Min Of Bilateral Renal Ischemia Research Articles

Treprostinil reduces mitochondrial injury during rat renal ischemia-reperfusion injury

BackgroundRenal ischemia-reperfusion injury (IRI) is a major factor contributing to acute kidney injury and it is associated with a high morbidity and mortality if untreated. Renal IRI depletes cellular and tissue adenosine triphosphate (ATP), which compromises mitochondrial function, further exacerbating renal tubular injury. Currently, no treatment for IRI is available. This study investigates the protective role of treprostinil in improving mitochondria biogenesis and recovery during rat renal IRI. MethodsMale Sprague Dawley rats were randomly assigned to groups: control, sham, IRI-placebo or IRI-treprostinil and subjected to 45 min of bilateral renal ischemia followed by 1–72 h reperfusion. Placebo or treprostinil (100 ng/kg/min) was administered subcutaneously via an osmotic minipump. ResultsTreprostinil significantly reduced peak elevated serum creatinine (SCr) levels and accelerated normalization relative to IRI-placebo (p < 0.0001). Treatment with treprostinil also inhibited IRI-mediated renal apoptosis, mitochondrial oxidative injury (p < 0.05), and the release of cytochrome c (p < 0.01) vs. IRI-placebo. In addition, treprostinil preserved renal mitochondrial DNA copy number (p < 0.0001) and renal ATP levels (p < 0.05) to nearly those of sham-operated animals. Non-targeted semi-quantitative proteomics showed reduced levels of ATP synthase subunits in the IRI-placebo group which were restored to sham levels by treprostinil treatment (p < 0.05). Furthermore, treprostinil reduced renal IRI-induced upregulated Drp1 and pErk protein levels, and restored Sirt3 and Pgc-1α levels to baseline (p < 0.05). ConclusionsTreprostinil reduces mitochondrial-mediated renal apoptosis, inhibits mitochondria fission, and promotes mitochondria fusion, thereby accelerating mitochondrial recovery and protecting renal proximal tubules from renal IRI. These results support the clinical investigation of treprostinil as a viable therapy to reduce renal IRI.

Intravital imaging of real-time endogenous actin dysregulation in proximal and distal tubules at the onset of severe ischemia-reperfusion injury

Severe renal ischemia-reperfusion injury (IRI) can lead to acute and chronic kidney dysfunction. Cytoskeletal modifications are among the main effects of this condition. The majority of studies that have contributed to the current understanding of IRI have relied on histological analyses using exogenous probes after the fact. Here we report the successful real-time visualization of actin cytoskeletal alterations in live proximal and distal tubules that arise at the onset of severe IRI. To achieve this, we induced fluorescent actin expression in these segments in rats with hydrodynamic gene delivery (HGD). Using intravital two-photon microscopy we then tracked and quantified endogenous actin dysregulation that occurred by subjecting these animals to 60 min of bilateral renal ischemia. Rapid (by 1-h post-reperfusion) and significant (up to 50%) declines in actin content were observed. The decline in fluorescence within proximal tubules was significantly greater than that observed in distal tubules. Actin-based fluorescence was not recovered during the measurement period extending 24 h post-reperfusion. Such injury decimated the renal architecture, in particular, actin brush borders, and hampered the reabsorptive and filtrative capacities of these tubular compartments. Thus, for the first time, we show that the combination of HGD and intravital microscopy can serve as an experimental tool to better understand how IRI modifies the cytoskeleton in vivo and provide an extension to current histopathological techniques.

