Protective effect of erythropoietin on renal ischemia and reperfusion injury

BACKGROUND: Multiple protective effects of erythropoietin (EPO), such as antiapoptotic, antioxidant, angiogenic and neuroprotective effects, against ischemia have been demonstrated in cell culture and animal models. Genistein is also a potent tyrosine kinase inhibitor. The aims of the present study were to evaluate the effects of EPO on renal ischemia/reperfusion injury and to determine the role of the tyrosine kinase pathway on this process. METHODS: Sprague-Dawley rats were assigned to five groups: (i) sham (Group I); (ii) control with renal ischemia (right nephrectomy and clamping on the left renal pedicle for 45 min and reperfusion; Group II); (iii) EPO + ischemia (Group III); (iv) genistein (an inhibitor of tyrosine kinase) + ischemia (Group IV); and (v) EPO + genistein + ischemia (Group V). Recombinant human EPO (1000 IU/kg) and genistein (10 mg/kg) were given 2 hours before ischemia. Blood samples and the left kidney were obtained after 45 min of reperfusion from half of the rats and after 24 h from the other half. RESULTS: The blood urea nitrogen, creatinine, tumour necrosis factor-alpha (P < 0.05) and interleukin-2 (P < 0.01) levels, and renal tissue lipid peroxidation (P < 0.05) were significantly lower in Group III than in Group II at 45 min of reperfusion. Following 24 h of reperfusion, EPO decreased tissue peroxidation and histopathological injury, whereas genistein reversed it. The most prominent ischemic injury was observed in Group IV in which genistein was administered. There was no significant difference between Groups II and V. CONCLUSIONS: These results suggest that EPO is effective in attenuating renal ischemia/reperfusion injury, and this effect may be related to tyrosine kinase activity.     

The effect of gradually increased blood flow on ischemia-reperfusion injury in rat kidney

BACKGROUND: Gradually increased blood flow to the ischemic rat kidney was studied to assess the ability to diminish ischemia-reperfusion injury. METHODS: The left renal artery and vein were isolated in 25 rats. Microclamps were applied for 45 minutes and were released at once (group II) or gradually (group III). Renal arterial blood flow and K+ activity were measured. Bilateral kidneys were harvested for histopathology and for malonyldealdehyde and myeloperoxidase levels. RESULTS: Increased K+ activity returned to preischemic values faster in group III than in group II. No statistically significant difference existed in malonyldealdehyde and myeloperoxidase levels; histopathologic scoring showed less tissue damage in group III (P < .05). Contralateral kidney samples showed signs of ischemia in group II. CONCLUSIONS: Gradually increased blood flow to the ischemic kidney decreases ischemic changes. Ischemic insult to 1 kidney causes histopathologically detectable changes to the contralateral kidney, which can be diminished by gradual reperfusion.     

Carnitine as a preventive agent in experimental renal ischemia-reperfusion injury

Reactive oxygen species generated during the reperfusion of ischemic kidney, as well as any other tissue, cause lipid peroxidation damaging the cell membrane. The aim of this study was to investigate the effect of carnitine in reperfusion injury of the kidney. Male albino rabbits were subjected to unilateral renal 1-h warm ischemia followed by 15 min of reperfusion. Group I (n=9): control group received 3 cc of isotonic saline solution and group II (n=9): carnitine group received 100 mg/kg of carnitine. Blood samples were collected at the 15th min of reperfusion from the left renal vein selectively. Preischemic and post-reperfusion serum and renal tissue MDA levels were measured by thiobarbituric acid reactive substances (TBARS) spectrophotometric analysis. The preischemic serum and tissue MDA values (sham values) for groups I and II were statistically comparable (P > 0.01). Serum and tissue MDA levels were markedly elevated after 15 min of reperfusion in group I (P < 0.01), while the values remained in the baseline levels following reperfusion in group II (P > 0.01). In group I, the major histological differences observed in the reperfused kidneys were marked edema and congestion whereas glomerular and tubular cellular integrity were well preserved in group II. Pre-treatment with carnitine in solid organ transplantations, preschock states, surgical procedures that require temporary vascular clamping etc. may be helpful to minimize the reperfusion injury in the involved tissue, reducing morbidity and mortality. Received: 22 May 2000 / Accepted: 1 February 2001     

