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Background: Subtotal nephrectomy (5/6 nephrectomy) is one of the most widely used animal models for modifying chronic kidney disease. Animal models of kidney disease play an important role to understand pathophysiology, progressivity, and therapies for the disease. The development of animal models that mimic the conditions in human disease is still a challenge. Methods: We conducted a systematic search in the main biomedical databases MEDLINE (PubMed) and the Directory of Open Access Journals (DOAJ)Conclusion: The subtotal nephrectomy procedure is a good model for chronic kidney disease. The kidney damage on this model most closely mimics with kidney damage in humans. This procedure used to remove or destroys 5/6 parts of the kidney, leaving only 1/3 of the kidney mass. There are variations to this procedure. Variations included in the type of incision, the location of the uninephrectomy, the type of ligase/ablation, the operation stage (one or two steps), the length of time between 2 operating procedures, the length of time for observation, and the type of animal used. Variations procedure in subtotal nephrectomy model have different effects on biochemical parameters, morphology, and markers of kidney damage.

Tubuloglomerular feedback (TGF) responses become anomalous in rats fed high-NaCl diet after subtotal nephrectomy (STN), such that stimulating TGF causes single nephron GFR (SNGFR) to increase rather than decrease. Micropuncture experiments were performed to determine whether this anomaly results from heightened nitric oxide response to distal delivery, which is a known mechanism for resetting TGF, or from connecting tubule TGF (cTGF), which is a novel amiloride-inhibitable system for offsetting TGF responses. Micropuncture was done in Wistar Froemter rats fed high-NaCl diet (HS) for 8–10 days after STN or sham nephrectomy. TGF was manipulated by orthograde microperfusion of Henle’s loop with artificial tubular fluid with or without NOS inhibitor, LNMMA, or the cell-impermeant amiloride analog, benzamil. SNGFR was measured by inulin clearance in tubular fluid collections from the late proximal tubule. TGF responses were quantified as the increase in SNGFR that occurred when the perfusion rate was reduced from 50 to 8 nl/min in STN or 40 to 8 nl/min in sham animals. The baseline TGF response was anomalous in STN HS (−4 ± 3 vs 14 ± 3 nl/min, P < 0.001). TGF response was normalized by perfusing STN nephron with LNMMA (14 ± 3 nl/min, P < 0.005 for ANOVA cross term) but not with benzamil (−3 ± 4 nl/min, P = 0.4 for ANOVA cross term). Anomalous TGF occurs in STN HS due to heightened effect of tubular flow on nitric oxide signaling, which increases to the point of overriding the normal TGF response. There is no role for cTGF in this phenomenon.

Objective: This study aims to assess the condition of cardiac histopathology through hematoxylin-eosin staining in 5/6 subtotal nephrectomyconditions.Methods: Fifteen male Swiss mice aged 3–5 months will be grouped into 3 treatment groups, namely the nephrectomy group (JSN, n=5), shamoperation (JSO, n=5), and simvastatin 20 mg/kg body weight (JSIM, n=5). The histopathology of the heart will be assessed blindly. Severity is assessedbased on scoring using a scale (−) no damage, (+) mild, (++) medium, and (+++) heavy. Assessment of severity refers to the irregularity of the heartmuscle, increased amount of connective tissue, myofibril hypertrophy, myofibril swelling, sarcoplasmic fragmentation, sarcoplasmic vacuolization,bleeding in a myofibril, myofibril degeneration, cardiomyocyte damage, and the presence of acidophilic cytoplasm.Results: The results showed no morphological changes in heart muscle tissue in the JSO group except for fragmentation and vacuolization in minimalamounts of sarcoplasm (+), whereas in the JSN and JSIM groups, there was moderate damage to sarcoplasm (++) and minimal changes in myofibrils(hypertrophy and bleeding) (+). The JSN group also found severe damage (+++) to the irregularity of the heart muscle, whereas in JSIM, only moderatedamage was found (++) to the irregularity of the heart muscle.Conclusion: Simvastatin seems to be able to correct the irregularity of the heart muscle in the condition of 5/6 subtotal nephrectomy.

Objectives The purpose of this preclinical study was to investigate whether moderate chronic kidney disease is a factor in potentiating gadolinium (Gd) uptake in the brain. Materials and Methods A comparative study was performed on renally impaired (subtotal nephrectomy) rats versus rats with normal renal function. The animals received 4 daily injections of 0.6 mmol Gd/kg a week for 5 weeks (cumulative dose of 12 mmol Gd/kg) of gadodiamide or saline solution. The MR signal enhancement in the deep cerebellar nuclei was monitored by weekly magnetic resonance imaging examinations. One week after the final injection, the total Gd concentration was determined by inductively coupled plasma mass spectrometry in different regions of the brain including the cerebellum, plasma, cerebrospinal fluid, parietal bone, and femur. Results After the administration of gadodiamide, the subtotal nephrectomy group presented a significantly higher T1 signal enhancement in the deep cerebellar nuclei and a major increase in the total Gd concentration in all the studied structures, compared with the normal renal function group receiving the same linear Gd-based contrast agent. Those potentiated animals also showed a pronounced hypersignal in the choroid plexus, still persistent 6 days after the last injection, whereas low concentration of Gd was found in the cerebrospinal fluid (

Xanthogranulomatous pyelonephritis (XGPN) is a rare, chronic disease characterized by the destruction of renal parenchyma and replacement with granulomatous tissue and is associated with long-term obstructive uropathy, chronic renal parenchymal infection, and nephrolithiasis. A 57-year-old patient with XGPN was unable to undergo total nephrectomy. Renal artery embolization (RAE) was performed post subtotal nephrectomy as adjunct therapy to prevent urine formation and decrease the risk of post-operative infection. Our case report demonstrates that RAE can be performed safely and effectively without evident complications and underscores the utility of cone-beam computed tomography in cases of altered post-surgical anatomy. To the author’s knowledge, this is the second case in the literature demonstrating perioperative management of XGPN with RAE.

