Prooxidant-antioxidant Equilibrium Research Articles

The study of the prooxidant-antioxidant equilibrium in the kidney tissue and blood on the background of ceruloplasmin administration under the conditions of acute kidney injury

Acute kidney injury (AKI) remains a relevant medical problem. The promising direction of the AKI treatment is the use of the antioxidants that inhibit free radical processes and prevent the destruction of cell membranes within pathological processes. Ceruloplasmin (CP) is the main antioxidant of blood plasma, that demonstrates membrane protecting effects and antitoxic activity.The aim of the study was to establish the influence of a single-dose administration of ceruloplasmin on the processes of the peroxidation in the kidney tissue and blood under the conditions of acute kidney injury.Materials and methods. The influence of ceruloplasmin on the prooxidant-antioxidant equilibrium in the kidney tissue and blood was studied in an experiment on white non-line rats under the conditions of rhabdomyolysis-induced acute kidney injury. The acute kidney injury was modeled by intramuscular administration of 50% glycerol solution at a dose of 8 mg/kg. Ceruloplasmin was administered intraperitoneally at a dose of 7 mg/kg/day. The level of main indicators of prooxidant-antioxidant balance in blood and kidney tissue was determined in 24 h after glycerol administration for induction of acute kidney injury.Research results and their discussion. There was a deep disruption of the prooxidant-antioxidant equilibrium as a result of the acute kidney injury. AKI causes an activation of the prooxidant processes by increasing the level of the malonic dialdehyde and the oxidized proteins in the kidney tissue and blood. AKI also reduces the antioxidant protection by decreasing the activity of the antioxidant enzymes in the kidneys and blood plasma.A single-dose administration of ceruloplasmin improved antioxidant protection and reduced peroxidation of lipids and proteins. There was a decrease in levels of malondialdehyde and oxidative modification of proteins. At the same time, the antioxidant protection intensified due to an increase in the activity of glutathione peroxidase and catalase in the kidneys and blood plasma.Conclusions. A single administration of ceruloplasmin influences prooxidant-antioxidant balance, reducing the content of lipid and protein peroxidation products and increasing the activity of antioxidant enzymes.

ANTI-OXIDANT ACTIVITY OF SESEWANUA (Clerodendrum fragrans [Vent.] Willd) LEAF EXTRACT AND FRACTION WITH 1,1-DiPHENYLl-2-PICRYLHYDRAZYL (DPPH) AND NITRATE-OXIDE FREE RADICAL SCAVENGING METHOD

Free radicals are molecules containing unpaired electrons so that they are not stable and very reactive to other molecules. ROS/RNS radicals have physiological function, but the overproduction of free radicals can initiate oxidative/nitrosative stress that contributes to a high number of diseases. Body has an ability to neutralize the free radicals by forming the endogenous antioxidant. Environmental changes, living style, certain pathological conditions can cause the shift of prooxidant-antioxidant equilibrium. Thus, endogenous antioxidant intake is needed, particularly that originating from natural materials. One of the plants believed to have antioxidant activity is sesewanua (Clerodendrum fragrans [Vent.] Willd.) leaf. This study was aimed to evaluate the antioxidant activity of ethanol extract, hexane fraction, ethyl acetate fraction, and water fraction of the sesewanua leaf using DPPH and nitrate-oxide free radical scavenging method. The study is a laboratory experiment. The sample was sesewanua (Clerodendrum fragrans) obtained from East Malalayang I village, Malalayang district, Manado city, North Sulawesi. The antioxidant activity testing utilized 1,1-Diphenyl-2-Picrylhydrazyl (DPPH) and nitrate-oxide free radical scavenging method. Data included percent inhibition of free radicals and were analyzed using linear regression to determine 50% inhibition concentration (IC50) of DPPH and nitrate-oxide free radicals. As conclusion, the ethanol extract, hexane fraction, ethyl acetate fraction, and water fraction of the sesewanua leaf had antioxidant activity through DPPH free antiradical activity, but not active as antiradical NO.

