Clinical and Experimental Evidence for Prevention of Acute Renal Failure Induced by Radiographic Contrast Media

Anti-Apoptotic and Antioxidant Effects of 3-Epi-Iso-Seco-Tanapartholide Isolated from Artemisia Argyi Against Iodixanol-Induced Kidney Epithelial Cell Death

Iodixanol is a non-ionic iso-osmolar contrast agent, but it is a risk factor for kidney damage and increases morbidity and mortality. In this study, we investigated the effect of 9 sesquiterpenes isolated from mugwort (Artemisia argyi) in contrast agent-induced cytotoxicity in LLC-PK1 cells. Cells were exposed to nine sesquiterpene compounds for 2 h, followed by incubation with iodixanol for 3 h. Cell viability was assessed using the Ez-Cytox assay. The level of reactive oxygen species was measured using 2′,7′-dichlorodihydrofluorescein diacetate staining. Apoptotic cell death was detected using annexin V/PI staining. In addition, immunofluorescence staining and western blotting were performed using antibodies against proteins related to apoptosis, oxidative stress, and MAPK pathways. The most effective 3-epi-iso-seco-tanapartholide (compound 8) among the 9 sesquiterpene compounds protected LLC-PK1 cells from iodixanol-induced cytotoxicity, oxidative stress, and apoptotic cell death. Pretreatment with compound 8 reversed iodixanol-induced increases in the expression of JNK, ERK, p38, Bax, caspase-3, and caspase-9. It also reversed the iodixanol-induced decrease in Bcl-2 expression. Furthermore, pretreatment with compound 8 caused nuclear translocation of Nrf2 and upregulated HO-1 via the Nrf2 pathway in iodixanol-treated LLC-PK1 cells. Thus, we demonstrated here that compound 8 isolated from A. argyi has the potential to effectively prevent iodixanol-induced kidney epithelial cell death via the caspase-3/MAPK pathways and HO-1 via the Nrf2 pathway.

Strategies to Reduce Acute Kidney Injury and Improve Clinical Outcomes Following Percutaneous Coronary Intervention: A Subgroup Analysis of the PRESERVE Trial

OBJECTIVES

The aim of this study was to compare intravenous (IV) sodium bicarbonate with IV sodium chloride and oral acetylcysteine with placebo for the prevention of contrast-associated acute kidney injury (CAAKI) and intermediate-term adverse outcomes.

BACKGROUND

Data are conflicting on the optimal strategy to reduce CAAKI and related complications after percutaneous coronary intervention (PCI).

METHODS

The PRESERVE (Prevention of Serious Adverse Events Following Angiography) trial used a 2 × 2 factorial design to randomize 5,177 patients with stage III or IV chronic kidney disease undergoing angiography to IV 1.26% sodium bicarbonate or IV 0.9% sodium chloride and 5 days of oral acetylcysteine or placebo. A subgroup analysis was conducted of the efficacy of these interventions in patients who underwent PCI during the study angiographic examination. The primary endpoint was a composite of death, need for dialysis, or persistent kidney impairment at 90 days; CAAKI was a secondary endpoint.

RESULTS

A total of 1,161 PRESERVE patients (mean age 69 ± 8 years) underwent PCI. The median estimated glomerular filtration rate was 50.7 ml/min/1.73 m² (interquartile range: 41.7 to 60.1 ml/min/1.73 m²), and 952 patients (82%) had diabetes mellitus. The primary endpoint occurred in 15 of 568 patients (2.6%) in the IV sodium bicarbonate group and 24 of 593 patients (4.0%) in the IV sodium chloride group (odds ratio: 0.64; 95% confidence interval: 0.33 to 1.24; p for interaction = 0.41) and in 23 of 598 patients (3.8%) in the acetylcysteine group and 16 of 563 patients (2.8%) in the placebo group (odds ratio: 1.37; 95% confidence interval: 0.71 to 2.62; p for interaction = 0.29). There were no significant between-group differences in the rates of CAAKI.

CONCLUSIONS

Among patients with CKD undergoing PCI, there was no benefit of IV sodium bicarbonate over IV sodium chloride or of acetylcysteine over placebo for the prevention of CAAKI or intermediate-term adverse outcomes.

Effects of Sustained-Release Beraprost in Patients With Primary Glomerular Disease or Nephrosclerosis: CASSIOPEIR Study Results

TRK-100STP, a sustained-release preparation of the orally active prostacyclin analogue beraprost sodium, targets renal hypoxia. This study aimed to show the superiority of TRK-100STP over placebos in patients with chronic kidney disease (with either primary glomerular disease or nephrosclerosis) to determine the recommended dose. CASSIOPEIR (Chronic Renal Failure Asian Study with Oral PGI₂ Derivative for Evaluating Improvement of Renal Function) was a randomized, double-blind, placebo-controlled study conducted at 160 sites in seven Asia-Pacific countries and regions. Eligible patients (n = 892) were randomized to TRK-100STP 120, 240 μg, or placebo for a treatment period of up to 4 years. The primary efficacy endpoint was time to first occurrence of a renal composite: doubling of serum creatinine or occurrence of end-stage renal disease. No significant differences were observed in composite endpoints between TRK-100STP and placebo (P = 0.5674). Hazard ratios (95% CI) in the TRK-100STP 120 and 240 μg vs. placebo groups were 0.98 (0.78, 1.22) and 0.91 (0.72, 1.14), respectively. The overall incidence of adverse events and adverse drug reactions was comparable between treatment arms.

Contrast media (meglumine diatrizoate) aggravates renal inflammation, oxidative DNA damage and apoptosis in diabetic rats which is restored by sulforaphane through Nrf2/HO-1 reactivation

Diabetes mellitus is an independent risk factor for renal impairment in patients exposed to contrast media. It doubles the risk and decreases survival rate of contrast induced nephropathy (CIN). Sulforaphane has antioxidant properties via Nrf2 activation. The interaction of diabetes and/or sulforaphane with contrast media on Nrf2 regulation is not yet understood. Herein, diabetes was induced by a single intra-peritoneal injection of streptozotocin. Animals were then divided into five groups; control non-diabetic group; diabetic group; diabetic/sulforaphane group; diabetic/CIN group; diabetic/CIN/sulforaphane group. Animals were assessed 24 h after CIN induction. Sulforaphane improved the impaired nephrotoxicity parameters, histopathological features, and oxidative stress markers induced by contrast media (meglumine diatrizoate) in diabetic rats. Immunofluorescence detection revealed increased Nrf2 expression in kidney sections after sulforaphane pretreatment. Moreover, gene expression of Nrf2 and HO-1 were up-regulated, while IL-6 and caspase3 were down-regulated in kidney tissues of animals pretreated with sulforaphane. In NRK-52E cells, sulforaphane pretreatment significantly ameliorated the cytotoxicity of meglumine diatrizoate. However, silencing Nrf2 using small interfering RNA (siRNA) abolished the cytoprotective effects of sulforaphane. Collectively, the results of this study suggest that Nrf2/HO-1 pathway has a protective role against CIN and support the clinical implication of Nrf2 activators, such as sulforaphane, in CIN particularly in diabetic patients.

