating higher oxidative stress in the ischemic region than that in the non-ischemic region. Early transient activation of cytoprotective extracellular signal-related kinase (ERK) was apparent in both the ischemic and non-ischemic lobules, reflecting oxidative stress in both regions. Early transient activation of c-Jun NH(2)-terminal kinase (JNK) was only apparent in the ischemic region, corresponding to extensive oxidative stress and liver cell death. These results demonstrate that significant oxidative stress was induced, but that JNK leading to cell death was not activated in the non-ischemic part of the liver.

Topics: Alanine Transaminase; Animals; Ascorbic Acid; Aspartate Aminotransferases; Ischemia; Liver; Male; Mitogen-Activated Protein Kinases; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Vitamin E

Ascorbic acid has important antioxidant properties, and may play a role in the protective effects of ischemic preconditioning on later ischemia-reperfusion. Herein, we examined the role of endogenous extracellular ascorbic acid in ischemic preconditioning in the kidney.. We developed a solitary rabbit kidney model where animals received ischemia-reperfusion only (ischemia-reperfusion group, n = 15) or ischemic preconditioning followed by ischemia-reperfusion (ischemic preconditioning group, n = 15). Ischemia-reperfusion was induced by occluding and loosening of the renal pedicle. The process of ischemic preconditioning included 15-minute brief ischemia and 10-minute reperfusion. In vivo microdialysis coupled with online electrochemical detection was used to determine levels of endogenous extracellular ascorbic acid in both groups. The extent of tissue damage was determined in kidney sections stained with hematoxylin and eosin. Serum creatinine and urea nitrogen were also detected to assess renal function.. During ischemia-reperfusion, the extracellular ascorbic acid concentration during ischemia increased rapidly to the peak level ((130.01 +/- 9.98)%), and then decreased slowly to near basal levels. Similar changes were observed during reperfusion (peak level, (126.78 +/- 18.24)%). In the ischemic preconditioning group there was a similar pattern of extracellular ascorbic acid concentration during ischemic preconditioning. However, the ascorbic acid level was significantly lower during the ischemia and early reperfusion stage compared to the ischemia-reperfusion group. Additionally, the extent of glomerular ischemic collapse, tubular dilation, tubular denudation, and loss of brush border were markedly attenuated in the ischemic preconditioning group. Levels of serum creatinine and urea nitrogen were also decreased significantly in the ischemic preconditioning group.. Ischemic preconditioning may protect renal tissue against ischemia-reperfusion injury via use of extracellular ascorbic acid. In vivo microdialysis coupled with online electrochemical detection is effective for continuous monitoring extracellular ascorbic acid in the renal cortex.

Topics: Animals; Ascorbic Acid; Disease Models, Animal; Ischemic Preconditioning; Kidney; Rabbits; Reperfusion Injury

There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of ascorbic acid (AA) in I/R-induced renal injury in rats. Thirty two male Sprague-Dawley rats were divided equally into four groups: group 1 (control; dissection of the right renal pedicle without nephrectomy), group 2 (sham operated; unilateral nephrectomy), group 3 (I/R; unilateral nephrectomy + I/R); and group 4 (AA+I/R; unilateral nephrectomy and I/R treated with ascorbic acid, 250mg kg(-1) i.p., for one hour prior to ischemia). On the 15th day following nephrectomy, groups 3 and 4 were subjected to 45 min of renal pedicle occlusion followed by 3 h of reperfusion. At the end of the treatment period, kidney samples were taken for histological examination or determination of the renal malondialdehyde (MDA) and glutathione (GSH) levels. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level, which was accompanied with a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH, were elevated in the I/R group as compared to the control group. In group four, AA treatment reversed all the changes in these biochemical indices, as well as histopathological alterations normally induced by I/R. The findings imply that reactive oxygen species play a causal role in I/R-induced renal injury, and that AA exerts renoprotective effects, probably by radical scavenging and antioxidant activities.

Topics: Acute Kidney Injury; Animals; Antioxidants; Ascorbic Acid; Blood Urea Nitrogen; Glutathione; Lipid Peroxidation; Male; Malondialdehyde; Rats; Rats, Sprague-Dawley; Reperfusion Injury

We examined the effect of vitamin C on muscle injury distal to the tourniquet which was applied for 4 hours with 10- and 20-minute reperfusion intervals after 2 hours of tourniquet. Sixty-four Sprague-Dawley rats were allocated to 4 randomized groups. After 2 hours tourniquet, 10- and 20-minutes of reperfusion were allowed to half of each group respectively. Afterward an additional 2 hours compression was applied. Except the control group the animals received vitamin C intravenously, before the first tourniquet in Group I, at the reperfusion interval in Group II, and at both times in Group III. Malondialdehyde levels were measured in blood and the tibialis anterior muscle. The muscle was histopathologically examined. The data was evaluated statistically. The effects of timing and the dose of vitamin C on ischemia reperfusion injury remain controversial and there was no statistical difference between 10- and 20-minute reperfusion intervals. But the blood malondialdehyde levels showed that vitamin C has a positive effect on the muscle injury caused by ischemia-reperfusion.

Topics: Animals; Antioxidants; Ascorbic Acid; Free Radical Scavengers; Male; Malondialdehyde; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Time Factors; Tourniquets

Recent data demonstrated that hind limb ischemia induces skeletal muscle mitochondrial dysfunctions. Improvement of such metabolic myopathy improves patient's symptomatology, supporting the development of experimental models focused on mitochondrial function analysis. However, although the nonischemic contralateral leg is often used as a control during unilateral leg ischemia, whether it might be useful when assessing ischemia-induced mitochondrial dysfunction remains to be investigated.. Both ischemic (IR) and nonischemic contralateral legs (CTL) of rats (n=13) submitted to 5 h ischemia induced by a rubber band tourniquet applied on the root of the hind limb were studied and compared to that of sham-operated animals (SHAM, n=13). Maximal oxidative capacities (V(max)) and complexes I, II and IV activities of the gastrocnemius mitochondrial respiratory chain were determined, using glutamate-malate, succinate (Vs) and TMPD-ascorbate (V(TMPD)) substrates.. V(max) was decreased in IR (4.6+/-0.4 microM/min/g dry weight) compared to both SHAM and CTL muscles (8.5+/-0.5 and 7.1+/-0.4 microM/min/g dry weight, -46% and -36%, P<0.001, respectively). V(S) and V(TMPD) were reduced in IR muscle (-56% and -48% for V(S); and -25% and -24% for V(TMPD), P<0.001) as compared to SHAM and CTL). V(S) and V(TMPD) were similar in SHAM and CTL muscles.. Five hours ischemia-reperfusion significantly impaired complexes I, II and IV of the ischemic skeletal muscle mitochondrial respiratory chain. Interestingly, only V(max) was slightly altered in the contralateral leg, supporting that the nonischemic leg might be used as a control when assessing mitochondrial function in the experimental setting of unilateral hind limb ischemia.

Topics: Animals; Ascorbic Acid; Cell Respiration; Electron Transport Chain Complex Proteins; Glutamic Acid; Ischemia; Lower Extremity; Malates; Male; Mitochondria, Muscle; Mitochondrial Diseases; Muscle, Skeletal; Rats; Rats, Wistar; Reperfusion Injury; Succinic Acid; Tetramethylphenylenediamine

Postischemic acute renal failure is worsened when occurs in a various conditions with impaired nitric oxide (NO) synthesis, such as arterial hypertension. Reoxygenation itself increases ischemic injury through the massive production of oxygen-free radicals. Therefore, we have directed our investigations to effects of both NO donor and antioxidant treatment on course of acute renal failure in experimental hypertension. Experiments were performed in anesthetized, adult male spontaneously hypertensive rats. In ARF groups the right kidney was removed, and rats were subjected to renal ischemia by clamping the left renal artery for 40 min. Experimental group received NO donor L-arginine (2 g/kg b.m.) (LArg group), or oxidant scavenger vitamin C (100 mg/kg b.m.) (Vit C group) during 3 days before the period of ischaemia. All parameters were measured 24 h after reperfusion. The mean arterial pressure was markedly reduced and renal vascular resistance significantly dropped in the ARF+L-Arg group vs. ARF group. Tubular injuries were similar between the ARF+L-Arg and ARF groups. Intensity of tubular necrosis and dilatation was markedly reduced in ARF+Vit C group in comparison to ARF. L-arginine failed to reduce tubular injury, despite its evident improvement of systemic and renal haemodynamic, thus NO seems to act as a double-egged sword, but reduction of tubular injury promotes vitamin C as an effective chemoprotectant against ishemia-reperfusion tubular injury in hypertension.

Topics: Animals; Antioxidants; Arginine; Ascorbic Acid; Hemodynamics; Hypertension; Kidney; Male; Nitric Oxide; Rats; Rats, Inbred SHR; Renal Insufficiency; Reperfusion Injury

Ischemia/reperfusion (I/R) of the rat liver can induce liver injury through mechanisms involving oxidative and nitrosative stresses. In this study we examined the effects of antioxidants Lycium barbarum (LB) and ascorbic acid on I/R-induced liver injury in rats.. Liver ischemia was induced by clamping the common hepatic artery and portal vein of rats for 40 minutes. Thereafter, flow was restored with reperfusion for 90 minutes. Blood samples collected before ischemia and after reperfusion were analyzed for alanine transaminase (ALT), lactic dehydrogenase (LDH), hydroxyl radical, and nitric oxide (NO) levels. Pharmacologic interventions included administration of ascorbic acid (100 mg/kg, i.p., 1 hour before I/R) or LB, an extract of Gogi berries: 600 mg in 100 mL of drinking water for 2 weeks prior to experimentation.. This protocol resulted in elevation of blood concentrations of NO, hydroxyl radical, ALT, and LDH (P < .001) in the I/R-induced liver injury group. Ascorbic acid significantly attenuated the reperfusion liver injury by attenuating hydroxyl radical (P < .01) and NO (P < .05) release. The LB aggravated I/R-induced liver injury by increasing hydroxyl radical release with no effect on NO release.. This I/R protocol resulted in oxidative and nitrosative stress and liver injury. Ascorbic acid showed significant protective effects on reperfusion liver injury by attenuating hydroxyl radical and NO release. In contrast, LB aggravated liver injury by increasing hydroxyl radical release.

Topics: Alanine Transaminase; Animals; Antioxidants; Ascorbic Acid; Hydroxyl Radical; L-Lactate Dehydrogenase; Lycium; Male; Methylguanidine; Oxidative Stress; Plant Extracts; Rats; Rats, Sprague-Dawley; Reperfusion Injury

To investigate the effect of vitamin C (VC) on visceral lipid oxidative injury during oral fluid resuscitation of burn shock.. Twelve male Beagle dogs were surgically prepared for arterial and venous cannulation, and 24 hours later they were subjected to a 50% TBSA full-thickness flame injury. In the first 24 hours after burn dogs were resuscitated with gastric infusion of either glucose-electrolyte solution (GES group, n = 6) or GES containing 250 mg/kg of VC (GES/VC group, n = 6). The delivery rate and volume of GES was in accordance with that of Parkland formula (4 ml x kg(-1) x 1% TBSA(-1) in the first 24 hours). In the second 24 hours all animals received delayed i.v. fluid resuscitation. At end of 72 hours after injury, animals were sacrificed, and specimens of heart, lung, liver, kidney and jejunum were harvested for evaluation of xanthine oxidase (XOD), malondialdehyde (MDA) and assessment of the tissue water content (ratio of dry to wet weight) of organs. The plasma levels of alanine aminotransferase (ALT), creatinine (Cr), MB isoenzyme of creatine kinase (CK-MB) and diamine oxidase (DAO) were determined at same time.. At 72 hours after burn it was showed significant higher activities of XOD in GES/CAR than GES group in heart, kidney and jejunum, and lower contents of MDA in heart, lung, liver, kidney and jejunum (P all < 0.01). Tissue water contents were significantly lower in GES/CAR than GES group in heart [(75.4 +/-1.1)% vs (78.5 +/- 0.8)%], lung [(68.1 +/- 0.9)% vs (73.9 +/- 1.0)%], liver [ (75.2 +/- 0.8)% vs (78.3 +/- 1.2)%], kidney [(73.8 +/- 1.1)% vs (78.1 +/- 0.8)%] and jejunum [(76.3 +/- 0.8)% vs ( 80.4 +/- 0.6)] respectively, all P < 0.01. The levels of ALT, CK-MB, Cr and DAO in GES/CAR group were (46.6 +/- 2.49) U/L, (43.4 +/- 7.05) mol/L, (7156 +/- 596) U/L and (1.86 +/- 0.45) U/L respectively, all significantly lower than those of the GES group [(86.9 +/- 7.89) U/L, (95.2 +/- 1.23) mol/L, (8023 +/- 384) U/L and (2.68 +/- 0.61) U/L respectively, all P < 0.05].. The results indicated that vitamin C alleviated visceral tissue edema and organ injury by inhibiting free radical production during oral fluid resuscitation of burn shock.

Topics: Animals; Ascorbic Acid; Burns; Dogs; Fluid Therapy; Male; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Shock

To investigate the effect of vitamin C (VC) on alleviating peroxidative damage in gut of dogs during enteral fluid resuscitation of severe burn shock.. Eighteen male Beagle dogs were subjected to 50% total body surface area (TBSA) full-thickness burn 24 hours after duodenostomy and cannulation of cervical artery and vein. The dogs were divided into no resuscitation (NR) group (no treatment after burn), enteral resuscitation (ER) group, and ER+VC group according to the random number table, with 6 dogs in each group. Dogs in ER and ER+VC groups were respectively infused with glucose-electrolyte solution (GES) and GES containing 250 mg/kg VC through duodenostomy tube 30 minutes after burn. The infusion rate and volume of GES were in accordance with Parkland formula. Venous blood of dogs was drawn before (0) and at 2, 4, 6, and 8 post burn hours (PBH) to determine the activity of diamine oxidase (DAO) in plasma. Dogs were sacrificed at PBH 8 to collect specimens of jejunum tissue for determining the content of malondialdehyde (MDA), and activity of myeloperoxidase (MPO), xanthine oxidase (XOD) and superoxide dismutase (SOD), and assessment of the water ratio of intestinal tissue by dry-wet weight method.. 50% TBSA burn injury resulted in significant elevation of DAO in every group. The activity of DAO in ER group was obviously higher than that in NR group at PBH 6 and 8 (P < 0.05), but DAO activity in ER+VC group was significantly lower than those in the other two groups after PBH 2 (P < 0.05 or P < 0.01). MDA content, MPO and XOD activity and the water ratio of intestinal tissue [(5.74 +/- 0.51) nmol/mg, (2.08 +/- 0.46) U/g, (58.4 +/- 3.8) U/mg, (81.5 +/- 1.8)%] in ER group at PBH 8 was respectively significantly higher than that in NR group [(5.43 +/- 0.25) nmol/mg, (1.55 +/- 0.21) U/g, (50.1 +/- 2.8) U/mg, (78.3 +/- 1.5)%, P < 0.05 or P < 0.01]. While the activity of SOD in ER group (72 +/- 12) U/mg was lower than that in NR group (97 +/- 20) U/mg. MDA content, MPO and XOD activity and water ratio of intestinal tissue in ER+VC group was respectively lower than that in ER group, with activity of SOD in the former group higher than that in the latter group (P < 0.01).. Vitamin C can alleviate peroxidative damage and tissue edema in gut induced by ischemia and reperfusion, and intestinal complications during oral rehydration during burn shock can be reduced.

Topics: Animals; Ascorbic Acid; Burns; Dogs; Fluid Therapy; Intestine, Small; Male; Oxidative Stress; Reactive Oxygen Species; Reperfusion Injury; Shock

Oxidative stress, which has been generated during reperfusion after a liver transplant, has been implicated in the higher rates of postoperative organ dysfunction. The aim of this study was to examine the effect of ascorbic acid on reperfusion injury after hepatic cold preservation. Isolated perfused rat livers were preserved in a University of Wisconsin solution for 30 h at 4 degrees C. The bile output was significantly lower after cold ischemia/reperfusion. In contrast, the portal pressure, lactate dehydrogenase and purine nucleoside phosphorylase activities were elevated by cold ischemia/reperfusion. These changes were attenuated at ascorbic acid concentrations of 0.25 and 0.5 mM. However, they were augmented at a concentration of 2 mM. Cold ischemia/reperfusion decreased the reduced to oxidized glutathione ratio, whereas it increased the level of lipid peroxidation and mitochondrial swelling. These changes were prevented exposing the liver to 0.5 mM ascorbic acid but were augmented at 2 mM ascorbic acid. These results suggest that cold ischemia/reperfusion injury is associated with a higher level of oxidative stress and ascorbic acid may act not only as an antioxidant but also as a prooxidant during cold ischemia/reperfusion.

Topics: Animals; Antioxidants; Ascorbic Acid; Bile; Cold Ischemia; Glutathione; Glutathione Disulfide; In Vitro Techniques; L-Lactate Dehydrogenase; Lipid Peroxidation; Liver; Male; Malondialdehyde; Mitochondrial Swelling; Models, Animal; Oxidants; Portal Pressure; Purine-Nucleoside Phosphorylase; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Time Factors

Information on the change in extracellular ascorbic acid (AA) during the acute period of cerebral ischemia is of great importance in the early therapeutic intervention of the cerebral ischemic injury since AA is known to be involved into most kinds of neurochemical changes in the cerebral ischemia. This study describes a fast and efficient method through integration of in vivo microdialysis with on-line electrochemical detection for continuous monitoring cerebral AA, allowing comparative study of the change in the extracellular AA level in different brain ischemia/reperfusion models. The method exhibits a high specificity for AA measurements, bearing a good tolerance against the fluctuation in the brain anoxia and acidity induced by cerebral ischemia/reperfusion. In the global two-vessel occlusion (2-VO) ischemia model, the striatum AA did not change with statistic significance until 60 min after occlusion and was decreased to be 91+/-3% (n=5, P<0.05) of the basal level (8.05+/-0.23 microM) at the time point of 60 min after occlusion. In the 2-VO ischemia/reperfusion model, AA remained unchanged during the 10 min of ischemia, and was sharply increased to be 267+/-74% (n=5, P<0.05) of the basal level after the initial 15 min of reperfusion, and then decreased to be 122+/-33% (n=5, P<0.05) of the basal level after 50 min of reperfusion. Extracellular AA was largely increased after 5 min of left middle cerebral artery occlusion (LMCAO) and was then gradually increased to be 257+/-49% (n=5, P<0.05) of the basal level after 60 min of LMCAO ischemia. In the LMCAO ischemia/reperfusion model, AA was greatly increased during 10 min of ischemia and then gradually increased to be 309+/-69% (n=5, P<0.05) of the basal level after the consecutive 50 min of reperfusion. The results demonstrated here may be useful for understanding the neurochemical processes in the acute period of cerebral ischemia and could thus be important for neuroprotective therapeutics for cerebral ischemic injury.