Gut derived-endotoxin contributes to inflammation in severe ischemic acute kidney injury

BackgroundRecent researches indicate that the intestinal consequences of renal ischemia reperfusion (IR) would predispose to the translocation of gut-derived endotoxin. Here, we designed experiments to test the hypothesis that the gut-derived endotoxin has a potential role in mediating local inflammatory processes in the acutely injured kidney.MethodsRats were performed sham or renal IR surgery (60 min of bilateral renal ischemia, then 24 h of reperfusion) (n = 5). The intestinal structural and mucosa permeability were evaluated. Serum endotoxin and bacterial load in liver and mesenteric lymph nodes (MLN) were measured. Separate groups were pretreated with oral norfloxacin 20 mg/kg/day or saline for 4 weeks and divided into sham plus saline, sham plus norfloxacin, renal IR plus saline and renal IR plus norfloxacin group. Serum biochemistry and endotoxin were determined. Kidney pathological changes were scored. Protein or mRNA expression of toll-like receptor 4 (TLR4) and proinflammatory mediators were measured in kidney homogenate.ResultsRenal IR led to marked intestinal integrity disruption and increase in intestinal permeability. These are accompanied by low grade of endotoxemia as well as increased bacterial load in liver and MLN. The group pretreated with norfloxacin showed significant attenuation of the increase in serum urea, ALAT, ASAT and endotoxin. The increased renal protein or mRNA of TLR4 and proinflammatory mediators (IL-6 and MCP-1) in the unpretreated animals was significantly attenuated in the norfloxacin-pretreated animals. However, norfloxacin pretreatment did not produce any protective effects on renal tubular integrity.ConclusionsOur results show for the first time that gut-derived endotoxin, resulting from an increased intestinal permeability after severe renal IR, subsequently amplifies intrarenal inflammatory response by activation renal TLR4 signaling. Our study results do not establish that antibiotic administration was effective in improving the overall renal outcome. However, our findings may be the first step to understanding how to tailor therapies to mitigate intrarenal inflammation in select groups of patients.

Estradiol attenuates ischemia reperfusion-induced acute kidney injury through PPAR-γ stimulated eNOS activation in rats.

We investigated the involvement of peroxisome proliferator activated receptor-γ (PPAR-γ)/endothelial nitric oxide synthase (eNOS) pathway in estradiol mediated protection against ischemia reperfusion (I/R)-induced acute kidney injury (AKI) in rats. To induce AKI, rats underwent 40min of bilateral renal ischemia followed by 24h of reperfusion. I/R-induced kidney damage was quantified by measuring serum creatinine, creatinine clearance, urea nitrogen, uric acid, potassium, fractional excretion of sodium, microproteinuria, and renal oxidative stress (thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione). Hematoxylin eosin stain demonstrated renal histology, while renal expression of apoptotic markers (Bcl-2, Bax), PPAR-γ and eNOS were quantified by immunohistochemistry. Estradiol (1mg/kg, i.p.) was administered 30min before I/R in rats. In separate groups, PPAR-γ antagonist, BADGE (30mg/kg, i.p.), and NOS inhibitor, L-NAME (20mg/kg, i.p.) were administered prior to estradiol treatment, which was followed by I/R in rats. I/R caused significant renal damage as demonstrated by biochemical (serum/urine), renal oxidative stress and histological changes alongwith increased expression of Bax and decreased levels of Bcl-2, PPAR-γ and eNOS, which were prevented by estradiol. Pre-treatment with BADGE and L-NAME abolished estradiol mediated renoprotection. Notably, I/R + estradiol + BADGE group revealed decreased expression of PPAR-γ and eNOS in renal tissues. In I/R + estradiol + L-NAME group, eNOS expression was reduced while PPAR-γ levels remained unchanged. These results suggest that estradiol modulates PPAR-γ which consequently regulates eNOS expression in rat kidneys. We conclude that estradiol protects against I/R-induced AKI through PPAR-γ stimulated eNOS activation in rats.