High Plasma Exposure of Statins Associated With Increased Risk of Contrast-Induced Acute Kidney Injury in Chinese Patients With Coronary Artery Disease

The role of statins in reducing the incidence of contrast-induced acute kidney injury (CI-AKI) remains controversial. We sought to evaluate the association between CI-AKI and high plasma exposure of statins in coronary artery disease (CAD) patients undergoing coronary angiography (CAG). This association was first evaluated in 1,219 patients with CAD receiving atorvastatin (AT) therapy and validated in 635 patients receiving rosuvastatin (RST) therapy. The plasma concentrations of statins were quantified using validated UPLC-MS/MS methods and CI-AKI incidence was assessed during the first 48 h postoperatively. Among all participants (n = 1,854), AKI occurred in 57 of 1219 (4.7%) in the AT cohort and 30 of 635 (4.7%) in the RST cohort. High plasma AT-all exposure was associated with increased risk of CI-AKI (odds ratio [OR]: 2.265; 95% confidence interval [CI]: 1.609–3.187; p < 0.0001). Plasma AT-all concentration in the CI-AKI group (22.40 ± 24.63 ng/mL) was 2.6-fold higher than that in the control group (8.60 ± 9.65 ng/mL). High plasma RST exposure also significantly increased the risk of CI-AKI (OR: 2.281; 95% CI: 1.441–3.612; p = 0.0004). We further divided patients into two subgroups for each statin according to baseline renal function, and association between high plasma statin exposure and CI-AKI still remained highly significant in both subgroups. This study suggests for the first time that high plasma exposure of statins may significantly increase the risk of CI-AKI. Statins should be used with greater caution in CAD patients undergoing CAG to reduce the occurrence of CI-AKI.

Atorvastatin attenuates experimental contrast-induced acute kidney injury: a role for TLR4/MyD88 signaling pathway

Objectives: To investigate the protective effect of different atorvastatin doses on contrast-induced acute kidney injury and the related mechanism.

Methods: Healthy male Sprague–Dawley (SD) rats were randomly divided into the blank control group, experimental control group and different-dose atorvastatin groups. A rat model of contrast-induced acute kidney injury was established. We detected changes in serum creatinine (Scr) and blood urea nitrogen (BUN) before and after model establishment, observed and scored renal tubular injury, analyzed rat renal cell apoptosis, and measure the expression of signal pathway proteins and downstream inflammatory factors.

Results: After contrast agent injection, the Scr and BUN levels of the experimental control group were significantly increased, the different doses applied in the atorvastatin group significantly reduced the Scr and BUN levels (p < .05) and ameliorated the contrast-induced acute kidney injury (p < .05) and significantly reduced Toll-like receptor 4 (TLR4), Myeloid differentiation factor 88 (Myd88), and Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) protein expression and relative mRNA expression levels (p < .05) and significantly decreased expression levels of downstream inflammatory factors (p < .05).

Conclusion: Different atorvastatin doses have protective effects on contrast-induced acute renal tubular injury in rats, possibly by targeting TLR4, suppressing TLR4 expression, regulating the TLR4/Myd88 signaling pathway, and inhibiting the expression of downstream inflammatory factors.

Atorvastatin attenuates contrast-induced nephropathy by modulating inflammatory responses through the regulation of JNK/p38/Hsp27 expression

This study aimed to investigate whether atorvastatin reduce the contrast-induced nephropathy inflammatory response and apoptosis of renal tubular epithelial cells and the relationship with MAPK signaling pathway. We utilized the iopamidol-induced contrast-induced nephropathy (CIN) rat model which was induced by a single dose of iopamidol (2.9 g iodine/kg) and a cell model in which human embryonic proximal tubular (HK2) cells were treated with iopamidol. The rats were divided into five groups: (1) control rats (CR); (2) atorvastatin (CA); (3) iopamidol (CM); (4) iopamidol and atorvastatin (20 mg/kg d) (CMA2); (5) iopamidol and atorvastatin (40 mg/kg d) (CMA4). On days 1, 2 and 6 after iopamidol injection, the urea nitrogen and cystatin C increased in CM compared with CR but decreased in CMA compared with CM. Inflammatory parameters and the percentage of apoptotic cells were increased in CM compared with CR and CA, but they were decreased in CMA compared with CM. We also found that atorvastatin ameliorated the renal tubular necrosis, apoptosis, and the deterioration of renal function in a dose dependent manner (P < 0.05). Furthermore, in vivo, both of SP600125 (JNK inhibitor) and SB203580 (p38 inhibitor) could decrease the expression of Bax and caspase-3, but increase Bcl-2 levels in HK2 cells treated with iopamidol. Our study demonstrates that high-dosage atorvastatin treatment attenuates both the inflammatory processes and apoptosis in contrast-induced acute kidney injury, and that the JNK/p38 MAPK pathway participates in the contrast-induced apoptosis of renal tubular cells. Finally, atorvastatin reduces CIN by suppression of apoptosis, which may be through inhibition of JNK/p38 MAPK pathways.

Resin from Virola oleifera Protects Against Radiocontrast-Induced Nephropathy in Mice

Contrast-induced nephropathy (CIN) is an iatrogenic medical event for which there is not yet a successful therapy. Increasing evidence in rodents has suggested that this disease is associated with renal tubular and vascular injury that is triggered directly by oxidative stress. In the present study, we evaluated whether the antioxidant resin from Virola oleifera (RV) could attenuate renal damage in an experimental mouse model of CIN. Adult male Swiss mice were divided into six groups and pre-treated orally with RV (10, 100 and 300 mg/kg), N-acetylcysteine (200 mg/kg) or vehicle for 5 days before the induction of CIN and Control group. Renal function was assessed by measuring plasma creatinine and urea levels. Additionally, renal oxidative stress and apoptosis/cell viability were determined with flow cytometry. Finally, kidney tissues were sectioned for histopathological examination. In this CIN model, pre-treatment with RV improved renal function, lowered the mortality rate, and reduced oxidative stress and apoptosis in both the medulla and cortex renal cells in a dose-dependent manner. Moreover, the RV treatment had beneficial effects on kidney histopathology that were superior to the standard treatment with N-acetylcysteine. These data suggest that because of its antioxidative and antiapoptotic effects and its ability to preserve renal function, resin from Virola oleifera may have potential as a new therapeutic approach for preventing CIN.