New Findings What is the central question of this study? Urotensin II is upregulated in patients in the later stages of chronic kidney disease (CKD), particularly in individuals requiring dialysis. Could treatment with a urotensin II receptor antagonist slow progression of renal disease? What is the main finding and its importance? In the rat, expression of urotensin II and its receptor increased, extending into cortical structures as CKD progressed towards end‐stage renal failure. Subchronic treatment with a urotensin receptor antagonist slowed but did not prevent progression of CKD. This suggests that urotensin II contributes to the decline in renal function in CKD. Abstract Elevated serum and urine urotensin II (UII) concentrations have been reported in patients with end‐stage chronic kidney disease (CKD). Similar increases in UII and its receptor, UT, have been reported in animal models of CKD, but only at much earlier stages of renal dysfunction. The aim of this study was to characterize urotensin system expression as renal disease progresses to end‐stage failure in a ⅚ subtotal nephrectomy (SNx) rat model. Male Sprague–Dawley rats underwent SNx or sham surgery and were killed at 8 weeks postsurgery [early (E)] or immediately before end‐stage renal failure [30 ± 3 weeks postsurgery; late (L)]. Systolic blood pressure, urinary albumin:creatinine ratio and glomerulosclerosis index were all increased in SNx‐E rats compared with sham‐E by 8 weeks postsurgery. These changes were associated with an increase in renal immunoreactive UII staining but little change in UT expression. As CKD progressed to end‐stage disease in the SNx‐L group, markers of renal function deteriorated further, in association with a marked increase in immunoreactive UII and UT staining. Subchronic administration of a UT antagonist, SB‐611812, at 30 mg kg−1 day−1 for 13 weeks, in a separate group of SNx rats resulted in a 2 week delay in the increase in both systolic blood pressure and urinary albumin:creatinine ratio observed in vehicle‐treated SNx but did not prevent the progression of renal dysfunction. The urotensin system is upregulated as renal function deteriorates in the rat; UT antagonism can slow but not prevent disease progression, suggesting that UII plays a role in CKD.

Background Left ventricular hypertrophy (LVH) increases the risk of death in chronic kidney disease (CKD). The transcription factor Kruppel-like factor 15 (KLF15) is expressed in the heart and regulates cardiac remodelling through inhibition of hypertrophy and fibrosis. It is unknown if KLF15 expression is changed in CKD induced LVH, or whether expression is modulated by blood pressure reduction using angiotensin converting enzyme (ACE) inhibition. Methods CKD was induced in Sprague–Dawley rats by subtotal nephrectomy (STNx), and rats received vehicle (n = 10) or ACE inhibition (ramipril, 1 mg/kg/day, n = 10) for 4 weeks. Control, sham-operated rats (n = 9) received vehicle. Cardiac structure and function and expression of KLF15 were assessed. Results STNx caused impaired kidney function (P

To address the pathophysiological mechanisms underlying chronic kidney disease with comorbid cardiac dysfunction, we investigated renal and cardiac, functional and structural damage when myocardial infarction (MI) was applied in the setting of kidney injury (induced by 5/6 nephrectomy—STNx). STNx or Sham surgery was induced in male Sprague–Dawley rats with MI or Sham surgery performed 4 weeks later. Rats were maintained for a further 8 weeks. Rats (n = 36) were randomized into four groups: Sham+Sham, Sham+MI, STNx+Sham and STNx+MI. Increased renal tubulointerstitial fibrosis (P < 0.01) and kidney injury molecule‐1 expression (P < 0.01) was observed in STNx+MI compared to STNx+Sham animals, while there were no further reductions in renal function. Heart weight was increased in STNx+MI compared to STNx+Sham or Sham+MI animals (P < 0.05), despite no difference in blood pressure. STNx+MI rats demonstrated greater cardiomyocyte cross‐sectional area and increased cardiac interstitial fibrosis compared to either STNx+Sham (P < 0.01) or Sham+MI (P < 0.01) animals which was accompanied by an increase in diastolic dysfunction. These changes were associated with increases in ANP, cTGF and collagen I gene expression and phospho‐p38 MAPK and phospho‐p44/42 MAPK protein expression in the left ventricle. Addition of MI accelerated STNx‐induced structural damage but failed to significantly exacerbate renal dysfunction. These findings highlight the bidirectional response in this model known to occur in cardiorenal syndrome (CRS) and provide a useful model for examining potential therapies for CRS.

Coexistence of chronic kidney disease (CKD) and heart failure (HF) in humans is associated with poor outcome. We hypothesized that preexistent CKD worsens cardiac outcome after myocardial infarction, and conversely that ensuing HF worsens progression of CKD. Subtotally nephrectomized (SNX) or sham-operated (CON) rats were subjected to coronary ligation (CL) or sham surgery in week 9 to realize four groups: CON, SNX, CON + CL, and SNX + CL. Blood pressure and renal function were measured in weeks 8, 11, 13, and 15. In week 16, cardiac hemodynamics and end-organ damage were assessed. Blood pressure was significantly lower in SNX + CL vs. SNX. Despite this, glomerulosclerosis was more severe in SNX + CL vs. SNX. Two weeks after CL, SNX + CL had more cardiac dilatation compared with CON + CL (end-diastolic volume index: 0.28 ± 0.04 vs. 0.19 ± 0.03 ml/100 g body wt; mean ± SD, P < 0.001), although infarct size was similar. During follow-up in SNX + CL, ejection fraction declined. Mortality was only observed in SNX + CL (2 out of 9). In SNX + CL, end-diastolic pressure (18 ± 4 mmHg) and tau (29 ± 9 ms), the time constant of active relaxation, were significantly higher compared with SNX (13 ± 3 mmHg, 20 ± 4 ms; P < 0.01) and CON + CL (11 ± 5 mmHg, 17 ± 2 ms; P < 0.01). The diameter of small arterioles in the myocardium was significantly decreased in SNX + CL vs. CON + CL ( P < 0.01). Urinary excretion of NO metabolites was significantly lower in SNX + CL compared with both CL and SNX. This study demonstrates the existence of more heart and more kidney damage in a new model of combined CKD and HF than in the individual models. Such enhanced damage appears to be separate from systemic hemodynamic changes. Reduced nitric oxide availability may have played a role in both worsened glomerulosclerosis and cardiac diastolic function and appears to be a connector in the cardiorenal syndrome.