A functional role for complement receptor C5L2 in the pathogenesis of renal ischemia-reperfusion injury

The complement system, and specifically C5a, is involved in renal ischemia-reperfusion (IR) injury. The two receptors for C5a, C5aR and C5L2, are expressed on leukocytes as well as in the kidney. Extensive evidence shows that C5aR inhibition protects kidneys from IR injury, but the role of C5L2 in IR injury has not been studied so far. Therefore, WT, C5aR−/− and C5L2−/− mice were subjected to 40 min of bilateral renal ischemia, followed by reperfusion for 1, 3 or 7 days. It was found that C5L2−/− mice were protected against IR injury, resulting in significant lower plasma creatinine and BUN levels, and reduced acute tubular necrosis. Next, an in vivo migration study, where WT, C5aR−/− and C5L2−/− mice were injected intraperitoneally with complement ligands, revealed that C5L2 is not involved in leukocyte migration. To investigate the contribution of renal-expressed C5L2 versus leukocyte-expressed C5L2 to renal IR injury, bone marrow chimeras were created. Our data show that renal-expressed C5L2 and leukocyte-expressed C5L2 mediate IR injury-induced renal dysfunction. Therefore, C5L2 is a functional receptor in renal IR injury rather than a simple decoy receptor. For that reason, next to C5aR, C5L2 is a potential target for intervention during renal IR injury.

Toll-like receptor 7 involves the injury in acute kidney ischemia/reperfusion of STZ-induced diabetic rats.

To determine whether Toll-like receptor 7 (TLR7) is the potential targets of prevention or progression in the renal ischemia/reperfusion (I/R) injury of STZ-induced diabetic rats. Thirty six Sprague-Dawley rats were randomly arranged to the nondiabetic (ND) or diabetic group (DM), with each group further divided into sham (no I/R injury), I/R (ischemia-reperfusion) and CD (given by Chloroquine) group. Preoperatively, Chloroquine (40 mg/kg, intraperitoneal injection.) was administrated 6 days for treatment group. I/R animals were subjected to 25 min of bilateral renal ischemia. Renal function, histology, apoptosis, cytokines, expression of TLR7, MyD88 and NF-κB were detected. The serum levels of blood urea nitrogen, creatinine, IL-6 and TNF-α, apoptotic tubular epithelial cells, expression of TLR7, MyD88 and NF-κB were significantly increased in DM+I/R group, compared with ND+I/R group (p<0.05). All these changes were further improved by TLR7 inhibition Chloroquine except Paller scores (p<0.05). Toll-like receptor 7 inhibition attenuates the acute renal ischemia/reperfusion injury of STZ-induced diabetic in SD rats.

Pioglitazone ameliorates renal ischemia reperfusion injury through NMDA receptor antagonism in rats.

The present study investigated the role of N-methyl-D-aspartate (NMDA) receptors in pioglitazone-mediated protection against renal ischemia reperfusion injury (IRI) in rats. Male wistar rats were subjected to 40min of bilateral renal ischemia followed by reperfusion for 24h to induce kidney injury. The renal damage was evaluated by measuring serum creatinine, creatinine clearance, blood urea nitrogen, uric acid, electrolytes, and microproteinuria in rats. Oxidative stress in renal tissues was quantified in terms of myeloperoxidase activity, thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione level. Hematoxylin-eosin and periodic acid Schiff staining of renal tissues were performed to observe histological changes. Pioglitazone (20 and 40mg/kg) was administered 1h prior to ischemia in rats. In separate groups, NMDA agonists, glutamic acid (200mg/kg), and spermidine (20mg/kg) were administered 1h prior to pioglitazone treatment, followed by renal IRI in rats. Ischemia reperfusion resulted in marked renal damage with significant changes in serum and urine parameters along with marked oxidative stress and histological changes in kidneys. Pioglitazone treatment afforded anti-oxidant effect and renoprotection in a dose-dependent manner in rats. Pioglitazone-mediated renoprotection was attenuated by glutamic acid and spermidine pretreatment in rats, which indicated the role of NMDA receptors in pioglitazone-mediated protection. It is concluded that NMDA antagonism serves as one of the mechanisms in pioglitazone-mediated protection against renal IRI in rats.

