Experimental Renal Ischemia-reperfusion Research Articles

Investigation of the effects of lipoic acid and dihydrolipoate on experimental renal ischemia-reperfusion model

Objective: Ischemic/reperfusion (I/R) causes tissue injury and the leading cause of acute kidney injury. In this study, we aimed to investigate the effects of the long and short-term usage of ALA and short-term DHLA on oxidative stress markers in the experimental renal ischemia-reperfusion model. Methods: Forty male rats (250 to 300 gr) were divided into 5 groups: control; I/R group; long-term ALA+IR group; short-term ALA+IR group; and short-term DHLA+IR group. Ischemia was carried out for 45 minutes followed by reperfusion for 4 hours. Thiobarbituric acid reactive sunstances (TBARM), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities in tissue samples and serum total antioxidant status (TAS) and total oxidative stress (TOS) assayed by the spectrophotometrically. Tissue samples were investigated by histopathological analyzes. Results: TBARM (Control: 0.38±0.05. I/R: 1.37±0.17, long-term ALA-treated group:1.025±0.15, short-term ALA-treated group: 0.68±0.09, short-term DHLA-treated group: 0.38±0.04 (nmol/mg protein); p<0,001) CAT (Control: 0.12±0.02, I/R: 0.04±0.008, long-term ALA-treated group: 0.07±0.01, short-term ALA-treated group:0.06±0.008, short-term DHLA-treated group: 0.08±0.01 (k/mg protein); p<0.001), GSH-Px (Control: 0.45±0.04, I/R: 0.21±0.028, long-term ALA-treated group: 0.37±0.05, short-term ALA-treated group :0.34±0.05, short-term DHLA-treated group: 0.37±0.04 (U/mg protein); p<0.001), and serum OSI levels (Control: 1.32±0.15, I/R: 3.08±0.44, long-term ALA-treated group: 1.775±0.21, short-term ALA-treated group: 1.85±0.37, short-term DHLA-treated group: 1.53±0.21 (arbitrary unit) ; p<0.001) were improved in the long and short-term ALA-treated group and short-term DHLA-treated group compared to the I/R group. These findings were more prominent in histopathological tissue samples in the DHLA-treated group. Conclusion: We consider that both long-term and short-term ALA applications have the potential for the treatment of renal I/R damage. Besides, DHLA is more effective than ALA.

Protective Effects of Gamma Oryzanol on Renal and Brain Damage Following Experimental Renal Ischemia-reperfusion Injury among Rats

Protective Effects of Gamma Oryzanol on Renal and Brain Damage Following Experimental Renal Ischemia-reperfusion Injury among Rats

Ratlarda böbrek iskemi-reperfüzyon hasarında proflaktik kalsiyum dobesilatın etkinliği

Aim: In this study, the objective was to investigate the protective effect of calcium dobesilate, which has antioxidant and anti-inflammatory properties, on the experimental renal ischemia-reperfusion injury (IRI). Methods: Twenty-four male Wistar-Albino rats were divided into three groups: Sham group (Group 1), ischemia-reperfusion group (Group 2), and treatment group (Group 3). Before the ischemia-reperfusion procedure, rats in Group 3 received calcium dobesilate through gavage (100mg/kg/day) for 10 days. Groups other than the sham group underwent ischemia for 45 minutes and reperfusion for 24 hours. Plasma urea and creatinine levels, erythrocyte superoxide dismutase and glutathione peroxidase enzyme activity levels were measured. In addition, histopathological changes that may be related to ischemia-reperfusion injury in the renal tissue, were investigated.Results: The median glutathione peroxidase and superoxide dismutase enzyme levels were higher in Group 2 compared to Groups 1 and 3. However, the differences were not statistically significant. The creatine levels were statistically lower in Group 3 compared to Group 1 and Group 2. The median urea levels were lower in Group 3 than in Group 1 and Group 2, but the differences were not statistically significant. The histopathological examination showed that parameters such as cellular necrosis, flattened tubular epithelial cells, cytoplasmic vacuolization, tubular lumen obstruction, and chronic inflammation, which are indicators of the ischemia-reperfusion injury, were statistically less common in the treatment group compared to the control group. Conclusion: Our study demonstrated that prophylactic calcium dobesilate had a protective effect on ischemia-reperfusion injury.