In subtotal nephrectomy (SN)- and salt-induced hypertension, calcitonin gene-related peptide (CGRP) plays a compensatory role to attenuate the blood pressure increase in the absence of an increase in the neuronal synthesis and release of this peptide. Therefore, the purpose of this study was to determine whether the mechanism of this antihypertensive activity is through enhanced sensitivity of the vasculature to the dilator actions of this neuropeptide. Hypertension was induced in Sprague-Dawley rats by SN and 1% saline drinking water. Control rats were sham-operated and given tap water to drink. After 11 days, rats had intravenous (drug administration) and arterial (continuous mean arterial pressure recording) catheters surgically placed and were studied in a conscious unrestrained state. Baseline mean arterial pressure was higher in the SN-salt rats (157 ± 5 mmHg) compared with controls (128 ± 3 mmHg). Administration of CGRP (and adrenomedullin) produced a significantly greater dose-dependent decrease in mean arterial pressure in SN-salt rats compared with controls (∼2.0-fold for both the low and high doses). Interestingly, isolated superior mesenteric arterioles from SN-salt rats were significantly more responsive to the dilator effects of CGRP (but not adenomedullin) than the controls (pEC50, SN-salt, 14.0 ± 0.1 vs. control, 12.0 ± 0.1). Analysis of the CGRP receptor proteins showed that only the receptor component protein was increased significantly in arterioles from SN-salt rats. These data indicate that the compensatory antihypertensive effects of CGRP result from an increased sensitivity of the vasculature to dilator activity of this peptide. The mechanism may be via the upregulation of receptor component protein, thereby providing a more efficient coupling of the receptor to the signal transduction pathways.

Chronic kidney disease is associated with higher risk of cardiovascular complication and this interaction can lead to accelerated dysfunction in both organs. Renalase, a kidney‐derived cytokine, not only protects against various renal diseases but also exerts cardio‐protective effects. Here, we investigated the role of renalase in the progression of cardiorenal syndrome (CRS) after subtotal nephrectomy. Sprague–Dawley rats were randomly subjected to sham operation or subtotal (5/6) nephrectomy (STNx). Two weeks after surgery, sham rats were intravenously injected with Hanks' balanced salt solution (sham), and STNx rats were randomly intravenously injected with adenovirus‐β‐gal (STNx+Ad‐β‐gal) or adenovirus‐renalase (STNx+Ad‐renalase) respectively. After 4 weeks of therapy, Ad‐renalase administration significantly restored plasma, kidney and heart renalase expression levels in STNx rats. We noticed that STNx rats receiving Ad‐renalase exhibited reduced proteinuria, glomerular hypertrophy and interstitial fibrosis after renal ablation compared with STNx rats receiving Ad‐β‐gal; these changes were associated with significant decreased expression of genes for fibrosis markers, proinflammatory cytokines and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase components. At the same time, systemic delivery of renalase attenuated hypertension, cardiomyocytes hypertrophy and cardiac interstitial fibrosis; prevented cardiac remodelling through inhibition of pro‐fibrotic genes expression and phosphorylation of extracellular signal‐regulated kinase (ERK)‐1/2. In summary, these results indicate that renalase protects against renal injury and cardiac remodelling after subtotal nephrectomy via inhibiting inflammation, oxidative stress and phosphorylation of ERK‐1/2. Renalase shows potential as a therapeutic target for the prevention and treatment of CRS in patients with chronic kidney disease.

Objective: The objective of this study to investigate the effect of simvastatin on kidney fibrosis in mice with a 5/6 subtotal nephrectomy.Methods: Thirty adults (3 mo old) male Swiss mice were submitted to a 5/6 subtotal nephrectomy and studied after 14 d. Animals were divided into five groups: 5/6 subtotal nephrectomy (SN, n=6), sham operation (SH, n=6), simvastatin 5.2 mg/kg body weight (SIM-1, n=6), simvastatin 10.4 mg/kg body weight (SIM-2, n=6), and simvastatin 20.8 mg/kg body weight (SIM-3, n=6) groups. At sacrifice, kidneys were harvested for morphology (glomerulosclerosis (GS), tubular injury and interstitial fibrosis), immunostaining (α-smooth muscle actin (α-SMA)) and platelet-derived growth factor receptor beta (PDGF-Rβ) and reverse transcriptase-polymerase chain reaction (RT-PCR) (MCP-1, ICAM-1, nephrin, and podocin) analysis.Results: Glomerulosclerosis, tubular injury and interstitial fibrosis in the simvastatin group was significantly lower than SN group (p

We have shown in subtotal nephrectomy (STN), a model of chronic kidney disease, there is increased oxygen consumption (QO2) factored for tubular Na reabsorption (TNa) leading to hypoxia. To demonst...

Remnant nephrons after subtotal nephrectomy (STN) show significant hyperfiltration. We have also shown increased oxygen consumption for tubular Na reabsorption in STN leading to hypoxia. We hypothe...