General, 21-Day Postoperative Rehabilitation Program Has Beneficial Effect on Oxidative Stress Markers in Patients after Total Hip or Knee Replacement.

Imbalance in prooxidant-antioxidant equilibrium plays an important role in the progression of osteoarthritis (OA). Postoperative rehabilitation significantly improves the functional activity of patients with OA. We aimed to assess the effect of the general 21-day postoperative rehabilitation on the oxidative stress markers in patients after total hip arthroplasty or knee replacement. Patients (n =41) started individually designed postoperative rehabilitation ca. 90 days after endoprosthesis implantation. We used the six-minute walk test (6MWT) to quantify the changes in their exercise capacity. We analyzed the oxidative stress markers: total antioxidant capacity (TAC), total superoxide dismutase (SOD), Cu-Zn-superoxide dismutase (CuZnSOD) and ceruloplasmin (Cp) activity, malondialdehyde (MDA) and lipofuscin (LPS) concentration in patients serum to asses changes in the oxidative stress intensity. We found that after 21-days postoperative rehabilitation program: the average distance walked by patients increased by 69 m; TAC increased by 0.20 ± 0.14 mmol/l; both SOD isoforms activities increased by 1.6 (±1.7) and 1.72 (±1.5) NU/ml, respectively; but Cp activity decreased by 1.8 (0.7-3.7) mg/dl. Also, we observed lower concentrations of lipid peroxidation markers: by 19.6 ± 24.4 μmol/l for MDA and by 0.4 ± 0.5 RF for LPS. A 21-day postoperative rehabilitation program effectively reduces oxidative processes, which helps the patients after total hip or knee replacement in a successful recovery.

CHARACTERISTICS CHANGES IN PRO-OXIDANT-ANTIOXIDANT STATUS IN PATIENTS WITH ACUTE LEUKEMIA DURING CHEMOTHERAPY

Changes in the processes of lipid peroxidation and antioxidant system activity are involved in the pathogenesis of carcinogenesis and can affect tumor resistance to chemotherapy. The aim of this study to investigate the nature of changes in pro-oxidant-antioxidant status in patients with acute leukemia during remission induction chemotherapy. Materials and methods. The study involved 42 patients with newly diagnosed acute leukemia, 22 of them were diagnosed to have acute myeloid leukemia and 20 patients had acute lymphoblastic leukemia. The age range was 18-58 years, there were 19 women (45.2%) and 23 men (54.8%). The patients were divided into two groups: I (n=22) included patients with acute myeloid leukemia, who had chemotherapy modes "7+3" and "5+2" for variants M0-2 and "7+3+etoposide" or "5+2+etoposide" for M4-5 variants; II (n=20) group included patients with acute lymphoblastic leukemia, who received chemotherapy according to D. Hoelzer protocol. Hemogram parameters (red blood cells, hemoglobin, white blood cells, platelets) were evaluated at baseline and on the 28th day of chemotherapy. The concentration of thiobarbituric acid reactive substances and catalase activity in the blood serum were assessed as well. Examination of acute myeloid leukemia patients was performed before the chemotherapy, on the 4th and 28th days since chemotherapy started; acute lymphoblastic leukemia patients were examined before chemotherapy, on the 23rd and 28th days. The group of healthy individuals consisted of 20 persons, including 9 (45%) women and 11 (55%) men, aged 22-26 years. Results. The detailed clinical picture of acute leukemia was accompanied by typical changes in hemogram in the patients of both test groups, and namely, by the development of leukocytosis, anemia, thrombocytopenia. At the same time, the patients with acute myeloid leukemia and acute lymphoblastic leukemia demonstrated an increased concentration of thiobarbituric acid reactive substances in 1.8 and 1.89 times, respectively (p<0.05) that was accompanied by an increased serum catalase activity in 1.96 and 1.8 times, respectively (p<0.05) compared to healthy individuals. During "7+3" chemotherapy, acute myeloid leukemia patients were found to show thiobarbituric acid reactive substances increased in 1.9 times on the 4th day of treatment and decreased on the 28th day.The patients with acute lymphoblastic leukemia managed according to the D. Hoelzer protocol demonstrated an increased concentration of thiobarbituric acid reactive substances in the blood serum in 1.33 times on the 23rd day of treatment (p<0.05), maintaining this level up to the 28th day. The catalase activity in the patients of the comparison groups did not change. Conclusion. The debut of acute leukemia is accompanied by activation of lipid peroxidation and antioxidant system enzymes. Сhemotherapy promotes the shift of the prooxidant-antioxidant equilibrium towards the lipid peroxidation activation.