Atrial natriuretic peptide attenuation of renal ischemia–reperfusion injury after major surgery

BackgroundIschemia–reperfusion (I/R) injury is one of the most important pathologic processes causing acute kidney injury. Human atrial natriuretic peptide (hANP) has various effects, including renal protection. The purpose of the present work was to study the effects of intrarenal angiotensin II (Ang II) and investigate the potential of hANP to prevent kidney injury. Materials and methodsMale Sprague–Dawley rats were divided into three groups as follows: (1) sham; (2) I/R (30 min of bilateral renal ischemia followed by 6 h reperfusion); and (3) I/R + hANP (I/R injury + continuous intravenous infusion of hANP at 0.025 μg/kg/min). After 6 h of reperfusion, both renal and plasma Ang II concentrations were measured. Urinary angiotensinogen and neutrophil gelatinase–associated lipocalin were measured before ischemia and 2, 4, and 6 h after reperfusion. To evaluate the renal-protective effects of hANP, serum creatinine was determined 6 and 24 h after reperfusion. In addition, mitochondrial oxygen consumption in kidney cortex was measured in the presence of Ang II and hANP. ResultsRenal Ang II concentrations were 24.5 ± 3.9 and 14.2 ± 3.4 pg/mg renal weight in the I/R and I/R + hANP groups, respectively. Urinary angiotensinogen and neutrophil gelatinase–associated lipocalin excretions were elevated after I/R injury. Treatment with hANP significantly attenuated this effect after 4 and 6 h. Oxygen consumption in renal mitochondria increased with the addition of Ang II, which was also attenuated by hANP. ConclusionsProduction of intrarenal Ang II was attenuated by hANP, indicating a potential to diminish renal I/R injury.

Sildenafil obviates ischemia-reperfusion injury–induced acute kidney injury through peroxisome proliferator–activated receptor γ agonism in rats

BackgroundSildenafil is a phosphodiesterase inhibitor used clinically for treating erectile dysfunction. Few studies suggest sildenafil to be a renoprotective agent. The present study investigated the involvement of peroxisome proliferator–activated receptor γ (PPAR-γ) in sildenafil-mediated protection against ischemia-reperfusion–induced acute kidney injury (AKI) in rats. Materials and methodsThe rats were subjected to ischemia–reperfusion injury (IRI) with 40 min of bilateral renal ischemia followed by reperfusion for 24 h. The renal damage was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, electrolytes, and microproteinuria in rats. The thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels were measured to assess oxidative stress in renal tissues. The hematoxylin-eosin staining was carried out to demonstrate histopathologic changes in renal tissues. Sildenafil (0.5 and 1.0 mg/kg, intraperitoneal) was administered 1 h before subjecting the rats to renal IRI. In a separate group, bisphenol A diglycidyl ether (30 mg/kg, intraperitoneal), a PPAR-γ receptor antagonist, was given before sildenafil administration followed by IRI. ResultsThe ischemia–reperfusion demonstrated marked AKI with significant changes in serum and urinary parameters, enhanced oxidative stress, and histopathologic changes in renal tissues. The administration of sildenafil demonstrated significant protection against ischemia-reperfusion–induced AKI. The prior treatment with bisphenol A diglycidyl ether abolished sildenafil-mediated renal protection, thereby confirming involvement of PPAR-γ agonism in the sildenafil-mediated renoprotective effect. ConclusionsIt is concluded that sildenafil protects against ischemia-reperfusion–induced AKI through PPAR-γ agonism in rats.

Hydrogen sulfide accelerates the recovery of kidney tubules after renal ischemia/reperfusion injury.

Progression of acute kidney injury to chronic kidney disease (CKD) is associated with inadequate recovery of damaged kidney. Hydrogen sulfide (H2S) regulates a variety of cellular signals involved in cell death, differentiation and proliferation. This study aimed to identify the role of H2S and its producing enzymes in the recovery of kidney following ischemia/reperfusion (I/R) injury. Mice were subjected to 30 min of bilateral renal ischemia. Some mice were administered daily NaHS, an H2S donor, and propargylglycine (PAG), an inhibitor of the H2S-producing enzyme cystathionine gamma-lyase (CSE), during the recovery phase. Cell proliferation was assessed via 5'-bromo-2'-deoxyuridine (BrdU) incorporation assay. Ischemia resulted in decreases in CSE and cystathionine beta-synthase (CBS) expression and activity, and H2S level in the kidney. These decreases did not return to sham level until 8 days after ischemia when kidney had fibrotic lesions. NaHS administration to I/R-injured mice accelerated the recovery of renal function and tubule morphology, whereas PAG delayed that. Furthermore, PAG increased mortality after ischemia. NaHS administration to I/R-injured mice accelerated tubular cell proliferation, whereas it inhibited interstitial cell proliferation. In addition, NaHS treatment reduced post-I/R superoxide formation, lipid peroxidation, level of GSSG/GSH and Nox4 expression, whereas it increased catalase and MnSOD expression. Our findings demonstrate that H2S accelerates the recovery of I/R-induced kidney damage, suggesting that the H2S-producing transsulfuration pathway plays an important role in kidney repair after acute injury.