Peroxisome Proliferator-Activated Receptor α Protects Renal Tubular Cells from Gentamicin-Induced Apoptosis via Upregulating Na+/H+ Exchanger NHE1

Peroxisome proliferator-activated receptor (PPAR)-α is a transcription factor that has been reported to inhibit gentamicin-induced apoptosis in renal tubular cells. However, the antiapoptotic mechanism of PPARα is still unknown. In this study, we found that PPARα overexpression induced Na⁺/H⁺ exchanger-1 (NHE1) expression in the rat renal tubular cells NRK-52E. Beraprost, a PPARα ligand, also increased NHE1 expression in the renal tubules in normal mice, but not in PPARα knockout mice. Chromatin immunoprecipitation assays revealed that two PPARα binding elements were located in the rat NHE1 promoter region. Na⁺/H⁺ exchanger activity also increased in the PPARα-overexpressed cells. Flow cytometry showed that the PPARα-overexpressed cells were resistant to apoptosis-induced shrinkage. Cariporide, a selective NHE1 inhibitor, inhibited the antiapoptotic effect of PPARα in the gentamicin-treated cells. The interaction between NHE1 and ezrin/radixin/moesin (ERM) and between ERM and phosphatidylinositol 4,5-bisphosphate in the PPARα-overexpressed cells was more than in the control cells. ERM short interfering RNA (siRNA) transfection inhibited the PPARα-induced antiapoptotic effect. PPARα overexpression also increased the phosphoinositide 3-kinase (PI3K) expression, which is dependent on NHE1 activity. Increased PI3K further increased the phosphorylation of the prosurvival kinase Akt in the PPARα-overexpressed cells. Wortmannin, a PI3K inhibitor, inhibited PPARα-induced Akt activity and the antiapoptotic effect. We conclude that PPARα induces NHE1 expression and then recruits ERM to promote PI3K/Akt-mediated cell survival in renal tubular cells. The application of PPARα activation reduces the nephrotoxicity of gentamicin and may expand the clinical use of gentamicin.

Orally active prostacyclin analogue beraprost sodium in patients with chronic kidney disease: a randomized, double-blind, placebo-controlled, phase II dose finding trial

BACKGROUND

Evidence increasingly points to the importance of chronic hypoxia in the tubulointerstitium as a final common pathway to end-stage renal disease (ESRD). Beraprost sodium (BPS) is an orally active prostacyclin (PGI2) analogue demonstrating prevention of the progression of chronic kidney disease (CKD) in various animal models by maintaining renal blood flow and attenuating renal ischemic condition.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, phase II trial was designed to determine the recommended dose of the sustained-release form of BPS (TRK-100STP 120 μg/day or 240 μg/day) in Japanese patients with CKD. TRK-100STP was administered to a total of 112 patients. The primary efficacy endpoint was the difference in the slope of the regression line of reciprocal of serum creatinine (1/SCr) over time, obtained by the least-squares method.

RESULTS

Regarding the primary endpoint, statistical superiority of TRK-100STP 240 μg over placebo was not confirmed and so a recommended dose was not determined. Compared to placebo, however, the slope of regression line of 1/SCr, elevation of SCr and serum cystatin C during the treatment period revealed greater improvement at 120 μg, at both doses, and at 240 μg, respectively. In terms of safety, both TRK-100STP treatment groups were well tolerated.

CONCLUSIONS

Although the study failed to meet the primary endpoint, results indicate that TRK-100STP may potentially prevent the decline in renal function of CKD patients independent of blood pressure or urinary protein levels.

TRIAL REGISTRATION

NCT02480751. June 21, 2015.

Contrast Induced Nephropathy and Long-term Renal Decline After Percutaneous Transluminal Angioplasty for Symptomatic Peripheral Arterial Disease

OBJECTIVE/BACKGROUND

Administration of iodinated contrast media during endovascular procedures for peripheral arterial disease (PAD) may cause contrast induced nephropathy (CIN). The aim of the present study was to establish the incidence of CIN after these procedures and to study its association with long-term loss of kidney function, cardiovascular events, and death.

METHODS

Consecutive patients first presenting with symptomatic PAD (Rutherford classification II-VI) who were treated with an endovascular procedure were included in this prospective observational cohort study. CIN was defined as >25% increase of serum creatinine concentration from baseline at 5 days after the intervention.

RESULTS

Some 337 patients were included with a mean estimated glomerular filtration rate (eGFR) of 67 mL/minute. Thirteen percent (95% confidence interval [CI] 9-16) of these patients developed CIN after endovascular interventions for PAD. One year after treatment, eGFR was reduced by 12.4 mL/minute (95% CI 8.6-16.2) in patients with CIN compared with 6.2 mL/minute (95% CI 4.9-7.0) in patients without acute kidney injury (p < .01). After correction for potential confounders, CIN was associated with a 7.8 mL/minute (95% CI 4.5-11.0) reduction of eGFR at 1 year after endovascular intervention (p < .01). Furthermore, patients with CIN were at increased risk of long-term cardiovascular events and mortality.

CONCLUSION

Exposure to iodinated contrast media during endovascular procedures for symptomatic PAD frequently results in CIN. Patients with CIN are at increased risk of long-term loss of renal function, cardiovascular events, and death.

Predictive Value of Gamma-Glutamyl Transferase Levels for Contrast-Induced Nephropathy in Patients With ST-Segment Elevation Myocardial Infarction Who Underwent Primary Percutaneous Coronary Intervention

Contrast-induced nephropathy (CIN) after primary percutaneous coronary intervention (PPCI) is associated with adverse short- and long-term outcomes. The aim of this study was to evaluate the predictive value of gamma-glutamyl transferase (GGT) for risk of CIN in patients with ST-segment elevation myocardial infarction who underwent PPCI. A total of 473 patients were enrolled in the study. A relative increase in serum creatinine ≥25%, or an absolute increase ≥0.5 mg/dl, from the baseline within 72 hours of contrast exposure was defined as CIN. Patients were divided into 3 groups according to GGT tertiles (tertile 1, GGT <19 U/L; tertile 2, GGT 19 to 33 U/L; and tertile 3, GGT >33 U/L) on admission. Demographics, clinical risk factors, laboratory parameters, CIN incidence, and other inhospital clinical outcomes were compared among GGT tertiles. CIN incidence was significantly higher in tertile 3 (29%) compared with tertiles 1 (11%) and 2 (11%, p <0.001). Inhospital death incidence was significantly increased across tertiles (from tertile 1 to tertiles 2 and 3, 1%, 4%, and 5%, respectively, p <0.05). In receiver operating characteristic analysis, a threshold value of GGT >26.5 U/L had 70% sensitivity and 60% specificity for CIN. After including variables found significant in univariate analysis, the presence of diabetes mellitus (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.22 to 2.31, p <0.001), C-reactive protein (for each 1 mg/L increase; OR 1.01, 95% CI 1.00 to 1.02, p = 0.007), contrast volume (for each 1-ml increase; OR 1.01, 95% CI 1.00 to 1.02, p = 0.012), and GGT >26.5 U/L (OR 2.59, 95% CI 1.48 to 4.53, p <0.001) were found as independent associates of CIN in multivariate regression analysis. Each 1 U/L increase in GGT was also associated with CIN risk (OR 1.04, 95% CI 1.03 to 1.06, p <0.001). In conclusion, GGT on admission was a significant and independent predictor of CIN after PPCI in patients with ST-segment elevation myocardial infarction.