Receptor activator of the NFκB ligand system protects renal function during experimental renal ischemia-reperfusion in mice

Renal ischemia-reperfusion (I/R) injury is closely associated with delayed graft function and poor long-term graft survival following transplantation. Various pathophysiologies can cause the deterioration of renal function; however, the immune system plays important roles in promoting and protecting renal tissues. Receptor activator of NFκB ligand (RANKL) is a member of the TNF superfamily and is produced by bone-forming osteoblasts; the receptor for RANKL is called RANK. In bone biology, RANKL-RANK signaling has been extensively studied, but its roles in the immune system are still obscure. We investigated the role of the RANK system in I/R injury of the kidney using an experimental mouse I/R model. The left renal pedicles of 10-week-old male mice were clamped for 60 min, and reperfusion and right nephrectomy were simultaneously performed. Separate groups were administered an anti-RANKL antibody and recombinant RANKL (rRANKL) 24 h prior to I/R. After reperfusion for a set period of time, the serum creatinine level was measured, and the left kidney was removed for histological examination and western blotting to evaluate the expression and localization of RANK-associated molecules and cytokines. The serum creatinine levels were significantly elevated after I/R injury. A time-dependent increase in RANKL was observed up to 24 h, whereas RANK was induced for 12 h after reperfusion. RANK was expressed in infiltrating inflammatory cells, which were positive for CD68, a marker of monocytes/macrophages. The pre-treatment with the anti-RANKL antibody significantly impaired renal function and increased the induction of inflammatory cytokines (TNFα and IL-6), Toll-like receptor (TLR4) and MyD88 (all p < .05) compared to the levels in the I/R group. However, rRANKL significantly improved renal function and decreased the levels of inflammatory cytokines (TNFα and IL-6), TLR4 and MyD88 (p < .05) compared to those in the I/R group. The present study is the first to evaluate the role of the RANK system in renal I/R injury. RANKL-RANK signaling affects macrophage function and results in the downregulation of TLR4 and reduction in TNFα and IL-6, leading to improved renal function following I/R injury.

Comparison of the protective effects of selective endothelin-a receptor antagonist, ambrisentan, and dual endothelin-A/B receptor antagonist, bosentan, in experimental renal ischemia reperfusion injury.

This study aims to compare the protective effects of ambrisentan, a selective endothelin typeA receptor antagonist, and bosentan, a dual endothelin typeA/B receptor antagonist, on experimental renal ischemia reperfusion injury. The study sample consisted of 21 female rats, which were divided into 3 groups: Control, Ambrisentan and Bosentan. For the ischemia-reperfusion injury model, left‑kidney nephrectomy was performed after sacrificing the animals. In the immunohistochemical examination, caspase-3 was examined, and then the apoptotic index was determined. In the biochemical examination, the activities of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase, and the levels of nitrite (NOx), TNF-α, and IL-1β were determined. There were statistically significant differences between the groups in terms of total injury score grade in range of 0‒3 (p=0.001).The glomerular and tubular apoptotic indices were higher in the control group as compared to those of the ambrisentan and bosentan groups (p=0.001).There were no statistically significant differences in terms of SOD, CAT, GPx, MDA, IL-1β and TNF-α measurements among the groups (p>0.05). In the experimentally created renal ischemia reperfusion model, both ambrisentan and bosentan increased the NOx level, decreased the apoptosis, and protected the kidney from renal ischemia reperfusion injury. However, no significant superiority was found between ambrisentan and bosentan in terms of their protective effects (Tab. 3, Fig. 2, Ref. 31).

The effects of resveratrol administration on lipid oxidation in experimental renal ischemia-reperfusion injury in rats

ABSTRACTWe investigated how resveratrol affects lipid oxidation during experimental renal ischemia-reperfusion injury in rats. We used 48 adult male rats assigned to five groups: group 1, control; group 2, renal ischemia; group 3, renal ischemia + reperfusion; group 4, resveratrol + renal ischemia; group 5, resveratrol + renal ischemia + reperfusion. Plasma and renal tissue malondialdehyde (MDA), and erythrocyte and renal tissue glutathione (GSH) levels were measured and histologic changes in the renal tissue were examined. Ischemia-reperfusion affected the MDA-GSH balance adversely and caused histopathological changes in the renal tissue of the ischemia and ischemia + reperfusion groups. Resveratrol treatment normalized MDA and GSH levels as well as the histopathology that occurred in the renal tissue of the ischemia and ischemia + reperfusion groups.