Glomerulosclerosis and progression: Effect of subantihypertensive doses of α and βblockers. Background Uremia is characterized by inadequately increased sympathetic activity. Sympathetic overactivity is involved in the genesis of hypertension in uremia, but its potential role on progression has not been well investigated. To address this issue, the effect of subantihypertensive doses of an α blocker and a βblocker, and their combination on renal morphology and on albuminuria were investigated in the model of the subtotally nephrectomized rat. Methods Male Sprague-Dawley rats were subjected to surgical ablation (SNX) or sham operation (sham). Three days after surgery groups were treated either with phenoxybenzamine (PBZ, 5 mg/kg body weight/day), metoprolol (MET, 150 mg/kg body weight/day) or their combination (PBZ 2.5 mg/kg body weight/day + MET, 50 mg/kg body weight/day). Renal morphology was evaluated after 12 weeks by quantitative histology, immunohistochemistry, and electron microscopy. Urine albumin excretion and kidney endothelin-1 (ET-1), platelet-derived growth factor (PDGF), and transforming growth factor-β(TGF-β) mRNA expression were assessed. Results Systolic blood pressure was significantly higher in all SNX groups compared with sham-operated controls with no difference in the SNX groups. The number of glomeruli per left kidney was reduced from 30,904 ± 3212 to 17,480 ± 2341 by SNX (-43.5%). Mean glomerular volume increased from 2.63 ± 0.7 in untreated sham operated to 4.11 ± 0.48 μm 3 × 10 6 in untreated SNX (56.3%). The glomerulosclerosis index did not change in SNX + PBZ rats, but was significantly lower in SNX + MET (0.56 ± 0.14) and particularly SNX + PBZ + MET rats (0.49 ± 0.11) than in untreated SNX (0.74 ± 0.24). Glomerular capillary length density (L V ) as a sensitive index of capillary obliteration was significantly lower in SNX and almost normalized in the three intervention groups. The same was true for the mean podocyte number per glomerulus. Glomerular ultrastructure in SNX was largely preserved by all treatments. The albumin excretion rate was significantly higher in untreated SNX than in sham; it was significantly lower in all treated SNX groups. Conclusion The beneficial effect of non-hypotensive doses of α and βblockers and their combination on renal morphology and albuminuria in the model of renal ablation argue for a blood pressure-independent role of sympathetic overactivity in the genesis of progression. In addition, the beneficial effect of adrenergic receptor blockade indicates that a substantial part is not mediated by sympathetic cotransmitters such as adenosine 5′-triphosphate (ATP) and neuropeptide Y (NPY).

Mycophenolate mofetil reduces myofibroblast infiltration and collagen III deposition in rat remnant kidney. Background Myofibroblasts have been shown to play a pivotal role in the synthesis of extracellular matrix components in several animal models of renal fibrosis. The purpose of the present study was to investigate whether mycophenolate mofetil (MMF) reduces interstitial myofibroblast infiltration and collagen III deposition in 5/6 nephrectomized rats. Methods Forty-five Wistar rats underwent 5/6 renal ablation and received by daily oral gavage either vehicle ( N = 20) or MMF ( N = 25) during the 60 days following surgery. Groups of five treated and five untreated rats were killed at two, four, and eight weeks after subtotal nephrectomy. Four untreated and three treated rats were killed at week 12, one month after treatment withdrawal. At the time of sacrifice, proteinuria, plasma, and urine creatinine were determined. Immunohistochemistry was performed on renal tissue for α-smooth muscle actin (α-SMA), a cytoskeletal marker of myofibroblasts, for type III collagen, and for proliferating cell nuclear antigen (PCNA). Moreover, in order to study the in vitro effects of MMF on fibroblast proliferation, rat fibroblasts were cultured in the presence or absence of mycophenolic acid (MPA). Results At all periods studied, MMF treatment improved renal functional parameters and progressively decreased remnant kidney hypertrophy and glomerular volume increment. Proliferating cells in renal tubules, interstitium, and glomeruli, as well as interstitial myofibroblast infiltration and interstitial type III collagen deposition, were also significantly reduced by MMF treatment. In addition, MPA exhibited a dose-dependent inhibitory effect on in vitro proliferation of rat fibroblasts. Conclusion Reduction of interstitial myofibroblast infiltration may be an important event by which MMF significantly prevents renal injury following subtotal renal ablation. Thus, our results suggest that MMF could be useful to limit the progression of chronic renal disease toward end-stage renal failure.

A simple mathematical model is proposed that predicts the dynamics of chronic progressive renal disease. The model consists of coupled linear differential equations formed from three state variables, four control parameters, and three parameters related to initial conditions. All have straightforward physical interpretations. Applied to a population of nephrons, the model predicted the hypertrophic and sclerotic features of parenchyma progressing towards end-stage renal disease. Simulation results compared favorably with measurements obtained from the literature involving the subtotal nephrectomy rat model for renal disease. The time course of disease progression and treatment were considered. Also, the implications of the model for designing new diagnostic techniques using ultrasonic analysis are discussed.

We previously reported internephron heterogeneity in the tubuloglomerular feedback (TGF) response 1 wk after subtotal nephrectomy (STN), with 50% of STN nephrons exhibiting anomalous TGF (Singh P, Deng A, Blantz RC, Thomson SC. Am J Physiol Renal Physiol 296: F1158–F1165, 2009). Presently, we tested the theory that anomalous TGF is an adaptation of the STN kidney to facilitate increased distal delivery when NaCl balance forces the per-nephron NaCl excretion to high levels. To this end, the effect of dietary NaCl on the TGF response was tested by micropuncture in STN and sham-operated Wistar rats. An NaCl-deficient (LS) or high-salt NaCl diet (HS; 1% NaCl in drinking water) was started on day 0 after STN or sham surgery. Micropuncture followed 8 days later with measurements of single-nephron GFR (SNGFR), proximal reabsorption, and tubular stop-flow pressure (PSF) obtained at both extremes of TGF activation, while TGF was manipulated by microperfusing Henle's loop (LOH) from the late proximal tubule. Activating TGF caused SNGFR to decline by similar amounts in Sham-LS, Sham-HS and STN-LS [ΔSNGFR (nl/min) = −16 ± 2, −11 ± 3, −11 ± 2; P = not significant by Tukey]. Activating TGF in STN-HS actually increased SNGFR by 5 ± 2 nl/min ( P < 0.0005 vs. each other group by Tukey). HS had no effect on the PSFresponse to LOH perfusion in sham [ΔPSF(mmHg) = −9.6 ± 1.1 vs. −9.8 ± 1.0] but eliminated the PSFresponse in STN (+0.3 ± 0.9 vs. −5.7 ± 1.0, P = 0.0002). An HS diet leads to anomalous TGF in the early remnant kidney, which facilitates NaCl and fluid delivery to the distal nephron.