The value and limitations of L-arginine infusion on glomerular and tubular function in the ischemic/reperfused kidney

Purpose: The nitric oxide precursor, L-arginine, has been shown to have a salutary effect on ischemia and reperfusion injury in skeletal muscle, skin, and intestines. Because L-arginine also increases renal blood flow, glomerular filtration, and urine flow in experimental animals with normal renal function, we postulated that L-arginine may also improve renal function after renal ischemic injury.Methods: Eighteen adult New Zealand white rabbits weighing 3 to 3.5 kg were subjected to bilateral normothermic renal ischemia by clamping both renal pedicles for 1 hour followed by 2 hours of reperfusion. The animals were randomized into three groups: group I (control, n = 6) received no additional treatment; group II (pretreatment, n = 6) received systemic intravenous L-arginine at 150 mg/kg over 20 minutes before induction of ischemia; group III (posttreatment, n = 6) received systemic intravenous L-arginine at 150 mg/kg over 20 minutes from the onset of reperfusion. Urine flow, creatinine clearance (C_CR), fractional excretion of sodium (FENa), and renal failure index (RFI) were calculated before ischemia and 2 hours after reperfusion, by use of standard formulas. The changes of the various renal parameters were compared among the three groups.Results: Bilateral normothermic renal ischemia for 1 hour produced a significant deterioration of glomerular filtration as evidenced by a C_CR decrease from 11.1 ± 1.8 to 2.49 ± 0.9 ml/min ( p < 0.01), FENa increase from 2.9% ± 1.0% to 20.8% ± 1.5% ( p < 0.01) and RFI increase from 4.0 ± 1.3 to 28.8 ± 2.6 ( p < 0.01). Pretreatment with L-arginine (group II) minimized the deleterious effects caused by ischemia on glomerular filtration (C_CR of 2.49 ± 0.9 ml/min in group I vs 4.95 ± 2.5 ml/min in group II, p < 0.05) and tubular function (FENa of 20.8% ± 1.5% in group I vs 13.0% ± 5.6% in group II and RFI of 28.8 ± 2.6 in group I vs 18.6 ± 8.0 in group II, p < 0.05). Infusion of L-arginine at the onset of reperfusion (group III) produced a significant diuretic effect (urine flow from 32.6 ± 13.4 ml/hr in group I to 63.3 ± 18.8 ml/hr in group III, p < 0.05) and also minimized glomerular damage (C_CR from 2.49 ± 0.9 ml/min in group I to 4.80 ± 1.2 ml/min in group III, p < 0.05); however, no beneficial effect was observed on tubular function.Conclusion: Induction of nitric oxide production by systemic L-arginine infusion can best preserve glomerular and tubular function in the ischemic/reperfused kidney when given before the ischemic insult. (J VASC SURG 1995;21:453-9.)     

The beneficial effect of intermediate normothermic perfusion during cold storage of ischemically injured kidneys. A study of renal nucleotide homeostasis during hypothermia in the dog