Use of cystatin C and serum creatinine for the diagnosis of contrast-induced nephropathy in patients undergoing contrast-enhanced computed tomography at an oncology centre

OBJECTIVE

Our aim was to assess renal function using as laboratory measurements serum creatinine and cystatin C concentrations before and after administration of low-osmolarity (nonionic) iodinated contrast medium in patients with cancer undergoing computed tomography (CT).

METHODS

This prospective study included 400 oncologic outpatients. Serum creatinine and cystatin C concentrations were measured before and 72 h after contrast administration. Glomerular filtration rates (GFRs) were estimated using serum creatinine-based [Modification of Diet in Renal Disease (MDRD) and Cockroft-Gault and cystatin C based (Larsson) equations. Exploratory data analysis was performed. The nonparametric Wilcoxon test was used to compare pre and post contrast of test results and estimated clearance. The confidence interval used in the analysis was 95%.

RESULTS

Compared with the pre-contrast values, the mean serum creatinine concentration was significantly higher and average GFRs estimated using MDRD and Cockcroft-Gault equations were significantly lower after the administration of contrast (p <0.001). It was also observed a significant increase after contrast in the concentration of Cystatin C (p = 0.015). In addition, a decrease in GFR estimated using the average Larsson (p = 0.021) was observed between time points. However, none of the patients presented clinically significant nephropathy.

CONCLUSIONS

Assessment using serum creatinine and cystatin C concentrations showed changes in renal function among patients with cancer undergoing contrast-enhanced CT examination in this study. No significant renal damage related to the use of low-osmolarity iodinated contrast medium of the type and dosage employed in this study was observed. This contrast medium is thus safe for use in patients with cancer.

Preventive effect of pentoxifylline on contrast-induced acute kidney injury in hypercholesterolemic rats

Oxidative stress is an important mechanism of contrast-induced acute kidney injury (CIAKI). The optimal strategy to prevent CIAKI remains unclear. The aim of the present study was to assess the effect of pentoxifylline, a nonspecific phosphodiesterase inhibitor, on the prevention of CIAKI. A total of 32 healthy male Sprague-Dawley rats were randomly divided into normal dietary group (NN; n=8) and a high cholesterol-supplemented dietary group (HN; 4% cholesterol and 1% cholic acid; n=24). At the end of eight weeks, the rats in the high cholesterol diet group were randomly divided into three subgroups (n=8 in each group). CIAKI was induced in two of the subgroups via intravenous injection of the radiocontrast media iohexol (10 ml/kg). Pentoxifylline (50 mg/kg) was administered to one of the iohexol-treated groups via intraperitoneal injection 12 h prior to and following contrast media (CM) injection. Kidney function parameters and oxidative stress markers were then measured. The renal pathological changes were evaluated using hematoxylin and eosin staining and scored semi-quantitatively. In iohexol-injected rats, serum creatinine (Scr), renal pathological scores, renal malondialdehyde (MDA) content, renal NADPH oxidase activity, fractional excretion of sodium (FENa%) and fractional excretion of potassium (FEK%) were significantly increased (P<0.01). The Scr, histologic scores, renal MDA content, NADPH oxidase activity, FENa% and FEK% in the rats treated with pentoxifylline prior to iohexol were observed to be reduced compared with those in rats treated with iohexol alone (P<0.01). This suggests that pentoxifylline significantly attenuates renal injuries, including tubular necrosis and proteinaceous casts induced by CM. It may be concluded that pentoxifylline protected the renal tissue from the nephrotoxicity induced by low-osmolar CM via an antioxidant effect.

Role of reactive oxygen species-mediated endoplasmic reticulum stress in contrast-induced renal tubular cell apoptosis

BACKGROUND

Renal tubular cell apoptosis is a key mechanism of contrast-induced acute kidney injury. It has been reported that endoplasmic reticulum (ER) stress is the underlying mechanism of high osmolar contrast-induced renal tubular cell apoptosis. Whether ER stress is involved in low osmolar contrast-induced renal tubular cell injury remains unclear. In the present study, the roles of ER stress in iopromide-induced (a low osmolar contrast) renal tubular cell apoptosis and the effects of N-acetylcysteine (NAC) on ER stress were investigated.

METHODS

NRK-52E cells were exposed to different concentrations of iopromide [50, 100 and 150 mg iodine (I)/ml] for 4 h. In a separate experiment, NRK-52E cells were exposed to iopromide (100 mg I/ml, 4 h) with or without NAC (10 mmol/l). NAC was added 1 h before incubation with iopromide. Apoptosis was determined by Hoechst staining and flow cytometry. The intracellular formation of reactive oxygen species (ROS) was detected by confocal microscopy with fluorescent probe CM-H2DCFDA. The expression of glucose-regulated protein 78 (GRP78) and CAAT/enhancer-binding protein homologous protein (CHOP) was determined by Western blot.

RESULTS

Iopromide induced NRK-52E cell apoptosis in a concentration-dependent manner. The intracellular ROS production increased significantly following iopromide exposure in the NRK-52E cells. Significantly increased expressions of GRP78 and CHOP were observed in the NRK-52E cells exposed to iopromide for 4 h; NAC attenuated iopromide-induced NRK-52E cell apoptosis by inhibiting the overproduction of intracellular ROS and subsequently suppressing the overexpression of GRP78 and CHOP.

CONCLUSION

ROS-mediated ER stress is involved in contrast-induced renal tubular cell apoptosis.

Role of intracellular Ca2+ and Na+/Ca2+ exchanger in the pathogenesis of contrast-induced acute kidney injury

The precise mechanisms underlying contrast-induced acute kidney injury (CI-AKI) are not well understood. Intracellular Ca²⁺ overload is considered to be a key factor in CI-AKI. Voltage-dependent Ca²⁺ channel (VDC) and Na⁺/Ca²⁺ exchanger (NCX) system are the main pathways of intracellular Ca²⁺ overload in pathological conditions. Here, we review the potential underlying mechanisms involved in CI-AKI and discuss the role of NCX-mediated intracellular Ca²⁺ overload in the contrast media-induced renal tubular cell injury and renal hemodynamic disorder.

