Close association between the reduction in myocardial energy metabolism and infarct size: dose-response assessment of cyclosporine

The Effect of Polyphenols on Kidney Disease: Targeting Mitochondria

Mitochondrial function, including oxidative phosphorylation (OXPHOS), mitochondrial biogenesis, and mitochondria dynamics, are essential for the maintenance of renal health. Through modulation of mitochondrial function, the kidneys are able to sustain or recover acute kidney injury (AKI), chronic kidney disease (CKD), nephrotoxicity, nephropathy, and ischemia perfusion. Therapeutic improvement in mitochondrial function in the kidneys is related to the regulation of adenosine triphosphate (ATP) production, free radicals scavenging, decline in apoptosis, and inflammation. Dietary antioxidants, notably polyphenols present in fruits, vegetables, and plants, have attracted attention as effective dietary and pharmacological interventions. Considerable evidence shows that polyphenols protect against mitochondrial damage in different experimental models of kidney disease. Mechanistically, polyphenols regulate the mitochondrial redox status, apoptosis, and multiple intercellular signaling pathways. Therefore, this review attempts to focus on the role of polyphenols in the prevention or treatment of kidney disease and explore the molecular mechanisms associated with their pharmacological activity.

Mitochondrial ion channels as targets for cardioprotection

Acute myocardial infarction (AMI) and the heart failure (HF) that often result remain the leading causes of death and disability worldwide. As such, new therapeutic targets need to be discovered to protect the myocardium against acute ischaemia/reperfusion (I/R) injury in order to reduce myocardial infarct (MI) size, preserve left ventricular function and prevent the onset of HF. Mitochondrial dysfunction during acute I/R injury is a critical determinant of cell death following AMI, and therefore, ion channels in the inner mitochondrial membrane, which are known to influence cell death and survival, provide potential therapeutic targets for cardioprotection. In this article, we review the role of mitochondrial ion channels, which are known to modulate susceptibility to acute myocardial I/R injury, and we explore their potential roles as therapeutic targets for reducing MI size and preventing HF following AMI.

Metabolic Pathway of Cyclosporine A and Its Correlation with Nephrotoxicity

Background:

Cyclosporine A (CsA) is widely used for organ transplantation and autoimmune disorders. However, CsA nephrotoxicity is a serious side effect that limits the clinical use of CsA. The metabolism of CsA has a close relationship with this disease in renal-transplant patients. However, the metabolic pathways of CsA and its metabolizing enzymes have rarely been comprehensively reviewed. In this review, we have summarized the specific metabolic profiles of CsA in humans, especially renal-transplant patients. Moreover, the specific metabolizing enzymes and the potential roles that CsA metabolism plays in CsA nephrotoxicity were summarized and discussed.

Methods:

Electronic databases including PubMed, Web of Science, and Scifinder were searched with the keywords "Cyclosporine A and metabolism", and "Cyclosporine A and nephrotoxicity", "Cyclosporine A metabolism and nephrotoxicity". All these studies published until 2018 were included in this review.

Results:

The major metabolic pathways of CsA in humans are hydroxylation and N-demethylation. Normally, these metabolites are relatively less toxic than CsA. However, the metabolism of CsA in the kidneys is much weaker than that in the liver, which explains why CsA is so toxic to the kidneys. CYP3A families, especially CYP3A4 and CYP3A5, play an important role in the biotransformation of CsA. Moreover, increased lines of evidence show that some metabolites (including AM19) associate directly with nephrotoxicity in CsA-treated organ-transplant patients.

Conclusion:

The findings of this review help to further understand the metabolic activities of CsA in renal-transplant patients and cast some light on the mechanisms of CsA nephrotoxicity.

Quantitative NMR-Based Metabolomics on Tissue Biomarkers and Its Translation into In Vivo Magnetic Resonance Spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy is an established analytical platform for analyzing metabolic profiles of cells, tissues, and body fluids. There are several advantages in introducing an NMR-based study design into metabolomics studies, including a fast and comprehensive detection, characterization, and quantification of dozens of endogenous metabolites in a single NMR spectrum. Quantitative proton ¹H-NMR is the most useful NMR-based platform for metabolomics. The frozen tissues can be analyzed noninvasively using a high-resolution magic angle spinning (HR-MAS) ¹H-NMR spectroscopy; or several extraction techniques can be applied to detect additional metabolites using a conventional liquid-based NMR technique. In this chapter, we report on tissue collection, handling, extraction methods, and ¹H-NMR acquisition protocols developed in the past decades for a precise and quantitative NMR-metabolomics approach. The NMR acquisition protocols (both HR-MAS and conventional ¹H-NMR spectroscopy) and spectral analysis steps are also presented. Since NMR can be applied "in vivo" using horizontal bore MRI scanners, several in vivo sequences for localized ¹H-MRS (magnetic resonance spectroscopy) are presented which can be directly applied for noninvasive detection of brain metabolites.