Protective Effect of p-Coumaric Acid as Free Oxygen Radical Scavenger in Experimental Renal Ischemia-Reperfusion Model

ÖZET Amaç: Bu çalışmanın amacı, sıçan böbrek dokusunda iskemi-reperfüzyona bağlı doku hasarı üzerine p-kumarik asit (p-CA)’in antioksidan etkisini değerlendirmektir. Gereç ve Yöntemler: 12-16 haftalık 200-250 gr otuz iki adet Wistar Albino cinsi dişi sıçan temin edildi. Sıçanlara intraperitonal olarak ketamine (75 mg/kg) ve xylazine (8 mg/kg) anestezisi altında sırt bölgesinden yapılan bir kesi ile sağ nefrektomi uygulandı. Bu sıçanlar randomize olarak dört gruba eşit olarak bölündü (n=8). Gruplar; sham (S), renal iskemi-reperfüzyon (R-IR), R-IR ile 50 mg/kg p-kumarik asit (p-CA 50) ve R-IR ile 100 mg/kg p-kumarik asit (p-CA 100) uygulanan grup olarak sınıflandırıldı. Sham hariç diğer gruplardaki sıçanların sırt bölgesi açılıp sağ nefrektomi yapıldıktan sonra sol renal arter klemplenerek iskemi ve reperfüzyon protokolü uygulandı. P-kumarik asit iskemiden 60 dk önce ve reperfüzyon başlangıcından 30 dk önce olmak üzere iki doz şeklinde uygulandı. İşlemler tamamlandıktan sonra sol böbrek total antioksidan düzeyi (TAS), total oksidan düzeyi (TOS), süperoksit dismutaz (SOD), malondialdehit (MDA) ve myeloperoksidaz (MPO) seviyeleri spektrofotometrik yöntemlerle ölçüldü. Oksidatif stres indeksi (OSI) hesaplandı. Bulgular: R-IR grubunda S ile karşılaştırıldığında TAS ve SOD değeri düşerken, TOS, MDA, MPO ve OSI değerleri yükseldi (p<0.01). P-CA uygulanan gruplarda TAS ve SOD değerinde yükselme, TOS, MDA ve MPO değerlerinde ise düşme gözlendi. (p<0.05). Sonuç: Bulgularımız, renal iskemi reperfüzyon hasarında p-CA uygulamasının oksidan hasarı azaltarak dokunun korunmasında rol oynayabileceğini göstermektedir.

The role of L-arginine and aerobic exercise in experimental renal ischemia reperfusion injury in male and female rats

: Introduction: Renal ischemia/reperfusion (I/R) injury due to reactive oxygen species (ROS) formation is the main cause of acute kidney damage. Nitric oxide (NO) biosynthesis and oxidative stress are closely related to the pathogenesis of renal I/R injury. This study was undertaken to determine the effects of L-arginine (L-arg) as NO donor and aerobic exercise (EX) and also the combination of L-arg with EX on renal I/R injury in male and female rats. Methods: 54 male and female Wistar rats were divided into four groups in each gender as control, L-arginine (L-arg), treadmill exercise (EX), and L-arginine plus exercise (Larg & EX). After 8 weeks of EX, animals were exposed to 45 min of bilateral kidney ischemia followed by 24 hours of reperfusion. We assessed serum creatinine (Cr), Kidney tissue damage score (KTDS), kidney weight (KW), serum nitrite and malondialdehyde (MDA) levels. Results: L-arg, EX or combination of L-arg &EX caused a significant decrease in serum level of creatinine (Cr) (P groups and male L-arg treated group (P However, the kidney weight was decreased significantly in male rats (P post reperfusion, and such observation was not seen in female. No significant differences were detected in serum nitrite levels between the groups, but combination of L-arg &EX decreased the serum level of malondialdehyde (MDA) in female significantly (P Conclusion: Pretreatment with L-arg seems to have protective effects against renal I/R injury. The protective effect of exercise against renal I/R injury seems to be less than Larg but the reno-protective effect of EX increases when combined with L-arg.