Subacute toxicity of decahedron and spheral silver nanoparticles in rats

The safety of nanomaterials and nanotechnologies is an important factor in the regulation of industrial production and the introduction of nanoproducts into practice. The toxicological aspect of the use of silver nanoparticles (SNP) is insufficiently studied, leaving many questions without answer. The problem of dependence of toxicity on the shape and the size of nanoparticles is controversial and not well-studied, and there is a lack of research on the nanosilver effect on human and animal organisms. Objective. The aim of the work was to provide the hygienic assessment of harmful effects of silver nanoparticles of spherical and decahedron shape. Materials and Methods. Samples of solutions of spherical and decahedron SNP, synthesized by the method of photostimulated restoration, were intraperitoneally administered to white nonlinear rats both males and females aged 4 months. For the subacute toxicity study of spherical 45-nm nanosilver the animals were subdivided into three groups of (16 rats in each, 8 animals in a subgroup — according to gender). Every day they were injected with spherical SNP at doses of 0.1,1 and 5 mg/kg intraperitoneally for 14 days. The fourth group was the biological control. For the subacute toxicity study of decahedron 45-nm nanosilver the animals were subdivided into four groups (16 rats in each, 8 animals in the subgroup according to gender). The animals were injected intraperitoneally with 10, 5,1, and 0.1 mg/kg doses of SNP daily for 14 days. Fifth group was biological control. On 14th day animals were withdrawn from the experiment by decapitation under a slight, ethereal athetic. Results and Discussion. It was grounded the expediency of taking into account the physical and chemical properties of silver nanoparticles, including geometrical characteristics (shape, specific area of surface), the number of silver ions in nanoparticle and the quantity of nanoparticles in the solution while the determination of exposition of nanosilver or other nanochemicals of different geometric shapes. On models of subacute effect there were determined the peculiarities of different shapes nanosilver exposure and hygienic meaning of biochemical and pathomorphological changes as criteria of harmful effect. With the help of morphometric analysis of pathomorphological changes of internal organs of rats there was ascertained doserelated harmful effect of decahedron and spherical silver nanoparticles. As a result of the experiment, dose-dependent circulating swelling of the epithelium of convoluted tubules of the kidneys, hepatocytes, nuclei of cardiomyocytes, alteration of the epithelium of bronchi of different caliber, repletion of the blood vessels of the walls of the respiratory parts of the lungs, karyopicnosis of neurons of the cerebral cortex were observed. The revealed changes in the indices of prooxidant-antioxidant equilibrium, some biochemical indices and the changes in internal organs of animals testified to the less toxic effect of silver nanospheres in comparison with silver nanodecahedrons. Conclusions. 1. According to the analysis of the geometric characteristics of decahedron silver nanoparticles, it is established that the specific area of decaheders is 2 times bigger than the specific area of the spherical SNP, which provides twice bigger area of the contact of silver nanodecahedron in the biological environment. The decahedron nanoparticle contains 4.3 times less atoms than spherical, and, at the same mass concentration, a solution of nanosilver contains 4 times more silver nano decahedrons than spheres. 2. With the help of biochemical analyses of blood and liver tissue, as well as the morphometric analysis of pathological changes in the internal organs of laboratory rats, the dose-dependent harmful effect of silver nanoparticles of decahedral and, partially, spherical shape was established. The revealed changes in the blood and internal organs of animals testified to a less toxic effect of silver nanospheres in comparison with silver nanodecahedrons. 3. It was established that the differences in biochemical and pathomorphological changes in the internal organs of laboratory animals at the same dose of SNP the decahedron and spherical shape, calculated in mg/kg body weight, are related to a 4-multiple dose difference expressed in the ratio of «the number of nanoparticles/kg» of body weight and a 9-multiple difference in favor of nanodecahedrons while calculating the dose «specific surface area/kg» of body weight. Key Words: silver nanoparticles, silver nanodecahedron, silver nanosphere, toxicity, nanosilver.

