Biomarker for early renal microvascular and diabetic kidney diseases.

Recognition of early stage of diabetic kidney disease, under common practice using biomarkers, namely microalbuminuria, serum creatinine level above 1 mg/dL and accepted definition of diabetic kidney disease associated with creatinine clearance value below 60 mL/min/1.73 m2, is unlikely. This would lead to delay treatment associated with therapeutic resistance to vasodilator due to a defective vascular homoeostasis. Other alternative biomarkers related to the state of microalbuminuria is not sensitive to screen for early diabetic kidney disease (stages I, II). In this regard, a better diagnostic markers to serve for this purpose are creatinine clearance, fractional excretion of magnesium (FE Mg), cystatin C. Recently, renal microvascular disease and renal ischemia have been demonstrated to correlate indirectly with the development of diabetic kidney disease and its function. Among these are angiogenic and anti-angiogenic factors, namely VEGF, VEGF receptors, angiopoietins and endostatin. With respect to therapeutic prevention, implementation of treatment at early stage of diabetic and nondiabetic kidney disease is able to restore renal perfusion and function.

CD147/basigin reflects renal dysfunction in patients with acute kidney injury.

BACKGROUND: Acute tubular necrosis (ATN) describes a form of intrinsic acute kidney injury (AKI) that results from persistent hypoperfusion and subsequent activation of the immune system. A glycosylated transmembrane protein, CD147/basigin, is involved in the pathogenesis of renal ischemia and fibrosis. The present study investigated whether CD147 can reflect pathological features and renal dysfunction in patients with AKI. METHODS: Plasma and spot urine samples were collected from 24 patients (12 controls and 12 with ATN) who underwent renal biopsy between 2008 and 2012. In another study, patients undergoing open surgery to treat abdominal aortic aneurysms (AAAs) were enrolled in 2004. We collected urine and plasma samples from seven patients with AKI and 33 patients without AKI, respectively. In these experiments, plasma and urinary CD147, and urinary L-fatty acid-binding protein (L-FABP) levels were measured, and the former expression in kidneys was examined by immunostaining. RESULTS: In biopsy tissues of ATN with severe histological features, CD147 induction was strikingly present in inflammatory cells such as macrophages and lymphocytes in the injured interstitium, but not in damaged tubules representing atrophy. Both plasma and urinary CD147 levels were strikingly increased in ATN patients; both values showed greater correlations with renal dysfunction compared to urinary L-FABP. In patients who had undergone open AAA surgery, urinary and plasma CD147 values in AKI patients were significantly higher than in non-AKI patients at post-operative day 1, similar to the profile of urinary L-FABP. CONCLUSION: CD147 was prominent in its ability to detect AKI and may allow the start of preemptive medication.

Prostaglandin E-major urinary metabolites as a new biomarker for acute mesenteric ischemia.

BACKGROUND: Acute mesenteric ischemia (AMI) is an emergent vascular disease caused by cessation of the blood supply to the small intestine. Despite advances in the diagnosis, intervention, and surgical procedures, AMI remains a life-threatening condition. Prostaglandin E2 major urinary metabolite (PGE-MUM), the urinary metabolite of prostaglandin E2, is known to be stable in urine and has been suggested to be a valuable biomarker for intestinal mucosal inflammation, such as ulcerative colitis. We therefore investigated whether or not PGE-MUM levels reflect the degree of ischemia in an intestinal ischemia-reperfusion model. METHODS: Male rats were used to establish a superior mesenteric artery occlusion (SMAO) group, in which the superior mesenteric artery was clamped, and a sham group. The clamping times in the SMAO group were either 30 minutes or 60 minutes, and reperfusion times were either 3 hours or 6 hours, after which PGE-MUM values were measured. RESULTS: The histological injury score of the SMAO (30-minute ischemia and 6-hour reperfusion group, 1.8 ± 0.4; 60-minute ischemia and 6-hour reperfusion group, 4.7 ± 0.5) and were significantly greater than that of the sham group (0.4 ± 0.7, p < 0.05). The PGE-MUM levels in the SMAO group (30-minutes ischemia and 6-hour reperfusion group, 483 ± 256; 60-minutes ischemia and 6-hour reperfusion group, 889 ± 402 ng/mL) were significantly higher than in the sham group (30-minute and 6-hour observation group, 51 ± 20; 60-minute and 6-hour observation group, 73 ± 32 ng/mL; p < 0.05). Furthermore, the PGE-MUM value was corrected by the concentration of urinary creatinine (Cr). The PGE-MUM/urinary Cr levels in the SMAO group were also significantly higher than in the sham group ( p < 0.05). CONCLUSION: We found that intestinal ischemia-reperfusion increased urinary PGE-MUM levels depending on the ischemic time. This suggests the potential utility of PGE-MUM as a noninvasive marker of intestinal ischemia.