The renoprotective effects of mannitol and udenafil in renal ischemia-reperfusion injury model

PurposeThe aim of this study was to investigate and compare the effects of udenafil and mannitol in an experimental renal ischemia-reperfusion (I/R) injury model.Materials and MethodsA total of 64 female Wister Albino rats were used. Right nephrectomy was performed in all groups. In the control group; I/R injury was not performed. In the I/R group; left renal pedicle was clamped for 45 minutes and then underwent 60 minutes and 24 hours of reperfusion. In the mannitol group; 1 mL 20% mannitol was given intravenously 15 minutes before clamping. In the udenafil group; 10-mg/kg udenafil was given orally 1 hour before clamping. Creatinine (Cr), blood urea nitrogen (BUN), Cr clearance, malondialdehyde, neutrophil gelatinase associated lipocalin (NGAL), histological examination and DNA damage (Comet Assay method) levels were compared in tissue, serum and urine samples.ResultsUdenafil had a better protective effect than mannitol according to biochemical parameters (Cr, BUN, Cr clearance, and NGAL levels) and histopathological findings when compared with the I/R group. In the Comet sampling analysis no significant difference was detected.ConclusionsUdenafil has a better renoprotective effect than mannitol against I/R injury and this effect supports more functional improvements. Further clinical trials are needed to demonstrate those effects and clinical utility of udenafil for that purpose in humans.

Effect of TREM-1 blockade and single nucleotide variants in experimental renal injury and kidney transplantation.

Renal ischemia reperfusion (IR)-injury induces activation of innate immune response which sustains renal injury and contributes to the development of delayed graft function (DGF). Triggering receptor expressed on myeloid cells-1 (TREM-1) is a pro-inflammatory evolutionary conserved pattern recognition receptor expressed on a variety of innate immune cells. TREM-1 expression increases following acute and chronic renal injury. However, the function of TREM-1 in renal IR is still unclear. Here, we investigated expression and function of TREM-1 in a murine model of renal IR using different TREM-1 inhibitors: LP17, LR12 and TREM-1 fusion protein. In a human study, we analyzed the association of non-synonymous single nucleotide variants in the TREM1 gene in a cohort comprising 1263 matching donors and recipients with post-transplant outcomes, including DGF. Our findings demonstrated that, following murine IR, renal TREM-1 expression increased due to the influx of Trem1 mRNA expressing cells detected by in situ hybridization. However, TREM-1 interventions by means of LP17, LR12 and TREM-1 fusion protein did not ameliorate IR-induced injury. In the human renal transplant cohort, donor and recipient TREM1 gene variant p.Thr25Ser was not associated with DGF, nor with biopsy-proven rejection or death-censored graft failure. We conclude that TREM-1 does not play a major role during experimental renal IR and after kidney transplantation.

CD47 regulates renal tubular epithelial cell self-renewal and proliferation following renal ischemia reperfusion

Defects in renal tubular epithelial cell repair contribute to renal ischemia reperfusion injury, cause acute kidney damage, and promote chronic renal disease. The matricellular protein thrombospondin-1 and its receptor CD47 are involved in experimental renal ischemia reperfusion injury, although the role of this interaction in renal recovery is unknown. We found upregulation of self-renewal genes (transcription factors Oct4, Sox2, Klf4 and cMyc) in the kidney of CD47(-/-) mice after ischemia reperfusion injury. Wild-type animals had minimal self-renewal gene expression, both before and after injury. Suggestive of cell autonomy, CD47(-/-) renal tubular epithelial cells were found to increase expression of the self-renewal genes. This correlated with enhanced proliferative capacity compared with cells from wild-type mice. Exogenous thrombospondin-1 inhibited self-renewal gene expression in renal tubular epithelial cells from wild-type but not CD47(-/-) mice, and this was associated with decreased proliferation. Treatment of renal tubular epithelial cells with a CD47 blocking antibody or CD47-targeting small interfering RNA increased expression of some self-renewal transcription factors and promoted cell proliferation. In a syngeneic kidney transplant model, treatment with a CD47 blocking antibody increased self-renewal transcription factor expression, decreased tissue damage, and improved renal function compared with that in control mice. Thus, thrombospondin-1 via CD47 inhibits renal tubular epithelial cell recovery after ischemia reperfusion injury through inhibition of proliferation/self-renewal.

Optimizing Mouse Surgery with Online Rectal Temperature Monitoring and Preoperative Heat Supply. Effects on Post-Ischemic Acute Kidney Injury.