Green tea polyphenols stimulate mitochondrial biogenesis and improve renal function after chronic cyclosporin a treatment in rats

Our previous studies showed that an extract from Camellia sinenesis (green tea), which contains several polyphenols, attenuates nephrotoxicity caused by cyclosporine A (CsA). Since polyphenols are stimulators of mitochondrial biogenesis (MB), this study investigated whether stimulation of MB plays a role in green tea polyphenol protection against CsA renal toxicity. Rats were fed a powdered diet containing green tea polyphenolic extract (0.1%) starting 3 days prior to CsA treatment (25 mg/kg, i.g. daily for 3 weeks). CsA alone decreased renal nuclear DNA-encoded oxidative phosphorylation (OXPHOS) protein ATP synthase-β (AS-β) by 42%, mitochondrial DNA (mtDNA)-encoded OXPHOS protein NADH dehydrogenase-3 (ND3) by 87% and their associated mRNAs. Mitochondrial DNA copy number was also decreased by 78% by CsA. Immunohistochemical analysis showed decreased cytochrome c oxidase subunit IV (COX-IV), an OXPHOS protein, in tubular cells. Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, the master regulator of MB, and mitochondrial transcription factor-A (Tfam), the transcription factor that regulates mtDNA replication and transcription, were 42% and 90% lower, respectively, in the kidneys of CsA-treated than in untreated rats. These results indicate suppression of MB by chronic CsA treatment. Green tea polyphenols alone and following CsA increased AS-β, ND3, COX-IV, mtDNA copy number, PGC-1α mRNA and protein, decreased acetylated PGC-1α, and increased Tfam mRNA and protein. In association with suppressed MB, CsA increased serum creatinine, caused loss of brush border and dilatation of proximal tubules, tubular atrophy, vacuolization, apoptosis, calcification, and increased neutrophil gelatinase-associated lipocalin expression, leukocyte infiltration, and renal fibrosis. Green tea polyphenols markedly attenuated CsA-induced renal injury and improved renal function. Together, these results demonstrate that green tea polyphenols attenuate CsA-induced kidney injury, at least in part, through the stimulation of MB.

Cyclosporin A and cardioprotection: from investigative tool to therapeutic agent

Ischaemic heart disease (IHD) is the leading cause of death and disability worldwide. The pathophysiological effects of IHD on the heart most often result from the detrimental effects of acute ischaemia-reperfusion injury (IRI) on the myocardium. Therefore, novel therapeutic targets for protecting the myocardium against acute IRI are required to reduce injury to the heart, preserve cardiac function and improve clinical outcomes in patients with IHD. In this regard, the mitochondrial permeability transition pore (mPTP) has emerged as a critical target for cardioprotection which is readily amenable to intervention at the time of myocardial reperfusion. The formation and opening of the mPTP at the onset of myocardial reperfusion is a major determinant of mitochondrial dysfunction and cardiomyocyte death in the setting of acute IRI. The seminal discovery in the late 1980s that mPTP opening could be pharmacologically inhibited by the immunosuppressive agent, cyclosporin A (CsA), has been fundamental in the elucidation of the critical role of the mPTP as a mediator of acute IRI and, therefore, a viable target for cardioprotection. Its initial role as an investigative tool was used to identify mitochondrial cyclophilin D to be a regulatory component of the mPTP. The mPTP as a viable target for cardioprotection has recently been translated into the clinical setting with CsA reducing myocardial infarct size in patients. In this article, we review the intriguing role of CsA as a tool for investigating the mPTP as a target for cardioprotection and its potential role as a therapeutic agent for patients with IHD.