ВПЛИВ ПРЕПАРАТУ КАРДОНАТ НА ПОКАЗНИКИ БІОХІМІЧНОГО ТА ГОРМОНАЛЬНОГО ГОМЕОСТАЗУ СПОРТСМЕНІВ З КАРДІОМІОПАТІЄЮ ХРОНІЧНОГО ФІЗИЧНОГО ПЕРЕНАПРУЖЕННЯ

Introduction. Modern sport of the highest achievements is inextricably linked with the constant physical activity of high intensity, which ultimately leads to the formation of overvoltage phenomena of various body systems. The purpose. To substantiate the expediency of appointment of athletes with clinical and instrumental signs of the cardiomyopathy, caused by chronic physical overload (CMPCPO) of the metabolic preparation Cardonat on the basis of evaluation of its influence on the indices of biochemical and hormonal homeostasis. Materials and methods. The study involved 48 athletes, representatives of cyclic sports, with a diagnosis CMPCPO who were randomized to 2 equivalent (n = 24) groups: the main group and the controls. The volume and intensity of training loads was reduced in athletes of both groups by 75%. The control group participants received only basic therapy (the combination of the drug panangin (potassium and magnesium aspartate) and the drug Trіovіt, at therapeutic doses of vitamin-mineral orientation and placebo (capsule with starch). Athletes of the main group in addition to basic therapy used Cardonat for one capsule three times a day for 4 weeks. A comprehensive laboratory study of athletes before and after the course of treatment included a study of the indicators of biochemical and hormonal homeostasis, as well as prooxidant-antioxidant balance. Results. The addition of Cardonat to the complex therapy of athletes from the CMPCPO during the month is accompanied by a positive effect on the structural characteristics of the erythrocyte membranes of the athletes, which is reflected in the improvement of the state of prooxidant-antioxidant equilibrium: in the representatives of the main group, the administration of the drug caused a statistically significant decrease, compared with the data in the control group, malodialdehyde (MDA), increase in the concentration of reduced glutathione (GSH) in erythrocyte membranes and decrease of prooxidant-antioxidant coefficient (Cpa), indicating the predominance of antioxidant processes over lipopereoxidation processes. It is also shown that taking a Cardonat with athletes with manifestations CMPCPO is not accompanied by negative changes in standard laboratory biochemical parameters that reflect the functional state of various organs and systems of the body's organs. The decrease in the activity of aspartate aminotransferase (AST) and the tendency towards a more pronounced decrease in alanine aminotransferase (ALT), α-amylase and urea content in comparison with the values of the corresponding indices in the control group, confirms the positive effect of the drug on the functional state of the liver and pancreas. Indicators of hormonal homeostasis are indicative of improving the ratio of anabolic and catabolic processes in the body of athletes and reducing the level of stress due to the use of the drug. Thus, after taking Cardonat in the main group, testosterone levels increased by 31.6 % (р < 0.05) compared to baseline data, and cortisol decreased by 63.8 % (р < 0.05); the average index of anabolism in the main group after treatment increased by 58.9 % (р < 0.05), which indicates a significant increase in the rate of anabolic processes. Conclusions. The additional use of сardonat in therapy is safe, expedient, pathogenetically justified, in particular for the treatment of homeostatic shifts in the body of athletes with clinical and electrocardiographic manifestations of CMPСPО.