The effect of simple cold storage on ice with or without preceding warm ischemic injury on the energy metabolism and posttransplant viability of canine kidneys was examined in the present study. In addition, we investigated the possible beneficial effect of an intermediate normothermic perfusion half-way through the storage period on the preservation of ischemically injured kidneys. Thirty mongrel dogs were allocated to 5 experimental groups. In groups I and II kidneys were simply stored on ice for 24 and 48 hr, respectively. In groups III and IV kidneys were additionally subjected to 30 min warm ischemia before storage. In group 5 kidneys were treated as in group IV, but halfway through the storage period an intermediate normothermic ex-vivo perfusion was performed. The effect of these procedures on renal viability was tested by autologous reimplantation of the kidneys. During implantation the contralateral kidney was immediately removed. In group I all animals survived, whereas in group IV none of the animals survived. In groups II, III, and V, 2 of 6, 1 of 6, and 3 of 6 animals survived, respectively. The relationship, if any, between poststorage renal viability and the tissue levels of adenine nucleotides, guanine nucleotides, IMP, and purine degradation products was assessed by measuring the content of these metabolites in tissue specimen of the renal cortex, on which biopsies were done at various intervals during the experimental procedures. After an initial drop of about 30% in the content of adenine and guanine nucleotides and an increase in IMP, these values remained constant during 48 hr of cold storage. In contrast to kidneys stored for 24 hr, reimplantation of kidneys stored for 48 hr resulted in a significant decrease of adenine nucleotides following 60 min of in vivo reperfusion. Warm ischemia for 30 min prior to cold storage lead to lower initial nucleotide levels at the start of the storage period. During the first 24 hr nucleotide levels did not change, but a further decrease was observed during the following 24 hr of storage. Reimplantation after 24 hr of storage resulted in an additional decrease in the content of nucleotides. This poststorage decrease was absent after 48 hr of cold storage. Intermediate normothermic perfusion halfway through the storage for 48 hr significantly prevented the drop in the nucleotide content observed during the last 24 hr of storage in the corresponding control group. This nucleotide-sparing effect did not increase the level of nucleotides at the end of 60 min of reperfusion following reimplantation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Contribution of T lymphocytes to rat renal ischemia/reperfusion injury

BACKGROUND: This study aimed to elucidate the early involvement of T lymphocytes in renal ischemia/reperfusion injury. METHODS: Athymic nude rats (F344/N_Jcl-nu) and control F344/Jcl were subjected to 45 min unilateral renal ischemia. To determine whether the observed differences might be derived from the T lymphocyte presence, T lymphocytes from the spleens of F344/Jcl were injected into F344/N_Jcl-nu via tail vein at the initiation of reperfusion. Immunohistochemical analysis was performed for CD3, the proliferative cell nuclear antigen (PCNA), vimentin, and E-cadherin. T lymphocytes were obtained from the green fluorescent protein transgenic (GFP) rats, and transplanted to F344/N_Jcl-nu 10 min before reperfusion. The animals were euthanized 15 min after reperfusion. RESULTS: F344/N_Jcl-nu showed less retention of both Cr and BUN at 24 and 48 h after reperfusion, compared with F344/Jcl. F344/N_Jcl-nu received T lymphocyte transplantation showed significantly higher retention of both Cr and BUN 24, 48, and 72 h after reperfusion than those without T lymphocyte. A rapid infiltration of T lymphocytes into proximal tubular epithelial cells and tubular lumen was observed using T lymphocytes with green fluorescent protein. In contrast, T lymphocytes were observed with much less frequency 24 h after ischemia. The number of PCNA-positive proximal tubular cells 24 h after the initiation of reperfusion was significantly smaller in the T lymphocyte transplantation group compared with the non-transplantation group. The vimentin positivity and cytoplasmic staining of E-cadherin were also more prominent in the transplantation group. CONCLUSION: These findings demonstrate a rapid renal T lymphocyte infiltration, which propagate renal functional deterioration.     

The Effects of Mibefradil,a T-Type Ca2 + Channels Blocker,on the Renal Dysfunction and Injury Caused by Ischemia-Reperfusion of the Rat Kidney

This study was designed to determine the possible protective effect of mibefradil on renal ischemia/reperfusion (I/R) injury. Unilaterally nephrectomized Sprague-Dawley rats were subjected to 60 min of left renal ischemia followed by 45 min of reperfusion. Group 1 were sham-operated animals; group 2, I/R/untreated animals; and group III, I/R/mibefradil-treated animals. A 99mTc-DTPA scan was taken to measure kidney perfusion, glomerular filtration rate (GFR) and the time elapsed from isotope injection to the maximum of the curve. Serum creatinine, blood urea nitrogen (BUN), kidney malondialdehyde (MDA) level were determined as well as examining the kidneys histologically. Treatment of rats with mibefradil produced a significant reduction in the serum levels of creatinine and urea nitrogen. T-max-sec (renal perfusion) was significantly lower in group 2 than in groups 1 and 3. The GFR was markedly greater in group 3 than in the group 2. The Tmax-min was significantly greater in group 2 than in group 3. Mibefradil treatment significantly decreased the MDA levels. The histopathologic score was significantly less in the group 3 rats compared with group 2 rats. Kidneys of group 2 rats showed tubular cell swelling, cellular vacuolization, pyknotic nuclei, medullary congestion, and moderate to severe necrosis. Treatment with mibefradil preserved the normal morphology of the kidney and shows normal glomeruli and slight edema of the tubular cells. These findings suggest that mibefradil reduces the renal dysfunction associated with I/R of the kidney.     