Mitochondria-targeted peptides prevent on contrast-induced acute kidney injury in the rats with hypercholesterolemia

OBJECTIVE

The objective of this study is to evaluate the effect and mechanism of mitochondria-targeted peptides (MTP131 and SPI20) on contrast-induced acute kidney injury (CI-AKI) in rats with hypercholesterolemia.

METHOD

Forty SD rats were randomly divided into normal diet group (NN, n = 8) and high cholesterol supplemented dietary group (HN, n = 32). At the end of 8 weeks, the group HN was divided into four subgroups. All Rats were given injection of either diatrizoate (10 mL/kg) or equal volume of normal saline, the rats pretreated with MTP131 or SPI20 were given injection with MTP131 or SPI 20 (3 mg/kg) by peritoneal cavity for 3 times. Blood, urine and renal tissue samples were prepared to determine biochemical parameters. The renal pathological changes were evaluated by hematoxylin and eosin staining and scored semiquantitatively, The protein expression of renal NOX4 was also measured by Western blotting.

RESULTS

In diatrizoate-injected rats, Serum creatinine (Scr), fractional excretion of sodium (FeNa%), fractional excretion of potassium (FeK%), pathological scores, renal malondialdehyde (MDA) content, the NADPH oxidase activity and the expression of NOX4 in kidney tissue were significantly increased (p < 0.01). In the groups pretreated with MTP131 or SPI20, the levels of Scr, FeNa%, FeK%, MDA content and NADPH oxidase activity in renal tissue decreased (p < 0.01), the levels of renal super oxygen dehydrogenises and ATPase activity increased (p < 0.01). The renal injuries induced by contrast media (CM) were alleviated.

CONCLUSION

MTP131 and SPI20 might protect acute kidney injury induced by CM in rats with hypercholesterolemia.

Alprostadil plays a protective role in contrast-induced nephropathy in the elderly

PURPOSE

To evaluate the protective effects of alprostadil on contrast-induced nephropathy (CIN) in elderly patients.

METHODS

We randomized 370 patients into the control or alprostadil group. The patients in the control group were injected with 100 ml sterile saline and the patients in the alprostadil group with alprostadil (0.4 μg/kg/day) in 100 ml sterile saline before and after iohexol-enhanced (100 ml) computed tomography (CT). Serum creatinine (Scr), blood urea nitrogen (BUN), cystatin C (CysC), and creatinine clearance (Ccr) were analyzed or calculated. ΔScr and ΔCysC were determined by the changes between baseline and highest Scr and CysC levels. The standard for CIN was a postdose Scr increase >44.2 μmol/l or >25 % over baseline.

RESULTS

In the control group, peak Scr (P < 0.05) and ΔScr (P < 0.01) were higher than those in the alprostadil group. The postdose CysC at 24 h (P < 0.05), 48 h (P < 0.05), and 72 h (P < 0.05), peak CysC (P < 0.01), and ΔCysC (P < 0.05) in the control group were higher than those in the alprostadil group. The incidence of CIN in the control group was 22.2 %, which was higher than in the alprostadil group (9.1 %, P < 0.01). Subgroup analyses in patients with advanced age (≥ 80 years), concomitant hypertension or diabetes, and abnormal baseline renal function (Ccr ≤ 60 ml/min) showed that the alprostadil group had lower ΔScr and ΔCysC than the control group after contrast-enhanced CT examination in all four subgroups (P < 0.05 or P < 0.01).

CONCLUSIONS

In this cohort of older patients undergoing contrast CT, the use of alprostadil reduced the incidence of CIN.

The effects of N-acetylcysteine on hepatic function during isoflurane anaesthesia for laparoscopic surgery patients

Introduction:

Although most general anaesthesia procedures are performed without any complications, volatile agents may have adverse effects on various living systems. This study aims to compare the antioxidant effects of isoflurane and N-acetylcysteine (NAC) on liver function.

Methods:

Forty-one patients in the ASA I-II risk groups, who were scheduled to undergo gynaecologic laparoscopy, were randomly divided into two groups: The placebo (group P, n=21) and the NAC group (group N, n=20). In both groups, anaesthesia was maintained with 1–2% isoflurane in 50% Oxygen–50% N₂O at 6 l/min, also administered by inhalation. Venous blood samples were obtained before anaesthesia induction, and then in the postoperative 1^st hour and at the 24^th hour. The samples were centrifuged and serum levels of glutathione S-transferase (GST), malondialdehyde (MDA), aspartate amino transferase (AST), alanine amino transferase (ALT), lactate dehydrogenase (LDH), gamma glutamyltranspeptidase (GGT), prothrombin time (PT), activated partial thromboplastin time (aPTT) and international normalised ratio were determined.

Results:

GST levels were significantly higher in group N than in group P in the postoperative 1^st hour. Postoperative values of GST in the two groups were higher when compared to preoperative values (P<0.05). When postoperative levels were compared with preoperative levels, the postoperative MDA levels of group N were significantly higher (P<0.05). Levels of AST, ALT, GGT and LDH in both groups revealed significant decreases at the postoperative 1^st hour and postoperative 24^th hour compared to preoperative values (P<0.05, P<0.001). PT values were significantly higher in both groups in the postoperative 1^st hour and 24^th hour (P<0.05, P<0.001), although there were no differences in aPTT levels.

Conclusion:

Our results showed that liver functions were well preserved with administration of NAC during anaesthesia with isoflurane. Isoflurane with NAC has lesser effect on liver function tests compared to isoflurane alone.

Comparing the Renal Safety of Isoosmolar Versus Low-Osmolar Contrast Medium by Renal Biomarkers N-Acetyl-β-d-Glucosaminidase and Endothelin

Iodixanol and iopamidol are commonly used contrast agents in coronary angiography. We evaluated the nephrotoxic effects of both contrast media in relation to renal biomarkers. A total of 38 low-risk patients who underwent coronary angiography were enrolled. Patients were randomized to receive either low-osmolar nonionic monomer or isoosmolar nonionic dimer contrast medium. N-Acetyl-β-d-glucosaminidase (NAG), endothelin, blood urea nitrogen, and urine and serum creatinine (SCr) levels were measured before  the procedure (T0), at 6 hours (T6), and at 1 year after the procedure. Plasma endothelin, urine NAG/creatinine, and SCr were higher; accordingly, the urine creatinine values were lower in both the groups when comparing T0 versus T6. The groups were similar with each other when comparing T0 and T6 values. Both the contrast agents may be safely used at a low volume for coronary angiography in low-risk patients. Endothelin and NAG are sensitive to acute renal changes in function. There is a need for further prospective investigations with more patients.