Urinary NGAL and KIM-1: biomarkers for assessment of acute ischemic kidney injury following nephron sparing surgery.

PURPOSE: Nephron sparing surgery is considered the treatment of choice in most patients with confined renal cancer. Interrupting renal blood flow is often necessary during such surgery, which can induce significant renal injury. We explored the possibility of using urinary NGAL and KIM-1 excretion as novel biomarkers to assess the extent of acute kidney injury after nephron sparing surgery. MATERIALS AND METHODS: The study group included 27 patients who underwent open nephron sparing surgery for enhancing solid renal tumors. During surgery the renal artery was clamped for between 6 and 47 minutes. Urine samples were collected before surgery, and 1, 3, 8, 24, 48 and 72 hours after renal pedicle clamp removal. Urinary levels of NGAL and KIM-1 were determined. RESULTS: Renal artery clamping induced renal injury, as reflected by increased urinary NGAL and KIM-1 in all participants. These increases in urinary NGAL excretion were evident after 1 hour of renal ischemia and lasted for 72 hours. Urinary NGAL correlated with the serum creatinine increase and ischemia duration. Compared with patients without significantly increased serum creatinine, those with significantly increased serum creatinine after nephron sparing surgery had a greater increase in urinary NGAL but not in KIM-1. CONCLUSIONS: Renal injury severity after nephron sparing surgery could be quantitatively assessed by measuring urinary NGAL and KIM-1.

Early urinary biomarkers of warm and cold ischemic injury in an experimental kidney model.

BACKGROUND: Early urinary biomarkers may be useful in determining the severity of ischemic injury in donation after circulatory death (DCD) kidneys. The aim of this study was to evaluate the efficacy of a collective series of urinary biomarkers in relation to the warm and cold ischemic intervals. METHODS: Porcine kidneys were retrieved after 0, 10, and 25 min of warm ischemia (WI), then preserved by static cold storage (CS) for period of 2 and 18 h. After preservation, kidneys were reperfused on an isolated organ perfusion system to assess renal function and injury. Levels of IL-6, TNFα, endothelin-1 (ET-1), and neutrophil gelatinase-associated lipocalin (NGAL) were measured in urine samples after 3 h of reperfusion. RESULTS: There was no significant difference in renal functional parameters or urinary biomarkers between the WI times when kidneys were stored for 2 h (P > 0.05). After 18 h CS, kidneys with 10 and 25 min of WI demonstrated a significant decline in renal function compared with kidneys without WI (P < 0.05). Levels of ET-1 and NGAL were significantly higher in kidneys with 25 min WI (25 m ET-1, 30.1 ± 21.2, versus 0 m 2.25 ± 1.5 pg/mL; P = 0.002: NGAL, 25 m 77 ± 51 versus 0 m 10 ± 0.1 pg/mL; P = 0.005). Levels of IL-6 and TNFα were significantly higher in kidneys with 10 and 25 min of WI (P = 0.001, 0.001). CONCLUSION: Early urinary biomarkers are a useful means to determine graft injury. ET-1 and NGAL are more accurate in predicting the severity of ischemic injury compared with inflammatory markers.

Use of urinary biomarkers of renal ischemia in a lamb preclinical left ventricular assist device model.

Evaluation of thrombogenicity is a critical component in the preclinical testing and development of blood pumps. Left ventricular assist devices (LVADs), because of their device routing, can produce thromboembolic showers to the kidney resulting in renal cortical ischemia or infarctions. Although postmortem evaluation of renal pathology can confirm ischemic events and infarctions, there are no validated and highly sensitive real-time measures of renal ischemia in the preclinical models. In this article, we report the evaluation of urinary biomarkers of ischemic tubular damage in a lamb preclinical LVAD model. We found that urinary excretion of glutathione-S-transferase-π, heat shock protein 1B, and hepatitis A virus cellular receptor 1 homologue precursor (HAVCR1/kidney injury molecule 1) were upregulated in toxic ischemic renal injury as well as in the immediate postoperative period in an LVAD-implanted lamb. These markers were consistent with both gross and histologic pathology, and proved far more sensitive for renal injury than serum blood urea nitrogen or creatinine concentrations.