Influence of long-term using of soft contact lenses on indicators of oxidative-reducing potential of glutathione, peroxidation of lipids, and the state of cell membranes and cellular structures of the epithelium of the cornea

Contact lenses are increasingly used worldwide for correcting refraction disorders. However, contact lenses can destroy a biochemical composition of the tear. Purpose — to determine the effect of long-term use of silicone-hydrogel contact lenses on the parameters of the oxidation-reduction potential of glutathione, lipid peroxidation and the stability of cell membranes and subcellular structures of the cornea of the epithelium by identifying marker enzymes in a tear. We determined the activity of lactate dehydrogenase, glucose-6-phosphate dehydrogenase, acid phosphatase, succinatе dehydrogenase, glutathione (recovered and oxidized forms) and products of lipid peroxidation (malonic dialdehyde, diene conjugates) in tears of patients divided into two groups. Study group comprised 72 people — mild and moderate myopia patients continuously wearing soft contact lenses. Control group consisted of 33 people — mild and moderate myopia patients, spectacles wearers. We revealed a significant increase in the activity of lactate dehydrogenase and glucose-6-phosphate dehydrogenase by &gt;33% and &gt;26%, respectively, as well as a significant increase in the activity of acid phosphatase by &gt;21% and of succinatе dehydrogenase by &gt;18% in the tudy group patients comparing to controls. The study of the level of products of lipid peroxidation in the tear fluid of the main group showed a significant accumulation of them, as well as a violation of the glutathione balance in comparison with the control group. The dependence of biochemical changes in the composition of the tear on the duration of contact lens wear has been revealed. Therefore, with prolonged wearing of MKL, prooxidant-antioxidant equilibrium in the tissues of the eye surface, in particular in the cornea, is violated, activation of free radical processes and reduction of antioxidant reserves occur, which leads to destruction of cellular and subcellular membranes. We assume that the medical correction of these pathological changes will help prevent the development of severe complications of contact correction.

The influence of mineral waters of the Luchinetsk deposit on the organism oxidation metabolism

The article has investigated the influence of mineral waters of the Luchinetsk deposit from wells 1-L and 729 on prooxidant-antioxidant equilibrium in peripheral blood of mice radiated at a dose of 5.0 Gy. It has been established that given mineral waters have a pronounced biological effect; their course application is an effective means of correcting oxidizing metabolism.

Impact of Chronic Lead Exposure on Selected Biological Markers

Lead poisoning remains a major problem in India due to the lack of awareness of its ill effects among the clinical community. Blood lead, δ-aminolevulinic acid dehydratase (δ-ALAD) and zinc protoporphyrin (ZPP) concentrations are widely used as biomarkers for lead toxicity The present study was designed to determine the impact of chronic lead exposure on selected biological markers. A total of 250 subjects, of both sexes, ranging in age from 20 to 70years, were recruited. On the basis of BLLs, the subjects were categorized into four groups: Group A (BLL: 0-10μg/dl), Group B (BLL: 10-20μg/dl). Group C (BLL: 20-30μg/dl) and Group D (BLL: 30-40μg/dl) having BLLs of 3.60±2.71μg/dl, 15.21±2.65μg/dl, 26.82±2.53μg/dl and 36.38±2.83μg/dl, respectively. Significant changes in biological markers due to elevated BLLs were noted. The relation of BLL and biological markers to demographic characteristics such as sex, habits, diet and substances abuse (smoking effect) were also studied in the present investigation. Males, urban population, non-vegetarians, and smokers had higher blood lead levels. δ-ALAD activity was found to be significantly lower with increased BLL (P<0.001), while the ZPP level was significantly higher with increased BLL (P<0.001). Further, BLL showed a negative correlation with δ-ALAD (r=-0.425, P<0.001, N=250) and a positive correlations with ZPP (r=0.669, P<0.001, N=250). Chronic lead exposure affects the prooxidant-antioxidant equilibrium leading to cellular oxidative stress.