Topics: Animals; Ascorbic Acid; Brain; Corpus Striatum; Disease Models, Animal; Electrochemistry; Extracellular Fluid; Hydrogen-Ion Concentration; Hypoxia-Ischemia, Brain; Infarction, Middle Cerebral Artery; Male; Microdialysis; Neurochemistry; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Processing, Computer-Assisted; Time Factors

Despite recent discoveries of molecules in podocytes, the mechanisms behind most conditions of proteinuria are still poorly understood. To understand more about this delicate barrier, we studied the functional and morphological effects of mild (15 min) renal ischemia-reperfusion injury (IRI). Renal function was studied in rats in vivo, followed by a more detailed analysis of the glomerular barrier in cooled (8 degrees C) isolated perfused kidneys (cIPK). Renal blood flow was quickly restored, whereas the glomerular filtration rate remained halved 30 min after IRI. Tubular cell activity was intact as judged from the unaffected Cr-EDTA U/P concentration ratio. In vivo, the fractional clearance (theta) for albumin increased 16 times. In rats subjected to cIPK starting 30 min after in vivo IRI, theta(albumin) was 15 times and theta(Ficoll_36angstroms) 1.8 times higher than in control cIPKs. According to the heterogeneous charged fiber model, IRI reduced the fiber charge density to 38% of control (P < 0.01, n = 7). Morphometric analysis with electron microscopy did not reveal any changes in the podocytes or the glomerular basement membrane (GBM) after IRI, suggesting more subtle changes of the GBM and/or the endothelial glycocalyx. We conclude that mild renal IRI induces formation of reactive oxygen species, massive proteinuria, and loss of charged fibers with no apparent change in morphology. These novel findings stress the importance of other components of the barrier, such as proteoglycans produced by the glomerular cells, and provide a tentative explanation for the mechanisms behind proteinuria in glomerulonephritis, for example.

Topics: Albumins; Animals; Ascorbic Acid; Blood Pressure; Capillary Permeability; Edetic Acid; Female; Glomerular Filtration Rate; Kidney Diseases; Kidney Glomerulus; Membranes, Artificial; Microscopy, Electron; Oxidative Stress; Proteoglycans; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Serum Albumin, Radio-Iodinated

Abdominal aortic surgery can cause ischemic/reperfusion (I/R) injury in not only the lower extremities, but also in the remote organs and tissues such as lungs, kidneys, heart, and liver during abdominal aortic surgery. It can result in mortality and morbidity because of the remote organ injury in early postoperative period. In this study, we investigate the effects of iloprost and vitamin C on the kidney remote organ damage after I/R following abdominal aortic surgery.. Thirty-four adult male Wistar rats were used and divided into five groups. I/R was studied infrarenally in the abdominal aorta following a median laparotomy. The left kidney was excised immediately following the laparotomy in group I (n = 6, normal group). Group II (n = 6) was the sham group. Group III (n = 6, control group) was subjected to 3 h of ischemia followed by an hour of reperfusion. Group IV (n = 8) was given iloprost 20 ng/kg/min during I/R period before aortic-clamping. Group V (n = 8) was given vitamin C 100 mg/kg during I/R period before aortic-clamping. Arterial blood samples were obtained to determine the levels of blood pH, pO(2) (mmHg), pCO2 (mmHg), HCO(3) (mmol/L), and plasma malondialdehyde (MDA, nmol/mL) at the end of reperfusion period in all groups. The left kidneys were used for remote measurements of tissue MDA (nmol/g.w.t) and scored by histopathological examination for acute inflammation.. While the arterial blood pO(2) and HCO(3) levels significantly increased, the plasma and renal parenchymal MDA levels significantly decreased in both group IV and group V when compared to group III (P < 0.05). Histopathological and acute inflammation scores statistically decreased in both group IV and V compared with group III (P < 0.05). Although MDA levels, histopathologic and acute inflammation scores in group V were lower than group IV, the differences were not statistically significant (P > 0.05).. Both iloprost and vitamin C decreased remote organ damage on the kidney after I/R of lower extremities in the rat model. However, vitamin C is more effective than iloprost in preventing postoperative renal dysfunction.

Topics: Animals; Antioxidants; Aorta, Abdominal; Ascorbic Acid; Atrophy; Carbon Dioxide; Hindlimb; Iloprost; Kidney; Kidney Diseases; Male; Malondialdehyde; Oxygen; Rats; Rats, Wistar; Reperfusion Injury; Vasodilator Agents

This study examined the in vivo effects of ischemic preconditioning (IPC), ascorbic acid (AA), or a combination (IPC + AA) on the level of mitochondrial injury caused by hepatic ischemia/reperfusion (I/R).. A rat liver was preconditioned with 10 min of ischemia followed by 10 min of reperfusion, and then subjected to 90 min of ischemia followed by 5 h of reperfusion. The rats were pretreated with AA (100 mg/kg, i.v.) 5 min before the sustained ischemia.. I/R increased the aminotransferase activity and level of mitochondrial lipid peroxidation, whereas it decreased the reduced glutathione:oxidized glutathione ratio. Either the IPC or AA pretreatment alone attenuated these changes, with the effect being enhanced by IPC + AA. The level of mitochondrial glutamate dehydrogenase, which is specifically located in the matrix, decreased after I/R but this was prevented by IPC + AA. Significant peroxide production was observed after 10 min of reperfusion after sustained ischemia. This change was attenuated by either IPC or AA alone and was further attenuated by IPC + AA. The mitochondria isolated after I/R were rapidly swollen, indicating an opening of the permeability transition pore. However, this was markedly reduced by IPC + AA. The hepatic ATP level was lower after I/R, which was restored by IPC alone and IPC + AA.. Our findings suggest that IPC and AA synergistically reduce the level of mitochondrial damage during I/R as a result of decreased postischemic oxidant stress.

Topics: Alanine Transaminase; Animals; Antioxidants; Ascorbic Acid; Aspartate Aminotransferases; Energy Metabolism; Glutamate Dehydrogenase; Glutathione; Ischemic Preconditioning; Liver; Male; Malondialdehyde; Mitochondria, Liver; Oxidative Stress; Peroxides; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury

Increasing evidence has shown that reactive oxygen species (ROS) are important mediators in liver ischemia/reperfusion injury(IRI). ROS include hydrogen peroxide (H(2)O(2)), superoxide anion (O(-2)), and hydroxyl radical (HO(-)), which may be generated by activated Kupffer cells in the liver, contributing to reperfusion injury. Hepatic IRI is a multistep process that damages liver graft function. To establish a series of therapeutic strategies to improve the outcome of liver transplantation, a good understanding of the mechanisms of IRI is essential. However, the detail mechanisms of how ROS lead to hepatocyte damage in IRI remains unclear. The aim of this review was to describe recent developments in the field of oxidative stress research. The first part of this review focused on the key roles and possible mechanisms of ROS in hepatic IRI. The second part of this review summarizes some findings including novel and classic antioxidant methods to ameliorate the hepatocyte damage during IRI.

Topics: Antioxidants; Ascorbic Acid; Free Radical Scavengers; Glutathione Peroxidase; Humans; Ischemic Preconditioning; Liver Circulation; Liver Failure; Liver Transplantation; Peroxidases; Peroxiredoxins; Reactive Oxygen Species; Reperfusion Injury; Thioredoxins

Ascorbic acid has shown promise in attenuation of intestinal ischemia-reperfusion (I/R) injury. The aim of this study was to determine the protective effects of ascorbic acid on intestinal morphology during IR injury in rats.. We examined morphological changes in the small intestine of Wistar rats after (i) 40 minutes of ischemia (I), (ii) ischemia followed by 30 min of reperfusion (IR), (iii) ischemia with ascorbic acid (IA), (iv) ischemia followed by reperfusion and ascorbic acid (IRA) and (v) in a sham group (S). We used morphometry to evaluate the amount of villous architecture, crypts, necrosis, hemorrhagic infarcts and inflammatory cells at the mesenteric and antimesenteric borders of the small intestine.. Ascorbic acid caused a significant reduction of antimesenteric villous hemorrhagic infarction (p<0.05) of the small intestine after ischemia followed by reperfusion as well as villous necrosis reduction at both borders after ischemia (p<0.05). The lesions found in the small intestine were more prominent along the antimesenteric margin.. Ascorbic acid pretreatment has a protective effect against the intestinal morphological lesions induced by ischemia-reperfusion injury in rats.

Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Intestine, Small; Male; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

The aim of this study was to investigate the protective effects of erdosteine and vitamins C and E (VCE) on the lungs after performing hind limb ischemia-reperfusion (I/R) by assessing oxidative stress, plasma copper (Cu), and zinc (Zn) analysis. The animals were divided randomly into four groups as nine rats each as follows: control, I/R, I/R plus erdosteine, and I/R plus VCE combination. I/R period for 60 min was performed on the both hind limbs of all the rats in the groups of I/R, erdosteine with I/R, VCE with I/R allowing 120 min of reperfusion. The animals received orally erdosteine one time in a day and 3 days before I/R in the erdosteine group. In the VCE group, the animals VCE combination received one time in a day and 3 days before I/R, although placebo was given to control and I/R group animals. Lung lipid peroxidation (malondialdehyde [MDA]) level, superoxide dismutase (SOD), and catalase activities were increased, although lung glutathione (GSH) and plasma Zn levels decreased in I/R group in lung tissue compared with the control group. Serum MDA level, creatine kinase, and lactate dehydrogenase activities were increased in I/R group compared with the control. Lung MDA and plasma Zn levels and lung SOD activity were decreased by erdosteine administration, whereas lung GSH levels after I/R increased. The plasma Zn levels and lung SOD activity were decreased by VCE administration, although the plasma Cu and lung GSH levels increased after I/R. In conclusion, erdosteine has an antioxidant role on the values in the rat model, and it has more protective affect than in VCE in attenuating I/R-induced lung injury in rats.

Topics: Animals; Antioxidants; Ascorbic Acid; Copper; Creatine Kinase; Expectorants; Glutathione; L-Lactate Dehydrogenase; Lower Extremity; Lung; Male; Malondialdehyde; Oxidative Stress; Protective Agents; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thioglycolates; Thiophenes; Vitamin E; Zinc

Topics: Animals; Ascorbic Acid; Brain Ischemia; Glutamic Acid; Hippocampus; Male; Propofol; Rats; Rats, Wistar; Reperfusion Injury

The objectives of this study were to compare the protective effects of ascorbic acid and iloprost on lung injury caused by ischemia reperfusion (I/R) of the lower extremities of rats. Wistar albino rats (n = 34) were divided into five groups. In the I/R group (n = 6), the aorta was cross-clamped for 3 hr, followed by 1 hr of reperfusion. In the vitamin C group (n = 8), animals were pretreated with 100 mg/kg ascorbic acid via the left jugular vein before aortic cross-clamping. In the iloprost group (n = 8), animals were pretreated with 20 ng/(kg x min) iloprost by constant intravenous infusion via the left jugular venous cannula. In the sham group (n = 6), the abdomen was left open at the same period and a juguler venous line was established. In the control group (n = 6), lungs were removed and blood samples taken immediately after sternotomy. No treatment was given in this group. After both lungs were removed, biochemical parameters were measured and histopathological evaluation was made. Although the arterial blood pO2 and HCO3 levels were statistically significantly high in both the vitamin C and iloprost groups compared to the I/R group, plasma malondialdehyde (MDA) levels were significantly low. Meanwhile, the MDA levels in the lung tissue were significantly low in the vitamin C group compared to the I/R group. The MDA level in the lung tissue in the iloprost group was also low compared to the I/R group, but it was not statistically significant. The lungs of the I/R group displayed intense interstitial leukocytic infiltration in histopathological examination compared to the other groups. Pretreatment of animals with iloprost and vitamin C significantly decreased the pulmonary injury characterized by decreased plasma leukocyte sequestration. The results suggest that both vitamin C and iloprost are useful agents for attenuating the lung injury caused by increased oxidative stress and neutrophil accumulation after a period of I/R of the lower extremities.

Topics: Animals; Aorta, Abdominal; Ascorbic Acid; Constriction; Disease Models, Animal; Free Radical Scavengers; Iloprost; Lipid Peroxidation; Lung; Neutrophils; Platelet Aggregation Inhibitors; Pulmonary Edema; Rats; Rats, Wistar; Reperfusion Injury

Renal ischemia as a course of renal transplantation is a common cause of renal dysfunction as renal failure. The purpose of this study was to investigate the influence of ascorbic acid on blood urea nitrogen (BUN), creatinine (Cr) and resistive index (RI) for dog models with renal ischemia-reperfusion (I/R) injury. Renal ischemia was induced on 6 Beagle dogs. The left kidney was exposed to normothermic ischemia for a short period at 30 min followed by reperfusion. On the blood Cr level and RI, there was no significant difference comparing both groups. 14 days after I/R injury a significant reduction on the blood BUN level was observed in the vehicle group (34.06 mg/dl) compared to that of ischemia induced treated group (10.3 mg/dl) (p < 0.05). In conclusion, administration of ascorbic acid for renal ischemic-reperfusion injury had influence on blood BUN level, but it was not revealed the influence on blood Cr and RI.

Topics: Animals; Antioxidants; Ascorbic Acid; Blood Urea Nitrogen; Creatinine; Dog Diseases; Dogs; Kidney Diseases; Male; Random Allocation; Reperfusion Injury; Ultrasonography, Doppler, Color

It has not been completely demonstrated if hypertension may, in part, develop as a result of increased oxidative stress (OS), inflammation and little is known about the short-term effects of antioxidant therapy. This study was designed to appreciate the effect of 7 days vitamin C-enriched diet (5 g/kg/day) on hemodynamic function and vascular OS in normotensive Wistar Kyoto rats and hypertensive rats (SHR). Aorta NAD(P)H oxidase activity was determinate and free radicals evaluated by electron spin resonance with a spin probe CP-H. Matrix metalloproteinase-1 (MMP-1) and monocyte chemoattractant protein-1 (MCP-1) expression were measured. The treatment with vitamin C did not change arterial pressure in SHR but prevented the increase in OS levels in SHR aortas. MMP-1 and MCP-1 expressions were more intense in the media of SHR aortas than in those of WKY rats but these expressions were not modified by vitamin C-pretreatment. Vitamin C-pretreatment was not able to protect heart against in vitro ischemia-reperfusion dysfunctions. These data may suggest that treatment with high doses of vitamin C in SHR can limit over-production of reactive oxygen species; however this effect was not accompanied with changes in arterial pressure and protection against I-R dysfunctions. Dissociation between vascular oxidative stress and cardiovascular function may be evoked.

Topics: Animals; Antioxidants; Aorta; Ascorbic Acid; Blood Pressure; Chemokine CCL2; Heart; Hypertension; Male; Matrix Metalloproteinase 1; NADPH Oxidases; Organ Culture Techniques; Oxidative Stress; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Reperfusion Injury; Time Factors

Oxidative damage has been implicated in the pathogenesis of cerebral ischemia. We previously demonstrated that exogenously supplied dehydroascorbic acid (DHA), an oxidized, blood-brain barrier transportable form of the antioxidant ascorbic acid (AA), improves outcome after experimental stroke.. To investigate the neuroprotective effect of DHA therapy, we measured cerebral AA levels using a novel assay, quantified markers of lipid peroxidation, and evaluated infarct volume after reperfused stroke in a murine model. All experiments were performed using a new citrate/sorbitol-stabilized DHA formulation to improve the stability of the compound.. Intraparenchymal AA levels declined after cerebral ischemia/reperfusion and were repleted in a dose-dependent fashion by postischemic administration of intravenous DHA (P < 0.01). Repletion of these levels was associated with reductions in cerebral malondialdehyde levels (P < 0.05), which were also elevated after reperfused stroke. DHA repletion of interstitial AA levels and reduction in cerebral lipid peroxidation was associated with dose-dependent reductions in infarct volume (P < 0.05).. Together, these results indicate that an intravenous cerebroprotective dose of citrate/sorbitol-stabilized DHA is correlated with increased brain ascorbate levels and a suppression of excessive oxidative metabolism.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Citric Acid; Dehydroascorbic Acid; Disease Models, Animal; Excipients; Infarction, Middle Cerebral Artery; Injections, Intravenous; Lipid Peroxidation; Mice; Mice, Inbred C57BL; Nerve Degeneration; Neuroprotective Agents; Oxidative Stress; Reperfusion Injury; Sorbitol; Treatment Outcome; Up-Regulation

This study examined the effects of ascorbic acid on the attenuation of an ischemia-reperfusion (I/R) injury after a canine renal transplantation. Eight beagle dogs were subjected to a renal auto-transplantation followed by the administration of ascorbic acid (treatment group) and the same amount of vehicle (physiological saline, control group). Blood samples were collected from these dogs to perform the kidney function tests and the invasive blood pressure was measured in the renal artery at pre- and post-anastomosis. The antioxidant enzymes of level 72 h after the transplant were measured. The kidneys were taken for a histopathology evaluation at day 21. The kidney function tests showed a significant difference between the control and treatment group. The invasive blood pressure in the renal artery was similar in the groups. The activity of the antioxidant enzymes in the blood plasma was significant lower in the control group than in the treatment group. The histopathology findings revealed the treatment group to have less damage than the control group. The results of this study suggest that ascorbic acid alone might play a role in attenuating I/R injury and assist in the recovery of the renal function in a renal transplantation model.