Cyclosporin variably and inconsistently reduces infarct size in experimental models of reperfused myocardial infarction: a systematic review and meta-analysis

Cyclosporin is an immunosuppressant that has recently been proposed as a treatment to prevent reperfusion injury in acute myocardial infarction (MI). We aimed to determine the overall efficacy of cyclosporin in experimental studies of acute reperfused MI. We conducted a systematic review and stratified meta-analysis of published studies describing the efficacy of cyclosporin in experimental models of acute reperfused MI. We included all in vivo publications of cyclosporin where infarct size was measured. A literature search identified 29 potential studies of which 20 fulfilled the eligibility criteria. In these studies (involving four species of animals), cyclosporin reduced myocardial infarct size by a standardized mean (95% confidence interval) difference of -1.60 (-2.17, -1.03) compared with controls. Cyclosporin failed to demonstrate a convincing benefit in studies involving pigs. Despite this observation, the overall efficacy of cyclosporin did not differ across species (P= 0.358). The dose of cyclosporin given did not affect final infarct size (P= 0.203). Funnel plots of these data suggested heterogeneity among the studies. Cyclosporin had variable effects on infarct size compared with placebo. Cyclosporin had no effect on myocardial infarct size in swine, raising a question over the potential cardioprotective effects of cyclosporin in man.

Metabonomics study of the acute graft rejection in rat renal transplantation using reversed-phase liquid chromatography and hydrophilic interaction chromatography coupled with mass spectrometry

Acute graft rejection is one of the most common and serious post complications in renal transplantation, noninvasive diagnosis of acute graft rejection is essential for reducing risk of surgery and timely treatment. In this study, a non-targeted metabonomics approach based on ultra performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (MS) is used to investigate the effect of acute graft rejection in rat renal transplantation on metabolism. To collect more metabolite information both hydrophilic interaction chromatography and reversed-phase liquid chromatography were used. Using the partial least squares-discriminant analysis, we found that the change of metabonome in a sham-operated group and a non-graft rejection group had a similar trend, while that of the acute graft rejection group was clearly different. Several discriminating metabolites of the acute graft rejection were identified, including creatinine, phosphatidyl-cholines, lyso-phosphatidylcholines, carnitine C16:0, free fatty acids and indoxyl sulfate etc. These discriminating metabolites suggested that acute graft rejection in renal transplantation can lead to the accumulation of creatinine in the body, and also the abnormal metabolism of phospholipids. These findings are useful to understand the mechanisms of the rejection, it also means that a UPLC-MS metabonomic approach is a suitable tool to investigate the metabolic abnormality in the acute graft rejection in renal transplantation.

Donor pre-treatment with everolimus or cyclosporine does not reduce ischaemia-reperfusion injury in a rat kidney transplant model

BACKGROUND

Immunosuppressive agents have been investigated in renal ischaemia-reperfusion injury (IRI) and have frequently demonstrated a beneficial effect. Most studies focused on treatment of the recipient at the time of transplantation. Pre-treatment of these organs before injury (pharmacological pre-conditioning) may particularly protect these organs. This study aimed to investigate the possible protective effects of donor pre-treatment with cyclosporine (CsA) or the mTOR inhibitor everolimus or their combination against IRI during renal transplantation in a rat model.

METHODS

Donors received vehicle, CsA (5 mg/kg), everolimus (0.5 mg/kg) or CsA + everolimus. Two oral doses were administered to the donors at 24 h and again at 6 h prior to donor kidney removal. Syngeneic rat kidneys were preserved in UW solution for 24 h prior to transplantation. After 24 h of reperfusion, blood and tissue samples were collected from recipients for further analysis.

RESULTS

Renal functions as determined by creatinine and necrosis scores were not different between the experimental groups. Cleaved caspase-3, heat shock protein 70 (HSP70), tumor-necrosis factor-alpha (TNF-α) and nitrotyrosine protein levels were not statistically different between the four treatment groups at 24 h post-transplantation. Blood NMR analysis on metabolic markers for IRI reveals no beneficial effects of donor pre-treatment on the 24-h outcome in transplantation.

CONCLUSIONS

When given alone or as a combination to donors before organ recovery, cyclosporine or everolimus does not appear to ameliorate IRI.

In vivo fluorometric assessment of cyclosporine on mitochondrial function during myocardial ischemia and reperfusion

BACKGROUND

Cyclosporine A (CsA) limits myocardial reperfusion injury and preserves mitochondrial integrity, but its influence on mitochondrial function has not been described in vivo. Auto-fluorescence of mitochondrial nicotinamide adenine dinucleotide and flavin adenine dinucleotide correlate with mitochondrial dysfunction. We hypothesized that CsA limits mitochondrial dysfunction and that fluorometry can quantify this influence.

