dimethylarginine and Reperfusion-Injury

The induction of heme oxygenase (HO), the rate-limiting enzyme in heme degradation, occurs as an adaptative response to oxidative stress and is consequent to decrease in cellular glutathione levels. Our previous studies demonstrated significant increase in survival rates of rats treated with glutathione depletors and submitted to transient cerebral ischemia. The aim of the present research was to test the effects of L-Buthionine sulfoximine (BSO), a glutathione depletor, during cerebral post-ischemic reperfusion. Cerebral ischemia was induced by bilateral clamping of common carotid arteries for 20 min. Each sample was used for glutathione ad lipid peroxidation level dosage and for evaluating the expression of heme oxygenase both after a single subcutaneous administration of BSO and without treatment. In the same experimental conditions, endothelial, inducible and neuronal Nitric Oxide Synthase (eNOS, iNOS and nNOS) and Dimethylarginine Dimethyl amine Hydrolases (DDAH-1 and DDAH-2) were also evaluated. Results obtained in the present study suggested that HO-1 over-expression may be implicated in the protective effect of BSO in post-ischemic reperfusion brain damage, although the involvement of other important stress mediators cannot be ruled out.

Topics: Analysis of Variance; Animals; Arginine; Brain; Brain Ischemia; Buthionine Sulfoximine; Glutathione; Injections, Subcutaneous; Lipid Peroxidation; Male; Neuroprotective Agents; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Reperfusion Injury; Time Factors

Liver function is affected during ischemia/reperfusion (IR). We evaluated the effect of the aging process on selected parameters determining the NO level in rat liver subjected to IR.. The animals were divided into the C-2 and the IR-2 group of young rats (2-4 months old) and the C-12 and the IR-12 group of older rats (12-14 months old). Livers belonging to the IR-2 and the IR-12 group were subjected to partial ischemia (60 min) and reperfusion (4 h). Blood samples were obtained after surgeries to estimate the activity of aminotransferases, as well as just before ischemia and during reperfusion (15, 120, and 240 min) to estimate concentration of arginine (Arg) and its derivatives: asymmetric and symmetric dimethylarginine (ADMA, SDMA). After IR, dimethylarginine dimethylaminohydrolase (DDAH) activity and protein concentration of inducible nitric oxide synthase (iNOS) were measured in liver homogenates.. In the IR-2 group ADMA level increased the most between 15 and 120 min of reperfusion and was the highest of all the groups (0.72±0.2 μmol/l). In the IR-12 group ADMA level decreased significantly and was lower compared to all the other groups at 15 min (0.42±0.2 μmol/l) and to IR-2 at 120 (0.52±0.1 μmol/l) and 240 min (0.38±0.1 μmol/l) of reperfusion. Only the IR-2 group SDMA level increased significantly between 15 (0.75±0.9 μmol/l) and 240 min (1.0±1.2 μmol/l) of reperfusion. At the beginning of the surgery the Arg level was significantly higher in young rats (C-2: 102.1±35.7 μmol/l; IR-2: 114.63±28.9 μmol/l) than in older ones (C-12: 41.88±44.7 μmol/l; IR-12: 28.64±30.6 μmol/l). In the C-2 group the Arg level (77.41±37.5 μmol/l) and Arg/ADMA (A/A) ratio (138.03±62.8 μmol/l) were significantly higher compared to the ischemic groups at 15 min and to all the other groups at 120 (Arg: 47.17±31.7 μmol/l; A/A: 88.28±66.2 μmol/l) and 240 min (Arg: 43.87±21.9 μmol/l; A/A: 118.02±106.3 μmol/l). In the IR-2 group Arg level (11.4±12.0 μmol/l) and A/A ratio (16.11±16.2 μmol/l) decreased significantly at 15 min and during the next phase of reperfusion the levels of those parameters were low, comparably to those in IR-12. As a result of IR, a decrease in DDAH activity and an increase in iNOS protein concentration were observed only in the young rats.. We found that in the non-ischemic groups the Arg level may be affected by the aging process. Under IR conditions, important changes in DDAH-ADMA-NO pathway were observed only in young livers.

Topics: Aging; Amidohydrolases; Animals; Arginine; Liver; Male; Nitric Oxide; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Reperfusion Injury; Signal Transduction; Transaminases

To investigate the protective effect of ethyl pyruvate (EP), an anti-oxidant agent, against ischemia-reperfusion injury in a rat model of ovarian torsion, considering biochemical and histopathological aspects.. Forty Wistar Albino rats were divided into five groups: Group I, sham operation; Group II, ischemia alone, Group III, ischemia-reperfusion; Group IV, ischemia-reperfusion+50 mg/kg EP; and Group V, ischemia-reperfusion+100 mg/kg EP. Through laparotomy, 360° torsion was performed and maintained for 3 h, and detorsion was maintained for a further 3 h. Intraperitoneal EP was given 30 min before the surgical procedure. Ovarian tissues and blood samples were obtained after surgery. Malondialdehyde (MDA) and asymmetric dimethyl arginine (ADMA) levels were measured in both plasma and tissue samples. Tissue sections were evaluated histopatologically. Analysis of variance was used for statistical analyses.. In both serum and tissue samples, ADMA and MDA levels were found to be significantly lower in the EP groups compared with the ischemia alone and ischemia-reperfusion groups (p=0.0001). However, no significant difference was found between groups treated with 50 mg/kg or 100 mg/kg EP. On histopathological evaluation, the total tissue injury score was found to be lower in rats treated with EP. No significant difference was detected between groups treated with 50 mg/kg or 100 mg/kg EP.. Ethyl pyruvate may exert positive effects in ischemia-reperfusion injury in cases of ovarian torsion. However, no difference was detected between 50 mg/kg and 100 mg/kg EP.