Assessment of uric acid and lipid peroxidation in serum and urine after hypoxia-ischemia neonatal in rats.

The aim of this study was to evaluate urinary uric acid (UA) and lipid peroxidation levels, plasma myeloperoxidase (MPO) and adenosine deaminase (ADA) activities, and serum UA in neonatal rats subjected to hypoxia-ischemia neonatal HI model. The relevance of the findings is the fact that urinary lipid peroxidation and UA levels were significantly higher in 8 days in HI group when compared with the control, returning to baseline levels 60 days after HI. Hence, being an indication of purinic degradation during these first days post-HI. Furthermore, the higher levels of malondialdehyde (MDA) in urine in this period may be related to inadequate scavenging abilities of the immature nervous system and being noninvasive it may suggest the use of urinary MDA measurement as a marker for lipid peroxidation after HI insult. In application terms, these findings can help develop therapeutic interventions as soon as 8 days after HI.

[Ischemic lesions in kidneys after extracorporeal shock wave lithotripsy demonstrated by Proton NMR spectroscopy of urine samples]. / Évaluation par spectroscopie RMN des lésions rénales provoquées par la lithotripsie extracorporelle à partir d'échantillons d'urine.

PURPOSE: The aim of this prospective study was to investigate the effect of extracorporeal shock wave lithotripsy (SWL) on kidneys of patients with pyelic stone disease. The effects of SWL were assessed by high-resolution proton nuclear magnetic resonance (HNMR) spectroscopy of urine samples. METHODS: Twenty-three patients, aged 31-80years (mean: 55years), with pyelic stone disease were investigated before and after SWL. Multiparameter analysis was performed by HNMR spectroscopy of urine samples collected before and 5h after SWL (second miction post-SWL). RESULTS: The most relevant resonances determined by HNMR spectroscopy were acetate, lactate, trimethylamine N-oxide and amino acids. Excretion of these markers increased significantly in comparison with pre-SWL urinary samples. CONCLUSION: These results show that early ischemic damage occurs after SWL. Post-SWL. HNMR spectroscopy is an effective tool for noninvasive follow-up of renal damage.

[Urine cholinesterase activity in full-term neonatal infants with ischemic nephropathy].

To determine urine cholinesterase activity in full-term neonatal infants with varying ischemic nephropathy in an intensive care unit, the investigators studied this enzyme on days 1 and 5-7 of life, by using a kinetic photometric test optimized according to the Deutsche Gesellschaft fur Klinische Chemie (German Society for Clinical Chemistry) recommendations. In the early neonatal period, the newborns with grade III ischemic nephropathy were found to have a high urine cholinesterase activity. The determination of urine cholinesterase activity just on the first day of life may be used for the early diagnosis of grade III ischemic nephropathy in the newborns until the clinical manifestations of this pathology develop.

Simultaneous monitoring of multiple urinary cytokines may predict renal and patient outcome in ischemic AKI.

Acute kidney injury (AKI) is a common disorder associated with high morbidity and mortality rates. Ischemia is the leading cause of AKI. This is a pilot study investigating the ability of multiple urinary cytokines to predict renal functional outcome and mortality in patients with ischemic AKI. Urine samples were obtained from 45 subjects with ischemic AKI on the day of renal consultation and 3 days later. The urinary concentrations of interleukin (IL)-1beta, IL-6, IL-8, monocyte chemotactic protein (MCP)-1, interferon-inducible protein (IP)-10, regulated on activation, normal T-expressed and secreted (RANTES), transforming growth factor (TGF)-alpha, vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were measured simultaneously using a microsphere-based immunofluorescence assay. Urinary cytokine levels (pg/mg urine creatinine), which predict renal functional recovery or no recovery the next day and 7 days and 3 months later, were identified. Increased urinary IP-10 and IL-8 predicted no renal functional recovery the next day. Increased urinary IP-10 and VEGF predicted no renal recovery by 7 days. Increased urinary IP-10 and VEGF predicted no renal recovery by 4 days, whereas increased urinary EGF predicted renal functional recovery at that time. Increased urinary IL-8, MCP-1, IP-10, RANTES, EGF, and VEGF predicted patient's death within 3 months. Our findings suggest that urinary IP-10, IL-8, VEGF, TGF-alpha, and EGF may predict renal functional outcome at various times along the course of ischemic AKI and that urinary IL-8, MCP-1, IP-10, RANTES, EGF, and VEGF may predict mortality of the patients within 3 months.