Growth arrest–specific protein 6 protects against renal ischemia–reperfusion injury

BackgroundRenal injury caused by ischemia–reperfusion (I/R) often occurs after shock or transplantation. Growth arrest–specific protein 6 (Gas6) is a secreted protein that binds to the TAM—Tyro3, Axl, Mer—family tyrosine kinase receptors, which modulate the inflammatory response and activate cell survival pathways. We hypothesized that Gas6 could have a protective role in attenuating the severity of renal injury after I/R. Materials and methodsAdult mice were subjected to 45 min of bilateral renal ischemia. Recombinant mouse Gas6 (rmGas6, 5 μg per mouse) or normal saline (vehicle) was administered intraperitoneally 1 h before ischemia and all subjects were sacrificed at 23 h after I/R for blood and tissue analysis. The expression of protein and messenger RNA (mRNA) was assessed by Western blotting and quantitative polymerase chain reaction, respectively. ResultsTreatment with rmGas6 significantly decreased serum levels of creatinine and blood urea nitrogen by 29% and 27%, respectively, improved the renal histologic injury index, and reduced the apoptosis in the kidneys, compared with the vehicle. Renal mRNA levels of interleukin 1β, interleukin 6, tumor necrosis factor α, keratinocyte-derived chemokine and macrophage inflammatory protein 2 were decreased significantly by 99%, 60%, 53%, 58%, and 43%, with rmGas6 treatment, respectively. After I/R, renal I-kappa-B α levels were reduced by 40%, whereas they returned to sham levels with rmGas6 treatment. The mRNA levels of inducible nitric oxide synthase and cyclooxygenase 2 were reduced by 79% and 70%, respectively, whereas the expression of cyclin D1 was increased by 2.1-fold in the rmGas6-treated group, compared with the vehicle. ConclusionsGas6 suppresses the nuclear factor κB pathway and promotes cell proliferation, leading to the reduction of inflammation and protection of renal injury induced by I/R.

Loss of matrix metalloproteinase-8 is associated with worsened recovery after ischemic kidney injury

Acute kidney injury (AKI) leads to chronic kidney disease. The mechanisms involved with recovery from AKI are poorly understood and molecular mediators responsible for healing and restoration of kidney function are understudied. We previously discovered differential expression of matrix metalloproteinase-8 (MMP-8) mRNA and protein in patients with severe sepsis associated AKI versus sepsis without AKI. Here, we demonstrate the involvement of MMP-8 in purely ischemic AKI. Mice subjected to 30 min of bilateral renal ischemia developed increased plasma creatinine and MMP-8 expression within 24 h versus sham controls. After an initial surge and subsequent return toward baseline, both kidney MMP-8 expression and activity exhibited a late increase (Days 5–7 post-ischemia reperfusion) in mice subjected to AKI. Neutrophil infiltration of the kidney was significantly higher after AKI in wild-type mice than in MMP-8 null mice, starting at 4 days. Additionally, MMP-8 null mice subjected to AKI demonstrated a persistent histopathologic and functional injury and worsened health (greater overall weight loss) versus wild-type cohorts after seven days. Taken together, our findings suggest that MMP-8 is involved with restoration of baseline kidney health after ischemic kidney injury and that a potential mechanism involves the interaction of MMP-8 and neutrophil recruitment to the site of injury.