Topics: Animals; Ascorbic Acid; Blood Pressure; Blood Urea Nitrogen; Catalase; Creatinine; Dog Diseases; Dogs; Female; Free Radical Scavengers; Glutathione Peroxidase; Histocytochemistry; Kidney Transplantation; Male; Random Allocation; Reperfusion Injury; Superoxide Dismutase

The 22 supersetnd Hohenheim Consensus Workshop took place in at the University of Stuttgart-Hohenheim. The subject of this conference was vitamin C and its role in the treatment of endothelial dysfunction. Scientists, who had published and reviewed scientific and regulatory papers on that topic were invited, among them basic researchers, toxicologists, clinicians and nutritionists. The participants were presented with eleven questions, which were discussed and answered at the workshop, with the aim of summarising the current state of knowledge. The explicatory text accompanying the short answers was produced and agreed on after the conference and was backed up by corresponding references. The therapeutic relevance of administration of the physiological antioxidant vitamin C in high parenteral doses in Endothelial Dependent Pathophysiological Conditions (EDPC) was discussed. Endothelial dysfunction is defined as including disturbed endothelial dependant relaxation of resistance vessels, breakdown of the microvascular endothelial barrier and/or loss of anti-adhesive function. It occurs in severe burn injury, intoxications, acute hyperglycemia, sepsis, trauma, and ischemic-reperfusion tissue injury and is induced by oxidative stress. Reduced plasma ascorbate levels are a hallmark of oxidative stress and occur in severe burns, sepsis, severe trauma, intoxication, chemotherapy/radiotherapy and organ transplantation. Vitamin C directly enhances the activity of nitric oxide synthase, the acyl CoA oxidase system and inhibits the actions of proinflammatory lipids. There is experimental evidence that parenteral high-dose vitamin C restores endothelial function in sepsis. In vitro, supraphysiological concentrations (> 1mM) of ascorbate restore nitric oxide bioavailability and endothelial function. Only parenterally, can enough vitamin C be administered to combat oxidative stress. There is no evidence that parenteral vitamin C exerts prooxidant effects in humans. Theoretical concerns in relation to competitive interactions between vitamin C and glucose cellular uptake are probably only relevant for oxidised vitamin C (dehydroascorbate).

Topics: Acute Disease; Acyl-CoA Oxidase; Ascorbic Acid; Burns; Endothelium, Vascular; Glucose; Heart Failure; Humans; Hyperglycemia; Infusions, Parenteral; Myocardial Ischemia; Nitric Oxide Synthase Type III; Oxidative Stress; Poisoning; Reperfusion Injury; Sepsis

Oxidative stress plays an important role in liver ischemia/reperfusion (I/R) injury. Thus, enhancing the liver antioxidant capacity could be a promising therapeutic strategy. Ascorbate (AA) is considered the perfect antioxidant, but its therapeutic efficacy is greatly limited by its slow achievement of high intracellular levels. This might be circumvented by administering dehydroascorbate (DHA), which presents a several-fold greater uptake than AA, and undergoes rapid intracellular reduction to AA. Thus, our aim was to assess the protective role of DHA in liver I/R injury.. Wistar rats (200-300 g bw) were pretreated iv with different doses of AA or DHA 20 min before liver ischemia, followed by 6 h reperfusion. Liver damage was assessed by biochemical and morphological indices.. DHA pretreatment induced a rapid increase in liver ascorbate levels, significantly higher than findings for AA, without any significant reduction in glutathione levels. Liver damage during I/R in controls showed significant increases in serum transaminases and hepatic thiobarbituric acid reactive substances with alterations of liver morphology. DHA administration induced a clear, significant protection against I/R injury, whereas liver damage was only moderately prevented by AA.. DHA might represent a simple, effective therapeutic option to prevent liver damage associated with ischemia/reperfusion.

Topics: Animals; Antioxidants; Ascorbic Acid; Dehydroascorbic Acid; Glutathione; Liver; Male; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Thiobarbituric Acid Reactive Substances

Low molecular weight antioxidants (LMWA), which reflect tissue reducing power, are among the endogenous mechanisms for neutralizing reactive oxygen species (ROS). Ischemic preconditioning (IPC) was associated with decreased oxidative stress. We examined the effect of focal ischemia on LMWA and on prostaglandin E(2) (PGE(2), a product of arachidonic acid oxidation) in the brain, heart, liver, and lungs of rats subjected to 90 min of ischemia and in IPC rats subjected to similar insult.. Transient right middle cerebral artery occlusion (MCAO) was performed for 90 min and at 0, 5, 30, 60, or 240 min of reperfusion, LMWA and PGE(2) were evaluated by cyclic voltametry (CV) and radioimmunoassay, respectively. IPC was induced by 2 min of MCAO, 24 h prior to the major ischemic episode.. LMWA decreased at 5 min of reperfusion in the brain, heart, liver, and lung and rose 4 h later only in the brain. PGE(2) levels increased three to fivefold in all tissues examined. Surprisingly, in IPC rats a dramatic increase of LMWA occurred at 5 min of reperfusion in the brain and in the peripheral organs. Uric acid, but not ascorbic, is the major LMWA increased.. We propose that after ischemia, ROS rapidly consume the antioxidants reserves in the brain and also in peripheral organs, suggesting that the whole body is under oxidative stress. Moreover, part of the neuroprotection afforded by IPC is mediated by the brain's ability to mobilize antioxidants, especially uric acid, that attenuate the massive ROS-mediated oxidative stress.

Topics: Animals; Antioxidants; Arachidonic Acid; Ascorbic Acid; Brain; Brain Ischemia; Dinoprostone; Disease Models, Animal; Free Radicals; Ischemic Preconditioning; Liver; Lung; Male; Myocardium; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Up-Regulation; Uric Acid

Free radicals seem to be involved in the development of cerebral white matter damage after asphyxia in the premature infant. The immature brain may be at increased risk of free radical mediated injury, as particularly the preterm infant has a relative deficiency in brain antioxidants systems, such as superoxide dismutase and glutathione peroxidase. In vitro studies show that immature oligodendrocytes express an intrinsic vulnerability to reactive oxygen species and free radical scavengers are able to protect immature oligodendrocytes from injury. The aim of this study was to examine the formation of ascorbyl radicals as a marker of oxidative stress in the preterm brain in association with cerebral white matter injury after intrauterine asphyxia. Fetal sheep at 0.65 gestation were chronically instrumented with vascular catheters and an occluder cuff around the umbilical cord. A microdialysis probe was placed in the periventricular white matter. Fetal asphyxia was induced by occlusion of the umbilical cord for 25 min (n = 10). Microdialysis samples were collected for 72 h and analyzed for ascorbyl radicals using electron spin resonance. Five instrumented fetuses served as controls. Three days after the insult, fetal brains were examined for morphologic injury. Umbilical cord occlusion resulted in prolonged and marked increase in ascorbyl radical production in the brain in connection with white matter injury, with activation of microglia cells in periventricular white matter and axonal injury. These data suggest that reperfusion injury following asphyxia in the immature brain is associated with marked free radical production.

Topics: Animals; Antioxidants; Ascorbic Acid; Asphyxia; Brain; Dehydroascorbic Acid; Electron Spin Resonance Spectroscopy; Female; Free Radicals; Glucose; Glutathione Peroxidase; Lactic Acid; Lectins; Oxygen; Pregnancy; Pregnancy, Animal; Reactive Oxygen Species; Regression Analysis; Reperfusion Injury; Risk; Sheep; Superoxide Dismutase; Time Factors

We have shown that acrolein, a lipid peroxidation byproduct, can inflict significant damage in isolated spinal cord white matter following oxygen glucose deprivation (OGD). The mechanism of such acrolein-induced damage is unclear. The aim of this study was to examine whether glutathione (GSH) and ascorbic acid, two reactive oxygen species (ROS) scavengers, can alleviate functional and anatomical damage due to acrolein.. We used an OGD injury model with isolated guinea pig spinal cord white matter. Sucrose gap recording was used to monitor axonal impulse conduction, and a horseradish peroxidase exclusion test was employed to determine membrane integrity. The functional and anatomical parameters were compared in three groups: acrolein, acrolein/GSH and acrolein/ascorbic acid.. We found that while GSH resulted in an 87% recovery of compound action potential conductance, ascorbic acid produced a 97% recovery, compared with a 69% recovery in an injured group without treatment. It is noted that GSH, and to a lesser extent ascorbic acid, preferentially enhanced functional recovery in smaller axons.. Acrolein-induced neuronal damage is likely mediated by ROS. Furthermore, GSH and ascorbic acid are effective in suppressing acrolein and free radical-induced injury in spinal cord white matter.

Topics: Acrolein; Action Potentials; Animals; Antioxidants; Ascorbic Acid; Axons; Female; Free Radical Scavengers; Glucose; Glutathione; Guinea Pigs; Histocytochemistry; Horseradish Peroxidase; Ischemia; Perfusion; Reperfusion Injury; Spinal Cord Ischemia

Reperfusion injury, caused by free oxygen radicals, is a chain of events that occurs in tissues exposed to a constant period of ischemia. The antioxidant vitamins E and C (VEC) and hyperbaric oxygenation (HBO) have beneficial effects in treating ischemic tissues following skin flap operations. In our study, we aimed to compare the effects of VEC and/or HBO in ischemia-reperfusion injury induced by free oxygen radicals in an experimental rat epigastric island skin-flap model. Eight hours of ischemia was provided by clamping the inferior epigastric pedicle following the flap elevation. The flap survey was determined to be 28.6% in controls, 59.2% in HBO group, 66.3% in VEC + HBO group, and 82% in VEC group (p < 0.05). We conclude that although HBO and/or VEC increased the flap viability significantly by reducing ischemia-reperfusion injury, the most promising results were obtained in the antioxidant vitamins group.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Ascorbic Acid; Female; Hyperbaric Oxygenation; Lipid Peroxidation; Oxygen; Oxygen Consumption; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Surgical Flaps; Vitamin E; Vitamins

Topics: Animals; Ascorbic Acid; Liver; Microscopy, Electron; Models, Animal; Organ Preservation; Rats; Rats, Wistar; Reperfusion Injury

Distribution of ascorbate into tissues is an essential process in ascorbate antioxidant defense. Hibernating animals are studied as a model of tolerance to ischemia-reperfusion because of their tolerance to fluctuations in blood flow associated with prolonged torpor and periodic arousal episodes. Throughout hibernation, plasma ascorbate concentration ([Asc](p)) repetitively increases during torpor, then falls during periodic arousal bouts. We previously proposed that high [Asc](p) provides a ready source of antioxidant protection for distribution to the central nervous system and peripheral tissues during arousal. Here we tested whether deliberate oxidation of plasma ascorbate by intravenous administration of ascorbate oxidase (AO), prior to arousal, compromised tissue levels of ascorbate or the other water-soluble antioxidants, glutathione (GSH) and urate. Although AO decreased [Asc](p) to below the level of detection during torpor and after arousal, ascorbate oxidation did not decrease post-arousal tissue levels of reduced ascorbate, glutathione, or urate in any tissue examined, except liver. The data imply that ascorbate is taken up equally well into brain and other tissues as either ascorbate or its oxidized product dehydroascorbate, with subsequent intracellular reduction of dehydroascorbate. Lack of effect of ascorbate oxidation on tissue levels of GSH or urate indicates that dehydroascorbate uptake and reduction do not compromise tissue concentrations of these other water-soluble antioxidants. Thus, we show equal availability of reduced and oxidized plasma ascorbate during metabolically demanding thermogenesis and reperfusion associated with arousal from hibernation.

Topics: Animals; Antioxidants; Ascorbate Oxidase; Ascorbic Acid; Brain; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Free Radicals; Glutathione; Hibernation; Oxidation-Reduction; Oxygen; Reperfusion Injury; Sciuridae; Temperature; Time Factors; Tissue Distribution; Uric Acid

The aim of this study was to ascertain the possibility of diminishing ischemia-reperfusion injury by intravenous application of the chosen antioxidants: vitamin C, mannitol, and N-acetylcysteine.. The study was performed on New Zealand Red male rabbits, which were divided into 6 groups of 8. In group 1, 5 segments of the small intestine were taken for histopathologic examination (normal intestine). In group 2, segments of the small intestine were taken for histopathologic examination after 3 hours of closure of the superior mesenteric artery (ischemic intestine). In group 3, after 3 hours of closure of the superior mesenteric artery, 1 hour of reperfusion took place. In this group, blood flow in the superior mesenteric artery was measured within the first 30 minutes, and segments of the small intestine were taken for histopathologic examination after 60 minutes of the reperfusion. In groups 4, 5, and 6 the procedure was similar to that in group 3, but additionally the rabbits were given antioxidants intravenously: in group 4, vitamin C, 250 mg/kg; in group 5, 20% mannitol, 3 mL/kg; and in group 6, N-acetylcysteine, 100 mg/kg.. All the chosen antioxidants had a beneficial influence on the blood flow in the superior mesenteric artery. The blood flow in the groups with antioxidants after 30 minutes of the reperfusion was 53% to 57% of initial values compared with 27% of initial values in group 3. In histopathologic evaluation, protective action of the antioxidants was seen in the groups with vitamin C and mannitol.. Application of the chosen antioxidants reduces injury of the rabbit small intestine caused by reperfusion after 3 hours of closure of the superior mesenteric artery.

Topics: Acetylcysteine; Animals; Antioxidants; Ascorbic Acid; Edema; Hemorrhage; Intestinal Mucosa; Intestine, Small; Ischemia; Ligation; Male; Mannitol; Mesenteric Artery, Superior; Oxidative Stress; Rabbits; Reperfusion Injury

Compartment syndrome is a unique form of ischaemia of skeletal muscle which occurs despite patency of the large vessels. Decompression allows the influx of activated leucocytes which cause further injury. Vitamin C is a powerful antioxidant which concentrates preferentially in leucocytes and attenuates reperfusion-induced muscle injury. We have evaluated the use of pretreatment with oral vitamin C in the prevention of injury caused by compartment syndrome in a rat cremasteric muscle model. Acute and delayed effects of pretreatment with vitamin C were assessed at one and 24 hours after decompression of compartment syndrome. Muscle function was assessed electrophysiologically. Vascular, cellular and tissue inflammation was assessed by staining of intercellular adhesion molecule-1 (ICAM-1) and by determination of the activity of myeloperoxidase (MPO) in neutrophils and tissue oedema. Compartment syndrome impaired skeletal muscle function and increased the expression of ICAM-1, activity of MPO and muscle weight increased significantly. Pretreatment with vitamin C preserved muscle function and reduced the expression of ICAM-1, infiltration of the neutrophils and oedema.

Topics: Administration, Oral; Animals; Ascorbic Acid; Compartment Syndromes; Edema; Intercellular Adhesion Molecule-1; Muscle, Skeletal; Peroxidase; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The maximum gene exhibition was shown to be achieved at 48 h after transfection with human bcl-2 (hbcl-2) genes built in an SV40 early promoter-based plasmid vector and HVJ-liposome for cultured rat hepatocytes. The similar procedure of hbcl-2 transfection was therefore conducted for livers in rats via the portal vein, and after 48 h followed by post-ischemic reperfusion (I/R) operation for some hepatic lobes. The I/R-induced hepatic injuries were in situ observed as both cell morphological degeneration and cellular DNA strand cleavages around capillary vessels of the ischemic liver lobes as detected by HE stain and TUNEL assay, and were biochemically observed as release of two hepatic marker enzymes AST and ALT into serum. All the I/R-induced injuries examined were appreciably repressed for rats transfected with hbcl-2; hbcl-2 was expressed in hepatocytes around the capillaries of ischemic regions such as the median lobe and the left lobe, but scarcely around those of non-ischemic regions. Thus cytoprotection against I/R-induced injuries may be attributed to the I/R-promoted expression of transferred hbcl-2 genes. The possibility was examined firstly by methylphenylindole method, which showed that I/R-enhanced lipid peroxidation in the reference vector-transfected livers were markedly repressed in the hbcl-2-transfected livers. Contents of ascorbic acid (Asc) in serum and livers of hbcl-2-transfected rats were enriched, unexpectedly, versus those of non-transfected rats, and were as abundant as 1.90-fold and 1.95- to 2.60-fold versus those in the pre-ischemic state, respectively. After I/R, an immediate decline in serum Asc occurred in hbcl-2-transfectants, and was followed by prompt restoration up to the pre-ischemic Asc levels in contrast to the unaltered lower Asc levels in non-transfectants except a transient delayed increase. Hepatic Asc contents were also diminished appreciably at the initial stage after I/R in the ischemic lobes of hbcl-2-transfectants, which however retained more abundant Asc versus non-transfectants especially at the initial I/R stage when scavenging of the oxidative stress should be most necessary for cytoprotection. The results showed a close correlation between cytoprotection by exogenously transferred hbcl-2 and repressive effects on the lipid peroxidation associated with Asc consumption or redistribution.

Topics: Animals; Antioxidants; Apoptosis; Ascorbic Acid; Cell Line; DNA Damage; Hepatocytes; Humans; In Situ Nick-End Labeling; Lipid Peroxidation; Liver; Male; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Transfection

To investigate the possible protection provided by oral quercetin pretreatment against hepatic ischemia-reperfusion injury in rats.. The quercetin (0.13 mmol/kg) was orally administrated in 50 min prior to hepatic ischemia-reperfusion injury. Ascorbic acid was also similarly administered. The hepatic content of quercetin was assayed by high performance liquid chromatography (HPLC). Plasma glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT) activities and malondialdehyde (MDA) concentration were measured as markers of hepatic ischemia-reperfusion injury. Meanwhile, hepatic content of glutathione (GSH), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and xanthine oxidase (XO), total antioxidant capacity (TAOC), contents of reactive oxygen species (ROS) and MDA, DNA fragmentation were also determined.. Hepatic content of quercetin after intragastric administration of quercetin was increased significantly. The increases in plasma GPT, GOT activities and MDA concentration after hepatic ischemia-reperfusion injury were reduced significantly by pretreatment with quercetin. Hepatic content of GSH and activities of SOD, GSH-Px and TAOC were restored remarkably while the ROS and MDA contents were significantly diminished by quercetin pretreatment after ischemia-reperfusion injury. However, quercetin pretreatment did not reduce significantly hepatic XO activity and DNA fragmentation. Ascorbic acid pretreatment had also protective effects against hepatic ischemia-reperfusion injury by restoring hepatic content of GSH, TAOC and diminishing ROS and MDA formation and DNA fragmentation.. It is indicated that quercetin can protect the liver against ischemia-reperfusion injury after oral pretreatment and the underlying mechanism is associated with improved hepatic antioxidant capacity.