The effects of mibefradil, a T-type Ca2+ channels blocker, on the renal dysfunction and injury caused by ischemia-reperfusion of the rat kidney

This study was designed to determine the possible protective effect of mibefradil on renal ischemia/reperfusion (I/R) injury. Unilaterally nephrectomized Sprague-Dawley rats were subjected to 60 min of left renal ischemia followed by 45 min of reperfusion. Group 1 were sham-operated animals; group 2, I/R/untreated animals; and group III, I/R/mibefradil-treated animals. A 99mTc-DTPA scan was taken to measure kidney perfusion, glomerular filtration rate (GFR) and the time elapsed from isotope injection to the maximum of the curve. Serum creatinine, blood urea nitrogen (BUN), kidney malondialdehyde (MDA) level were determined as well as examining the kidneys histologically. Treatment of rats with mibefradil produced a significant reduction in the serum levels of creatinine and urea nitrogen. T-max-sec (renal perfusion) was significantly lower in group 2 than in groups 1 and 3. The GFR was markedly greater in group 3 than in the group 2. The Tmax-min was significantly greater in group 2 than in group 3. Mibefradil treatment significantly decreased the MDA levels. The histopathologic score was significantly less in the group 3 rats compared with group 2 rats. Kidneys of group 2 rats showed tubular cell swelling, cellular vacuolization, pyknotic nuclei, medullary congestion, and moderate to severe necrosis. Treatment with mibefradil preserved the normal morphology of the kidney and shows normal glomeruli and slight edema of the tubular cells. These findings suggest that mibefradil reduces the renal dysfunction associated with I/R of the kidney.     

Efeitos de dexmedetomidina em conjunto com o pré‐condicionamento isquêmico remoto em lesão de isquemia‐reperfusão renal em ratos

Background and objectivesThe aim of this study was to evaluate the effects of remote ischemic preconditioning by brief ischemia of unilateral hind limb when combined with dexmedetomidine on renal ischemia–reperfusion injury by histopathology and active caspase‐3 immunoreactivity in rats.Methods28 Wistar albino male rats were divided into 4 groups. Group I (Sham, n = 7): Laparotomy and renal pedicle dissection were performed at 65th minute of anesthesia and the rats were observed under anesthesia for 130 min. Group II (ischemia–reperfusion, n = 7): At 65th minute of anesthesia bilateral renal pedicles were clamped. After 60 min ischemia 24 h of reperfusion was performed. Group III (ischemia–reperfusion + dexmedetomidine, n = 7): At the fifth minute of reperfusion (100 μg/kg intra‐peritoneal) dexmedetomidine was administered with ischemia–reperfusion group. Reperfusion lasted 24 h. Group IV (ischemia–reperfusion + remote ischemic preconditioning + dexmedetomidine, n = 7): After laparotomy, three cycles of ischemic preconditioning (10 min ischemia and 10 min reperfusion) were applied to the left hind limb and after 5 min with group III.ResultsHistopathological injury scores and active caspase‐3 immunoreactivity were significantly lower in the Sham group compared to the other groups. Histopathological injury scores in groups III and IV were significantly lower than group II (p = 0.03 and p = 0.05). Active caspase‐3 immunoreactivity was significantly lower in the group IV than group II (p = 0.01) and there was no significant difference between group II and group III (p = 0.06).ConclusionsPharmacologic conditioning with dexmedetomidine and remote ischemic preconditioning when combined with dexmedetomidine significantly decreases renal ischemia–reperfusion injury histomorphologically. Combined use of two methods prevents apoptosis via active caspase‐3.     