Kidney oxygenation in the subacute phase of ischemia‐reperfusion injury (890.1)

We determined the status of kidney tissue oxygenation during the subacute phase of renal ischemia reperfusion injury in 10‐12 week old male Sprague‐Dawley rats. Inner medullary oxygen tension (PO2) was determined using a carbon paste electrode attached to a telemetry transmitter, for 24 hours before and for 5 days after 60 min of bilateral renal ischemia (n=4) or sham (n=4) surgery. In a second protocol, renal tissue PO2 was measured by Clark electrode under thiobutabarbital anesthesia, either 1 or 5 days after recovery from renal ischemia (n = 6 and 3 respectively) or sham surgery (n = 5 and 3 respectively). Inner medullary tissue PO2 measured by telemetry was increased by 45 ± 15% 24 h after reperfusion, but then progressively fell over the next 5 days. Tissue PO2 measured by Clark electrode was well maintained 24 h after ischemia. However, outer medullary PO2 was 69% less 5 days after ischemia than after sham surgery. Our observations suggest that widespread renal hypoxia may not be obligatory in the subacute phase of renal ischemia‐reperfusion injury. However, medullary hypoxia may evolve over a period of days following reperfusion.Grant Funding Source: Supported by the National Health and Medical Research Council of Australia

Possible role of nitric oxide in hepatic injury secondary to renal ischemia-reperfusion (I/R) injury.

Hepatic injury secondary to renal I/R injury has been documented in several studies. This study aimed to investigate the role of NO in hepatic injury secondary to renal I/R in rat model. Sprague-Dawley rats (n = 48) were divided into 4 equal groups; sham-operated, I/R injury group (45 min of bilateral renal ischemia), L-arginine group (I/R with 300 mg/kg L-arginine, 20 min before ischemia), L-NAME group (I/R with 50 mg/kg L-NAME, 20 min before ischemia). L-NAME (NO synthase inhibitor) caused significant elevation in serum creatinine, BUN, liver enzymes, liver histopathological damage score (p ≤ 0.05) and MDA production (p ≤ 0.001); on the other hand significantly decreased NO and GSH levels (p ≤ 0.05). L-arginine significantly decreased serum creatinine, BUN and GSH (p ≤ 0.05) and caused significant elevation in liver enzymes and NO (p ≤ 0.05), and also in MDA levels (p ≤ 0.001) in liver tissues. We conclude that endogenous NO might have protective effect against hepatic injury induced by renal I/R injury and inhibition of this endogenous NO by L-NAME or exogenous administration of NO (by L-arginine) might be harmful.

TNF-α mediates increased susceptibility to ischemic AKI in diabetes

Diabetes is a risk factor for the development of acute kidney injury (AKI) in humans and rodents. However, the mechanistic basis for this observation is unknown. The present studies evaluated the role of inflammation and TNF-α in ischemic AKI in a model of type 2 diabetes mellitus (DM). Diabetic (db/db) and nondiabetic (db/+) littermates were subjected to 20 min of bilateral renal ischemia. The nondiabetic mice developed only mild and transient renal dysfunction. In contrast, the equivalent ischemic insult provoked severe and sustained renal dysfunction in the db/db mice. The expression of TNF-α and Toll-like receptor 4 (TLR4) mRNA was measured in the kidneys of diabetic mice before and after renal ischemia; db/db mice exhibited greater increases in TNF-α and TLR4 mRNA expression following ischemia than did db/+. In addition, urinary excretion of TNF-α after ischemia was higher in db/db mice than in db/+ mice. To determine the possible role of TNF-α in mediating the enhanced susceptibility of diabetic mice to ischemic injury, db/db mice were injected with either a neutralizing anti-mouse TNF-α antibody or nonimmune globulin and then subjected to 20 min of bilateral renal ischemia. Treatment of the db/db mice with the TNF-α antibody provided significant protection against the ischemic injury. These data support the view that diabetes increases the susceptibility to ischemia-induced renal dysfunction. This increased susceptibility derives from a heightened inflammatory response involving TNF-α and perhaps TLR4 signaling.