Topics: Administration, Oral; Animals; Antioxidants; Ascorbic Acid; Biological Availability; Biomarkers; DNA Fragmentation; Glutathione Peroxidase; Liver; Male; Malondialdehyde; Quercetin; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase; Transaminases; Xanthine Oxidase

Cerebral ischaemia-reperfusion injury is associated with the generation of reactive oxygen species during the early phases of reoxygenation. EPC-K1, a phosphate diester of vitamins C and E, has been reported to possess potent hydroxyl radical scavenging activity. This study was performed to investigate the effectiveness of EPC-K1 in attenuating cerebral ischaemia-reperfusion injury in a rat model of transient focal cerebral ischaemia.. We evaluated the efficacy of EPC-K1 by measuring the concentration of cerebral thiobarbituric acid reactive substances (TBARS), an indicator of the extent of lipid peroxidation by free radicals, and infarct size in rats subjected to one hour of cerebral ischaemia and 4, 24, or 72 hours of reperfusion.. EPC-K1 significantly reduced both the cerebral TBARS level and the infarct size in a rat model of transient focal cerebral ischaemia. These results indicate that EPC-K1 administration during the early stages of reperfusion ameliorates ischaemic brain injury by inhibiting lipid peroxidation.. This report is the first to describe the protective mechanism of EPC-K1 by measuring both the TBARS level and infarct size in a rat model of transient focal cerebral ischaemia, and may suggest a potential clinical approach for the treatment of ischaemic cerebrovascular disease.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain Ischemia; Disease Models, Animal; Free Radicals; Lipid Peroxidation; Male; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury; Thiobarbituric Acid Reactive Substances; Vitamin E

This study was designed to investigate the influence of intraischemic liver temperature on oxidative stress during postischemic normothermic reperfusion. In C57BL/6 mice, partial hepatic ischemia was induced for 90 min and intraischemic organ temperature adjusted to 4 degrees C, 15 degrees C, 26 degrees C, 32 degrees C, and 37 degrees C. As detected by electron spin-resonance spectroscopy, plasma/blood concentrations of hydroxyl and ascorbyl radicals were significantly increased in all groups after ischemia/reperfusion independent of the intraischemic temperature. In tissue, however, postischemic lipid peroxidation was attenuated after organ cooling down to 32 degrees C-26 degrees C and not detectable after ischemia at 15 degrees C-4 degrees C. mRNA expression of superoxide dismutase-1 and heme oxygenase-1, measured during reperfusion, was significantly elevated in the group at 37 degrees C as compared to the hypothermic groups at 4 degrees C-32 degrees C. The reduction of radical generation was associated with a prevention of adenosine monophosphate hydrolysis during ischemia in the hypothermic groups. In conclusion, ischemia-reperfusion-induced oxidative stress in the liver tissue is non-linearly-dependent on intraischemic temperature, whereas the plasma/blood concentration of radicals is not affected by organ cooling. Oxidative stress is reduced through mild hypothermia at 32 degrees C-26 degrees C and inhibited completely at 15 degrees C. Reduction of initial intracellular radical generation and prevention of secondary oxidant-induced tissue injury are possible mechanisms of this protection.

Topics: Adenosine Monophosphate; Animals; Ascorbic Acid; Disease Models, Animal; Electron Spin Resonance Spectroscopy; Female; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hydroxyl Radical; Hypothermia, Induced; Lipid Peroxidation; Liver; Membrane Proteins; Mice; Mice, Inbred C57BL; Microcirculation; Oxidative Stress; Reperfusion; Reperfusion Injury; RNA, Messenger; Superoxide Dismutase; Superoxide Dismutase-1; Temperature

To search a regimen for prevention of post-ischemic reperfusional (I/R) injuries, I/R in the liver was induced by 30-min clamping and subsequent unfastening of the portal vein of a rat, which underwent previous i.v. administration with ascorbic acid (Asc) of 1 mg/kg or the autooxidation-resistant pro-vitamin C, 2-O-alpha-D-glucosylated Asc (Asc2G) or 2-O-phosphorylated Asc (Asc2P) of 1 mg Asc equivalent/kg from the viewpoint of utilization of antioxidants that can promptly scavenge I/R-derived reactive oxygen species. The administration with Asc, Asc2P or Asc2G prevented some features of hepatic I/R injuries such as release of hepatic marker enzymes GOT and GPT into the blood vessel, cellular degenerative symptoms including vacuolation and cell fragmentation, and nuclear DNA strand cleavage as detected by TUNEL staining. The preventive effects on I/R injuries were in the order: Asc2G > Asc2P >> Asc. This order of preventive degrees of three anti-oxidants is partly attributable to proper efficiency of conversion to vitamin C and stability in blood stream; Asc2P was moderately converted to a free monoanion form of Asc in human serum, but, in rat serum, so efficiently converted to Asc as to undergo the resultant oxidative decomposition before reaching the liver, whereas Asc2G underwent scarce conversion to Asc in human serum but moderate conversion in rat serum, suggesting that Asc2P might be less cytoprotective against I/R injury than Asc2G in the rat liver in a way different from the human liver. In contrast Asc was so susceptible to autooxidation as to be rapidly decomposed in either rat or human serum. The concentrations of ascorbyl radicals (AscR) in serum were unchanged during I/R for sham-operated rats, but appreciably diminished time-dependently for I/R-operated rats as shown by ESR spectra. A marked increase in serum AscR occurred in rats receiving Asc, Asc2G or Asc2P, but it was time-dependently restored down to the pre-ischemic level of AscR in I/R-operated rats more rapidly than in sham-operated rats. Thus, hepatic I/R injuries were shown to be prevented more markedly by Asc2G or Asc2P than by Asc, which is attributable to efficiencies of both vitamin C conversion and subsequent AscR retention.

Topics: Animals; Ascorbic Acid; Cytoprotection; DNA; Electron Spin Resonance Spectroscopy; Hydrolysis; In Situ Nick-End Labeling; Liver; Male; Rats; Rats, Wistar; Reperfusion Injury; Sugar Acids

To investigate whether combined pretreatment with lipid- and water-soluble antioxidants gave better restoration of energy phosphates after ischaemia-reperfusion of rabbit kidneys than single pretreatment with a lipid-soluble antioxidant.. Thirteen New Zealand white rabbits were used for the study. Changes in energy phosphates were measured in vivo using volume-selective 31P magnetic resonance spectroscopy. The indeno-indole compound H290/51 was chosen as a lipid-soluble antioxidant and ascorbate as a water-soluble antioxidant.. The combined pretreatment led to significantly better restoration of the beta-adenosine triphosphate:inorganic phosphate ratio after 60 min of ischaemia and 120 min of reperfusion compared with the single pretreatment. Analyses of blood pressure and blood gas changes showed that the beneficial effect of combined pretreatment was not caused by a better general condition of the animals in that group but by a direct effect on the kidneys.. Combined pretreatment with lipid- and water-soluble antioxidants leads to better restoration of energy phosphates in rabbit kidneys subjected to ischaemia-reperfusion compared with single pretreatment with a lipid-soluble antioxidant.

Topics: Analysis of Variance; Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Female; Indoles; Ischemia; Kidney Diseases; Kidney Function Tests; Lipid Peroxidation; Magnetic Resonance Spectroscopy; Male; Monitoring, Physiologic; Phosphorus Isotopes; Probability; Rabbits; Random Allocation; Reperfusion Injury; Sensitivity and Specificity; Solubility

Controversy exists over whether the predominant cell death of hepatocytes is due to apoptosis or necrosis after ischemia/reperfusion injury. In this study we investigated the predominant cell death of hepatocytes after cold ischemia/reperfusion injury using the Annexin V-based assay, and evaluated the anti-apoptotic effect of ascorbic acid 2-glucoside (AA-2G) added to the University of Wisconsin solution (UW solution) in rat liver transplantation. The retrieved liver was preserved in 4 UW solution for 24 h, and then transplanted orthotopically to the syngeneic Wistar recipient. The animals were divided into 2 groups, a control group (n=10), in which liver grafts were preserved in UW solution (4), and an AA-2G group (n=10), in which liver grafts were preserved in UW solution (4) with AA-2G (100 ug/ml). The serum AST level 4 h after reperfusion in the control group was significantly suppressed in the AA-2G group, and the bile production of the liver graft in the AA-2G group was well recovered. The mean survival time in the AA-2G group was significantly improved compared with that in the control group. Annexin-V and Propidium iodide staining 4 h after reperfusion showed a significantly higher percentage of viable hepatocytes in the AA-2G group compared with the control group (93.4 +/- 2.0 vs. 80.3 +- 2.1%, P<0.05). In the control group, the main cell death of hepatocytes was apoptosis (early apoptosis: 10.0 +- 4.7%, late apoptosis: 6.4 +/- 1.7%). The addition of AA-2G to the UW solution significantly inhibited both early and late apoptotic cell death 4 h after reperfusion (early apoptosis: 0.98 +/- 0.88%, late apoptosis: 2.2 +/- 1.1%). The expression of caspase 9 in the immunostaining of the liver graft was suppressed in the AA-2G group compared with in the control group. Our study using the Annexin V-based assay provided evidence that the predominant cell death of hepatocytes was apoptosis after 24 h cold ischemia/reperfusion injury in rat liver transplantation. The addition of AA-2G to the UW solution attenuated 24 h cold ischemia/reperfusion injury by inhibiting the apoptosis of hepatocytes.

Topics: Animals; Annexin A5; Apoptosis; Ascorbic Acid; Aspartate Aminotransferases; Bile; Caspase 9; Caspases; Cryopreservation; Flow Cytometry; Hepatocytes; Immunohistochemistry; Liver; Liver Circulation; Liver Transplantation; Male; Rats; Rats, Wistar; Reperfusion Injury; Staining and Labeling; Survival Analysis

The objectives of this study were to compare the protective influence of exogenous nitric oxide on renal ischemia reperfusion (I/R) injury with that of the antioxidant vitamins C and E. Sprague-Dawley rats were divided into three groups ( n=12 per group). Normal saline solution was given in group 1, a vitamin C (200 mg/kg/d) plus vitamin E (100 mg/kg/d) combination in group 2 for 3 days before operating and Na-nitroprusside (5 mg/kg/d) in group 3 before reperfusion. The left kidneys were exposed to warm ischemia for 40 min followed by reperfusion for 90 min. The right kidneys were used as internal controls. After both kidneys were removed, histopathological examinations were performed, and oxidative and antioxidative parameters were measured. In the postischemic reperfused rat kidneys, the renal lipid peroxidation level was significantly lower, and the renal GSH level higher in the group given Na-nitroprusside compared with groups 1 and 2. Renal specific xanthine oxidase activity was also significantly lower in the group treated with Na-nitroprusside than in the groups given vitamins or saline. There was a significant, negative correlation between lipid peroxidation and reduced glutathione levels. Our results suggest that the exogenous nitric oxide (Na-nitroprusside) inhibits xanthine oxidase, and has more apparent preventive features for renal I/R injury than the antioxidant vitamins C+E.

Topics: Animals; Antioxidants; Ascorbic Acid; Glutathione; Ischemia; Kidney; Lipid Peroxides; Male; Nitric Oxide; Rats; Rats, Sprague-Dawley; Reference Values; Renal Circulation; Reperfusion Injury; Vitamin E; Xanthine Oxidase

Ischemic-reperfusion injury (IRI) is thought to be caused by oxygen radicals. Nitric oxide (NO) also has been thought to play a key role in IRI. This experiment was designed to evaluate the effects of antioxidants and NO supplement on hepatic IRI. Male Sprague-Dawley rats were divided into five groups: a sham operation group, a group with IRI, and three groups with vitamin C combined with vitamin E (VC&VE), L-arginine and N(G)-nitro-L-arginine (NNLA) injected after IRI. IRI was induced by clamping of the porta hepatis for 30 minutes and then by declamping. To prevent mesenteric blood congestion, a porto-systemic shunt had been made four weeks before the portal clamping. Biochemical assays of TNF-alpha level and NO2- level in the blood, malondialdehyde level, catalase activity and NO synthase activity in the liver tissue were performed. The results were as follows: IRI increased the malondialdehyde level and exhausted the catalase activity remarkably. VC&VE lowered the malondialdehyde levels and protected against catalase exhaustion, but had no significant effect on the NO production. L-arginine had a definite antioxidant effect, which was much weaker than that of VC&VE. In conclusion, antioxidants and a supplement of NO protected the liver tissue against IRI.

Topics: Animals; Antioxidants; Arginine; Ascorbic Acid; Catalase; Enzyme Inhibitors; Liver; Male; Malondialdehyde; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Nitroarginine; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Tumor Necrosis Factor-alpha; Vitamin E

Reperfusion of the ischemic myocardium results in structural changes in the capillary bed, which may contribute to decreased microcirculatory flow ("no reflow"). This study was designed to correlate the endothelial cell shape changes with both oxidative stress and lipid peroxidation and to evaluate the beneficial potential of Trolox (a hydrophilic analogue of alpha-tocopherol) and ascorbic acid. Isolated buffer-perfused rat hearts were made ischemic for 45 min and then reperfused with 100 microM Trolox and/or 100 microM ascorbic acid. Morphological changes were quantified by measuring capillary cross-sectional areas. Increased myocardial content of oxidized glutathione and its release into the coronary effluent were used as indices of oxidative stress. Myocardial MDA, an end product of lipid peroxidation, was also measured. Luminal membrane blebs and capillary "constriction" in the ischemic groups occurred when there was no change in either glutathione status or MDA concentrations. Reperfusion altered the redox state of the heart sufficiently to induce lipid peroxidation. It also induced endothelial cell swelling and a reduction in luminal area. Ascorbic acid was a more effective antioxidant than Trolox as it significantly reduced both oxidative stress and ultrastructural injury. The combined antioxidant treatment returned both the stress ratio and the capillary measurements to control values. We conclude that endothelial cell swelling correlates with the degree of oxidative stress and that antioxidant vitamins reduce membrane damage by preventing lipid peroxidation.

Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; Capillaries; Endothelium, Vascular; Glutathione; Lipid Peroxidation; Male; Microcirculation; Myocardium; Oxidative Stress; Perfusion; Rats; Rats, Wistar; Reperfusion Injury; Time Factors; Vitamins

We established an in vivo pig model of standardized lung ischemia to analyze pulmonary reperfusion injury. Enhanced chemiluminescence measurement (CM) allowed immediate quantification of reactive oxygen species (ROS) and subsequent lipid peroxidation. In such model we analyzed efficacy of vitamins C and E to prevent reperfusion injury.. After left lateral thoracotomy in group I (n = 6), normothermic lung ischemia was maintained for 90 minutes followed by a 5-hour reperfusion period. In group II, animals (n = 6) underwent ischemia as in group I, but received vitamins (preoperative IV bolus C = 1 g, E = 0.75 g, then continuous infusion (125 mg/h) each throughout the study). In Group III, animals (n = 6) underwent sham surgery and served as controls. Hemodynamic variables and gas exchange were assessed. The CM was performed for injury quantification in blood samples and to determine activation of isolated PMNs. The Wilcox rank test was used for statistical analysis.. During reperfusion, all animals in group I developed significant pulmonary edema with significant loss of pulmonary function. The addition of vitamins (group II) improved oxygenation and almost abolished pulmonary inflammatory cell infiltration; however, as in group I, pulmonary compliance still tended to decline and the number of circulating leucocytes increased. The CM showed that, compared with group I, vitamins reduced O2- basic release by PMNs significantly (460% to 170%, p < 0.05; control 165%), but could not prevent an increase of free ROS in whole blood similar to group I (443% to 270%, p = ns, control 207%). With regard to lipid peroxidation only a trend of reduction was observed (117% to 105%, p = ns, control 100%).. Differentiated analysis by CM demonstrated that vitamins C and E inhibited PMN activation but were not able to prevent radical production by other sources. This offers a potential explanation why radical scavengers like vitamins only attenuate but ultimately do not prevent reperfusion injury.

Topics: Acute-Phase Reaction; Animals; Ascorbic Acid; Lipid Peroxidation; Lung; Lung Compliance; Oxygen; Reactive Oxygen Species; Reperfusion Injury; Swine; Vitamin E

In this prospective controlled study, the aim was to examine the effects of vitamin C, mannitol and verapamil on adnexial ischaemia-reperfusion injury in the rat ovary.. Thirty-six female Wistar rats were used. In the controls (group 1), only laparotomy was performed. In group 2, ovarian ischaemia was produced and the bilateral ovaries were surgically removed 4 h later. In group 3, an ischaemic period of 4 h was followed by reperfusion for 1 h; the bilateral ovaries were then removed. In groups 4, 5 and 6, after 4 h of ischaemia, either vitamin C, mannitol or verapamil respectively was infused before reperfusion; after 1 h of reperfusion the ovaries were removed. Thiobarbituric acid reactive substance (TBARS) levels were measured in all ovary tissues.. TBARS levels of the reperfusion group were significantly higher than those of groups treated with vitamin C or mannitol (P = 0.013 and P = 0.045 respectively), but not of the verapamil group.. Vitamin C and mannitol were found to be effective in reducing ischaemia-reperfusion injury of the ovary during its early stages, but verapamil was ineffective.

Topics: Animals; Antioxidants; Ascorbic Acid; Calcium Channel Blockers; Female; Free Radical Scavengers; Ischemia; Mannitol; Ovary; Rats; Rats, Wistar; Reperfusion Injury; Thiobarbituric Acid Reactive Substances; Verapamil

The aim of this study was to investigate the effect of ascorbic acid (AA) an alterations in hepatic secretory and microsomal functions during hepatic ischemia and reperfusion.. Rats were subjected to 60 min of hepatic ischemia, and 1 and 5 h of reperfusion. Five minutes prior to ischemia, the animals were administered either vehicle or ascorbic acid (AA) (30, 100, 300, and 1000 mg/kg) intravenously.. The serum aminotransferase level and lipid peroxidation were markedly higher as a result of ischemia/reperfusion. These increases were significantly attenuated by AA doses of 30 and 100 mg/kg but were augmented by dose of 1000 mg/kg. Bile flow and cholate output were markedly decreased by ischemia/reperfusion. AA doses of 30 and 100 mg/kg restored but dose of 1000 mg/kg inhibited their secretion. Both the cytochrome P(450) content and aminopyrine N-demethylase activity were decreased by ischemia/reperfusion, which were prevented by AA doses of 30 and 100 mg/kg but were aggravated by dose of 1000 mg/kg. Aniline p-hydroxylase activity was elevated by ischemia/reperfusion, and this was prevented by AA doses of 100, 300 and 1000 mg/kg.. Ischemia/reperfusion diminishes the hepatic secretory and microsomal functions. AA has both antioxidant and pro-oxidant effects, depending upon the dose.