METHODS

Seventeen rabbits were studied: untreated (UnT, n = 7), CsA preinfarction (CsAp, n = 6), and CsA on reperfusion (CsAr, n = 4). Animals underwent 30 minutes of myocardial ischemia and 3 hours reperfusion. Infarct size was determined by staining. Nicotinamide adenine dinucleotide and flavin adenine dinucleotide fluorescence was continually measured in the risk area. The redox ratio was calculated [flavin adenine dinucleotide(f)/(flavin adenine dinucleotide(f) + nicotinamide adenine dinucleotide(f))]. Electron microscopy evaluated mitochondria morphology.

RESULTS

The infarct size by group was 39.1% +/- 1.7% in CsAp, 39.1% +/- 1.7% in CsAr, and 53.4% +/- 1.9% in UnT (p < 0.001). During ischemia, the CsAp group demonstrated less hypoxic reduction, with the redox ratio decreasing to 75.6% +/- 4.1% of baseline. The UnT and CsAr groups deceased to 67.1% +/- 4.0% and 67.2% +/- 3.6%, respectively (p < 0.005). During reperfusion the UnT group redox ratio increased to 1.59 +/- 0.04 times baseline. This increase was blunted in the CsAp (1.17 +/- 0.04, p = 0.026) and CsAr (1.35 +/- 0.02, p = 0.056) groups. Electron microscopy revealed reduced mitochondrial disruption in CsAp (19.7% +/- 7.6%) and CsAr (18.1% +/- 7.1%) rabbits compared with UnT (53.3% +/- 12.5%).

CONCLUSIONS

Fluorometric spectroscopy can be used in vivo to quantitatively assess the time course of CsA's influence on the mitochondrial dysfunction associated with myocardial ischemia and reperfusion.

Effect of dimerized thrombin fragment TP508 on acute myocardial ischemia reperfusion injury in hypercholesterolemic swine

The thrombin-related peptide TP508 is a 23-amino acid monomer that represents a portion of the receptor binding domain in the thrombin molecule. TP508 is also known to readily convert to a dimer in an aqueous environment. In this study the dimeric form of TP508 was investigated in a porcine model of acute myocardial ischemia reperfusion injury (and compared with its monomer). Twenty-four hypercholesterolemic pigs underwent 60 min of mid-left anterior descending coronary artery occlusion followed by 120 min of reperfusion and received either vehicle (n = 6), TP508 monomer (n = 6), or two different doses of dimer (n = 6). Infarct size was significantly reduced in the monomer and two dimer groups compared with vehicle. Improvement in both endothelium-dependent and -independent coronary microvascular relaxations was also observed in treated groups. In addition, the expression of 27-kDa heat shock protein, alphaB-crystalline, and phosphorylated B-cell lymphoma 2 (Ser70) in the ischemic area at risk were higher in treated groups than in vehicle, whereas the expression of cleaved poly-ADP ribose polymerase was lower in treated groups. Finally, there were fewer apoptotic cells in treated groups than in vehicle. This study suggests that TP508 dimer provides a myocardial-protective effect on acute ischemia reperfusion injury in hypercholesterolemic swine, similar to TP508 monomer, by up-regulating cell survival pathways or down-regulating apoptotic pathways.

Metabonomic identification of novel biomarkers in doxorubicin cardiotoxicity and protective effect of the natural antioxidant oleuropein

Doxorubicin (DXR) is a commonly used antineoplastic agent; however, its use is limited due to cardiotoxicity. Oxidative stress and consequent alterations of cardiac energetics are involved in the development of DXR toxicity. Oleuropein (Oleu) is a phenolic antioxidant, present in olive tree, reported to confer protection against DXR cardiotoxicity. In this study, NMR based-metabonomics was applied to characterize the metabolic profile of the acute DXR cardiotoxicity in rats and to evaluate the metabolic alterations conferred by co-treatment with Oleu. Wistar rats were divided into six groups and treated as follows: control group with a single injection of 2 mL normal saline intraperitoneally (i.p.), DXR group with a single dose of 20 mg/kg, i.p and DXR plus Oleu groups with 20mg/kg DXR i.p., and 100 or 200 mg/kg/BW of Oleu i.p. for 5 or 3 consecutive days starting either 2 days before or on the day of DXR administration. Hearts were excised 72 h after DXR treatment and (1)H-NMR spectra of aqueous myocardium extracts were recorded. Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS-DA) revealed differences in the metabolic profile between control and DXR attributed to several metabolites. A number of them were quantified by integration of the NMR spectra. Myocardial levels of acetate and succinate were increased in DXR compared to controls, while branched amino acids were decreased. These results correlate with nonenzymatic conversion of pyruvate to acetate and of alpha-ketoglutarate to succinate by DXR free radicals. Oleu completely restored the changes of metabolites to the normal levels. Acetate and succinate constitute novel biomarkers related to DXR, and Oleu treatment aids the compensation of distressed energy metabolic pathways.