Sesame oil prevents acute kidney injury induced by the synergistic action of aminoglycoside and iodinated contrast in rats

The aim of the study was to investigate the effect of sesame oil on acute kidney injury induced by the synergistic action of aminoglycoside and iodinated contrast in rats. Acute kidney injury was induced by a 5-day course of daily gentamicin injections (100 mg/kg of body weight, subcutaneously) and then iodinated contrast (4 ml/kg, intravenously) in male specific-pathogen-free Sprague-Dawley rats. Sesame oil (0.5 ml/kg, orally) was given 1 h before iodinated contrast. Renal function and oxidative stress were assessed 6 h after iodinated contrast injection. Renal function was evaluated by measuring serum blood urea nitrogen and creatinine levels. Renal oxidative stress was assessed by determining renal lipid peroxidation, myeloperoxidase, hydroxyl radical, superoxide anion, nitrite/nitrate, and inducible nitric oxide synthase levels. Sesame oil significantly prevented the rise of serum blood urea nitrogen and creatinine levels. Furthermore, there was a parallel inhibition of the rise in levels of expression of renal lipid peroxidation, myeloperoxidase, hydroxyl radicals, superoxide anion, nitrite/nitrate, and inducible nitric oxide synthase in rats with gentamicin-plus-iodinated contrast-induced acute kidney injury. We conclude that sesame oil may attenuate aminoglycoside-plus-iodinated contrast-induced acute kidney injury by inhibiting renal oxidative stress in rats.

Anesthetic concerns in patients presenting with renal failure

Anesthesiologists often care for patients with renal insufficiency or renal failure. These patients may present to the operating room for a minor procedure such as an inguinal hernia repair or an arteriovenous fistula/graft. Alternatively, they may present for major abdominal operations or coronary artery bypass grafting. Critically ill patients presenting to the operating room may have acute kidney injury. It is imperative that the anesthesiologist understands the ramifications of renal failure and adjusts the anesthetic plan accordingly. Hemodynamic monitoring and fluid management can be challenging in this patient population. Various metabolic abnormalities can ensue that the anesthesiologist must be able to manage in the acute setting of the operating room.

Reactive oxygen species promote caspase-12 expression and tubular apoptosis in diabetic nephropathy

Apoptosis of tubular epithelial cells contributes to the tubular atrophy that accompanies diabetic nephropathy. Reactive oxygen species (ROS) promote tubular apoptosis, but the mechanisms by which this occurs are incompletely understood. Here, we sought proapoptotic genes that ROS differentially upregulate in renal proximal tubular cells of diabetic (db/db) mice. We performed microarray analysis using total RNA from freshly isolated renal proximal tubules of nondiabetic, diabetic, and diabetic transgenic mice overexpressing catalase in the proximal tubule (thereby attenuating ROS). We observed greater expression of caspase-12 in the proximal tubules of the diabetic mice compared with the nondiabetic and diabetic transgenic mice. Quantitative PCR and immunohistochemistry confirmed the enhanced expression of caspase-12, as well as members of the endoplasmic reticulum stress-induced apoptotic pathway. Ex vivo, albumin induced caspase-12 activity and expression (protein and mRNA) and mRNA expression of the CCAT/enhancer-binding protein homologous protein in freshly isolated wild-type proximal tubules but not in catalase-overexpressing proximal tubules. In vitro, albumin stimulated activity of both caspase-12 and caspase-3 as well as expression of caspase-12 and CCAT/enhancer-binding protein homologous protein in a human proximal tubule cell line (HK-2). The free radical scavenger tiron inhibited these effects. Furthermore, knockdown of caspase-12 with small interfering RNA reduced albumin-induced apoptosis in HK-2 cells. Taken together, these studies demonstrate that albuminuria may induce tubular apoptosis through generation of ROS and the subsequent expression and activation of endoplasmic reticulum stress genes in the diabetic kidney.

The role of endoplasmic reticulum stress-related unfolded protein response in the radiocontrast medium-induced renal tubular cell injury

Contrast medium (CM) induces a direct toxic effect on renal tubular cells. This toxic effect may have a role in the pathophysiology of CM-induced nephropathy. CM has been shown to affect the endoplasmic reticulum (ER)-related capacity. Unfolded protein response (UPR) is known as a prosurvival response to reduce the accumulation of unfolded proteins and restore normal ER function. However, the role of ER stress-related UPR in the CM-induced renal cell injury still remains unclear. In this study, we examined whether UPR participates in urografin (an ionic CM)-induced renal tubular cells apoptosis. Treatment with urografin in normal rat renal tubular cell line (NRK52E) markedly increased cell apoptosis and decreased cell viability with a dose- and time-dependent manner. The cell necrosis was not increased in urografin-treated cells. Urografin also enhance the induction of ER stress-related markers in NRK52E cells, including glucose-regulated protein (GRP)78 and GRP94 expressions, procaspase-12 cleavage, phosphorylation of PERK (PKR [double-stranded RNA-activated protein kinase]-like ER kinase), and eukaryotic initiation factor 2alpha (eIF2alpha). Salubrinal, a selective inhibitor of eIF2alpha dephosphorylation, effectively decreased urografin-induced cell apoptosis. Furthermore, transfection of GRP78-small interfering RNA in NRK52E cells significantly enhanced urografin-induced cell apoptosis. These results suggest that GRP78/eIF2alpha-related signals play a protective role during UPR, and the activation of ER stress-related UPR may play an important regulative role in urografin-induced renal tubular injury.

Iloprost prevents contrast-induced nephropathy in patients with renal dysfunction undergoing coronary angiography or intervention

BACKGROUND

The prevention of contrast-induced nephropathy, which accounts for considerable morbidity and mortality, remains a vexing problem. Contrast-induced renal vasoconstriction is believed to play a pivotal role in the pathogenesis of contrast-induced nephropathy. The aim of this study was to examine the efficacy of the prostacyclin analog iloprost in preventing contrast-induced nephropathy in patients with renal dysfunction undergoing a coronary procedure.

METHODS AND RESULTS

We conducted a randomized, double-blind, placebo-controlled trial of iloprost in 208 patients with a serum creatinine concentration >or=1.4 mg/dL who underwent coronary angiography and/or intervention. Iloprost 1 ng kg(-1) min(-1) or placebo was administered intravenously beginning 30 to 90 minutes before and ending 4 hours after the procedure. Contrast-induced nephropathy was defined by an absolute increase in serum creatinine >or=0.5 mg/dL or a relative increase >or=25% measured 2 to 5 days after the procedure. Contrast-induced nephropathy occurred in 23 of the 105 patients (22%) in the control group and in 8 of the 103 patients (8%) in the iloprost group (odds ratio, 0.29; 95% confidence interval, 0.12 to 0.69; P=0.005). In the control group, the estimated glomerular filtration rate declined from 49.7+/-15.5 to 46.6+/-16.6 mL min(-1) 1.73 m(-2) (P=0.01). In the iloprost group, the estimated glomerular filtration rate increased marginally from 47.5+/-14.5 to 48.6+/-16.1 mL min(-1) 1.73 m(-2) (P=0.26). The mean absolute estimated glomerular filtration rate decline in the control group was greater than its change in the iloprost group (difference, 4.2 mL min(-1) 1.73 m(-2); 95% confidence interval, 1.1 to 7.3; P=0.008).