Urinary and proximal tubular iron are increased after subtotal nephrectomy, and iron depletion has been shown to be beneficial in proteinuric models of chronic renal disease in rats. In this study, iron depletion by low iron pair-fed diet and periodic phlebotomy was induced for 6 months in rats with partial (5/6) nephrectomy, resulting in a reduction in hematocrit and serum iron in all iron-deficiency subgroups. Tubular iron, assessed by energy dispersive analysis and electron microscopy, was reduced in quantity but not number of iron-containing lysosomes only within 1 subgroup of severe iron deficiency (p0.05). There was no improvement in serial isotopic glomerular filtration rate measurements, urinary protein and transferrin excretion, tubular damage scores, serum creatinine, or measures of reactive oxygen species (ROS) generation. In a subgroup of rats with no supplementation of sulfhydryl amino acids (cysteine and methionine) which can act as ROS scavengers, iron deficiency increased urinary protein excretion (213.3 +/- 23.0 mg/24 h, mean +/- SEM, vs. 87.4 +/- 16.1, p0.001), urinary transferrin excretion (p0.05), kidney weight (p0.05) and tissue malondialdehyde, a lipid peroxidation product (0.78 +/- 0.16 nmol/mg protein vs. 0.57 +/- 0.19, p0.05), consistent with increased ROS generation. Hence, no beneficial effect of iron-deficiency was demonstrated by any measure of structure of function in the remnant kidney, and it may enhance damage if sulfhydryl repletion is not provided.

We are grateful to Csont and Ferdinandy for their letter in response to our recent article.1 We are encouraged by their work, which demonstrated the cardioprotective effect of postconditioning 10 weeks after a subtotal nephrectomy. The 4-week subtotal nephrectomy model is the most widely used model of chronic uremia and displays many of the common characteristics that define the uremic phenotype. The 4-week subtotal nephrectomy model leads to animals that are growth restricted, hypertensive, anemic, dyslipidemic, …

Background: Cardiac events are the main cause of death among patients with end-stage renal failure. Even a mild renal disease is currently considered a major risk factor for cardiovascular complications following myocardial infarction (MI). The aim of the present study was to detect histological, sera and urine characteristics of kidney injury in cardiorenal syndrome (CRS) compared to chronic kidney disease (CKD) with an intact cardiac function. Methods: We employed a rat model for CRS, in which an acute MI (AMI) was induced 4 weeks after establishment of subtotal nephrectomy. Four weeks later, left ventricular function was assessed by echocardiography and changes in renal performance were examined using histological and biochemical parameters. Results: Increased interstitial fibrosis as well as renal inflammation were observed in renal sections derived from CRS rats, compared to subtotal nephrectomy (CKD)-only animals. Moreover, we found that even though AMI on the background of CKD was not associated with a further decrease in creatinine clearance or a further increase in sera BUN levels compared to CKD only, a significant long-term elevation in urine neutrophil gelatinase-associated lipocalin (Ngal) levels was detectable post-MI induction. Conclusions: AMI in the CKD setting is associated with accelerated renal fibrosis and long-term elevated urine Ngal values, suggesting that cardiac dysfunction contributes to accelerated intrinsic kidney injury in CKD. The data indicate that elevated urine Ngal may potentially serve as an early non-invasive laboratory parameter for a left ventricular dysfunction-related renal injury.

This study was designed to examine the potential effect(s) of dietary supplementation with L-arginine on the renal microcirculation of female Munich-Wistar rats with ablation of 60 to 70% of total renal mass. All rats were fed a standard rat chow containing 22.8% protein (1.42% L-arginine). Groups 1 (N = 6) and 3 (N = 7) drank tap water and had micropuncture studies after 5 to 6 or 15 to 16 wk, respectively, of subtotal renal ablation. Groups 2 (N = 5) and 4 (N = 7) drank tap water supplemented with L-arginine (1%) and had micropuncture studies after 5 to 6 or 15 to 16 wk, respectively, of subtotal renal ablation. Glomerular micropuncture studies revealed no differences in any of the parameters of glomerular hemodynamics measured 5 to 6 wk after renal ablation (Groups 1 versus 2). However, by 15 to 16 wk postnephrectomy, values of glomerular capillary pressure and efferent arteriolar resistance were significantly greater and the glomerular capillary ultrafiltration coefficient was significantly lower in rats drinking tap water than in rats drinking tap water supplemented with L-arginine. Single-nephron GFR, single-nephron plasma flow rate, and afferent arteriolar resistance were not different between these two groups. The data suggest that the long-term administration of L-arginine prevents the progression of glomerular sclerosis in rats with subtotal nephrectomy, at least in part, by ameliorating glomerular capillary hypertension.

the purpose of this study was to compare the clinical, pathologic, and biochemical effects of repeated administrations of ionic macrocyclic or nonionic linear gadolinium chelates (GC) in rats with impaired renal function.rats submitted to subtotal nephrectomy were allocated to single injections of 2.5 mmol/kg of gadodiamide (nonionic linear chelate), nonformulated gadodiamide (ie, without the free ligand caldiamide), gadoterate (ionic macrocyclic chelate), or saline for 5 consecutive days. Blinded semi-quantitative histopathologic and immunohistochemical examinations of the skin were performed, as well as clinical, hematological, and biochemical follow-up. Rats were killed at day 11. Long-term (up to day 32) follow-up of rats was also performed in an auxiliary study.epidermal lesions (ulcerations and scabs) were found in 4 of the 10 rats treated with nonformulated gadodiamide. Two rats survived the study period. Inflammatory signs were observed in this group. No clinical, hematological, or biochemical signs were observed in the saline and gadoterate- or gadodiamide-treated groups. Plasma fibroblast growth factor-23 levels were significantly higher in the gadodiamide group than in the gadoterate group (day 11). Decreased plasma transferrin-bound iron levels were measured in the nonformulated gadodiamide group. Histologic lesions were in the range: nonformulated gadodiamide (superficial epidermal lesions, inflammation, necrosis, and increased cellularity in papillary dermis)gadodiamide (small superficial epidermal lesions and signs of degradation of collagen fibers in the dermis)gadoterate (very few pathologic lesions, similar to control rats).repeated administration of the nonionic linear GC gadodiamide to renally impaired rats is associated with more severe histologic lesions and higher FGF-23 plasma levels than the macrocyclic GC gadoterate.