Topics: Animals; Antioxidants; Arginine; Disease Models, Animal; Female; Malondialdehyde; Ovary; Pyruvates; Rats; Rats, Wistar; Reperfusion Injury; Torsion Abnormality

Cold perfusion through the renal arteries during renal ischemia has been suggested to diminish postoperative renal damage after juxtarenal aortic aneurysm repair. As the kidneys play a key role in dimethylarginine metabolism, which in turn is associated with renal hemodynamics, we hypothesized that the protective effect of cold perfusion is associated with a preserved renal extraction of dimethylarginines. Renal ischemia was induced in three groups of anesthetized Wistar rats (n = 7/group), which underwent suprarenal aortic clamping (45 min) with no perfusion (group 1), renal perfusion with 37°C saline (group 2), or renal perfusion with 4°C saline (group 3), respectively, followed by 90 min of renal reperfusion in all groups. The sham group had no clamping. In group 3 (renal ischemia with cold perfusion), postoperative serum creatinine levels as well as the presence of luminal lipocalin-2 and its associated brush-border damage were lower compared with groups 1 and 2 (P < 0.05). Also, renal extraction of asymmetrical (ADMA) and symmetrical (SDMA) dimethylarginine as well as the arginine/ADMA ratio, which defines the bioavailability of nitric oxide, remained intact in group 3 only (P < 0.04). The arginine/ADMA ratio correlated with cortical flow, lipocalin-2, and creatinine rises. Warm and cold renal perfusion (groups 2 and 3) during ischemia were similarly effective in lowering protein nitrosylation levels, renal leukocyte accumulation, neutrophil gelatinase-associated lipocalin (NGAL) expression in distal tubules, and urine NGAL (P < 0.05). These data support the use of cold renal perfusion during renal ischemia in situations where renal ischemia is inevitable, as it reduces tubular damage and preserves renal extraction of dimethylarginines. Renal perfusion with saline per se during renal ischemia is effective in diminishing renal leukocyte accumulation and oxidative stress.

Topics: Animals; Aorta; Arginine; Creatinine; Hypothermia, Induced; Kidney; Lipocalin-2; Lipocalins; Male; Perfusion; Rats; Rats, Wistar; Reperfusion Injury; Vascular Surgical Procedures

Recently, both asymmetrical dimethylarginine and IL-6 have been suggested to be associated with the induction and severity of single and multiple organ dysfunction. The aims of the present study were to elucidate if these factors were increased in an ischemia reperfusion (IR) model and whether pre-operative carbohydrate supplementation can reduce the risk factors along with the IR injury.. One group of male Wistar rats was fasted for 16 h (water ad libitum) prior to clamping the superior mesenteric artery (IR fasted n=14). A second group had ad libitum access to a carbohydrate solution prior to clamping (IR fasted CHO group n=11). Sham-fasted animals, which only received laparotomy and no clamping, served as controls (n=4).. Plasma urea and ALAT activity were both increased in the IR fasted animals when compared to the sham rats (P=0.007 and P<0.02, respectively). Furthermore, it was shown that IR fasted rats had increased ADMA and IL-6 concentration in plasma when compared to sham animals (P<0.02). Moreover, the GSH level in lung was significantly decreased in the IR fasted animals (P=0.014). IR CHO supplemented showed no significant increase of ALAT activity and decrease of lung GSH. Furthermore, significantly lower plasma urea, ADMA and IL-6 concentration was seen in the IR CHO supplemented group when compared to the IR fasted rats (P=0.028, P<0.01 and P<0.02, respectively). The liver glycogen concentration in IR fasted rats was 48% of that IR rats supplemented the carbohydrate mixture.. The present rat intestinal ischemia reperfusion model not only induces organ injury indicated by the classical parameters such as plasma urea and ALAT activity, but also increased plasma IL-6 and ADMA and decreased lung GSH concentration in IR fasted rats. Pre-operative supplementation with the carbohydrate mixture significantly lowered the plasma urea, IL-6 and ADMA concentrations and maintained lung GSH concentration. This indicates that pre-operative carbohydrate supplementation reduces post-operative organ injury.

Topics: Alanine Transaminase; Animals; Arginine; Blood Urea Nitrogen; Dietary Carbohydrates; Dietary Supplements; Disease Models, Animal; Glutathione; Glycogen; Interleukin-6; Liver; Male; Multiple Organ Failure; Preoperative Care; Random Allocation; Rats; Rats, Wistar; Reperfusion Injury; Risk Factors