Urinary cysteinyl leukotriene E4 significantly increases during pain in children and adults with sickle cell disease.

Baseline level of the cysteinyl leukotriene (CysLT), leukotriene E4 (LTE4), is associated with an increased pain rate in children and adults with sickle cell disease (SCD). To provide additional evidence for a role of CysLTs in the pathogenesis of vaso-occlusion, we tested the hypothesis that LTE4 levels will increase within an individual during painful episodes compared to baseline. In a cohort of 19 children and adults with SCD, median LTE4 levels increased from 82.36 pg/mg creatinine at baseline to 162.81 pg/mg creatinine during a painful episode (P < 0.001). These data further support a contribution of CysLTs to the process of vaso-occlusion.

[Determination of medium-weight molecules in the plasma and urine of neonatal infants with ischemic nephropathy].

To ascertain the level of medium-weight molecules in the plasma and urine in critically ill neonatal infants with varying ischemic nephropathy, the authors determined the content of medium-weight molecules by N. I. Gabrielyan's procedure modified by M. Ya. Malakhova. Within the first 24 hours of life, the newborn infants with ischemic nephropathy had high plasma levels of medium-weight proteins. The high plasma levels of medium-weight molecules were attended by their urinary elimination in first- and second-grade ischemic nephropathy and these were not compensated for by their elimination in third-grade nephropathy, which was linked to decreased renal excretory function. The determination of medium-weight molecules in the plasma and urine permits identification of acute renal failure in the newborn.

The Impact of Chronic Pelvic Ischemia on LUTS and Urinary Levels of Neuroinflammatory, Inflammatory, and Oxidative Stress Markers in Elderly Men: A Case-control Study.

OBJECTIVE: To investigate lower urinary tract symptoms (LUTS) and urinary levels of neuroinflammatory, inflammatory, and oxidative stress markers in elderly men with chronic pelvic ischemia (CPI) caused by significant aortoiliac disease. MATERIALS AND METHODS: Thirteen men aged over 60 years, with aorta, unilateral or bilateral common/internal iliac artery occlusion documented by computed tomography angiography or angiography, were enrolled from the vascular surgery department. Twelve sex- and age-matched controls without significant aortoiliac disease were used for comparison. Exclusion criteria included neurogenic bladder dysfunction, bladder or prostate cancer, prostatic surgery, pelvic radiotherapy, or chronic treatment for LUTS. Participants underwent urological examination, including assessment of International Prostate Symptom Score (IPSS), uroflowmetry, postvoid residual (PVR), and prostate volume. Urine samples were collected, and levels of neuroinflammatory (nerve growth factor, NGF), inflammatory (cytokines), and oxidative stress markers (8-hydroxy-2'-deoxyguanosine) were determined by enzyme-linked immunosorbent assay. RESULTS: Groups were similar for age, PVR, prostate volume, and most cardiovascular risk factors. IPSS was higher in patients with CPI (11 ± 3 vs 8 ± 2, P = .02), with a significant mean difference between groups of three points. Urinary NGF was significantly higher in men with CPI (3.7 ± 0.8 vs 2.9 ± 0.7, P = .02), but no differences were found in inflammatory and oxidative biomarkers among groups. CONCLUSION: Severe CPI in elderly men is associated with a significant increase in LUTS and bladder neurogenic inflammation, as suggested by the increase of NGF release in urine, sensitizing bladder afferents. These findings confirm the relevance of ischemia in bladder function and appear to validate animal models of bilateral iliac artery occlusion.

SerpinA3 in the Early Recognition of Acute Kidney Injury to Chronic Kidney Disease (CKD) transition in the rat and its Potentiality in the Recognition of Patients with CKD.