Since the association between nephrogenic systemic fibrosis (NSF) and gadolinium contrast agents (Gd-CAs) was suggested in 2006, several experimental studies have been published to elucidate the role of these agents in the pathogenesis of NSF. Low stability Gd-CAs have a stimulant effect on human skin and fibroblasts in culture and modulate the production of collagen by these cells. Low stability agents have also induced NSF-like skin changes in a rat model with normal renal function after multiple repeat administrations. The role of the 5/6 subtotal nephrectomy rat model in investigating NSF remains under evaluation.

The role of γ-glutamyltransferase (γ-GT) in renal ammoniagenesis, glutamine (Gin), and glutathione (GSH) utilization was evaluated in the intact functioning rat kidney of subtotal nephrectomy (SNX) model of chronic renal failure (CRF). NK+4derived from extracellular γ-GT hydrolysis of Gin and GSH was differentiated from the intramitochondrial phosphate-dependent glutaminase by using acivicin, a γ-GT-specific inhibitor. In the control (C) group Gin extraction accounted for 61% of total NH+4 production (sum of renal venous and urinary NH+4, but only 41% in SNX group. In the SNX group GSH extraction accounted for 10% of total NH+4 production, but only 1% in the C group. Acivicin inhibited 44% and 33% of total NH+4roduction in SNX and C group respectively, as compared to baseline before acivicin. In CRF, γ-GT a key enzyme of the γ-glutamyl cycle plays a significant role in adaptive ammoniagenesis.

Effects of a Japanese medicinal plant named Sairei-To, were examined in a rat experimental renal disease. Thirteen weeks after subtotal nephrectomy, the blood pressures in rats given Sairei-To (Sairei-To rats) were lower that those without Sairei-To. The urinary protein excretions and glomerular sclerosis were markedly decreased in the Sairei-To treated rats. Arteriolar diameters were measured using microvascular casts. The afferent and efferent arterioles were both significantly dilatated. The efferent arterioles in Sairei-To rats were dilated to a greater extent than that of the afferent. These results indicated that Sairei-To lessened renal damages in the rat subtotal nephrectomy model, possibly through the blood pressure reduction and the efferent arteriolar dilatation.

Insulin-like growth factor I (IGF-I) has been proposed as a mediator of kidney scarring, although no interventional studies on the role of IGF-I in models of chronic kidney disease have been reported. The effect of a peptide IGF-I receptor antagonist (JB3) has been examined on kidney fibrosis and function in the rat following 5/6 subtotal nephrectomy (SNx). Male Wistar rats were anesthetized with halothane and subjected to SNx. JB3 was delivered by subcutaneous infusion using Alzet osmotic minipumps. In vitro studies showed JB3 to displace125I-IGF-I binding to isolated rat glomeruli and to inhibit IGF-I-induced receptor phosphorylation in renal tubular cells in culture. In the 7-day SNx rats, IGF-I immunostain was present in collecting tubules and JB3 inhibited compensatory renal growth, the maximum effect occuring at 10 μg·kg−1·day−1. After 90 days, the SNx rats developed proteinuria, hypertension, and a fall in glomerular filtration rate. IGF-I immunostain was present in the tubulointerstitial space of the remnant kidney together with marked tubulointerstitial fibrosis. Treatment with JB3 at a dose of 10 μg·kg−1·day−1had no effect on the renal fibrosis measured by Masson's trichrome staining or immunostain for collagen III and collagen IV. The proteinuria, hypertension, and lower creatinine clearance all remained unchanged. The remnant kidney was associated with a 50% decrease in renal IGF-I mRNA, which was partially restored by treatment with JB3. Thus an interventional study with an IGF-I receptor antagonist does not support a role for IGF-I in the development of renal fibrosis in the SNx rat, although IGF-I does make an important contribution to compensatory kidney growth.

Induction of MIF synthesis and secretion by tubular epithelial cells: A novel action of angiotensin II. Background Angiotensin II (Ang II) plays an important role in the development of renal injury through its vasoactive and proinflammatory activities. We investigated whether some of the effects of Ang II could be mediated through the production of macrophage migration inhibitory factor (MIF). Methods Groups of rats underwent sham surgery (sham), subtotal nephrectomy (STNx), or STNx plus treatment with irbesartan. Renal tissue was examined 12 weeks postsurgery for MIF mRNA expression and leukocyte accumulation. To determine whether Ang II had a direct effect on MIF production, mRNA synthesis and protein secretion were examined in proximal tubular epithelial (NRK52E and MCT) cell lines. Results MIF mRNA was strongly expressed in 5.4%± 1.1% (mean ± SD) of cortical tubules of sham-operated rats. This was significantly up-regulated in STNx rats (44.9%± 22.6%) and was abrogated by administration of irbesartan (2.8%± 2.4%). STNx resulted in significant glomerular and interstitial accumulation of macrophages and T cells, which correlated with glomerular and tubular MIF mRNA expression, respectively. In vitro studies of tubular epithelial cells revealed that Ang II caused a twofold increase in MIF mRNA expression in NRK52E and MCT cells, which was abrogated by irbesartan. In addition, Ang II induced a rapid release of 50% of MIF protein from NRK52E cells within 20 minutes. Conclusion This study has demonstrated that Ang II up-regulates MIF mRNA production and MIF protein secretion by tubular epithelial cells. Ang II may promote accumulation and activation of interstitial leukocytes via induction of MIF synthesis and secretion in renal tubular epithelial cells. This may be an important mechanism by which Ang II mediates renal injury.