Melatonin with 1,25-Dihydroxyvitamin D3 Protects against Apoptotic Ischemia–Reperfusion Injury in the Rat Kidney

This study was designed to evaluate the preventive role of melatonin (Mel) and 1,25-dihydroxyvitamin D3 (VD3) in biochemical and apoptotic events leading to tissue injury and renal dysfunction after ischemia–reperfusion (I/R). Thirty male Wistar rats were divided into five groups: sham-operated, I/R, Mel + I/R, VD3 + I/R, and Mel + VD3 + I/R. The rats were intraperitoneally administered with Mel (10 mg/kg), VD3 (0.5 μg/kg), or Mel (10 mg/kg) plus VD3 (0.5 μg/kg) each day at 1 week prior to ischemia. Right nephrectomy was initially performed and left renal I/R injury was induced by 45 min of bilateral renal ischemia followed by 45 min of reperfusion. After reperfusion, kidneys and blood were obtained for histopathologic and biochemical evaluation. Mel and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, and apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP–biotin nick end labeling staining) in the kidneys against renal I/R injury in rats. Additionally, VD3 combined with Mel significantly reduced apoptotic and histological alterations when compared with Mel or VD3 alone. This preventive effect on renal tubular apoptosis was remarkable when Mel was combined with VD3.

Previous ischemia and reperfusion injury results in resistance of the kidney against subsequent ischemia and reperfusion insult in mice; a role for the Akt signal pathway

Kidneys previously exposed to ischemia and reperfusion (I/R), pre-conditioned by I/R, are less susceptible to subsequent I/R injury. Here, we investigated the role for protein kinase B (Akt) survival signaling pathways including anti-apoptosis pathways in the reduced susceptibility of I/R-pre-conditioned kidneys. Mice were exposed to either a single I/R pre-conditioning event (SIRPC, 30 min of bilateral renal ischemia followed by 8 days of reperfusion) or sham-operation (non-SIRPC) and then subjected to either 30 min of bilateral renal ischemia or sham-operation (sham). Some of the mice received intra-peritoneal administrations of wortmannin, which is an inhibitor of phosphatidylinositol-3 kinase, PI3K. Thirty minutes of bilateral renal ischemia in non-SIRPC mice induced a dramatic increase in plasma creatinine (PCr) levels, but this was not observed in the SIRPC mouse. Consistent with the PCr results, tubular damage and apoptotic tubular cell death were more severe in the non-SIRPC mouse kidney than in the SIRPC mice. SIRPC increased the levels of phosphorylated-Akt and -Bad expression as well as the ratio of Bcl-2 to Bax expression in the kidney. I/R resulted in greater increases of phosphorylated-Akt and -Bad, Bcl-xL and Bcl-2, but a lower level of increase of Bax, in the SIRPC mouse kidneys than those in the non-SIRPC-mouse kidneys. Treatment with wortmannin during the SIRPC period inhibited SIRPC-induced increase in phosphorylated-Akt and -Bad expressions and eliminated tolerance of SIRPC mice kidneys to I/R insult. Ischemic pre-conditioning confers renal resistance to I/R-induced apoptosis via activation of the Akt signal pathway.

Cell therapy: intravenous renal cell transplantation for acute and chronic renal failure