Suramin promotes recovery from renal ischemia/reperfusion injury in mice

Suramin is a polysulfonated naphthylurea originally designed as a treatment for trypanosomiasis; but that has also been used to treat rodent models of fulminant hepatic failure and focal brain ischemia. In this study, we determined the effects of suramin on renal ischemia/reperfusion-induced acute kidney injury in mice, in particular its effect when administered after renal injury has been established. Increasing concentrations of suramin were given 24 hours following reperfusion, a time when serum creatinine levels were at their highest level. This treatment improved renal function, as evidenced by decreased blood urea nitrogen and serum creatinine to control values and diminished histopathologic tubular damage. Suramin-treated animals had a significant reduction in apoptotic tubular cells and infiltrating leukocytes. There was also an increase of proliferating tubular cells following reperfusion compared to the number found in untreated animals. Our study shows that suramin promotes the recovery of renal function and has effective therapeutic applications when given after the occurrence of renal injury.     

Nebivolol reduces experimentally induced warm renal ischemia reperfusion injury in rats

Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. The objective of the present study was to examine the role of nebivolol in modulating peroxynitrite species-induced inflammation and apoptosis after renal warm ischemia/reperfusion injury in rats. The present study was designed to investigate the effects of nebivolol on the renal warm ischemia/reperfusion injury in rats treated with the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine methyl ester. After right nephrectomy, nebivolol was administered for 15 days. On the 16(th) day, ischemia was induced in contra lateral kidney for 45 min, followed by reperfusion for 24 hr. Renal function, inflammation, and apoptosis were estimated at the end of 24 hr reperfusion. Nebivolol improved the renal dysfunction and reduced inflammation and apoptosis after renal ischemia/reperfusion injury. In conclusion, nebivolol shows potent anti-apoptotic and anti-inflammatory properties due to its NO-releasing property. These findings may have major implications in the treatment of human ischemic acute renal failure.     

Changes in hepatic TNF-alpha levels,antioxidant status,and oxidation products after renal ischemia/reperfusion injury in mice

BACKGROUND: Ischemia/reperfusion (I/R) injury induces an inflammatory response and production of reactive oxygen species (ROS), which affects the organs remote to the sites of I/R. The aim was to assess the hepatic changes after renal I/R injury. MATERIALS AND METHODS: Twenty mice were subjected to either sham operation or varying degrees of renal I/R injury. Hepatic TNF-alpha levels, myeloperoxidase (MPO), superoxide dismutase (SOD), and catalase (CAT) activities and reduced glutathione (GSH) levels, thiobarbituric acid-reactive substances (TBARS), and protein carbonyl levels were evaluated to show hepatic response to renal I/R injury. RESULTS: Hepatic tumor necrosis factor-alpha levels were found to be increased significantly after 30 min ischemia-1 h reperfusion and remained elevated through 60 min ischemia-1 h reperfusion. Supporting the neutrophil recruitment, about 10-fold increase in MPO activity was detected after 30 min ischemia-1 h reperfusion. Antioxidant enzymes were detected to be decreased after 30 min ischemia-1 h reperfusion and reached to the minimum levels after 60 min ischemia-1 h reperfusion. Decreased levels of GSH and increased levels of TBARS and protein carbonyls after 60 min ischemia-1 h reperfusion supported the ROS-mediated biomolecular alterations. CONCLUSIONS: A minumum of 30 min ischemia-1 h reperfusion is enough to elicit remote effects of renal I/R injury. Care should be taken to protect other organs remote from I/R sites especially during renal surgery.     

Transient limb ischemia induces remote preconditioning in liver among rats: the protective role of heme oxygenase-1