Topics: Alanine Transaminase; Aminopyrine N-Demethylase; Animals; Antioxidants; Ascorbic Acid; Bile; Cytochrome P-450 Enzyme System; Lipid Peroxidation; Liver; Male; Microsomes, Liver; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The present experiment determined the effects of glutathione and ascorbic acid, the two most important hydrophilic antioxidants, on myocardial ischemia-reperfusion injury and evaluated their relative therapeutic values. Isolated rat hearts were subjected to ischemia (30 min) and reperfusion (120 min) and treated with ascorbic acid, glutathione monoethyl ester (GSHme), or their combination at the onset of reperfusion. Administration of 1 mM GSHme alone, but not 1 mM ascorbic acid alone, significantly attenuated postischemic injury (P < 0.05 versus vehicle). Most interestingly, coadministration of ascorbic acid with GSHme markedly enhanced the protective effects of GSHme (P < 0.01 versus vehicle). The protection exerted by the combination of GSHme and ascorbic acid at 1 mM each was significantly greater than that observed with 1 mM GSHme alone (P < 0.05). Moreover, treatment with GSHme alone or GSHme plus ascorbic acid markedly reduced myocardial nitrotyrosine levels, suggesting that these treatments attenuated myocardial peroxynitrite formation. These results demonstrated that 1) GSHme, but not ascorbic acid, exerted protective effects against ischemia-reperfusion injury; and 2) the protective effects of GSHme were further enhanced by coadministration with ascorbic acid, suggesting a synergistic effect between GSHme and ascorbic acid.

Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Glutathione; Heart; Heart Rate; Incidence; Lipid Peroxidation; Myocardial Reperfusion Injury; Myocardium; Protective Agents; Rats; Reperfusion Injury; Tachycardia; Tyrosine; Ventricular Fibrillation

Low-grade ischemia-reperfusion in claudicants leads to damage of local tissues and remote organs. Since this damage is partly caused by oxygen-derived free radicals (ODFR), scavenging these ODFR could reduce the local and remote injury.. Using a new method by which a free radical reaction product (ortho-APOH) of the exogenous marker antipyrine is measured to quantify the oxidative stress, 16 stable claudicants performed a standard walking test before and after administration of vitamin E (200 mg) and vitamin C (500 mg) daily for 4 weeks.. Ortho-APOH was significantly increased during the reperfusion period (P = 0.026) before administration of the vitamins. After 4 weeks of vitamin supplementation no rise was found in the reperfusion period. Malondialdehyde showed no changes in either group.. These findings indicate that administering extra antioxidants to claudicants reduces oxidative stress in these patients. This may also have an effect on the remote ischemia-reperfusion damage and reduce cardiovascular morbidity in this group.

Topics: Aged; Antioxidants; Antipyrine; Ascorbic Acid; Exercise Test; Female; Humans; Intermittent Claudication; Male; Middle Aged; Oxidative Stress; Pilot Projects; Reperfusion Injury; Vitamin E

Ascorbate is highly concentrated in neuropils, and its extracellular release is closely related to that of the excitatory neurotransmitters. Thus, the extracellular release of ascorbate and glutamate was measured during the early stage of forebrain ischemia-reperfusion in the rat hippocampus using a microdialysis biosensor system. Male Wistar rats were anesthetized with halothane under mechanical ventilation and normothermia. Two probes of the microdialysis biosensor electrode were inserted in the hippocampus bilaterally. One probe was perfused with phosphate-buffered saline (PBS) and the oxidation signal of dialyzed ascorbate was recorded. A second electropolymerized probe was perfused with PBS containing glutamate oxidase for glutamate measurement. Forebrain ischemia-reperfusion was performed by bilateral carotid artery occlusion with hemorrhagic hypotension (MAP=30 mmHg) for 10 min (Group 10, n=10) or 15 min (Group 15, n=10), followed by reperfusion for 60 min. The release of glutamate increased significantly to 294% (Group 10) and 334% (Group 15) during ischemia, and then decreased rapidly. In Group 15, however, it remained significantly higher after reperfusion than in Group 10. The release of ascorbate increased significantly to 504% (Group 10) and 334% (Group 15) after reperfusion. In Group 10, it was significantly higher for 5-15 min after reperfusion than in Group 15. The marked increase of ascorbate during reperfusion was associated with the rapid decrease in glutamate. The extended time of ischemia significantly inhibited glutamate re-uptake and ascorbate release during reperfusion. These findings suggest the extracellular ascorbate release during reperfusion after global ischemia as a marker of glutamate re-uptake.

Topics: Animals; Antioxidants; Ascorbic Acid; Biosensing Techniques; Extracellular Space; Glutamic Acid; Ischemic Attack, Transient; Male; Microdialysis; Prosencephalon; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Isolated Langendorff-perfused rat hearts were subjected to a fixed period of ischemia followed by increasing periods of reperfusion for investigating the changes in the extent of ischemia-reperfusion (IR) injury and tissue levels of non-enzymatic antioxidants. Effects of schisandrin B (Sch B) and (+/-) alpha-lipoic acid (LA) pretreatment were also examined. A 40-min of ischemia (40-I) followed by 20- or 40-min of reperfusion (20-R or 40-R) caused sustainable tissue damage in isolated hearts, as indicated by the increased extent of lactate dehydrogenase (LDH) leakage and impaired contractile force. The myocardial IR injury was associated with a marked decrease in tissue ascorbic acid (V(C)) level. However, myocardial reduced glutathione (GSH) and alpha-tocopherol (V(E)) levels remained relatively unchanged except under a more severe IR condition (40-I, 40-R). Pretreating rats with Sch B or LA at a daily dose of 1.2 mmol/kg for 3 days protected against IR injury in isolated hearts to varying degrees. While only Sch B pretreatment could improve the recovery of contractile force, LA pretreatment produced a better inhibitory effect on LDH leakage. The protection against IR injury was associated with significant increases in myocardial V(E) and V(C) levels in both Sch B and LA pretreated hearts. The ensemble of results suggests that the cardioprotection afforded by Sch B or LA pretreatment may at least in part be attributed to the modulation on the interplay among non-enzymatic antioxidants under oxidative stress induced by IR.

Topics: Animals; Antioxidants; Ascorbic Acid; Cyclooctanes; Female; Heart; L-Lactate Dehydrogenase; Lignans; Male; Models, Chemical; Myocardium; Oxidative Stress; Perfusion; Polycyclic Compounds; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thioctic Acid; Time Factors

EPC-K1, L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl-hydrogen phosphate] potassium salt, is a novel antioxidant. In this study, we investigated a reduction of oxidative neuronal cell damage with EPC-K1 by immunohistochemical analysis for 8-hydroxy-2'-deoxyguanosine (8-OHdG) in rat brain with 60 min transient middle cerebral artery occlusion, in association with terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) and staining for total and active caspase-3. Treatment with EPC-K1 (20 mg kg(-1) i.v.) significantly reduced infarct size (p < 0.05) at 24 h of reperfusion. There were no positive cells for 8-OHdG and TUNEL in sham-operated brain, but numerous cells became positive for 8-OHdG, TUNEL and caspase-3 in the brains with ischemia. The number was markedly reduced in the EPC-K1 treated group. These reductions were particularly evident in the border zone of the infarct area, but the degree of reduction was less in caspase-3 staining than in 8-OHdG and TUNEL stainings. These results indicate EPC-K1 attenuates oxidative neuronal cell damage and prevents neuronal cell death.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Brain; Brain Infarction; Brain Ischemia; Caspase 3; Caspases; Deoxyguanosine; DNA Damage; Free Radicals; Immunohistochemistry; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Male; Nerve Degeneration; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Vitamin E

Oxygen free radicals (OFR) and neutrophils are potent sources of reperfusion injury. We compared the effect of EPC-K1, a new OFR scavenger, and neutrophil depletion on the reperfusion injury in skeletal muscle, using an ischemic revascularized hindlimb model in rats. Warm ischemia, produced by vascular pedicle clamping, was sustained for 4 h. After 24 h of reperfusion, muscle function and damage were evaluated in 4 groups: a sham operation group, a control study group, a group treated by EPC-K1 (EPC group), and a group that received nitrogen mustard to induce neutropenia (NM group). Both the EPC and NM groups had limited muscle damage compared to the control group. The EPC group preserved muscle function significantly better than the control group and the mean isometric tetanic tension in the EPC group appeared to be higher than that in the NM group. Furthermore, levels of lipid peroxides in muscle and serum, and muscle edema in the EPC group, were significantly lower than in the NM group. Histological examinations supported these results. These findings suggest that limiting OFR generation by EPC-K1 in the early phase of reoxygenation is more potent than depletion of neutrophils in reducing reperfusion injury.

Topics: Animals; Ascorbic Acid; Disease Models, Animal; Drug Evaluation, Preclinical; Free Radical Scavengers; Isometric Contraction; Leukocyte Count; Lipid Peroxidation; Male; Muscle, Skeletal; Neutropenia; Neutrophils; Random Allocation; Rats; Rats, Inbred Lew; Reperfusion Injury; Vitamin E

The purpose of this study was to modify the amount of 22:4 n-6, 22:5 n-6 and 20:5 n-3 in cardiac phospholipids and to evaluate the influence of these changes on the functioning of working rat hearts and mitochondrial energy metabolism under normoxic conditions and during postischemic reperfusion. The animals were fed one of these four diets: (i) 10% sunflower seed oil (SSO); (ii) 10% SSO + 1% cholesterol; (iii) 5% fish oil (FO, EPAX 3000TG, Pronova) + 5% SSO; (iv) 5% FO + 5% SSO + 1% cholesterol. Feeding n-3 PUFA decreased n-6 PUFA and increased n-3 PUFA in plasma lipids. In the phospholipids of cardiac mitochondria, this dietary modification also induced a decrease in the n-6/n-3 PUFA ratio. Cholesterol feeding induced marked hepatic steatosis (HS) characterized by the whitish appearance of the liver. It also brought about marked changes in the fatty acid composition of plasma and mitochondrial phospholipids. These changes, characterized by the impairment of deltaS- and delta6-desaturases, were more obvious in the SSO-fed rats, probably because of the presence of the precursor of the n-6 family (linoleate) in the diet whereas the FO diet contained large amounts of eicosapentaenoic and docosahexaenoic acids. In the mitochondrial phospholipids of SSO-fed rats, the (22:4 n-6 + 22:5 n-6) to 18:2 n-6 ratio was decreased by HS, without modification of the proportion of 20:4 n-6. In the mitochondrial phospholipids of FO-fed rats, the amount of 20:5 n-3 tended to be higher (+56%). Cardiac functioning was modulated by the diets. Myocardial coronary flow was enhanced by HS in the SSO-fed rats, whereas it was decreased in the FO-fed animals. The rate constant k012 representing the activity of the adenylate kinase varied in the opposite direction, suggesting that decreased ADP concentrations could cause oxygen wasting through the opening of the permeability transition pore. The recovery of the pump function tended to be increased by n-3 PUFA feeding (+22%) and HS (+45%). However, the release of ascorbyl free radical during reperfusion was not significantly modified by the diets. Conversely, energy production was increased by ischemia/reperfusion in the SSO group, whereas it was not modified in the FO group. This supports greater ischemia/reperfusion-induced calcium accumulation in the SSO groups than in the FO groups. HS did not modify the mitochondrial energy metabolism during ischemia/reperfusion. Taken together, these data suggest that HS- and n-3 PUFA-induced de

Topics: Adenine; Animals; Aorta; Ascorbic Acid; Body Weight; Cardiac Output; Cell Respiration; Cholesterol, Dietary; Coronary Circulation; Dietary Fats; Fatty Acids, Unsaturated; Fish Oils; Free Radicals; Heart; Liver; Mitochondria, Heart; Myocardial Ischemia; Organ Size; Oxygen; Palmitoylcarnitine; Phosphates; Plant Oils; Pyruvic Acid; Rats; Reperfusion Injury; Sunflower Oil

Ischaemia-reperfusion injury (IRI) is caused by endothelial and subendothelial damage by neutrophil-derived oxidants. Vitamin C is an antioxidant which attenuates endothelial injury after IRI. Our aim was to evaluate the effect of oral vitamin C in the prevention of IRI in skeletal muscle. We used a model of cross-clamping (3 hours) and reperfusion (1 hour) of the cremaster muscle in rats. Muscle function was assessed electrophysiologically by electrical field stimulation. Infiltration by neutrophils was determined by the activity of tissue myeloperoxidase (MPO) and tissue oedema by the wet-to-dry ratio. Neutrophil respiratory burst activity was measured in control animals and groups pretreated with vitamin C. IRI significantly decreased muscle function and increased muscle neutrophil MPO activity and muscle oedema. Pretreatment with vitamin C preserved muscle function and reduced tissue oedema and neutrophil infiltration. Neutrophil respiratory burst activity was reduced in the group treated with vitamin C compared with the control group. We conclude that pretreatment with oral vitamin C protects against acute muscle IRI, possibly by attenuating neutrophil respiratory burst activity.

Topics: Acute Disease; Animals; Ascorbic Acid; Muscle, Skeletal; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Respiratory Burst

Apart from its physiological role as a major antioxidant, ascorbate is highly concentrated in neuropils and ascorbate-mediated protection from excitotoxins has been demonstrated in vitro. Therefore, extracellular release of ascorbate during the early stage of ischemia-reperfusion was measured using a microdialysis electrode technique. One or two probes of the microdialysis biosensor were inserted into the rat striatum. One probe (n=16) was perfused with phosphate-buffered saline (PBS) for continuous oxidative signal recording. A second electropolymerised probe inserted into the other side of the striatum was perfused with PBS containing ascorbate oxidase in six rats. Forebrain ischemia-reperfusion was performed for 10min, followed by reperfusion for 60min. Ascorbate increased transiently during ischemia, and markedly to a maximum of 247.5+/-55. 8 microM from the baseline of 68.5+/-25.3 microM after reperfusion. The marked increase of extracellular ascorbate may be a marker of the early stage of reperfusion.

Topics: Animals; Ascorbic Acid; Brain Ischemia; Corpus Striatum; Electrochemistry; Extracellular Matrix; Male; Microdialysis; Prosencephalon; Rats; Rats, Wistar; Reperfusion Injury; Signal Processing, Computer-Assisted; Stereotaxic Techniques

Reperfusion injury is the leading cause of early graft dysfunction after lung transplantation. Activation of neutrophilic granulocytes with generation of free oxygen radicals appears to play a key role in this process. The efficacy of ascorbic acid as an antioxidant in the amelioration of reperfusion injury after lung transplantation has not been studied yet.. An in situ autotransplantation model in sheep is presented. The left lung was flushed (Euro-Collins solution) and reperfused; after 2 hours of cold storage, the right hilus was then clamped (group R [reference], n = 6). Group AA animals (n = 6) were treated with 1 g/kg ascorbic acid before reperfusion. Controls (group C, n = 6) underwent hilar preparation and instrumentation only.. In group R, arterio-alveolar oxygen difference (AaDO2) and pulmonary vascular resistance (PVR) were significantly elevated after reperfusion. Five of 6 animals developed frank alveolar edema. All biochemical parameters showed significant PMN activation. In group AA, AaDO2, PVR, work of breathing, and the level of PMN activation were significantly lower.. The experimental model reproduces all aspects of lung reperfusion injury reliably. Ascorbic acid was able to weaken reperfusion injury in this experimental setup.

Topics: Animals; Antioxidants; Ascorbic Acid; Female; Lung Transplantation; Models, Animal; Neutrophil Activation; Oxygen; Pulmonary Circulation; Reperfusion Injury; Sheep; Transplantation, Autologous; Vascular Resistance; Work of Breathing

The objective of this study was to investigate the effect of singlet oxygen ((1)O2) scavengers on functional recovery and ascorbyl free radical (AFR) formation in isolated ischemic rat hearts. Hearts were subjected to 40 min. of global ischemia followed by 30 min. of reperfusion. Hemodynamics were measured as heart rate (HR), coronary flow (CF), left ventricular developed pressure (LVDP) and contractility (dP/dt). Electron paramagnetic resonance (EPR) spectroscopy was used to measure AFR release in coronary perfusate during the first two min. of reperfusion as a function of ROS scavengers. Relative to ischemic controls the administration of the (1)O2 scavengers 2,2,6,6-tetramethyl-4-piperidone x HCl (4-oxo-TEMP), carnosine (beta-alanyl-L-histidine) or a combination of the two significantly improved functional recovery as measured by LVDP. While no AFR signal was detected in coronary perfusate collected during preischemic perfusion with and without (1)O2 scavengers, the AFR background signal due to ischemia was significantly increased with the (1)O2 and *O2- scavengers. No such increase was observed with the hydroxyl radical (*OH) scavenger mannitol. Besides the AFR increase with the (1)O2 and *O2- scavengers the functional recovery was only significantly improved with the (1)O2 scavengers. In contrast to previous AFR studies we found with endogenous AFR that an increased AFR formation is not necessarily only reflecting increased oxidative stress but can also report improved functional recovery. Combining the hemodynamic data with increased AFR formation in the presence of several different ROS scavengers gives supportive evidence for (1)O2 also being involved in reperfusion injury.

Topics: Animals; Ascorbic Acid; Blood Flow Velocity; Blood Pressure; Carnosine; Diuretics, Osmotic; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Free Radicals; Heart; Heart Rate; Male; Mannitol; Models, Biological; Models, Chemical; Myocardium; Oxygen; Piperidones; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase; Time Factors; Tranquilizing Agents; Triacetoneamine-N-Oxyl

Antioxidants are known to play an important role in mitigating oxidative stress injury. Regional concentrations of non-enzymatic antioxidants, redox ratio and lipid peroxides were studied in normal, ischemic and ischemic-reperfused rat hearts. Isolated perfused rat hearts were made globally ischemic for 45 min and reperfused for 15 min. Right ventricular wall (RVW), septum (S) and left ventricular wall (LVW) from control, ischemic (I) and reperfused (I-R) hearts were analysed. Tocopherol, retinol and ascorbic acid concentrations in different regions of perfused control hearts were not different. Reduced glutathione (GSH) was significantly lower in the RVW, while S and LVW had about three-fold higher levels. Oxidized glutathione (GSSG) was lower in the RVW and most concentrated in the LVW. The GSH:GSSG ratio was highest in the septum while RVW and LVW had similar values. Lipid hydroperoxide (LPx) concentrations in the three regions of control hearts were not different from each other. In I and I-R hearts, vitamin E declined in all three regions but the loss was significant only in the septum in the I group and in the septum and LVW of the I-R group. Vitamin A showed significant loss in all three regions of the I-R group. Vitamin C declined significantly only in the RVW of the I-R group. GSH increased in the RVW of the I and I-R groups compared to controls. GSSG was increased in the RVW and septum of the I group and in all regions of the I-R group. The redox ratio, GSH:GSSG, decreased in all regions of both I and I-R groups. LPx were increased in the septum of the I group and in all regions of the I-R group. Despite unique regional differences in non-enzymatic antioxidants, a comparable increase in LPx in the I-R group and similar extent of reduction in the redox ratio in different regions of the I and I-R groups, suggest that each myocardial region may use different antioxidant mechanisms to withstand oxidative stress.