Temporal responses to intrinsically coupled calcium and zinc dyshomeostasis in cardiac myocytes and mitochondria during aldosteronism

Intracellular Ca(2+) overloading, coupled to induction of oxidative stress, is present at 4-wk aldosterone/salt treatment (ALDOST). This prooxidant reaction in cardiac myocytes and mitochondria accounts for necrotic cell death and subsequent myocardial scarring. It is intrinsically linked to increased intracellular zinc concentration ([Zn(2+)](i)) serving as an antioxidant. Herein, we addressed the temporal responses in coupled Ca(2+) and Zn(2+) dyshomeostasis, reflecting the prooxidant-antioxidant equilibrium, by examining preclinical (week 1) and pathological (week 4) stages of ALDOST to determine whether endogenous antioxidant defenses would be ultimately overwhelmed to account for this delay in cardiac remodeling. We compared responses in cardiomyocyte free [Ca(2+)](i) and [Zn(2+)](i) and mitochondrial total [Ca(2+)](m) and [Zn(2+)](m), together with biomarkers of oxidative stress and antioxidant defenses, during 1- and 4-wk ALDOST. At week 1 and compared with controls, we found: 1) elevations in [Ca(2+)](i) and [Ca(2+)](m) were coupled with [Zn(2+)](i) and [Zn(2+)](m); 2) increased mitochondrial H(2)O(2) production, cardiomyocyte xanthine oxidase activity, and cardiac and mitochondrial 8-isoprostane levels, counterbalanced by increased activity of antioxidant proteins, enzymes, and the nonenzymatic antioxidants that can be considered as cumulative antioxidant capacity; some of these enzymes and proteins (e.g., metallothionein-1, Cu/Zn-superoxide, glutathione synthase) are regulated by metal-responsive transcription factor-1; and 3) although these augmented antioxidant defenses were sustained at week 4, they fell short in combating the persistent intracellular Ca(2+) overloading and marked rise in cardiac tissue 8-isoprostane and mitochondrial transition pore opening. Thus a coupled Ca(2+) and Zn(2+) dyshomeostasis occurs early during ALDOST in cardiac myocytes and mitochondria that regulate redox equilibrium until week 4 when ongoing intracellular Ca(2+) overloading and prooxidants overwhelm antioxidant defenses.

Oxidation of lipid and protein in horse mackerel ( Trachurus trachurus) mince and washed minces during processing and storage

Protein and lipid oxidation was followed during processing and storage of mince and washed minces prepared from horse mackerel ( Trachurus trachurus). Briefly horse mackerel mince (M0) was washed with three volumes of water, mimicking the surimi production and different washed products were obtained: M1, M2 and M3, with one, two and three washing steps, respectively. The different products were characterised (i.e. lipid content, protein, water, iron, fatty acid profile and tocopherol content) and analysed for protein and lipid oxidation in order to investigate the impact of the washing steps on oxidation. Subsequently the different products were stored for up to 96 h at 5 °C and samples were taken out regularly for analysis. Lipid oxidation was investigated by measuring primary oxidation products (lipid hydroperoxides) and secondary oxidation products (volatiles). Protein oxidation was followed by determination of protein solubility, protein thiol groups and protein carbonyl groups using colorimetric methods as well as western blotting for protein carbonyl groups. Lipid and protein oxidation markers indicated that both lipid and protein oxidation took place during processing and the ranking for oxidation was as follows M0 < M1 < M2 ⩽ M3 with M0 being significantly less oxidised than M3. Results indicated that washing creates an imbalance in the initial prooxidant-antioxidant equilibrium in the muscle tissue and contributes to the observed differences in the oxidative status of the four products obtained. In contrast, during storage of different products, lipid oxidation development was faster in M0 and the ranking was as follows M0 > M1 > M2 ⩾ M3. Lipid and protein oxidation developed simultaneously in different minces during storage, but it was not possible to determine at which level these two reactions were coupled.

Effect of transplantation of human fetal tissues on prooxidant-antioxidant equilibrium in the liver and blood rats after partial hepatectomy in rats.

We studied the effect of transplantation of fetal liver cells and postnuclear cytoplasmic fraction from human fetal soft tissues on the prooxidant-antioxidant equilibrium in the liver and blood of rats after partial hepatectomy. The preparations increased antioxidant activity and decreased the intensity of lipid peroxidation, which probably contributes to their therapeutic effects.