Body temperature affects outcomes of tissue injury. We hypothesized that online body core temperature recording and selective interventions help to standardize peri-interventional temperature control and the reliability of outcomes in experimental renal ischemia reperfusion injury (IRI). We recorded core temperature in up to seven mice in parallel using a Thermes USB recorder and ret-3-iso rectal probes with three different protocols. Setup A: Heating pad during ischemia time; Setup B: Heating pad from incision to wound closure; Setup C: A ventilated heating chamber before surgery and during ischemia time with surgeries performed on a heating pad. Temperature profile recording displayed significant declines upon installing anesthesia. The profile of the baseline experimental setup A revealed that <1% of the temperature readings were within the target range of 36.5 to 38.5°C. Setup B and C increased the target range readings to 34.6 ± 28.0% and 99.3 ± 1.5%, respectively. Setup C significantly increased S3 tubular necrosis, neutrophil influx, and mRNA expression of kidney injury markers. In addition, using setup C different ischemia times generated a linear correlation with acute tubular necrosis parameters at a low variability, which further correlated with the degree of kidney atrophy 5 weeks after surgery. Changing temperature control setup A to C was equivalent to 10 minutes more ischemia time. We conclude that body temperature drops quickly in mice upon initiating anesthesia. Immediate heat supply, e.g. in a ventilated heating chamber, and online core temperature monitoring can help to standardize and optimize experimental outcomes.

Matrix Metalloproteinase-9 and Graft Preservation Injury in Clinical Renal Transplantation

BackgroundDeleterious effects of matrix metalloproteinase-9 (MMP-9) have been established in experimental renal ischemia-reperfusion models but not in clinical renal transplantation thus far. MethodsWe studied MMP-9 and its physiological inhibitor tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in 45 consecutive patients of a larger trial in renal transplantation: perioperative anti-thymocyte globulin (group A, n = 15), perioperative basiliximab (group B, n = 16), and conventional triple therapy (group C, n = 14). In addition to systemic blood samples, local blood samples were obtained simultaneously at 1 and 5 minutes after reperfusion from iliac artery and graft vein for calculation of transrenal changes. Because anti-thymocyte globulin activates inflammation, group A was analyzed separately. Groups B and C were pooled (group BC). ResultsAnti-thymocyte globulin infusion caused a robust rise of MMP-9 in the systemic circulation in group A. No significant transrenal difference of MMP-9 or TIMP-1 occurred in either group during graft reperfusion. In group BC, strong transrenal release of MMP-9 at 1 minute after reperfusion correlated with cold ischemia time (R = 0.66, P = .0001) and was associated with delayed graft function (P = .052). ConclusionsRenal production of MMP-9 on graft reperfusion is associated with cold ischemia time and emergence of delayed graft function. MMP inhibition may offer a means to reduce reperfusion injury in renal transplantation.

Protective Effects of Hydrocortisone, Vitamin C and E Alone or in Combination against Renal Ischemia-Reperfusion Injury in Rat.

Renal ischemia reperfusion injury may occur in a variety of clinical situations, following a transient drop in total or regional blood flow to the kidney. This study was performed to investigate the protective effects of different antioxidants such as vitamin C, vitamin E, hydrocortisone and combination of these agents against experimental renal ischemia-reperfusion injury. Thirty male rats were divided into six groups. Group Sham, Group I/R: (45 min of ischemia followed by 1h of reperfusion), Group I/R+Vit C: (50 mg/kg Vit C, IV, immediately after reperfusion), Group I/R+Vit E: (20 mg/kg Vit E, IM, 15 min before reperfusion), Group I/R+Hydrocortisone: (50 mg/kg, IV, immediately after reperfusion), and Group Combination: Ischemia-reperfusion plus combination of Vit C, E and hydrocortisone. After the experiments, the left kidney was removed and the tissues were processed for histopathological examination. Severe injuries such as necrosis of tubules, atrophy of glomerulus, and hemorrhage were observed in group I/R. Histological scores indicating tissue injury significantly decreased in all treatment groups compared to the group I/R. The renal tissue in group treatment was preserved in comparison with the group I/R. Comparison between the treatment groups showed that group combination was more effective and group vit E was less effective in protecting of renal tissue against I/R injuries. The results demonstrated simultaneous administration of combination of Vit C, E and hydrocortisone before reperfusion of blood flow to the ischemic tissue could show a synergy against deleterious effects of I/R injuries in kidney.