Topics: Animals; Antioxidants; Ascorbic Acid; Glutathione; Glutathione Disulfide; Heart; Hypoxia; Ischemia; Lipid Peroxides; Male; Oxidative Stress; Perfusion; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Tissue Distribution; Vitamin A; Vitamin E

In experiment on muscle flaps of 20 rabbits the peculiarities of their tissues damage in the ischemia period, and also due to the oxygen-dependent processes activation (peroxidal and free radical oxidation of a membrane phospholipids) in period of its reperfusion were studied. Preliminary introduction of a lipin, unitiol and ascorbic acid mixture in the flap arterial channel had promoted the reduction of damage severity in the translocated flap cells biomembranes due to ischemia and reperfusion, causing inhibition of the lipids peroxidal oxidation processes, rising of the flap tissues antioxidant defense, the cell and subcell membranes stabilization which preserves the vessels endothelium integrity. This showed a promising future for application of these preparations in a free transplantation of compound tissue complexes.

Topics: Animals; Anti-Infective Agents; Antioxidants; Ascorbic Acid; Chelating Agents; Drug Therapy, Combination; Muscle, Skeletal; Organic Chemicals; Rabbits; Reperfusion Injury; Surgical Flaps; Unithiol

EPC-K1, a phosphate diester of alpha-tocopherol and ascorbic acid, is a new hydroxyl radical scavenger. We examined the effects of EPC-K1 according to differences in the timing of its administration. Warm ischemia, produced by vascular pedicle clamping, was sustained for 4 hours. After 24 hours of reperfusion, muscle injury was evaluated in 4 groups: the first group received a sham operation, the second group was treated with an intravenous injection of EPC-K1 prior to ischemia, the third group was treated with EPC-K1 prior to reperfusion, and the fourth group was controls. Compared with the control group, both the preischemic and pre-reperfusion EPC-K1-treated groups showed a statistically significant amelioration in the reduction of isometric muscle contraction. There were also significant reductions in the muscle and serum levels of thiobarbituric acid reactive substances (TBA-RS) and muscle damage, indicated by the biochemical and histological study. A comparison of the timing of EPC-K1 administration revealed that only the muscle TBA-RS level in the pre-reperfusion EPC-K1-treated group was significantly higher than that in the preischemic EPC-K1-treated group. These observations indicate that EPC-K1 not only by preischemic but also by pre-reperfusion administration acted effectively on reperfusion injury in muscle, thereby improving muscle function.

Topics: Animals; Antioxidants; Ascorbic Acid; Biopsy; Disease Models, Animal; Drug Administration Schedule; Drug Evaluation, Preclinical; Free Radical Scavengers; Injections, Intravenous; Ischemia; Isometric Contraction; Male; Muscle, Skeletal; Random Allocation; Rats; Rats, Inbred Lew; Reperfusion Injury; Thiobarbituric Acid Reactive Substances; Time Factors; Vitamin E

to evaluate vitamin C supplementation in the prevention of ischaemia-reperfusion (I-R) induced acute lung injury.. Sprague-Dawley rats (n =6/group) were randomised into Control, I-R and I-R pretreated with vitamin C (3.3 g over 5 days). Ischaemia-reperfusion injury was induced by 30 minutes infrarenal aortic cross-clamping and 120 minutes reperfusion.. pulmonary microvascular injury was measured by broncho-alveolar lavage protein concentration, pulmonary neutrophil infiltration by tissue myeloperoxidase activity and bronchoalveolar lavage neutrophil counts. In a second experiment (n =5/group) neutrophil respiratory burst activity was measured in Control and vitamin C groups.. ischaemia-reperfusion resulted in a significant increase in both microvascular leakage and pulmonary neutrophil infiltration as measured by bronchoalveolar lavage protein concentration and pulmonary myeloperoxidase activity respectively. Pretreatment with vitamin C significantly attenuated both microvascular leakage and neutrophil infiltration. Neutrophil respiratory burst activity was significantly reduced in the vitamin C group (13.02 m.c.f.+/-0.3) compared with Control (19.04 m.c.f.+/-1. 9),p <0.02.. these data suggest that oral vitamin C therapy protects against ischaemia-reperfusion-induced acute lung injury, possibly by attenuating neutrophil respiratory burst activity.

Topics: Animals; Ascorbic Acid; Bronchoalveolar Lavage Fluid; Lung; Male; Microcirculation; Neutrophils; Peroxidase; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Respiratory Burst

The purpose of this study was to examine distribution and time history of oxidative stress during the hyperacute period of reperfusion in the liver grafts undergoing cold ischemia and to investigate roles of Kupffer cells as a potential oxidant source. Rat livers were harvested at 4 degrees C in University of Wisconsin solution and followed by reperfusion with Krebs-Henseleit buffer under monitoring bile excretion. To investigate oxidative changes, laser-confocal microfluorography was performed in reperfused livers preloaded with dichlorodihydrofluorescein diacetate succinimidyl ester, a fluorescence precursor sensing intracellular hydroperoxide generation. Livers undergoing the 16-hour cold storage displayed an impaired recovery of bile acid-dependent bile output concurrent with a marked increase in hydroperoxide generation in hepatocytes, which occurred as early as 5 minutes after the onset of reperfusion, whereas the status of lobular perfusion was well maintained. Pretreatment with liposome-encapsulated dichloromethylene diphosphonate, a Kupffer cell-depleting reagent, did neither alter the reperfusion-induced periportal oxidative changes nor improve the recovery of bile output in the graft. On the other hand, EPCK, a hepatotropic antioxidant composed of vitamin E phosphate ester bound to vitamin C, not only diminished the oxidative changes but also improved the reduction of bile acid-dependent bile output. Furthermore, the reagent was capable of inhibiting H(2)O(2)-induced oxidative stress in cultured hepatocytes. These results suggest that hepatocytes constitute a major site of the oxidative insult triggered through Kupffer cell-independent mechanisms and serve as an important cellular component to be protected by antioxidant therapeutics.

Topics: Animals; Antioxidants; Ascorbic Acid; Bile; Clodronic Acid; Cold Temperature; Deferoxamine; Fluoresceins; Hydrogen Peroxide; Kupffer Cells; Liver; Liver Transplantation; Male; Mitochondria, Liver; Oxidative Stress; Rats; Rats, Wistar; Reperfusion Injury; Taurocholic Acid; Vitamin E

To establish the antioxidant status of rat intestinal tissues after ischemia-reperfusion and to determine if pretreatment with an allopurinol and antioxidant vitamin combination gives any protection against mucosal injury.. Twenty rats were divided into 4 groups of 5 animals each.. Group 1 (control) rats were not subjected to ischemia-reperfusion and received no allopurinol plus vitamin combination; group 2 rats received vitamins C (200 mg/kg) and E (100 mg/kg) and allopurinol (50 mg/kg) combination daily for 3 days preoperatively; group 3 rats were subjected to ischemia-reperfusion only; and group 4 rats were subjected to ischemia-reperfusion and received the vitamin and allopurinol combination.. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes, the level of thiobarbituric acid-reagent substances (TBARS) and histologic grading of tissue samples.. SOD and GSH-Px activities were decreased, but the CAT activity and TBARS level increased. Pretreatment of the rats with the allopurinol-vitamin C-vitamin E combination did not have any significant effect on the enzyme activities. However, it resulted in important reductions in the TBARS tissue levels. Histologic investigation revealed significant mucosal injury in group 3 rats compared with group 4 rats (mean [and standard deviation] for grading, 4.6 [0.5] versus 1.8 [0.4]).. The enzymatic antioxidant defence system was significantly changed after ischemia-reperfusion and intestinal tissue was exposed to increased oxidant stress, the results of which were peroxidation of some cellular structures and increased concentrations of oxidative products. Although antioxidant treatment did not drastically affect the enzyme activities or afford complete protection of cellular structures against deformation, it apparently could eliminate oxygen radicals and prevent peroxidative reactions.

Topics: Allopurinol; Animals; Antioxidants; Ascorbic Acid; Catalase; Drug Therapy, Combination; Free Radicals; Glutathione Peroxidase; Intestinal Mucosa; Lipid Peroxidation; Oxidative Stress; Premedication; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Vitamin E

Topics: Animals; Ascorbic Acid; Brain; Cell Line; Ferrous Compounds; Free Radical Scavengers; Hippocampus; Imidazoles; Ischemic Attack, Transient; Lactates; Malondialdehyde; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Nerve Degeneration; Neurons; Neuroprotective Agents; Rats; Reperfusion Injury

Induced erythrocyte membrane peroxidation (EMP) is considered as an accurate model of reperfusion injuries and as such was used to investigate protective effects of various drugs. EMP was induced by an azo initiator and monitored by oxygen uptake. Both hydrophilic (ascorbic acid) and lipophilic (alpha-tocopherol, probucol, nicanartine) chain-breaking antioxidants as well as ferriheme-bound drugs (deferoxamine, chloroquine) inhibited EMP. When antioxidants and ferriheme-bound drugs were combined, synergistic effects were observed. It is proposed that ferriheme compounds which catalyse peroxide induced lipid peroxidation were blocked by deferoxamine and/or chloroquine. So these drugs inhibited at least partly the membrane peroxidation process and added their effects to the ones of chain-breaking antioxidants.

Topics: Adult; Amidines; Antioxidants; Ascorbic Acid; Chloroquine; Deferoxamine; Drug Synergism; Erythrocyte Membrane; Fatty Acids; Female; Hemin; Humans; Linoleic Acid; Lipid Peroxidation; Male; Membrane Lipids; Oxidation-Reduction; Oxygen Consumption; Oxyhemoglobins; Probucol; Pyridines; Reperfusion Injury; Vitamin E

Cardiac arrhythmias during ischemia/reperfusion are believed to be related to free radicals generated in the heart especially during the period of reperfusion. Since melatonin functions as a free radical scavenger and antioxidant, the ability of this molecule to influence cardiac arrhythmias was investigated. The pineal secretory product, melatonin, reduced the incidence and severity of arrhythmias induced by ischemia/reperfusion due to ligation of the anterior descending coronary artery in the isolated rat heart. Melatonin was either infused during both the ischemia and reperfusion periods or only late in the ischemia period and throughout reperfusion. The percentage of hearts that developed cardiac arrhythmias during reperfusion as indicated by the incidence of premature ventricular contraction (PVC) and ventricular fibrillation (VF) were recorded. Melatonin either infused during both the ischemia and reperfusion periods or during essentially the period of reperfusion greatly reduced PVC and VF due to occlusion and reopening the anterior descending coronary artery. Presumably melatonin's beneficial effect in reducing cardiac arrhythmias was due in part to its free radical scavenging activity, which is greatly assisted by the rapidity with which it is taken up into cells. Previous studies have shown that vitamin C is effective in reducing the severity of cardiac arrhythmias induced by ischemia/reperfusion; thus, we also compared the efficacy of melatonin with this well-known antioxidant. Melatonin was more potent than vitamin C in protecting against arrhythmias induced by ischemia/reperfusion. Besides melatonin's function as a broad spectrum free radical scavenger, melatonin may have also reduced cardiac arrhythmias due to its regulation of intracellular calcium levels, i.e., by preventing calcium overloading, or due to its ability to suppress sympathetic nerve function and reduce adrenergic receptor function in the myocardium. Additional studies into the mechanisms of melatonin's action in reducing cardiac arrhythmias due to ischemia/reperfusion or other causes are warranted because of the possible application of this information to humans with heart disease.

Topics: Animals; Antioxidants; Arrhythmias, Cardiac; Ascorbic Acid; Dose-Response Relationship, Drug; Free Radical Scavengers; Heart; Ischemia; Male; Melatonin; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury

A number of antioxidants are present in human tissues, which comprise the secondary defence system against the oxygen-free radicals and oxidative stress. Therefore, this study was undertaken in an animal model to investigate the effects of antioxidants such as vitamin E, vitamin C, methyl prednisolone, and mannitol, on the treatment of intestinal reperfusion injury when given during ischemia.. The study was performed on six groups of animals, each composed of six rabbits: Group I, mesenteric ischemia group; group R, ischemia-reperfusion group; group E, ischemia-reperfusion plus Vitamin E treatment; group C, ischemia-reperfusion plus vitamin C treatment; group CS, ischemia-reperfusion plus corticosteroid treatment; and Group M, ischemia-reperfusion plus mannitol treatment. Malondialdehyde (MDA) and glutathione (GSH) levels of the intestinal mucosa were assayed to reflect the free radical formation.. Mucosal injury scores in the M and C groups were significantly lower than the R group (P< .01 and P< .01, respectively), and in the E and CS groups, mucosal injury scores were not significantly different from R group. MDA levels in the M and C groups were significantly lower than the R group (P < .01 and P < .01, respectively). GSH levels in the E, C, and M groups, were significantly higher than R group (P < .01, P < .05, and P < .01, respectively).. The results of this study showed that antioxidant drugs, such as vitamin C and mannitol, may play a role in attenuating reperfusion injury of the gut demonstrated by depression of tissue MDA levels and by elevation of tissue GSH levels.

Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Glucocorticoids; Glutathione; Intestinal Mucosa; Intestines; Ischemia; Malondialdehyde; Mannitol; Methylprednisolone; Rabbits; Reperfusion Injury; Vitamin E

Temporary occlusion of major cerebral blood vessels occasionally becomes necessary during surgical procedures. Ascorbic acid (Vitamin C) is an important non-enzymatic scavenger of free radicals and its protective effect on the brain in permanent focal cerebral ischaemia has been proven in a primate model of focal cerebral ischaemia [16]. Additional damage caused by reperfusion of the infarcted area has been shown in the rat model [22]. This study was undertaken to study the efficacy of ascorbic acid in decreasing infarct size in ischaemic reperfused brain. Maccaca radiata monkeys in the treated group were given two grams of ascorbic acid, parentally immediately before clipping the middle cerebral artery and the control group was given placebo. Reperfusion was done after four hours. Mean infarct size in all the three brain slices in the ascorbic acid pretreated group was 7.3% +/- 2.7 and in the placebo group 22.1 +/- 6.7 under similar conditions. The mean infarct size in the ascorbic acid pretreated group of monkeys was significantly lower when compared with the placebo group (p = 0.0003).

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Cerebral Infarction; Macaca radiata; Male; Neuroprotective Agents; Premedication; Rats; Reperfusion Injury

Ischemia-reperfusion injury by free radicals and lipid peroxides is observed in various organs. Ascorbic acid (AsA) or glutathione (GSH) in various doses (AsA:2, 0.5, 0.1 mmol/kg, GSH:2 mmol/kg) was intraperitoneally administered to male Wistar rats. The entire small intestines were resected just before ischemia, after ischemia, and after 20 min of reperfusion (n = 7-10 at each time point). At each time point, the specimens were subjected to assays of lipid peroxides, GSH, and glutaminase activity of the tissues; they were also examined histologically. In the AsA group, the production of lipid peroxides after reperfusion was significantly suppressed in a dose-dependent manner, and the ratio of oxidized GSH to total GSH was also significantly low. Tissue glutaminase activity decreased to a lesser extent, and the degree of injury was apparently less marked in the AsA group. This study indicates that AsA acts as an antioxidant against peroxidative tissue injury, possibly by scavenging radicals, preserving reduced GSH, and reducing the peroxidative reaction.

Topics: Animals; Ascorbic Acid; Dehydroascorbic Acid; Free Radicals; Glutathione; Glutathione Disulfide; Intestinal Mucosa; Intestine, Small; Ischemia; Lipid Peroxidation; Male; Mesenteric Arteries; Rats; Rats, Wistar; Reperfusion Injury; Thiobarbituric Acid Reactive Substances

Recent evidence has suggested that ischemia-reperfusion injury is fundamental to the pathogenesis of acute pancreatitis. This study was designed to determine whether acute pancreatitis is associated with elevated serum manganese superoxide dismutase (MnSOD), a key antioxidant enzyme, considered a marker of ischemia-reperfusion injury in myocardial infarction. Thirty-four patients with acute pancreatitis had measurements of MnSOD on days 0, 2, and 5 after recruitment. The patients were recruited within 12 h of admission to hospital and had measurements of MnSOD on days 0, 2, and 5. Patients with severe acute pancreatitis had significantly elevated serum MnSOD concentrations on days 2 and 5 compared with patients with mild acute pancreatitis, but not on the day of recruitment. Elevated serum MnSOD correlated with peripheral plasma markers of lipid peroxidation (malondialdehyde) and neutrophil activation (myeloperoxidase) and was associated with decreased plasma ascorbic acid concentrations. The serial measurement of serum MnSOD may prove useful as a marker of the effectiveness of treatment designed to limit ischemia-reperfusion injury in patients with severe acute pancreatitis.

Topics: Acute Disease; Adult; Aged; Ascorbic Acid; Biomarkers; C-Reactive Protein; Female; Humans; Male; Malondialdehyde; Middle Aged; Pancreatitis; Peroxidase; Reperfusion Injury; Superoxide Dismutase

L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl- 2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-yl hydrogen phosphate] potassium salt (EPC-K1), a phosphate diester of alpha-tocopherol and ascorbic acid, is a potent antioxidant. We examined the effects of EPC-K1 on ischemia-reperfusion injury in the skeletal muscle of rats, using an ischemic revascularized hind limb model. Warm ischemia (25 degrees C), produced by vascular pedicle clamping, was sustained for 4 hours. After 24 hours of reperfusion, skeletal muscle injury was evaluated in 2 groups: one group treated by intravenous injection of EPC-K1 (10 mg/kg) prior to ischemia, and a group of controls. The EPC-K1-treated group showed a statistically significant amelioration in the reduction of the isometric muscle contraction, inhibition of the elevation of the muscle wet- to dry-weight ratio, limitation of the muscle level of thiobarbituric acid reactive substances and the serum levels of creatine phosphokinase, lactate dehydrogenase and mitochondrial glutamic oxaloacetic transaminase, and reduction of the extent of muscle injury according to the histological findings. These observations indicate that EPC-K1 acted effectively on ischemia-reperfusion injury in the rat skeletal muscle and thereby improved muscle function.

Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Drug Evaluation, Preclinical; Free Radical Scavengers; Isometric Contraction; Male; Muscle, Skeletal; Rats; Rats, Inbred Lew; Reperfusion Injury; Vitamin E

Reactive oxygen species (ROS) have been implicated in a variety of pathological processes. The generation of highly reactive oxygen metabolites is an integral feature of normal cellular metabolism (mitochondrial respiratory chain, phagocytosis, arachidonic acid metabolism, ovulation and fertilization), however their production can multiply during pathological circumstances. Free oxygen radicals act either on the extracellular matrix or directly upon cellular membranes themselves. The fundamental defense of the organism against ROS include scavenger enzymes (superoxide dismutase, catalase, glutathione peroxidase) and lipid- and water soluble antioxidant compound (ascorbic acid, glutathione, albumin, transferrin, etc.). Their role in ischemia-reperfusion models have now been comprehensively investigated and it has become clear that ROS is to be blamed for the bulk of post-ischemic injuries, hence the basis for newly established antioxidant therapy in such cases. Also more and more studies have concluded a pivotal role of ROS in degenerative and inflammatory conditions, post-radiation processes and aging. Therefore it seems as we are continuously shedding light on the crucial part played by these molecules regarding a wide range of pathologies, we are discovering new therapeutic windows that would clinically assist us in managing such conditions.

Topics: Aging; Albumins; Antioxidants; Arachidonic Acids; Ascorbic Acid; Catalase; Cell Membrane; Cell Respiration; Extracellular Matrix; Female; Fertilization; Free Radical Scavengers; Free Radicals; Glutathione; Glutathione Peroxidase; Humans; Inflammation; Ischemia; Mitochondria; Ovulation; Phagocytosis; Radiation Injuries; Reactive Oxygen Species; Reperfusion Injury; Superoxide Dismutase; Transferrin

In this experimental study is illustrated an original model of cerebral asymmetric ischemia and reperfusion in the rat, induced by unilaterally elevating ICP and clamping the corresponding common carotid artery, that allows a direct comparison of the two brain hemispheres, one normal and the other ischemic, of the same animal.. The experimental procedure consisted in grafting two screws through the skull on the right side of the sagittal suture, one of them being connected to a Queckenstedt manometer for monitoring ICP variations. A nitroprusside solution (1 mg/ml administered through the femoral vein at a flow rate of 0.103 ml/min) was infused to achieve a significant drop of MABP. At this time point, animals were subjected to 5 min of ischemia and 10 min of reperfusion induced by clamping and declamping the right common carotid artery. During the whole period of ischemia and reperfusion ICP and MABP were constantly monitored. In order to provide an outlook on the metabolic alterations of brain tissue occurring during ischemia and reperfusion phenomena, several biochemical parameters of cellular energy metabolism and of oxygen radical-induced membrane damage were determined by a sensitive and reproducible HPLC method on perchloric acid tissue extracts.. The validity of the present model was supported by the finding of significant intrahemispheric differences in the concentration of several compounds considered as biochemical markers of tissue injury, such as adenosine 5'-triphosphate catabolites and malondialdehyde, this last indicating the damaging action of oxygen free radicals on cell membrane phospholipids.

Topics: Animals; Ascorbic Acid; Blood Pressure; Brain Ischemia; Carotid Stenosis; Chromatography, High Pressure Liquid; Disease Models, Animal; Intracranial Pressure; Lipid Peroxidation; Male; Malondialdehyde; Neurons; Rats; Rats, Wistar; Reperfusion Injury; Reproducibility of Results; Sensitivity and Specificity

We examined the potential protective effect of pretreatment with corticosteroids or antioxidants (ascorbic acid or allopurinol) in rabbits with reperfusion-induced damage to skeletal muscle after ischemia. 4 hours of limb ischemia induced by a pneumatic tourniquet, followed by reperfusion for 1 hour, caused a considerable amount of ultrastructural damage to the anterior tibialis muscles accompanied by a rise in circulating creatine kinase activity. Pretreatment of animals with depomedrone by a single 8 mg bolus injection led to a preservation of the anterior tibialis structure on both light and electron microscopy. High-dose continuous intravenous infusion with ascorbic acid (80 mg/hr) throughout the period of ischemia and reperfusion also preserved skeletal muscle structure, although allopurinol in various doses had no protective effect. These data are fully compatible with a mechanism of ischemia/reperfusion-induced injury to skeletal muscle, involving generation of oxygen radicals and neutrophil sequestration and activation. They also indicate that damage to human skeletal muscle caused by prolonged use of a tourniquet is likely to be reduced by simple pharmacological interventions.

Topics: Allopurinol; Animals; Anti-Inflammatory Agents; Antimetabolites; Antioxidants; Ascorbic Acid; Ischemia; Methylprednisolone; Methylprednisolone Acetate; Muscles; Rabbits; Reperfusion Injury

The in vivo uptake and distribution of 6-deoxy-6-[18F]fluoro-L-ascorbic acid (18F-DFA) were investigated in rat brains following postischemic reperfusion. Global cerebral ischemia was induced in male Wistar rats for 20 min by occlusion of four major arteries. Two time points were chosen for 18F-DFA injection to rats subjected to cerebral ischemia, at the start of recirculation and 5 days following recirculation. The rats were then killed at 2 h after tail-vein administration of 18F-DFA and tissue radioactivity concentration was determined. Increased uptake of radioactivity in particular brain regions, including the cerebral cortex, hypothalamus, and amygdala following injection of 18F-DFA, compared to the sham-operated control, was observed 5 days after reperfusion. Similar results were also obtained in in vitro experiments using brain slices. Abnormal in vivo accumulation of 45Ca, a marker of regional postischemic injury, was observed in these brain regions in tissue dissection experiments. Furthermore, metabolite analysis of nonradioactive DFA using 19F-NMR showed that DFA remained intact in the postischemic reperfusion brain. The present results indicate that 18F-DFA increasingly accumulates in damaged regions of postischemic reperfusion brain.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Calcium Radioisotopes; Fluorine Radioisotopes; Ischemic Attack, Transient; Magnetic Resonance Spectroscopy; Male; Rats; Rats, Wistar; Reperfusion Injury; Tissue Distribution

We evaluated experimentally (80 Lewis-rats) possible pharmacological strategies in the treatment of intestinal reperfusion injury in hypo- and normothermia. We used a specific perfusion solution containing PGI2 or radical scavengers (superoxide dismutase, oxypurinol, tocopherol, ascorbate). Decreased malondialdehyde (MDA) plasma release after reperfusion proved the antioxidative efficiency of the administered radical scavengers (normothermia-control group: MDA increase after 15 min of reperfusion to 160 +/- 30% compared to level at the end of ischemia, oxypurinol: 110 +/- 23%, tocopherol: 112 +/- 12%, ascorbate: 104 +/- 20%; p < 0.05). The ATP/ADP-ratio of the therapy groups was stable in contrast to the control group. Alkaline phosphatase release was significantly diminished under radical scavenger administration (normothermia/15 min reperfusion-control group: 7.7 +/- 0.9 mumol/ls, oxypurinol: 4.4 +/- 0.4 mumol/ls, tocopherol: 3.5 +/- 0.1 mumol/ls, ascorbate: 5.9 +/- 0.3 mumol/ls; p < 0.05). Histologically we observed a mucosa protective effect particularly in the ascorbate group. Other pharmacological strategies are discussed.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Energy Metabolism; Epoprostenol; Free Radical Scavengers; Hypothermia, Induced; Intestinal Mucosa; Intestines; Male; Malondialdehyde; Oxypurinol; Rats; Rats, Inbred Lew; Reperfusion Injury; Superoxide Dismutase; Tocopherols; Vasodilator Agents; Vitamin E

The antioxidants, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, a water soluble analog of vitamin E) and ascorbic acid (AA), protect the heart from ischemia-reperfusion injury. We hypothesized that maternal infusion of Trolox and AA, would reduce the fetal bradycardia and myocardial damage observed in fetal hypoxia and increase the total antioxidant activity in fetal plasma. Either i.v. saline (control group) or Trolox + AA (drug group) was randomly administered to 29-d-old pregnant rabbits. Fetal hypoxia was induced by uterine ischemia. Fetal heart rate, plasma CK-MB activity, and plasma total radical antioxidant potential (TRAP) were measured in different sets of animals. Fetal heart rate in the drug group was higher than in the control group for the first 35 min (p < 0.05 at every 5-min interval). Fetal bradycardia (<60 beats/min) occurred after 39 min (median) in the drug group, and 29 min in the control group (p < 0.05). After 50 min of hypoxia, plasma CK-MB was lower in the drug group, 1204 +/- 132 U/L (mean +/- SEM), than in the control group, 2633 +/- 233 U/L (p < 0.05). TRAP was higher in the drug group, 3.01 +/- 0.15 mM (Trolox equivalent concentration), than in the control group, 1.48 +/- 0.27 mM (p < 0.05). Higher TRAP levels (> or = 2.0 mM) were associated with lower CK-MB levels (<2500 U/L) (p < 0.05). Administration of Trolox and AA to the mother has a beneficial effect on fetal myocardial damage after fetal hypoxia, and a small beneficial effect on fetal bradycardia during hypoxia. The beneficial effect may be due to the augmentation of fetal plasma antioxidants from maternal antioxidant pretreatment.

Topics: Animals; Antioxidants; Ascorbic Acid; Bradycardia; Chromans; Creatine Kinase; Female; Fetal Hypoxia; Heart; Pregnancy; Rabbits; Reperfusion Injury; Survival

To ascertain whether surgery causes ischaemia-reperfusion (I-R) related injury, if this injury is augmented by preoperative shock, and reduced with low dose allopurinol.. Randomised blind placebo controlled trial.. Surgical laboratory.. 22 pigs were randomly allocated to four groups; OP = operation/placebo, OA = operation/ allopurinol, SOP = shock + operation/placebo, SOA = shock + operation/allopurinol. An aortic tube prosthesis was inserted in all. In groups SOP and SOA preoperative shock was induced by exsanguination. Allopurinol was administered in group OA on the preoperative day and peroperatively, in group SOA during shock and peroperatively.. Perioperative blood concentrations of thiobarbituric acid reactive species (TBARS), ascorbic acid (AA), albumin, 99mTc-albumin and creatine phosphokinase (CPK) as indicators of oxidative membrane damage, antioxidant activity, microvascular permeability changes and muscular cell damage respectively.. In the OP and OA groups TBARS gradually increased, while AA, 99mTc-albumin and CPK remained unchanged and albumin decreased. No effect of allopurinol was observed in these groups. In the SOP group TBARS and AA were not significantly different from groups OP and OA. Yet, albumin, 99mTc-albumin and CPK decreased significantly more in the SOP group. Compared with the SOP group, allopurinol treatment (SOA) produced lower TBARS and higher AA levels, and reduced the effect of shock on albumin, 99mTc-albumin and CPK concentrations.. Aortic surgery causes no I-R related damage. Pre-operative shock produces I-R related damage, which is reduced by allopurinol.

Topics: Allopurinol; Animals; Antioxidants; Aorta, Abdominal; Ascorbic Acid; Blood Vessel Prosthesis; Capillary Permeability; Creatine Kinase; Female; Granulocytes; Ischemia; Muscle, Skeletal; Oxidation-Reduction; Placebos; Random Allocation; Reperfusion Injury; Serum Albumin; Shock; Single-Blind Method; Swine; Technetium; Thiobarbituric Acid Reactive Substances

The in vivo effects of ascorbic acid on the reoxygenated liver tissue were examined, with regard to the following effects: (i) the effects of scavenging radicals and/or reducing peroxidative reactions, and (ii) the effects of the chelation with low-molecular-weight iron and increasing its reactivity (radical production). Ascorbic acid is one of the water-soluble vitamins known to have various physiological effects involving both chelating and reducing properties at once. Lipid peroxidation of the reoxygenated liver tissue estimated by the production of TBARS (thiobarbituric acid-reactive substance) and LPO (lipid hydroperoxides) was suppressed effectively by the preischemic intraperitoneal administration of ascorbic acid. Ascorbic acid also showed this anti-oxidant effect in a dose-dependent manner. The analysis of the levels of ascorbic acid and glutathione of the liver tissue revealed that ascorbic acid works as an anti-oxidant probably by being oxydized finally to dehydroascorbic acid just after the reoxygenation. The latter was reduced to ascorbic acid again, coupled with the conversion of GSH to GSSG in the postischemic time course. The predominant effect of ascorbic acid on the reoxygenated liver tissue seems to be caused by the scavenging radicals and/or reducing peroxidative reactions, rather than by chelating iron and increasing its reactivity (radical production). Cellular integrity (estimated by the release of GOT, GPT, and LDH) and the energy state of the postischemic liver tissue (estimated by the tissue ATP level) were also well preserved by the administration of ascorbic acid.

Topics: Adenosine Triphosphate; Alanine Transaminase; Animals; Ascorbic Acid; Aspartate Aminotransferases; Deferoxamine; Dehydroascorbic Acid; Dose-Response Relationship, Drug; Glutathione; Iron; Ischemia; Kinetics; L-Lactate Dehydrogenase; Lipid Peroxidation; Liver; Male; Rats; Rats, Wistar; Reperfusion Injury; Thiobarbituric Acid Reactive Substances; Time Factors

The effect of 32 mM ascorbate on the time courses of phosphocreatine (PCr), inorganic phosphate (Pi), adenosine triphosphate (ATP) and intracellular pH in rat skeletal muscle during ischemia and reperfusion was investigated in vivo using 31P nuclear magnetic resonance (NMR) spectroscopy. Ascorbate was administered intravenously prior to induction of ischemia and at the time of reperfusion. The changes in PCr/(PCr+Pi), ATP and pH were similar in the non-treated and in the treated groups during ischemia. PCr/(PCr+Pi) fell to < 10% and ATP to approximately 30% of the preischemic values after 4 hours of arrested circulation, and pH decreased considerably. Postischemic reperfusion was followed continuously for 150 minutes. At the time of reflow, treatment with ascorbate had an immediate, positive effect on the recovery of high energy phosphates and pH. The level of PCr/(PCr+Pi) was 86% higher (p < 0.001) and the ATP level was 40% higher (p < 0.001) in the treated group than in the control group by the end of the reperfusion period. The results provide in vivo evidence for a salvaging effect of ascorbate on ischemia-reperfusion injury in skeletal muscle, probably owing to its antioxidant function and other ancillary effects, mainly its provision of additional buffer capacity.

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Female; Hydrogen-Ion Concentration; Infusions, Intravenous; Magnetic Resonance Spectroscopy; Muscle, Skeletal; Phosphates; Phosphocreatine; Phosphorus Isotopes; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The gastric mucosal microcirculation and purine nucleotide metabolism were studied in rats after hemorrhagic shock and retransfusion. The mucosal surface density of perfused vessels (SDPV) and the mucosal levels of ATP, ADP, AMP, IMP, hypoxanthine and uric acid were measured following 15 min of hemorrhagic shock and 10 and 30 min after retransfusion, and the effects of pretreatment with allopurinol or ascorbate were studied. During shock there was a dephosphorylation of nucleotides and a decline in the SDPV. Retransfusion led to an additional reduction in the SDPV, but a complete restoration of preshock nucleotide levels 30 min after retransfusion. Allopurinol accelerated early rephosphorylation of nucleotides without effects upon SDPV while ascorbate completely preserved the mucosal level of energy-rich nucleotides 15 min after hemorrhagic shock and increased SDPV during early reperfusion. The results showed that there was a renewal of energy stores in gastric mucosa after hemorrhagic shock and retransfusion although parts of the vascular bed were not reperfused. The mucosal energy depletion after 15 min of hemorrhagic shock and part of the mucosal vessel injury after retransfusion were prevented by pretreatment with ascorbate.

Topics: Allopurinol; Animals; Ascorbic Acid; Blood Transfusion, Autologous; Gastric Mucosa; Male; Microcirculation; Purine Nucleotides; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Shock, Hemorrhagic

The aim was to define the following: (1) if reperfusion of ischaemic limbs could cause myocardial damage; (2) if reactive oxygen metabolites are involved in such possible damage.. Ten rats underwent ischaemia-reperfusion of the lower limbs (group A) and 10 underwent the same procedure following treatment with ascorbic acid (group B). Ten rats were used as a control group (group C).. The incidence of severe myocardial mitochondrial damage and serum malondialdehyde concentrations 30 min after reperfusion were both higher in group A than in groups B and C [8/10, 2/10, and 0/10, p < 0.05 and 7.25 (SEM 0.33), 5.30(0.26), and 4.89(0.23) mumol.litre-1, p < 0.05, respectively].. Ischaemia-reperfusion of the lower limbs may cause mitochondrial damage in the myocardium and reactive oxygen metabolites could mediate this damage.

Topics: Animals; Ascorbic Acid; Extremities; Ischemia; Male; Mitochondria, Heart; Rats; Reactive Oxygen Species; Reperfusion; Reperfusion Injury

Free radicals have been implicated in the cause of ischemia-reperfusion injury. Various agents have been used in an attempt to reduce ischemia-reperfusion injury pharmacologically, including free radical scavengers. Vitamin C (ascorbic acid), a well-known free radical scavenger, has not, to the best of our knowledge, been evaluated in this respect. Previous work at our institution has shown that vitamin C decreases capillary permeability, thus significantly reducing fluid resuscitation requirements in postburn cases. Because this is due in part to the scavenging effect of vitamin C on free radicals, we investigated the role, if any, of vitamin C on ischemia-reperfusion injury in a rat epigastric island skin flap model. Twenty-four adult Sprague-Dawley rats were divided into control and vitamin C groups. Superficial epigastric island skin flaps measuring 6.0 x 3.5 cm were raised. Pedicles were isolated and occluded with microvascular clamps for 6 hours. The flaps were then sutured back to their beds over Steri-Drape barriers. Fifteen minutes before reperfusion, the control group flaps were perfused via femoral artery cannulation with normal saline (2.5 ml/kg). The vitamin C-treated group was perfused in a similar fashion with 2.5 ml/kg of a vitamin C/normal saline solution (27 mg/ml). The animals were observed for 7 days, and the percentage of flap survival was determined using a paper template technique. The vitamin C-treated group demonstrated a significantly higher percentage of flap survival than did the control group (25.8% mean vs. 7.5% mean, p < 0.025). In this animal model, vitamin C reduced or limited reperfusion injury after 6 hours of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Ascorbic Acid; Graft Survival; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Surgical Flaps

The rat gastric mucosa, superfused with 0.1 N HCl, was investigated following 15 min of hemorrhagic shock and 30 min of retransfusion after pretreatment with ascorbate (1 mg/100 g b.w. or 5 mg/100 g b.w.). The size of the ischemic areas and the amount of mucosal bleeding using 51Cr labeling of red blood cells were assessed. Ischemic areas developed during shock. Following retransfusion, bleedings occurred at the border zones between ischemic and surrounding circulated areas. Ascorbate in both doses protected the gastric mucosa by reducing the amount of bleeding following 30 min of retransfusion as well as by reducing the area of ischemia 5 min after retransfusion.