CONCLUSIONS

Prophylactic administration of iloprost may protect against contrast-induced nephropathy in high-risk patients undergoing a coronary procedure.

Risk Factors and Therapy Strategies for Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is associated with increased morbidity and mortality, as well as increased costs for medical care, particularly in patients with diabetes mellitus and chronic renal failure. A key step to safer CIN is to identify patients at risk and applying proven preventive interventions. Extracellular volume expansion, minimizing the dose of contrast media, using low-osmolar non-ionic contrast media, stopping the intake of nephrotoxic drugs, and avoiding short intervals between procedures have all been shown to be effective in reducing CIN. The aim of the present review is to summarize the knowledge about the risk factors and prophylactic treatments of CIN.

A comparison of sodium bicarbonate infusion versus normal saline infusion and its combination with oral acetazolamide for prevention of contrast-induced nephropathy: a randomized, double-blind trial

BACKGROUND

Contrast-induced nephropathy (CIN) is commonly encountered. Because the therapy of choice for prevention of CIN is controversial, in this study we compared the preventive efficacy of bicarbonate (Bi) infusion in dextrose water versus normal saline (NLS) infusion alone or in combination with oral acetazolamide (AZ).

METHODS

In a double-blind and randomized clinical trial, all patients undergoing coronary angiography or percutaneous coronary intervention received NLS (NLS group), its combination with AZ (AZ group) or infusion of Bi (Bi group) before the procedures. RIFLE (risk of renal failure, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage renal disease) criteria were used to define CIN-associated acute kidney injury (AKI).

RESULTS

The risk of AKI in CIN was significantly lower in the Bi and AZ groups than in the NLS group (P <or= 0.04). Comparing pre-treatment and post-treatment values in each group the following results were obtained: serum creatinine (Scr) increased and eGFR decreased significantly in the NLS group (P = 0.04) and in all patients (P = 0.001, P = 0.02, respectively). In addition, serum potassium decreased significantly in the Bi and NLS groups (P <or= 0.02). Also, serum Bi increased significantly in the Bi group (P = 0.001) whereas it decreased significantly in the AZ group (P = 0.001). Urinary pH also increased in all groups (P <or= 0.04) except the NLS group (P > 0.05).

CONCLUSIONS

It seems that both Bi and AZ reduce the risk of CIN-related AKI, and close monitoring of serum potassium is needed during bicarbonate infusion.

Predictors for contrast media-induced nephropathy and long-term survival: prospectively assessed data from the randomized controlled Dialysis-Versus-Diuresis (DVD) trial

BACKGROUND

Among the numerous studies concerning contrast media-induced nephropathy (CIN), there was no prospective trial that provided data on the long-term outcomes.

OBJECTIVES

To prospectively assess predictors of CIN and long-term outcomes of affected patients.

METHODS

Four hundred twelve consecutive patients with serum creatinine levels of 115 micromol/L to 309 micromol/L (1.3 mg/dL to 3.5 mg/dL) undergoing elective coronary angiography were included. Patients were randomly assigned to periprocedural hydration alone, hydration plus one-time hemodialysis or hydration plus N-acetylcysteine.

RESULTS

Multivariate logistic regression identified the following as predictors of CIN within 72 h (equivalent to an increase in creatinine 44.2 micromol/L [0.5 mg/dL] or more) : prophylactic postprocedural hemodialysis (OR 2.86, 95% CI 1.07 to 7.69), use of angiotensin-converting enzyme inhibitors (OR 6.16, 95% CI 2.01 to 18.93), baseline glomerular filtration rate (OR 0.94, 95% CI 0.90 to 0.98) and the amount of contrast media given (OR 1.01, 95% CI 1.00 to 1.01). With regard to long-term outcome (mean follow-up 649 days), multivariate Cox regression models found elevated creatinine levels at 30 days (hazard rate ratio [HRR] 5.48, 95% CI 2.85 to 10.53), but not CIN within 72 h (HRR 1.12, 95% CI 0.63 to 2.02), to be associated with increased mortality. In addition, independent predictors for death during follow-up included left ventricular ejection fraction lower than 35% (HRR 4.01, 95% CI 2.22 to 7.26), serum phosphate (HRR 1.64, 95% CI 1.10 to 2.43) and hemoglobin (HRR 0.80, 95% CI 0.67 to 0.96).

CONCLUSION

From the present prospective trial, performance of postprocedural hemodialysis, use of angiotensin-converting enzyme inhibitors, reduced baseline glomerular filtration rate and amount of contrast media were independent predictors of CIN within 72 h after catheterization. Assessing renal function after 30 days, rather than within 72 h, seemed to be more predictive for patients' long-term survival.

Renal cell apoptosis induced by nephrotoxic drugs: cellular and molecular mechanisms and potential approaches to modulation

Apoptosis plays a central role not only in the physiological processes of kidney growth and remodeling, but also in various human renal diseases and drug-induced nephrotoxicity. We present in a synthetic fashion the main molecular and cellular pathways leading to drug-induced apoptosis in kidney and the mechanisms regulating it. We illustrate them using three main nephrotoxic drugs (cisplatin, gentamicin, and cyclosporine A). We discuss the main regulators and effectors that have emerged as key targets for the design of therapeutic strategies. Novel approaches using gene therapy, antisense strategies, recombinant proteins, or compounds obtained from both classical organic and combinatorial chemistry are examined. Finally, key issues that need to be addressed for the success of apoptosis-based therapies are underlined.

Modulatory effects of N-acetylcysteine on hyperoxaluric manifestations in rat kidney

Hyperoxaluria is a condition where excessive oxalate is present in the urine. Many reports have documented free radical generation followed by hyperoxaluria as a consequence of which calcium oxalate deposition occurs in the kidney tissue. The present invivo study was designed to investigate the potential of N-acetylcysteine in modulating hyperoxaluric manifestation induced by sodium oxalate in the rat kidneys. Male wistar rats in one group were administered single dose of sodium oxalate (70mg/kg body weight) intraperitoneally to induce hyperoxaluric conditions and in the other group, rats were injected N-acetylcysteine (NAC) (200mg/kg body weight) intraperitoneally, half an hour after sodium oxalate dose. The treatment is for a period of 24h. N-acetylcysteine significantly reduced hyperoxaluria caused oxidative stress by reducing lipid peroxidation, restoring antioxidant enzymes activity in kidney tissue, followed by reduction in impairment of renal functioning. In addition, NAC administration reduced the number of calcium oxalate monohydrate (COM) crystals in the urine as observed under polarization microscope. Histological analysis depicted that NAC treatment decreased renal epithelial damage, inflammation and restored normal glomeruli morphology. Thus, it shows that use of an extraneous antioxidant may prove beneficial for combating the conditions of oxidative stress produced by hyperoxaluria.