Affinity of hemoglobin for oxygen and prooxidant-antioxidant equilibrium after administration of lipopolysaccharide during correction of the L-arginine—NO pathway

Effects of correction of the L-arginine—NO pathway on the fever reaction, oxygen transport function of the blood, and prooxidant-antioxidant equilibrium in rats injected intramuscularly with lipopolysaccharide were studied. pH, Pco2, Po2, and the index of hemoglobin oxygen affinity (p50) were measured in mixed venous blood. Levels of Schiff bases, α-tocopherol, and catalase activity were determined in erythrocytes and in the liver, kidneys, and heart. NO synthase inhibitor attenuated the fever reaction and decreased p50 to 28.89±0.83 mm Hg (in rats administered with lipopolysaccharide, p50 was 34.21±1.63 mm Hg). The increase in the content of Schiff bases and the exhaustion of the antioxidant system in erythrocytes and tissues were less pronounced in rats injected with the NO synthase inhibitor than in animals receiving lipopolysaccharide only. Various parameters of the prooxidant-antioxidant equilibrium correlated with p50. Thus, hemoglobin oxygen affinity and NO are important factors involved in the maintenance of the prooxidant-antioxidant equilibrium in the body.

Role of lipid peroxidation and the glutathione-dependent antioxidant system in the impairment of endothelium-dependent relaxations with age.

1. Age-related changes in the blood prooxidant-antioxidant state, as well as its influence on the relaxant responses to acetylcholine (ACh) were studied in the tail artery from 6-, 24- and 30-month-old Sprague-Dawley (SD) rats. 2. Malondialdehyde (MDA) plasma levels increased 2 and 3 times in 24- and 30-month-old rats, respectively, when compared with 6-month-old rats (0.43+/-0.09 microM). This increase was accompanied by an induction of 6-phosphogluconate dehydrogenase (6PG-DH) and glutathione reductase (GR) activities in red blood cells from 24-month-old rats. In 30-month-old rats, a further induction of these enzymatic activities, as well as glucose-6-phosphate dehydrogenase (G6P-DH) and glutathione peroxidase (GPx) activities was observed. 3. No differences with age were found in the concentration-response curves to ACh in isolated tail artery segments from 6- and 24-month-old rats precontracted with 0.3 microM noradrenaline (NA). However, a decrease in sensitivity to ACh-induced relaxation was observed in 30-month-old rats; EC30 values were 3.5 (1.3-8.0) x 10(-7) M and 18.1 (8.9-30.1) x 10(-7) M for 6- and 30-month-old rats, respectively. Moreover, a decrease in maximum ACh relaxation (10 microM) was found in 30-month-old rats in comparison with that obtained in 6-month-old rats (58.5+/-3.9% and 42.5+/-3.4% of previous NA contraction, respectively). 4. Incubation of tail artery segments with MDA (0.5, 1 or 10 microM) caused a reduction of ACh-induced relaxations that was different in the three ages. Thus, the reduction of ACh-induced relaxations became significant with 0.5 microM MDA in 6-, with 1 microM MDA in 24-, and with 10 microM MDA in 30-month-old rats. In addition, MDA did not cause a shift in the concentration-response curve to ACh, but a decrease in the maximum response. 5. Superoxide dismutase (SOD; 150 u ml(-1), a superoxide anion scavenger) reversed the inhibitory effect of MDA on ACh-induced relaxations at all ages studied. 6. We conclude that: (1) ageing produces an increase in lipid peroxidation process, as indicated by the increase in MDA plasma levels, that is accompanied by an induction of lipid peroxide detoxification enzymes: (2) the changes in prooxidant-antioxidant equilibrium with age contribute, at least partially, to the impairment of the relaxant responses evoked by ACh; and (3) the effect of MDA appears to be mediated by superoxide anion at all ages studied.

Role of reactive oxygen species in biological processes.

SummaryThe steady-state formation of prooxidants in cells and organs is balanced by a similar rate of their consumption by antioxidants that are enzymatic and/or nonenzymatic. “Oxidative stress” results from imbalance in this prooxidantantioxidant equilibrium in favor of the prooxidants. A number of diseases are associated with oxidative stress, being the basis of a potential antioxidant therapy. However, current evidence in clinical research does not show unequivocal distinction between causal or associative relationships of prooxidants to the disease process.