Topics: Animals; Ascorbic Acid; Gastric Mucosa; Gastrointestinal Hemorrhage; Male; Rats; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury; Shock, Hemorrhagic

The free radical-scavenging activity of captopril and ascorbic acid was determined by assessing their ability to inhibit the peroxidation of linoleic acid in sodium dodecyl sulphate (SDS) micelles at 37 degrees C. The extent of peroxidation was monitored polarographically using an oxygen electrode to determine oxygen consumption rates. Ascorbic acid was observed to inhibit the peroxidation in a concentration-dependent fashion with an IC50 value of 17 microM. In contrast, the addition of captopril at concentrations up to 500 microM did not result in any detectable inhibition. Unlike ascorbic acid, no synergistic effect, as evidenced by the duration of inhibition, was observed with captopril/alpha-tocopherol mixtures. Measurements of the partitioning of captopril between SDS micelles and the aqueous phase show that 37% of the bulk captopril concentration is localized within the micellar phase; this indicates that phase separation of captopril from the lipid peroxyl radicals is not the cause of the observed lack of inhibitory activity.

Topics: Angiotensin-Converting Enzyme Inhibitors; Ascorbic Acid; Captopril; Diffusion; Free Radical Scavengers; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Micelles; Oxidation-Reduction; Oxygen Consumption; Phospholipids; Reperfusion Injury; Sodium Dodecyl Sulfate

We present a clinically available method to protect the spinal cord against ischemic or reperfusion injury and to prevent paraplegia after cross-clamping of the aorta. We separated 35 rabbits into five equal groups and clamped each animal's abdominal aorta distal to the left renal artery. We also occluded the aortas 2 cm above the iliac bifurcation for 45 minutes with inflated 5F balloon catheters. Through the catheter port distal to each balloon one of four different solutions was infused at 3 degrees C for 3 minutes at a rate of 5 mL/min (group I, uninfused control; group II, lactated Ringer's solution; group III, lactated Ringer's solution + 30 mg/kg of methylprednisolone; group IV, lactated Ringer's solution+methylprednisolone + 3 mL of 20% mannitol; group V, lactated Ringer's solution+methylprednisolone+mannitol + 10 mg/kg of vitamins E and C). We assessed the neurologic status of the hind limbs on the second postoperative day using Tarlov's criteria. The neurologic status in groups III, IV, and V was significantly superior to that of group I (p < 0.05, groups III versus I; p < 0.01, groups IV and V versus I). Spastic paraplegia occurred in 71% of group I, in 43% of group II, in 29% of group III, in 14% of group IV, and not at all in group V. The infusion of our specially blended solution with several spinal cord neuroprotective properties (hypothermia, methylprednisolone, mannitol, and vitamins E and C) achieved the best spinal cord protection against ischemic or reperfusion injury and prevented postoperative paraplegia.

Topics: Animals; Aorta, Abdominal; Ascorbic Acid; Constriction; Electrolytes; Hindlimb; Hypothermia, Induced; Isotonic Solutions; Mannitol; Methylprednisolone; Osmolar Concentration; Paraplegia; Rabbits; Regional Blood Flow; Reperfusion Injury; Ringer's Lactate; Spinal Cord; Time Factors; Vitamin E

Recently, it was reported that Ginkgo biloba extract (EGb 761), which is known to have antioxidant properties, also has antiarrhythmic effects on cardiac reperfusion-induced arrhythmias. In the present study, effects of EGb 761 on cardiac ischemia-reperfusion injury were investigated from the point of view of recovery of mechanical function as well as the endogenous antioxidant status of ascorbate. Isolated rat hearts were perfused using the Langendorff technique, and 40 min of global ischemia were followed by 20 min of reperfusion. EGb 761 improved cardiac mechanical recovery and suppressed the leakage of lactate dehydrogenase (LDH) during reperfusion. Furthermore, EGb 761 diminished the decrease of myocardial ascorbate content after 40 min of ischemia and 20 min of reperfusion. Interestingly, EGb 761 also suppressed the increase of dehydroascorbate. These results indicate that EGb 761 protects against cardiac ischemia-reperfusion injury and suggest that the protective effects of EGb 761 depend on its antioxidant properties.

Topics: Analysis of Variance; Animals; Antioxidants; Ascorbic Acid; Dehydroascorbic Acid; Electron Spin Resonance Spectroscopy; Ginkgo biloba; Heart; In Vitro Techniques; L-Lactate Dehydrogenase; Male; Myocardial Ischemia; Myocardium; Plant Extracts; Rats; Rats, Sprague-Dawley; Reperfusion; Reperfusion Injury; Time Factors

Using electron spin resonance (ESR) spectroscopy, we examined whether reactive oxygen intermediates (ROIs) are produced after reperfusion of isolated, perfused rat livers subjected to global ischemia (10, 30, 60, and 90 min of ischemia). A few drops of effluent (200 microliters) flowed from reperfused liver was mixed immediately with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO, final concentration 1 M), and ESR measurements were then performed. Immediately after reperfusion, a small amount of ascorbic acid radical and DMPO-OOH, which was formed by the reaction of superoxide with DMPO, was detected. The amount of ascorbic acid radical peaked immediately after reperfusion, but became hardly detectable at 6 min after reperfusion, irrespective of the period of ischemia. Six minutes after reperfusion, not only DMPO-OOH but also DMPO-OH, which was formed by the reaction of hydroxyl radical with DMPO, was detected. Thereafter, DMPO-OOH and DMPO-OH gradually declined and became hardly detectable at 40 min after reperfusion. In accordance with the duration of ischemia, the concentrations of DMPO-OOH and DMPO-OH were highest after 60 min of ischemia, and then after 30, 90, and 10 min of ischemia in decreasing order. These results directly demonstrate that the production of ROIs occurs at an early stage of reperfusion in ischemic liver and that the amount of ROI production is closely related to the duration of ischemia.

Topics: Animals; Ascorbic Acid; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Free Radicals; Hydroxyl Radical; In Vitro Techniques; Ischemia; Kinetics; Liver; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxides; Time Factors

The present study set out to investigate whether plasma phosphatidylcholine hydroperoxide (PCOOH) levels could accurately reflect lipid peroxidation linking to liver damage due to ischemia--reperfusion. PCOOH is a primary peroxidative product of phosphatidylcholine (PC), which is the most important functional lipid in the hepatocellular membrane, and may mediate oxidative stress. We quantified PCOOH and PC in the plasma and liver of rats subjected to hepatic ischemia-reperfusion by chemiluminescence detecting HPLC (CL-HPLC) method. Plasma PCOOH levels showed no significant rise in either the ischemia only group or in the sham-operation group, compared to controls (0.7 nmol/mL plasma). At 60 min subsequent to reperfusion, the PCOOH levels in plasma and liver, as well as the levels of several serum markers of liver injury [lactic dehydrogenase (LDH), glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT)] increased in proportion to the duration of ischemia (up to 60 min). During periods of reperfusion following 30 min of ischemia, plasma PCOOH increased biphasically (2 nmol/mL; 12-24 hr duration of reperfusion), and generally ran parallel to that in the liver after more than 60 min of reperfusion. Dose-dependent protective effects against warm ischemia (30 min)-reperfusion (12 hr) injury were clearly demonstrated in the groups treated with allopurinol, diclofenac Na, ascorbic acid (V.C), alpha-tocopherol and coenzyme Q10, but not in those treated with r-h-superoxide dismutase or betamethasone. The rises in plasma PCOOH and serum GOT, GPT and LDH of the ischemia-reperfused rats were ameliorated most in the group pretreated with diclofenac Na, and next most in the group pretreated with V.C. These results indicate that the plasma PCOOH levels are a useful index both for liver cell damage induced by oxygen free radicals generated during ischemia-reperfusion, and to investigate the efficacy of drugs against oxidative stress.

Topics: Animals; Ascorbic Acid; Chromatography, High Pressure Liquid; Diclofenac; Free Radicals; Ischemia; Liver; Male; Phosphatidylcholines; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Superoxide dismutase is well known to act as an effective antioxidant enzyme against cellular damage caused by oxidative stresses including ischemia/reperfusion-induced cerebral injury. However, it is still controversial whether or not the activity of endogenous superoxide dismutase changes during cerebral ischemia and reperfusion. In order to elucidate this phenomenon, we assayed the superoxide dismutase activity in the cerebral tissues of gerbils using the chemiluminescence method with a Cypridina luciferin analog. This method was demonstrated to be a sensitive and specific assay for the enzymatic activity of superoxide dismutase in cerebral tissues, which was not subject to interference from proteins or ascorbate. After 3 h of focal and global ischemia, there were no changes in the cerebral tissue superoxide dismutase activities. After 24 h of reperfusion following 1 h of ischemia, the superoxide dismutase activity decreased only approx 20%, whereas the adenylate kinase activities, measured in the same cerebral tissues as those used for superoxide dismutase assay, started to decline 1 h after reperfusion commenced and were approx 50% of the control levels after 24 h. These results show that almost all the activity of endogenous superoxide dismutase is maintained and does not decrease significantly as a result of ischemia/reperfusion-induced cerebral injury.

Topics: Animals; Ascorbic Acid; Brain; Brain Ischemia; Gerbillinae; Hot Temperature; Luminescent Measurements; Male; Nerve Tissue Proteins; Reperfusion Injury; Sensitivity and Specificity; Superoxide Dismutase

Complete, reversible forebrain ischemia was induced with a seven-vessel occlusion rat model. Previous studies of ischemic (M. A. Sciamanna, J. Zinkel, A. Y. Fabi, and C. P. Lee, 1992, Biochim. Biophys. Acta 1134, 223-232) rat brain mitochondria (RBM) showed that ischemia of 30 min caused an approximately 60% decrease in State 3 respiratory rates with both succinate and NAD-linked substrates and also in energy-linked Ca2+ transport. No significant change was seen in the State 4 rates. The inhibition of respiration could be prevented by EGTA or ruthenium red. In this paper it is shown that reperfusion (5 h) following ischemia (30 min) further impaired RBM respiratory activities (succinate and NAD-linked substrates). The presence of EGTA or ruthenium red in the assay medium did not protect against ischemia/reperfusion-induced injury. The effects of ascorbate, an oxygen radical scavenger, were studied. RBM isolated from ascorbate-treated animals (0.8 mg ascorbate/kg body weight) after ischemia (30 min) alone showed only a slight increase in State 3 (approximately 25%) and a decrease in State 4 (approximately 20%) activities with succinate, when compared to untreated 30-min ischemic animals, whereas, with glutamate+malate little or no effect was seen. The respiratory activities of RBM from ascorbate-treated, ischemic/reperfused (30 min/5 h) rats were restored to approximately 65% of controls levels. Ascorbate protection was dose-dependent with maximum protection at 0.8 mg ascorbate/kg body weight of rat. The k of succinate oxidase-supported Ca2+ uptake also returned to 62% of control values. Protection by ascorbate was most effective when administered prior to the onset of ischemia and provided partial protection when administered after the onset of reperfusion. These results suggest that ischemia-induced injury is primarily mediated by disruption of cellular Ca2+ homeostasis, and reperfusion-induced injury by peroxidative events.

Topics: Animals; Ascorbic Acid; Biological Transport; Calcium; Chelating Agents; Energy Metabolism; Male; Mitochondria; Phosphorylation; Prosencephalon; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Time Factors

Oxymyoglobin at 'physiological' concentrations of 20-100 micromolar protected cultured endothelial cells from damage by xanthine/xanthine oxidase or by hydrogen peroxide. Metmyoglobin also provided a degree of protection, but apomyoglobin was ineffective. Protection was enhanced in the presence of ascorbate (0.01-1 mM). Myoglobin may have a physiological role in the protection of muscular tissue from ischaemia/reperfusion-induced damage.

Topics: Adenine; Animals; Aorta; Ascorbic Acid; Cattle; Cells, Cultured; Endothelium, Vascular; Hydrogen Peroxide; Metmyoglobin; Myoglobin; Reperfusion Injury; Xanthine; Xanthine Oxidase; Xanthines

Using a swine orthotopic liver transplantation (SOLTx) model, we assessed the effect of a new hydroxyl radical scavenger EPC-K1 on warm ischemic damage of the liver graft and recipient survival. Animals were divided into 5 groups. The first group (control group 1) consisted of 5 pigs which were not operated on but served as controls for the indocianine green disappearance rate (K-ICG) determinations. In the second group (control group 2), 10 livers were transplanted without warm ischemia (WI) and the K-ICG values were measured. The third group (control group 3) was the main control group for the study groups and consisted of 5 liver transplants with 30 min of WI without any special treatment. The fourth and fifth groups served as study groups 1 and 2. Five transplants were carried out in each group, as in control group 3. In study group 1 recipients were treated with an additional 5 mg/kg i.v. EPC-K1 and in study group 2 with 20 mg/kg i.v. EPC-K1. Significant improvement in glutamic oxaloacetic transaminase (GOT) and lactate dehydrogenase (LDH) levels, K-ICG values and histological findings were observed in the EPC-K1 treated groups. The intravenous administration of this agent had a strong protective effect on warm ischemic damage after 30 min of WI and could significantly prolong the graft and recipient survival.

Topics: Animals; Ascorbic Acid; Biopsy; Free Radical Scavengers; Graft Survival; L-Lactate Dehydrogenase; Liver Transplantation; Models, Animal; Reperfusion; Reperfusion Injury; Swine; Transplantation, Isogeneic; Vitamin E

Oxygen-derived free radicals have been shown to play an important role in reperfusion injury. The protective effect of CV-3611, a new free radical scavenger, on reperfusion injury in an ischemic revascularized hind limb model in rats was examined. Warm ischemia (25 degrees C) was produced by vascular pedicle clamping and sustained for 0, 3, and 6 hr. Histologic and fluorochrome bone-labeling analyses demonstrated improved overall viability of osteocytes, osteoblasts, and marrow cells in the CV-3611-treated group compared to controls. The CV-3611-treated group had statistically significant improvement in the ratio of lacunae, maintained osteogenetic ability, and preserved normal growth plate architecture after 6 hr of ischemia. The control group showed local central areas of disorganization by 3 hr and complete destruction of the growth plate with early growth arrest after 6 hr of ischemia. These results indicate that administration of CV-3611 prior to reperfusion can prevent reperfusion damage in bone tissue and maintain osteogenetic ability. This technique may have clinical application for reducing the complications of prolonged ischemia to bone tissue.

Topics: Animals; Ascorbic Acid; Bone and Bones; Bone Transplantation; Cell Survival; Free Radical Scavengers; Free Radicals; Ischemia; Male; Microsurgery; Osteocytes; Rats; Rats, Inbred Lew; Reperfusion Injury; Superoxides

Topics: Antioxidants; Ascorbic Acid; Brain Diseases; Cardiovascular Diseases; Cells; Free Radical Scavengers; Free Radicals; Humans; Ischemia; Phagocytes; Reactive Oxygen Species; Reperfusion Injury; Respiratory Tract Diseases; Superoxide Dismutase

Brain concentrations of the antioxidant vitamins C and E decreased following unilateral carotid occlusion and reperfusion for 2 or 24 h in gerbils. Administration of the 21-aminosteroid inhibitor of lipid peroxidation, tirilazad mesylate (U74006F), prevented the decrease in level of both of these vitamins following 2 h of reperfusion. After 24 h of reperfusion, however, alpha-tocopherol (vitamin E) continued to be protected, but ascorbic acid (vitamin C) showed a pronounced decrease in content. The changes in concentrations of these vitamins are consistent with U74006F acting to inhibit peroxidation in the CNS by scavenging of lipid peroxyl radicals and suggest that, in the presence of this agent, injury-induced depletion of ascorbic acid may occur without irreversible tissue damage.

Topics: Animals; Ascorbic Acid; Brain; Brain Chemistry; Brain Ischemia; Gerbillinae; Lipid Peroxides; Male; Pregnatrienes; Reperfusion Injury; Time Factors; Vitamin E

Lipid peroxidation disrupts membrane integrity and causes structural and functional alterations in ischemic tissues. Taurine and ketamine are putative ischemic protectants that affect Ca2+ influx. Here we report the influence of these compounds on lipid peroxidation in subcellular fractions, isolated cells and intact tissue from bovine retinas. P2 membrane fractions and isolated cells were exposed to the lipid peroxidation inducers cadmium chloride (200 microM) or L-ascorbic acid (1 mM) in the presence of 0-50 mM taurine, 0-10 mM ketamine, 1 mM kynurenic acid or 1 mM dextromethorphan. The latter compounds are N-methyl-D-aspartate receptor antagonists. Lipid peroxidation in isolated eyes reperfused after 1 h of ischemia either with or without protectants was determined by thiobarbituric acid assay. Glutathione was measured in isolated retinas subjected in vitro to simulated ischemia (no glucose or oxygenation) for 60 min either alone or in the presence of taurine or ketamine. Ketamine inhibited chemical- or ischemia-induced lipid peroxidation as well as ischemic glutathione depletion. Under the same conditions, taurine failed to affect lipid peroxidation or glutathione. The data show a direct effect of ketamine on lipid peroxidation and point to separate mechanisms of action for ketamine and taurine.

Topics: Animals; Ascorbic Acid; Cadmium; Cadmium Chloride; Calcium; Cattle; Dextromethorphan; Female; Ischemia; Ketamine; Kynurenic Acid; Lipid Peroxidation; Membrane Lipids; Receptors, N-Methyl-D-Aspartate; Reperfusion Injury; Retina; Taurine; Trifluoperazine

Metmyoglobin catalyzes the decomposition of H2O2 as well as other hydroperoxides by using ascorbic acid as a substrate. The ratio of H2O2 reduced to ascorbate oxidized is close to one, whereas the rate of oxidation is directly proportional to both H2O2 and metmyoglobin concentrations. Ascorbate also prevents the protein modifications and the O2 evolution that accompany the reaction of metmyoglobin with hydroperoxides. In the absence of ascorbate, myoglobin and H2O2 promote the peroxidation of unsaturated fatty acids and, thus, may cause damage to cellular constituents. However, lipid peroxidation is inhibited in the presence of ascorbate and, for this reason, it is suggested that this heme protein functions in the opposite manner. The redox cycling of myoglobin by ascorbate may act as an important electron "sink" and defense mechanism against peroxides during oxidative challenge to muscle.

Topics: Ascorbic Acid; Hydrogen Peroxide; Lipid Peroxidation; Metmyoglobin; Muscles; Myoglobin; Oxidation-Reduction; Reperfusion Injury

Topics: Animals; Antioxidants; Ascorbic Acid; Biphenyl Compounds; Brain; Depression, Chemical; Dogs; Free Radicals; Hydrazines; Lipid Peroxidation; Picrates; Reperfusion Injury