BACKGROUND: We have reported the protective role of heme oxygenase-1 (HO-1) in the mechanism of hypoxic preconditioning. We wish to investigate the role of HO-1 in remote preconditioning (RP) against hepatic ischemia/reperfusion (I/R) injury in rats. METHODS: The remote preconditioning was produced by four cycles of 10-min ischemia-reperfusion of the hind limb of rats. Partial hepatic ischemia was produced in the left lobes for 45 min followed by 240 min of reperfusion. Zinc-protoporphyrin IX (ZnPP), a specific inhibitor of HO enzymatic activity, was intra-peritoneally injected 1 hr before the ischemia-reperfusion injury in separate groups of RP rats. Serum alanine transaminase (ALT) levels, expression of hepatic HO-1 protein and mRNA, immunohistochemical staining and HO enzymatic activity were measured. RESULTS: HO-1 was induced in the livers of rats 4 hr after the RP stimuli, and the overexpression persisted for 24 hr. Immunohistochemical staining demonstrated induction of HO-1 in the hepatocytes. The peripheral lymphocytes did not express HO-1 after RP. RP diminished the elevation of serum ALT levels 4 hr after I/R injury (283.7+/-167.4 U L) when compared with controls (1297.7+/-729.3 U L) and RP+ ZnPP pretreated groups (1429.9+/-750.9 U L). The heme oxygenase activity in treated rats also correlated these results (286.8+/-34.3 pmol mg protein hr for the RP group, 156.3+/-27.5 pmol mg protein hr for the RP+ ZnPP pretreated group, and 170.6+/-19.4 pmol mg protein hr for the control group, 144.8+/-7.8 pmol mg protein hr for the control+ ZnPP pretreated group). CONCLUSION: Our results indicated that the induction of HO-1 in remote preconditioning played a protective role against hepatic I/R injury.     

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

Abstract

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.     

The effects of iloprost and vitamin C on kidney as a remote organ after ischemia/reperfusion of lower extremities

BACKGROUND: 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. MATERIAL AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.     

Nebivolol Reduces Experimentally Induced Warm Renal Ischemia Reperfusion Injury in Rats

Ischemia/reperfusion injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure. The objective of the present study was to examine the role of nebivolol in modulating peroxynitrite species-induced inflammation and apoptosis after renal warm ischemia/reperfusion injury in rats. The present study was designed to investigate the effects of nebivolol on the renal warm ischemia/reperfusion injury in rats treated with the nitric oxide synthase inhibitor, N^ω-nitro-L-arginine methyl ester. After right nephrectomy, nebivolol was administered for 15 days. On the 16^th day, ischemia was induced in contra lateral kidney for 45 min, followed by reperfusion for 24 hr. Renal function, inflammation, and apoptosis were estimated at the end of 24 hr reperfusion. Nebivolol improved the renal dysfunction and reduced inflammation and apoptosis after renal ischemia/reperfusion injury. In conclusion, nebivolol shows potent anti-apoptotic and anti-inflammatory properties due to its NO-releasing property. These findings may have major implications in the treatment of human ischemic acute renal failure.     

L-Arginine transport is augmented through up-regulation of tubular CAT-2 mRNA in ischemic acute renal failure in rats

BACKGROUND: Ischemic acute renal failure (iARF) is associated with increased nitric oxide (NO) production during the reperfusion period, as endothelial nitric oxide synthase (eNOS) is maximally activated, and renal tubular inducible NOS (iNOS) is stimulated. Increased NO production leads to augmented tubular injury, probably through the formation of peroxynitrite. l-Arginine (l-Arg), the only precursor for NO, is transported into cells by cationic amino acid transporters, CAT-1 and CAT-2. We hypothesized that the increased NO production observed in iARF may result from increased l-Arg uptake, which would be reflected in the augmented expression of l-Arg transporter(s). METHODS: Ischemic acute renal failure was induced in rats by right nephrectomy + left renal artery clamping for 60 minutes. l-Arg uptake was examined in freshly harvested glomeruli and tubuli from control, sham operated, and animals subjected to 15, 30, and 60 minutes, and 24 hours of reperfusion, following 60 minutes of ischemia. Using RT-PCR, renal tissues were examined further for the expression of iNOS, CAT-1, CAT-2, arginase I and arginase II. RESULTS: Tubular expression of iNOS mRNA was initiated by ischemia, continued to increase after 60 minutes of reperfusion, and decreased after 24 hours. l-Arg transport into glomeruli was similar in all experimental groups. l-Arg uptake into tubuli was markedly augmented following the 60-minute reperfusion, while it moderately increased after 24 hours of reperfusion. This was accompanied by a parallel, preferential increase in tubular CAT-2 mRNA expression at 60 minutes of reperfusion. CAT-1 mRNA expression was unchanged, as detected by RT-PCR. In addition, the expression of arginase II and arginase I mRNA was attenuated by 30 minutes and one hour of reperfusion, and returned to baseline values after 24 hours of reperfusion. CONCLUSIONS: Ischemic ARF is associated with augmented tubular CAT-2 mRNA expression, which leads to enhanced l-Arg transport and increased NO production. This may contribute to the renal injury exhibited in iARF.     