Acute kidney injury (AKI), chronic kidney disease (CKD) and end‐stage renal disease (ESRD) are major health problems that lack good solutions. We tested the hypothesis that kidney cells from one donor male rat given iv, could regenerate female rat kidneys with AKI or CKD. Isolated rat renal tubules were transfected with empty vector (A) or with SAA cDNA encoding tubulogenic serum amyloid A1 protein (B) and grown. Kidney cells were infused to rats with severe AKI from 50 min of bilateral renal ischemia or CKD from 3 cisplatin injections. Serum creatinine was 3.9 ± 0.7 in A rats and 1.0 ± in B rats after 48 hr. post‐ischemia (mg/dl, mean ± SE, p ≤ 0.05), and renal inflammation and fibrosis were significantly improved. Donor cell engraftment was documented up to 30 days in recipient kidneys. CKD was induced by cisplatin (1.5 mg/Kg), and 3 weeks later rats were infused with either A cells (7 rats) or B cells (7 rats). Twelve days later blood urea nitrogen (BUN) was 101 ± 4 in A rats and 38 ± 18 in B rats (mg/dl, p ≤ 0.05). Renal fibrosis and tubular atrophy was improved in B rats. We also removed one kidney of 6 rats with cisplatin CKD, and auto‐transplanted these cells iv with correction of BUN after 12 days: 53 ± 5 (n = 6 p ≤0.05). We conclude that renal cell transplantation with kidney primary cells restores function and structure in AKI and CKD.

Beneficial Effects of N-Acetylcysteine and Ebselen on Renal Ischemia/Reperfusion Injury

Introduction: It has been demonstrated that peroxynitrite accompanies acute renal ischemia and contributes to the pathophysiology of renal damage. Therefore, we aimed to investigate the roles of N-acetylcysteine (NAC), a well-known powerful antioxidant, and ebselen (E), a scavenger of peroxynitrite, on renal injury induced by renal ischemia/reperfusion injury (IRI) of rat kidney. Materials and methods: Forty male Sprague–Dawley rats were divided into five groups: sham, renal IRI, renal IRI+NAC, renal IRI+E, and renal IRI+NAC+E. IR injury was induced by 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood samples were obtained for histopathological and biochemical evaluations. Results: Renal IR resulted in increased malondialdehyde and nitrite/nitrate levels suggesting increased lipid peroxidation and peroxynitrite production and decreased superoxide dismutase and glutathione peroxidase activities. Both NAC and E alone significantly decreased malondialdehyde and nitrite/nitrate levels and increased superoxide dismutase and glutathione peroxidase activities. Additionally in the renal IRI+NAC+E group, all biochemical results were quite close to those of sham group. Histopathologically, the kidney injury in rats treated with combination of NAC and E was found significantly less than the other groups. Conclusions: Both NAC and E are able to ameliorate IRI of the kidney by decreasing oxidative and nitrosative stresses and increasing free radical scavenger properties. Additionally, combination of NAC and E prevents kidney damage more than when each drug is used alone, suggesting that scavenging peroxynitrite nearby antioxidant activity is important in preventing renal IRI.

Ameliorative effects of proanthocyanidin on renal ischemia/reperfusion injury

NTRODUCTION Several natural products have been reported to have beneficial effects on ischemia/reperfusion (I/R) injury, particularly from a preventative perspective. Therefore, this study was designed to investigate the efficiency of proanthocyanidin (PA), a natural product derived from grape seed, on renal dysfunction and injury induced by I/R of rat kidney. MATERIALS AND METHODS Twenty-four male Sprague-Dawley rats were divided into three groups: sham-operated, I/R, I/R+PA. Rats were given PA (100 mg/kg/day peroral) 7 days prior to I/R. All rats except sham-operated underwent 60 min of bilateral renal ischemia followed by 6 h of reperfusion. After reperfusion, kidneys and blood were obtained for evaluation. Superoxide dismutase, glutathione peroxidase, malondialdehyde, protein carbonyl content, and nitrite/nitrate level (NO(x)) were determined in the renal tissue. Serum creatinine (S(Cr)), blood urea nitrogen (BUN), and aspartate aminotransferase (AST) were determined in the blood. Additionally, renal sections were used for histological grade of renal injury. RESULTS PA significantly reduced the I/R-induced increases in S(Cr), BUN, and AST. In addition, PA markedly reduced elevated oxidative stress product, restored decreased antioxidant enzymes, and attenuated histological alterations. Moreover, PA attenuated the tissue NO(x), levels indicating reduced NO production. CONCLUSIONS The pretreatment of rats with PA reduced the renal dysfunction and morphological changes, ameliorated cellular injury, and restored renal antioxidant enzymes caused by renal I/R.