Improved visualization of vessels and hepatic tumors by micro-computed tomography (CT) using iodinated liposomes

OBJECTIVE

The goal of this study was to determine whether iodinated liposomes are a suitable tracer for mice microvessel and liver imaging by preclinical computed tomography (CT).

MATERIALS AND METHODS

Iodinated liposomes were evaluated for vessel and liver imaging. A first group of nude mice was imaged by micro-CT after i.v. injection of liposomes at 1 or 2 gI/kg body weight (b.w.) for intervals up to 24 hours. A second group of mice bearing liver micrometastases was imaged after injection of liposomes at 2 gI/kg b.w. for intervals up to 24 hours.

RESULTS

Vascular enhancements of 120 +/- 8 and 322 +/- 20 Hounsfield unit (HU) were obtained after injection of liposomes at 1 or 2 gI/kg b.w., respectively. This enhancement decreased with a blood half-life of 135 +/- 10 and 86 +/- 9 minutes, respectively. Liver enhancement of 157 +/- 5 and 235 +/- 23 HU were obtained after injection of iodinated liposomes at 1 and 2 gI/kg b.w., respectively. Liver micrometastases (250 microm) were detectable after injection of iodinated liposomes at 2 gI/kg b.w.

CONCLUSIONS

Iodinated liposomes are a suitable contrast agent for vessels and liver imaging by micro-CT allowing clear vascular enhancement and detection of small liver metastases.

Protective effect of erythropoietin against radiocontrast-induced renal tubular epithelial cell injury

BACKGROUND/AIMS

Recombinant human erythropoietin (rhEpo) has been shown to reduce tissue injury following ischemia-reperfusion. We examined whether rhEpo protects in vitro renal tubular epithelial cells against radiocontrast media-induced injury.

METHODS

LLC-PK1 renal tubular epithelial cells were exposed to non-ionic radiocontrast agent iohexol (low-osmolar) or iodixanol (iso-osmolar), with or without rhEpo (200 U/ml). Following a 6-hour exposure, cells were incubated for 24 h in radiocontrast-free culture medium. Cell viability was then assessed by the MTT assay. We also assessed cell apoptosis by the TUNEL assay, and activities of caspase-3, caspase-8, and caspase-9 were determined by a luminescence assay.

RESULTS

rhEpo improved viability of iohexol-treated LLC-PK1 cells by 27 +/- 6% (88.1 +/- 1.5 vs. 70.8 +/- 3.3%, p = 0.008). Similarly, rhEpo improved the viability of iodixanol-treated LLC-PK1 cells by 26 +/- 4% (82.5 +/- 2.1vs. 65.7 +/- 1.7%, p = 0.028). rhEpo also decreased apoptosis rates of iohexol-treated LLC-PK1 cells (6.4 +/- 0.9/1,000 cells vs. 14.8 +/- 2.4/1,000 cells, p = 0.028), and iodixanol-treated LLC-PK1 cells (8.0 +/- 1.2/1,000 cells vs. 13.5 +/- 1.9/1,000 cells, p = 0.028). In iohexol-treated LLC-PK1 cells, rhEpo attenuated activation of caspase-3 (p = 0.003), caspase-8 (p = 0.033) and caspase-9 (p = 0.055).

CONCLUSION

rhEpo attenuates in vitro renal tubular epithelial cell injury induced by low- and iso-osmolar radiocontrast media, possibly by reduction of caspases activation and apoptosis rates.

Renal disease: the anesthesiologist's perspective

The kidney is a remarkable organ whose functions include maintaining fluid and electrolyte balance, excreting metabolic waste products, and controlling vascular tone. Blood flow within the kidney is very heterogeneous, which places the metabolically active medulla at high risk for ischemic injury. A number of mediators play a role in the modulation of renal blood flow, including angiotensin II, dopamine, vasopressin, prostaglandins, atrial natriuretic peptide, endothelin, and nitric oxide. Early markers of renal injury elicit strong interest, although currently there is no reliable marker available. Surgery causes the release of catecholamines, renin, angiotensin, and AVP that lead to a redistribution of renal blood flow and a decrease in GFR. Additionally, general anesthesia often results in some degree of hypotension and depressed cardiac output, which further reduces renal perfusion and potentially jeopardizes renal function. A careful anesthetic plan is imperative in the patient with renal insufficiency or failure because acute renal failure in the perioperative period is associated with a high morbidity and mortality. Factors including advanced age, diabetes, underlying renal insufficiency, and heart failure place a patient at high risk for developing acute renal failure. It is imperative to maintain euvolemia, normotension, and cardiac output, and to avoid nephrotoxic agents to optimize renal blood flow and renal perfusion as the best prevention of renal dysfunction. Further studies are needed to establish if any therapies exist to prevent or treat renal dysfunction effectively.

The reno-protective effect of hydration with sodium bicarbonate plus N-acetylcysteine in patients undergoing emergency percutaneous coronary intervention: the RENO Study

OBJECTIVES

This study was designed to determine the effectiveness of a protocol for rapid intravenous hydration to prevent contrast-induced nephropathy (CIN) in patients undergoing emergency percutaneous coronary intervention (PCI).

BACKGROUND

Contrast-induced nephropathy frequently complicates PCI, resulting in prolonged hospitalization and increased in-hospital and long-term morbidity and mortality. Little is known regarding prevention of CIN in patients undergoing urgent PCI.

METHODS

We conducted a prospective, controlled, randomized, single-center trial in 111 consecutive patients with acute coronary syndrome undergoing emergency PCI. As part of the hydration therapy, 56 patients (group A) received an infusion of sodium bicarbonate plus N-acetylcysteine (N-AC) started just before contrast injection and continued for 12 h after PCI. The remaining 55 patients (group B) received the standard hydration protocol consisting of intravenous isotonic saline for 12 h after PCI. In both groups, 2 doses of oral N-AC were administered the next day.

RESULTS

The 2 groups were similar with respect to age, gender, diabetes mellitus, and baseline serum creatinine. A serum creatinine concentration >0.5 mg/dl from baseline after emergency PCI was observed in 1 patient in group A (1.8%) and in 12 patients in group B (21.8%; p < 0.001). Acute anuric renal failure was observed in 1 patient (1.8%) in group A and in 7 patients (12.7%) in group B (p = 0.032).

CONCLUSIONS

Rapid intravenous hydration with sodium bicarbonate plus N-AC before contrast injection is effective and safe in the prevention of CIN in patients undergoing emergency PCI.