Neuroprotective antioxidant STAZN protects against myocardial ischemia/reperfusion injury

BACKGROUND

Protecting the myocardium from ischemia-reperfusion injury has significant potential to reduce the complications of myocardial infarction and interventional revascularization procedures. Reperfusion damage is thought to result, in part, from oxidative stress. Here we use a novel method of percutaneous coronary occlusion to show that the potent antioxidant and neuroprotective free-radical scavenger, stilbazulenyl nitrone (STAZN), confers marked cardioprotection when given immediately prior to reperfusion.

METHODS AND RESULTS

Physiologically controlled male Sprague-Dawley rats were anesthetized with isoflurane, paralyzed with pancuronium and mechanically ventilated. A guide wire was introduced via the femoral artery and advanced retrogradely via the aorta into the left coronary artery under fluoroscopic guidance. Rats with established coronary ischemia (85 min after occlusion) were given STAZN 3.5 mg/kg or its vehicle 5 min before and 2 h after reperfusion, and were subjected to functional and histopathologic studies at 3 days. Ischemia-associated Q wave amplitude was reduced by 73% in STAZN-treated rats (P=0.01), while infarct-related ejection fraction, fractional shortening and severe regional wall-motion impairments were improved by 48%, 54% and 37%, respectively, relative to vehicle-treated controls (P=0.05). Total myocardial infarct volume in STAZN-treated rats was correspondingly reduced by 43% (P<0.05), representing a sparing of 14% of the total left ventricular myocardium.

CONCLUSIONS

STAZN, a second-generation azulenyl nitrone with potent neuroprotective efficacy in brain ischemia, is also a rapidly acting and highly effective cardioprotective agent in acute coronary ischemia. Our results suggest the potential for clinical benefit in the setting of acute coronary syndromes.

Mitochondria: pharmacological manipulation of cell death

Cell death by apoptosis or necrosis is often important in the etiology and treatment of disease. Since mitochondria play important roles in cell death pathways, these organelles are potentially prime targets for therapeutic intervention. Here we discuss the mechanisms through which mitochondria participate in the cell death process and also survey some of the pharmacological approaches that target mitochondria in various ways.

In vivo protective effects of urocortin on ischemia-reperfusion injury in rat heart via free radical mechanisms

The aim of this study was to investigate the effects of urocortin (UCN) on oxidative stress and the mechanisms of urocortin on ischemia–reperfusion injury in vivo in the rat model. Thirty-six Sprague–Dawley rats were divided into 6 groups, including sham, control (normal saline solution), UCN1, UCN2, UCN3, and verapamil groups. The left anterior descending coronary artery of all rats except those in the sham group was treated with a 30-min occlusion followed by a 60-min reperfusion. Just before the occlusion, normal saline solution, UCN (5, 10, and 20 µg/kg body mass), or verapamil (1 mg/kg body mass) was administered. Heart rates, beating rhythm, and S-T segments were constantly monitored using an ECG. At the completion of the drug adminstration, blood samples were taken to measure the activity of superoxide dismutase (SOD), malonaldehyde (MDA), glutathione peroxidase (GSH-PX), and nitric oxide (NO) to evaluate the effects of UCN on oxidative stress. Finally, the size of infarction was measured. Arrhythmia rates were significantly lower, and the infarction size was significantly smaller (p < 0.01), in the UCN groups vs. the control group. Verapamil also significantly reduced arrhythmia rates and infarction size. The MDA activities were remarkably diminished, whereas the SOD, GSH-PX, and NO activities were significantly higher in the UCN and VER groups (p < 0.01). MDA, SOD, and NO activities were strongly correlated with UCN doses. These results suggest that UCN may play a protective role in ischemia–reperfusion injury in rat hearts against the oxidative stress by inhibiting free radicals' activities. Key words: urocortin, ischemia–reperfusion injury, arrhythmias, free radical anti-oxidative enzymes, oxidative stress.