Different mitogens are involved in the pathogenesis of kidney damage after subtotal nephrectomy. One of them, TGF-beta, controls mesangial cell proliferation and interstitial fibrosclerosis. The transduction of the TGF-beta signal is controlled by intracellular signalling molecules such as Ras G monomeric proteins. Renal damage after subtotal nephrectomy (5/6 Nx) can be prevented by heparins, but so far no immunohistochemical correlation between TGF-beta, TGF-beta induced matrix molecules and Rho proteins has been investigated. Since the Ras transduction pathway has recently been associated with progression of renal damage, we evaluated the effect of heparan sulphate (HS) on the expression of TGF-beta, laminin, fibronectin and a Ras protein, RhoA, in the rat remnant kidney model.The immunoperoxidase technique was employed to reveal the antigens on 18 remnant kidneys from 5/6 nephrectomized rats, nine untreated and nine treated with oral HS, and on seven normal kidneys from sham-operated rats. Data were semiquantitatively analyzed by an image analyzer (Quantimet, Leica).The expression of the antigens was significantly higher in the remnant kidneys than in normals. The high TGF-beta, laminin, fibronectin and RhoA expression observed in subtotally nephrectomized rats suggests a role for these molecules in the pathogenesis of progressive renal damage. However, apart from RhoA, HS-treated rats had significantly lower levels of the antigens than the untreated rats.HS treatment is associated with significantly lower renal expression of TGF-beta, laminin and fibronectin, but not of RhoA. This suggests that the renal-protective effect of HS may be obtained by modulating the TGF-beta pathway, independently of RhoA-mediated transduction.

Clinical and experimental evidence has indicated that chronic renal failure (CRF) is related to increased free radical production. CRF patients show increased lipid peroxidation after a progressive reduction in vitamin E, one of the most important antioxidants. In the present study the role of vitamin E deficiency in lipid peroxidation was investigated in rats submitted to subtotal nephrectomy. Male Wistar rats were divided into groups receiving different diets for a period of 45 days: SND - sham rats submitted to a regular diet containing vitamin E; ERD nephrectomized rats submitted to a regular diet containing vitamin E; SDD - sham rats submitted to a vitamin E-deficient diet; EDD nephrectomized rats submitted to a vitamin E-deficient diet. After 30 days the Experimental animals were submitted to 5/6 nephrectomy and the Controls were submitted to sham operation. The vitamin E levels of the SDD and EDD groups were significantly reduced (p0.05) in plasma (4.92 +/- 1.22 and 8.37 +/- 2.09 mmol/L, respectively), liver (7.57 +/- 2.72 and 9.44 +/- 2.55mg/g tissue, respectively) and kidney (8.17 +/- 2.38 and 9.40 +/- 3.10 mg/g tissue, respectively) when compared to the SRD and ERD groups. In contrast, in the EDD group the levels of thiobarbituric acid-reactive substances, expressed as nmol/mg protein, were significantly increased (p0.05) in the liver (1.41 +/- 0.27) and kidney (1.67 +/- 0.47), and superoxide dismutase activity was significantly increased in the erythrocytes (4455.80 +/- 1322.63 Ug/Hb) compared to all other groups. The vitamin E-deficient diet associated with subtotal nephrectomy determined an increase in lipid peroxidation, suggesting an important role of free radicals in the development of chronic renal failure.

To clarify the role of brain ouabain-like compound in reduced renal mass-saline hypertension, we examined the effects of intracerebroventricular infusion of the Fab fragments of antidigoxin antibody (Digibind) on the change in blood pressure of saline-drinking subtotally nephrectomized rats. Twenty male Wistar rats weighing 250 g each underwent subtotal nephrectomy. Two groups of 10 rats received intracerebroventricular infusion of Digibind (20 mg/ml) or normal sheep IgG (20 mg/ml) at a rate of 0.5 microliters/h for 11 days. All rats began to drink 1% NaCl solution after two days of infusion. Systolic blood pressure was measured by the tail-cuff method on days 2, 6 and 9 of infusion. Two groups of saline-drinking rats with reduced renal mass developed hypertension. However, systolic blood pressure was significantly higher in Digibind-infused rats than in IgG-infused rats (day 2, 144 +/- 3(SEM) vs. 133 +/- 1 mmHg, p < 0.05; day 6, 161 +/- 4 vs. 151 +/- 2 mmHg, 0.05 < p < 0.1, day 9, 181 +/- 8 vs. 155 +/- 2 mmHg, p < 0.05). In spite of similar renal dysfunction, plasma aldosterone concentrations, and plasma OLC levels, the accelerated increase in blood pressure was accompanied by a significantly impaired pressure-natriuresis relationship (0.089 +/- 0.013 vs. 0.131 +/- 0.013 mmol/day/mmHg, p < 0.05). These results indicate that chronic intracerebroventricular infusion of Digibind augmented reduced renal mass-saline hypertension in rats and suggest that brain ouabain-like compound may play a protective role against the elevation of blood pressure, at least in this model of hypertension.

Ouabainlike compound (OLC) has recently been identified as a likely mammalian endogenous digitalis-like factor (EDLF) from human plasma. In this study, plasma levels of OLC were determined to assess the role of OLC in a model known as volume-expanded, reduced renal mass (RRM)-saline (S) hypertension in rats with use of a newly developed radioimmunoassay for ouabain. In the first experiment, at 3 wk after subtotal nephrectomy and drinking 1% saline solution, sysolic blood pressure (SBP) of 18 rats with reduced renal mass (RRM-S rats) was significantly higher than in 17 sham-operated saline-drinking control (C-S) rats [154 +/- 4 (SE) vs. 132 +/- 2 mmHg; P < 0.01]. Plasma OLC levels were 355 +/- 68 pmol/l in RRM-S rats, sevenfold higher than in C-S rats (54 +/- 4 pmol/l; P < 0.01). In the second experiment, we measured plasma OLC levels of 10 RRM-S, 12 sham-operated control (C), and 10 subtotally nephrectomized rats drinking distilled water (RRM rats). Concomitant with a marked increase in blood pressure (203 +/- 5 mmHg), RRM-S rats showed significantly higher plasma OLC levels compared with C and RRM rats (RRM-S 114 +/- 24, C 47 +/- 11, and RRM 52 +/- 9 pmol/l; P < 0.05). In both experiments, plasma OLC levels correlated significantly with SBP (P < 0.05). These findings suggest that plasma OLC shows a similar behavior to that of EDLFs or Na(+)-K(+)-adenosinetriphosphatase inhibitors reported in previous publications and may play a role in hypertensive mechanisms in rats with RRM and excess Na intake.