Lycopene has reduced renal damage histopathologically and biochemically in experimental renal ischemia-reperfusion injury

Background: The present study aimed to investigate whether the inflammatory and antioxidant lycopene has a therapeutic effect against renal ischemia/reperfusion (I/R) injury. Materials and methods: In this study, 24 Wistar-Albino rats, weighing from 200 to 250 g, were divided into four groups. All rats underwent median laparotomy under anesthesia. No procedures were performed in the control group (Group C), whereas 100 mg/kg lycopene was administered by gavage in the lycopene group (Group L). The arteries of both kidneys were clamped for 45 min in the ischemia group (Group I), whereas 100 mg/kg lycopene was administered by gavage 30 min before clamping renal arteries, and ischemia was performed in the treatment group (Group T) rats. For all rats, blood samples and renal tissues were collected at 6 h of reperfusion. Samples were used to examine serum BUN, creatinine, MDA and GSH levels, and the renal tissues were used to examine MDA and GSH levels, and renal histopathologies. Results: The treatment group had statistically significant lower serum MDA levels, histopathological tubular vacuolization, loss of brush border and tubular dilatation (p < 0.05), whereas serum BUN, creatinine, tissue MDA, and tissue and serum GSH levels were improved in favor of the treatment group, even though it was not statistically significant (p > 0.05). Conclusion: The present study demonstrated that lycopene, which was administered prior to renal I/R injury, prevented renal damage through biochemical and histopathological parameters.

Pretreatment of sildenafil attenuates ischemia-reperfusion renal injury in rats

Sildenafil was the first selective inhibitor of phosphodiesterase-5 (PDE5) to be widely used for treating erectile dysfunction. Many recent studies have investigated the cardioprotective role of sildenafil in animal models. We evaluated the protective effects of sildenafil in experimental renal ischemia-reperfusion (IR) injury in two studies. In study 1, male Sprague-Dawley rats were divided into four groups: sham, sildenafil-treated sham, vehicle-treated IR, and sildenafil-treated IR groups. In study 2, we divided the rats into two groups: sildenafil-treated IR rats and PD98059 (ERK inhibitor)+sildenafil-treated IR rats. Functional parameters of the kidney were evaluated at the molecular and structural levels. Blood urea nitrogen (BUN) and serum creatinine levels were lower in sildenafil-treated IR rats than in vehicle-treated IR rats. The expression of inducible (iNOS) and endothelial nitric oxide synthase (eNOS) proteins in sildenafil-treated IR rats was significantly higher than in vehicle-treated IR rats. Pretreatment with sildenafil in IR rats increased ERK phosphorylation and reduced the renal Bax/Bcl-2 ratio, renal caspase-3 activity, and terminal dUTP nick end-labeling-positive apoptotic cells. In contrast, PD98059 treatment increased BUN and serum creatinine levels and attenuated the sildenafil-induced expression of pERK, iNOS, eNOS, and Bcl-2. PD98059 also increased caspase-3 activity but did not decrease the sildenafil-induced accumulation of cGMP. In conclusion, this study suggests that sildenafil has antiapoptotic effects in experimental IR renal injury via ERK phosphorylation, induction of iNOS and eNOS production, and a decrease in the Bax/Bcl-2 ratio.

Redox-Active Iron Released During Machine Perfusion Predicts Viability of Ischemically Injured Deceased Donor Kidneys

Redox-active iron, catalyzing the generation of reactive oxygen species, has been implicated in experimental renal ischemia-reperfusion injury. However, in clinical transplantation, it is unknown whether redox-active iron is involved in the pathophysiology of ischemic injury of non-heart-beating (NHB) donor kidneys. We measured redox-active iron concentrations in perfusate samples of 231 deceased donor kidneys that were preserved by machine pulsatile perfusion at our institution between May 1998 and November 2002 using the bleomycin detectable iron assay. During machine pulsatile perfusion, redox-active iron was released into the preservation solution. Ischemically injured NHB donor kidneys had significantly higher perfusate redox-active iron concentrations than heart-beating (HB) donor kidneys that were not subjected to warm ischemia (3.9 +/- 1.1 vs. 2.8 +/- 1.0 micromol/L, p = 0.001). Moreover, redox-active iron concentration was an independent predictor of post-transplant graft viability (odds ratio 1.68, p = 0.01) and added predictive value to currently available donor and graft characteristics. This was particularly evident in uncontrolled NHB donor kidneys for which there is the greatest uncertainty about transplant outcomes. Therefore, perfusate redox-active iron concentration shows promise as a novel viability marker of NHB donor kidneys.