Benefit-Risk Assessment of Sirolimus in Renal Transplantation

Sirolimus (rapamycin) is a macrocyclic lactone isolated from a strain of Streptomyces hygroscopicus that inhibits the mammalian target of rapamycin (mTOR)-mediated signal-transduction pathways, resulting in the arrest of cell cycle of various cell types, including T- and B-lymphocytes. Sirolimus has been demonstrated to prolong graft survival in various animal models of transplantation, ranging from rodents to primates for both heterotopic, as well as orthotopic organ grafting, bone marrow transplantation and islet cell grafting. In human clinical renal transplantation, sirolimus in combination with ciclosporin (cyclosporine) efficiently reduces the incidence of acute allograft rejection. Because of the synergistic effect of sirolimus on ciclosporin-induced nephrotoxicity, a prolonged combination of the two drugs inevitably leads to progressive irreversible renal allograft damage. Early elimination of calcineurin inhibitor therapy or complete avoidance of the latter by using sirolimus therapy is the optimal strategy for this drug. Prospective randomised phase II and III clinical studies have confirmed this approach, at least for recipients with a low to moderate immunological risk. For patients with a high immunological risk or recipients exposed to delayed graft function, sirolimus might not constitute the best therapeutic choice--despite its ability to enable calcineurin inhibitor sparing in the latter situation--because of its anti-proliferative effects on recovering renal tubular cells. Whether lower doses of sirolimus or a combination with a reduced dose of tacrolimus would be advantageous in these high risk situations remains to be determined. Clinically relevant adverse effects of sirolimus that require a specific therapeutic response or can potentially influence short- and long-term patient morbidity and mortality as well as graft survival include hypercholesterolaemia, hypertriglyceridaemia, infectious and non-infectious pneumonia, anaemia, lymphocele formation and impaired wound healing. These drug-related adverse effects are important determinants in the choice of a tailor-made immunosuppressive drug regimen that complies with the individual patient risk profile. Equally important in the latter decision is the lack of severe intrinsic nephrotoxicity associated with sirolimus and its advantageous effects on arterial hypertension, post-transplantation diabetes mellitus and esthetic changes induced by calcineurin inhibitors. Mild and transient thrombocytopenia, leukopenia, gastrointestinal adverse effects and mucosal ulcerations are all minor complications of sirolimus therapy that have less impact on the decision for choosing this drug as the basis for tailor-made immunosuppressive therapy. It is clear that sirolimus has gained a proper place in the present-day immunosuppressive armament used in renal transplantation and will contribute to the development of a tailor-made immunosuppressive therapy aimed at fulfilling the requirements outlined by the individual patient profile.

Influence of donor pretreatment with N-acetylcysteine on ischemia/reperfusion injury in rat kidney grafts

PURPOSE

N-acetylcysteine (NAC) has been shown to ameliorate ischemic acute renal failure. We determined the effect of donor pretreatment with NAC on ischemia reperfusion (I/R) injury in rat kidney grafts.

MATERIALS AND METHODS

Lewis rats were divided into 3 groups (8 per group) and treated with saline, mannitol (1 gm/kg) or NAC (1 gm/kg intravenously) prior to donor nephrectomy. Cold stored kidneys (24 hours in UW solution) were transplanted into bilaterally nephrectomized recipients. Blood and graft tissue samples were taken 24 hours after transplantation for assessment of metabolic changes, histological damage and renal function. Metabolites associated with renal I/R injury were quantified in blood and renal tissue by magnetic resonance spectroscopy.

RESULTS

The degree of histological damage was similar between the treatment groups. Of the counted tubules 60%were mildly damaged, whereas 40% showed moderate damage. Measurement of the metabolites allantoin and trimethylamine-N-oxide (TMAO) indicated a beneficial effect of NAC treatment. In graft tissue and recipient blood allantoin, a uric acid metabolite, was significantly lower in the NAC group vs the mannitol and saline groups (p <0.05). In recipient blood TMAO, an established marker of renal medullary injury, was significantly decreased in the NAC group vs mannitol and saline (p <0.05). Serum creatinine levels were not different between treatment groups.

CONCLUSIONS

Donor pretreatment with NAC preserves renal metabolism and may improve outcomes of I/R injured kidney transplants. Allantoin and TMAO are sensitive metabolic markers of renal I/R injury that can be detected before the onset of functional and morphological changes.