Recognizing patients at early phases of chronic kidney disease (CKD) is difficult, and it is even more challenging to predict acute kidney injury (AKI) and its transition to CKD. The gold standard to timely identify renal fibrosis is the kidney biopsy, an invasive procedure not usually performed for this purpose in clinical practice. SerpinA3 was identified by high-resolution-mass-spectrometry in urines from animals with CKD. An early and progressive elevation of urinary SerpinA3 (uSerpinA3) was observed during the AKI to CKD transition together with SerpinA3 relocation from the cytoplasm to the apical tubular membrane in the rat kidney. uSerpinA3/alpha-1-antichymotrypsin was significantly increased in patients with CKD secondary to focal and segmental glomerulosclerosis (FSGS), ANCA associated vasculitis (AAV) and proliferative class III and IV lupus nephritis (LN). uSerpinA3 levels were independently and positively associated with renal fibrosis. In patients with class V LN, uSerpinA3 levels were not different from healthy volunteers. uSerpinA3 was not found in patients with systemic inflammatory diseases without renal dysfunction. Our observations suggest that uSerpinA3 can detect renal fibrosis and inflammation, with a particular potential for the early detection of AKI to CKD transition and for the differentiation among lupus nephritis classes III/IV and V.

Renal L-type fatty acid--binding protein in acute ischemic injury.

Fatty acid-binding proteins (FABPs) bind unsaturated fatty acids and lipid peroxidation products during tissue injury from hypoxia. We evaluated the potential role of L-type FABP (L-FABP) as a biomarker of renal ischemia in both human kidney transplant patients and animal models. Urinary L-FABP levels were measured in the first urine produced from 12 living-related kidney transplant patients immediately after reperfusion of their transplanted organs, and intravital video analysis of peritubular capillary blood flow was performed simultaneously. A significant direct correlation was found between urinary L-FABP level and both peritubular capillary blood flow and the ischemic time of the transplanted kidney (both P < 0.0001), as well as hospital stay (P < 0.05). In human-L-FABP transgenic mice subjected to ischemia-reperfusion injury, immunohistological analyses demonstrated the transition of L-FABP from the cytoplasm of proximal tubular cells to the tubular lumen. In addition, after injury, these transgenic mice demonstrated lower blood urea nitrogen levels and less histological injury than injured wild-type mice, likely due to a reduction of tissue hypoxia. In vitro experiments using a stable cell line of mouse proximal tubule cells transfected with h-L-FABP cDNA showed reduction of oxidative stress during hypoxia compared to untransfected cells. Taken together, these data show that increased urinary L-FABP after ischemic-reperfusion injury may find future use as a biomarker of acute ischemic injury.

De novo NAD+ biosynthetic impairment in acute kidney injury in humans.

Nicotinamide adenine dinucleotide (NAD+) extends longevity in experimental organisms, raising interest in its impact on human health. De novo NAD+ biosynthesis from tryptophan is evolutionarily conserved yet considered supplanted among higher species by biosynthesis from nicotinamide (NAM). Here we show that a bottleneck enzyme in de novo biosynthesis, quinolinate phosphoribosyltransferase (QPRT), defends renal NAD+ and mediates resistance to acute kidney injury (AKI). Following murine AKI, renal NAD+ fell, quinolinate rose, and QPRT declined. QPRT+/- mice exhibited higher quinolinate, lower NAD+, and higher AKI susceptibility. Metabolomics suggested an elevated urinary quinolinate/tryptophan ratio (uQ/T) as an indicator of reduced QPRT. Elevated uQ/T predicted AKI and other adverse outcomes in critically ill patients. A phase 1 placebo-controlled study of oral NAM demonstrated a dose-related increase in circulating NAD+ metabolites. NAM was well tolerated and was associated with less AKI. Therefore, impaired NAD+ biosynthesis may be a feature of high-risk hospitalizations for which NAD+ augmentation could be beneficial.

[Succinic acid infusions for correction of renal ischemia in patients with acute purulent pyelonephritis].

The activity of lactate dehydrogenase (LDG), malate dehydrogenase (MDG), concentrations of lactic acid and lipid peroxidation (LPO) products in the blood serum and urine were estimated in 119 patients with acute pyelonephritis (70 cases of serous and 49 cases of purulent). The results of the study showed that acute pyelonephritis patients have activated anaerobic glycolysis. Ischemia leads to accumulation of lactic acid, activation of LPO. Significant differences between the groups of patients reflect strong influence of renaltissue ischemia on activity of systemic metabolic processes and metabolism in renal parenchyma. Standard infusion therapy was given to 30 patients with acute purulent pyelonephritis. 19 patients received solution of succinic acid reamberin. On day 4 of reamberin therapy plasma and urine activity of LDG and MDG attenuated, lactic acid concentration decreased, content of dienic conjugates was close to normal. Patients on reamberin treatment exhibited earlier relief of endogenic intoxication and improvement of blood count. Thus, succinic acid drugs reduce renal ischemia, improve a course of postoperative period in patients with acute purulent pyelonephritis.