Carvedilol protects tubular epithelial cells from ischemia–reperfusion injury by inhibiting oxidative stress

Objectives: Renal ischemia–reperfusion injury (IRI), leading to acute kidney injury, is a frequent complication with renal transplantation and it is associated with graft function. Its pathogenesis involves ischemia, vascular congestion and reactive oxygen metabolites. Carvedilol is an antihypertensive drug with potent anti‐oxidant properties. In this study we investigated the protective effects of carvedilol in a rat renal IRI model. Methods: Twenty‐four rats were randomized into sham, untreated control and carvedilol (2 mg/kg 30 min before surgery and 12 hr after reperfusion) treatment groups and were subjected to 60 min of left renal ischemia followed by reperfusion at 24, 48, 96 and 168 hr. Results: Treatment with carvedilol significantly decreased plasma creatinine levels after IRI (up to 168 hr) compared to controls (P < 0.001), suggesting an improvement in renal function. Histopathological analysis revealed decreased IRI‐induced damage in kidneys from carvedilol‐treated rats. A significant increase in the expression levels of Cu/Zn superoxide dismutase and reduction of 8‐hydroxydeoxyguanosine and apoptosis levels (P < 0.005) suggested a protective effect after treatment with carvedilol. Conclusions: Our findings suggest that carvedilol ameliorates IRI resulting in improved renal function.     

肾脏缺血预适应及细胞间黏附分子1的作用

目的建立肾脏缺血预适应大鼠模型,探讨缺血预适应对细胞间黏附分子(ICAM)-1mRNA表达的影响。方法摘除右肾后,对左肾采用2min缺血 5min再灌注,4个循环后再缺血45min,建立大鼠肾脏缺血预适应模型。RT-PCR检测肾脏ICAM-1mRNA表达。结果缺血预适应使肾缺血后Scr的升高幅度值减少,肾小管损伤减轻,髓质ICAM-1mRNA表达降低。结论肾脏缺血预适应可从组织学和功能上减轻肾脏的急性缺血性损伤,这可能与肾组织ICAM-1表达降低及局部炎症减轻有关。     

Repetitive brief ischemia: intermittent reperfusion during ischemia ameliorates the extent of injury in the perfused kidney

Acute renal failure commonly follows reduced renal perfusion or ischemia. Reperfusion is essential for recovery but can itself cause functional and structural injury to the kidney. The separate contributions of ischemia and of reperfusion were examined in the isolated perfused rat kidney. Three groups were studied: brief (5 min) ischemia, 20 min ischemia, and repetitive brief ischemia (4 periods of 5 min) with repetitive intervening reperfusion of 5 min. A control group had no intervention, the three ischemia groups were given a baseline perfusion of 30 min before intervention and all groups were perfused for a total of 80 min. In addition, the effects of exogenous *NO from sodium nitroprusside and xanthine oxidase inhibition by allopurinol were assessed in the repetitive brief ischemia-reperfusion model. Brief ischemia produced minimal morphological injury with near normal functional recovery. Repetitive brief ischemia-reperfusion caused less functional and morphological injury than an equivalent single period of ischemia (20 min) suggesting that intermittent reperfusion is less injurious than ischemia alone over the time course of study. Pretreatment with allopurinol improved renal function after repetitive brief ischemia-reperfusion compared with the allopurinol-untreated repetitive brief ischemia-reperfusion group. Similarly, sodium nitroprusside reduced renal vascular resistance but did not improve the glomerular filtration rate or sodium reabsorption in the repetitive brief ischemia-reperfusion model. Thus, these studies show that the duration of uninterrupted ischemia is more critical than reperfusion in determining the extent of renal ischemia-reperfusion injury and that allopurinol, in particular, counteracts the oxidative stress of reperfusion.