The changes in muscle mechanical properties caused by the myopathy of chronic uremia was examined in the soleus and the diaphragm muscles of rats in which chronic uremia was produced by subtotal nephrectomy. Using an in vitro muscle preparation in two groups of rats (moderately and severely uremic), we determined that uremia had a significant detrimental effect on both muscles with respect to the force-frequency relationships. In the diaphragm it decreased by 15% in the moderate group and by 43% in the severe group. In the soleus it decreased by 20% in both groups. Twitch characteristics behaved differently in the soleus and the diaphragm muscles in that 1/2 RT and TPT increased significantly (p0.05) in the soleus (severely uremic group) but not in the diaphragm. Fatigability was increased in both muscles in the moderately uremic rats and in the diaphragm in the severely uremic rats; however, the fatigability of the soleus in the severely uremic group was not different from that in the control group. Our findings suggest that the myopathic changes occurring in chronic uremia affects the function of the soleus and the diaphragm in different ways. Other findings in the severely uremic group indicate that additional factors such as marked electrolyte imbalances may also affect the excitation-contraction coupling in different ways.

The accumulation of extracellular matrix (ECM) is an important feature of most forms of progressive glomerular diseases. In order to examine the relationship between ECM synthesis and glomerulosclerosis, we evaluated fibronectin synthesis by glomeruli with the immunoprecipitation of conditioned media from isolated glomeruli in 5/6 nephrectomized spontaneously hypertensive rats (5/6N-SHR). There was no difference in blood pressure between 5/6N-SHR and control SHR throughout the experiment. Two weeks after the nephrectomy, most of the glomeruli were intact and no difference in the synthesis of fibronectin was observed between either groups. Twenty weeks after the nephrectomy, marked glomerulosclerosis associated with an increase in urinary protein was revealed in 5/6N-SHR but no glomerular lesions in control SHR. The synthesis of fibronectin by isolated glomeruli increased in 5/6N-SHR compared to control SHR. The administration of enalapril or hydralazine + reserpine + hydrochlorothiazide markedly attenuated the glomerular sclerosis and urinary protein excretion to a comparable degree, although the later therapy reduced blood pressure more effectively. These antihypertensive therapies also suppressed fibronectin synthesis in the 5/6N-SHR group at week 20. In conclusion, increased synthesis of glomerular fibronectin appeared to contribute to the glomerulosclerosis caused by subtotal nephrectomy and hypertension.

Cardiac hypertrophy of various aetiologies is consistently associated with increased expression of V3 isomyosin. Uraemia is associated with cardiac hypertrophy. In the present study, we examined regulation of isomyosin in uraemic rats, using gel electrophoresis. Cardiac hypertrophy in uraemic animals was associated with a relative increase in V1 isomyosin. An increased proportion of V1 isomyosin was demonstrable 3 days after subtotal nephrectomy (NX 63.0 +/- 8.8%; control 43.6 +/- 7.2%; P less than 0.01) and persisted during uraemia of 80 days duration. Elevation of V1 isomyosin, relative to pair-fed controls, was observed in uraemic animals of various age. The proportion of V1 isomyosin changed in the same direction as controls when several manouevers were used which changed the isomyosin pattern, but the difference between uraemic animals and controls persisted. We studied the effect of carbohydrate loading or deprivation, starvation or administration of energetically inadequate diets, castration or administration of androgens and sodium depletion. With each of the above interventions, a difference between subtotally nephrectomized animals and sham-operated pair-fed control animals was statistically significant (P less than 0.05). Elevation of V1 isomyosin persisted during combined alpha and beta blockade and was still found when blood pressure was normalized by ACE inhibition using Ramipril. It is concluded that cardiac hypertrophy of uraemia differs from all other forms of cardiac hypertrophy by the occurrence of increased proportion of V1 isomyosin. The proportion of V1 isomyosin responds adequately to regulatory signals but is set at an abnormally high level.

Early studies by Pitts demonstrated that protein intake (meat meal) or intravenous administration of amino acid (glycine) to dogs were associated with significant increases in glomerular filtration rate (GFR) and renal plasma flow (RPF) (1, 2). Variations in daily protein intake are also capable of modifying GFR and RPF in both man and experimental animals, with increments in GFR and RPF paralleling the increase in quantity of protein (1–3). Although the acute and chronic effects of protein loading on renal function have been established for nearly 50 years, it is not until recently that major interest has accumulated with respect to the potential role of protein in the progression of renal disease. Pioneer work by Hostetter et al (4) demonstrated in a model of radical subtotal nephrectomy in rats that increased protein intake was associated with hyperfiltration secondary to glomerular hypertension and hyperperfusion. Reducing protein intake in this experimental model decreased hyperfiltration and prevented albuminuria and glomerular sclerosis. Further studies in different experimental models, which include streptozotocininduced diabetes mellitus, hypertension and partial renal ablation, confirmed previous findings by Hostetter et al and supported the concept that hyperfiltration may play an important role in the progression of kidney disease (5–7). The presence of hyperfiltration in experimental models led many investigators to evaluate the role of hyperfiltration as a mechanism for progression of renal disease in man. Normal pregnancy, early stages of insulin-dependent diabetes mellitus and sickle cell disease are a few clinical conditions associated with absolute increases in GFR (8–10). Since most patients with renal disease have normal or low values of GFR, it is impossible to detect the presence of hyperfiltration by evaluation of absolute GFR values under normal conditions.