Megalin dependent urinary cystatin C excretion in ischemic kidney injury in rats.

BACKGROUND: Cystatin C, a marker of kidney injury, is freely filtered in the glomeruli and reabsorbed by the proximal tubules. Megalin and cubilin are endocytic receptors essential for reabsorption of most filtered proteins. This study examines the role of these receptors for the uptake and excretion of cystatin C and explores the effect of renal ischemia/reperfusion injury on renal cystatin C uptake and excretion in a rat model. METHODS: Binding of cystatin C to megalin and cubilin was analyzed by surface plasmon resonance analysis. ELISA and/or immunoblotting and immunohistochemistry were used to study the urinary excretion and tubular uptake of endogenous cystatin C in mice. Furthermore, renal uptake and urinary excretion of cystatin C was investigated in rats exposed to ischemia/reperfusion injury. RESULTS: A high affinity binding of cystatin C to megalin and cubilin was identified. Megalin deficient mice revealed an increased urinary excretion of cystatin C associated with defective uptake by endocytosis. In rats exposed to ischemia/reperfusion injury urinary cystatin C excretion was increased and associated with a focal decrease in proximal tubule endocytosis with no apparent change in megalin expression. CONCLUSIONS: Megalin is essential for the normal tubular recovery of endogenous cystatin C. The increase in urinary cystatin C excretion after ischemia/reperfusion injury is associated with decreased tubular uptake but not with reduced megalin expression.

[Effects of alpha-tocopherol on partial functions of the ischemic kidney].

The experiments on 45 rats and 20 rabbits were made to investigate antiischemic efficacy of alpha-tocopherol in respect of various partial functions of the kidneys compared to its antioxidant activity. It is demonstrated that administration of alpha-tocopherol prior to 30-min heat ischemia arrests activation of membrane lipid peroxidation (LPO) in the tissue of ischemic kidney both in rabbits and rats. Rabbit filtration renal function 1 hour after circulation recovery improved insignificantly, 24 hours after the recovery no difference with the control was registered, while secretory and reabsorption functions of the renal tubules under conditions of pretreatment with alpha-tocopherol significantly improved both in rabbits and rats both 1 hour and 24 hours after ischemia. Estimation of Ca-ATP activity of a microsomal fraction of the cortical substance of the ischemic kidneys has detected alpha-tocopherol induced suppression of LPO in sub-cellular membrane and high activity of this enzyme. Mechanisms of different protective action of alpha-tocopherol on renal glomeruli and tubules are discussed.

Renal function and cortical (Na(+)+K(+))-ATPase activity, abundance and distribution after ischaemia-reperfusion in rats.

The effects of ischaemic injury and reperfusion on renal function, cortical ATP content, alkaline phosphatase activity and (Na(+)+K(+))-ATPase activity and abundance in cortical homogenates and isolated basolateral and apical membranes were examined. Rats were submitted to 5 or 40 min of right renal artery occlusion and 60 min of reperfusion. Renal function of the ischaemic-reperfused kidney was studied by conventional clearance techniques. Our results show that 1 h of reperfusion after a short period of renal ischaemia (5 min) allows the complete restoration of the biochemical features of cortical cells and functional properties of the injured kidney. A longer period of ischaemia, such as 40 min, followed by 1 h of reperfusion showed functional and biochemical alterations. ATP recovered from 26% after 40 min of ischaemia to 50% of control values after 1 h reperfusion. However, renal function was strongly impaired. Brush border integrity was compromised, as suggested by AP excretion and actin appearance in urine. Although total cortical (Na(+)+K(+))-ATPase activity was not different from controls, its distribution in isolated apical and basolateral membranes was abnormal. Remarkably, we detected an increase in alpha-subunit protein abundance that may suggest that (Na(+)+K(+))-ATPase synthesis is promoted by ischaemia-reperfusion. This increase may play an important role in the pathophysiology of ischaemic acute renal failure.