Role of Glyceryl Trinitrate, a Nitric Oxide Donor, in the Renal Ischemia-Reperfusion Injury of Rats

Background/Aims: Ischemia-reperfusion injury is a serious clinical situation which can cause serious morbidity and mortality. An experimental renal ischemia-reperfusion injury model was designed to evaluate the role of glyceryl trinitrate (GTN) on renal function and histology. Methods: 50 Wistar albino rats were used in our study. Five groups were formed: (1) sham-control group; (2) acute renal ischemia (ARI) group with placebo (0.9% NaCl) infusion; (3) GTN infusion with a 75 µg/kg/min dose prior to ARI was administered; (4) GTN infusion with a 150 µg/kg/min dose prior to ARI was given, and finally (5) 150 µg/kg/min GTN infusion after the ARI period was applied. Serum BUN and creatinine levels were measured for evaluation of renal function. T_max-sec, glomerular filtration rate (GFR), and T_max-min results following a ^99mTc-DTPA diuretic renal scintigraphy were used. Histological examination was performed on nephrectomy specimens. Results: Groups 2 and 5 showed higher BUN, creatinine, and lower GFR values than the other groups (p = 0.0001). There was no difference in BUN, creatinine, and GFR levels between groups 2 and 5 (p = 0.971, p = 0.739, p = 0.393). Also the T_max-sec values were higher in groups 2 and 5 compared with the other groups (p = 0.0001). The presence of tubular necrosis was different between groups and was higher in groups 2 and 5 (p = 0.002). Conclusion: The application of GTN, a nitric oxide donor, has caused significant improvement in renal function when applied prior to an experimentally designed renal ischemia-reperfusion model. But administration of GTN had no effect after occurrence of ischemia.

Contrasting roles for STAT4 and STAT6 signal transduction pathways in murine renal ischemia-reperfusion injury.

Recent data support a modulatory role for CD4 T cells in experimental renal ischemia-reperfusion injury (IRI). CD4 T cells can functionally differentiate to either a Th1 (IFN-gamma producing) or the counterbalancing Th2 (IL-4) phenotype. The enzymes signal transducers and activators of transcription (STAT) 4 and STAT6 regulate Th1 or Th2 differentiation and cytokine production, respectively. We therefore hypothesized that mice that were STAT4 deficient would be protected from renal IRI and that STAT6-deficient mice would have a more severe course. Intracellular cytokine staining of splenocytes from STAT4-/- or STAT6-/- exhibited distinct IFN-gamma and IL-4 cytokine expression profiles. STAT6-/- had markedly worse renal function and tubular injury postischemia compared with wild type. STAT4-/- had only mildly improved function. Renal phagocyte infiltration and ICAM-1 upregulation were similar in STAT4-/-, STAT6-/-, and wild type. To evaluate if the mechanism of the marked worsening in the STAT6-/- mice could be due to IL-4 deficiency, IL-4-deficient mice were studied and had similar postischemic phenotype to STAT6-/- mice. These data demonstrate that the STAT6 pathway has a major protective role in renal IRI. IL-4 deficiency is a likely mechanism underlying the STAT6 effect. A "yin-yang" role for inflammation is emerging in renal IRI, similar to recent observations in atherosclerosis.

Utility and limitations of serum creatinine as a measure of renal function in experimental renal ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI) is the major cause of delayed graft function in renal allografts. The present study was performed to investigate the validity of serum creatinine (SCr) level as an indicator of postischemic renal dysfunction in mice. Renal IRI or sham surgery was induced in C57BL/6 mice, and SCr level and inulin clearance (Cin) were measured between 24 hr and 7 days after ischemia. Cin in IRI mice was reduced 75% at 72 hr after ischemia in association with a nearly threefold increase in SCr level. Cin in IRI mice did not recover between 72 hr and 7 days after ischemia, even though SCr level at 7 days was not different between control and IRI mice. In IRI mice, SCr level measured at 24, 48, and 72 hr after ischemia correlated inversely with Cin measured at 72 hr, but not 7 days, after ischemia. SCr level in the early postischemic period (24-72 hr) seems to be a valid indicator of early postischemic renal dysfunction, and that renal function remains markedly depressed at 7 days despite suggestion from the SCr value that renal function is improving.