Increased expression of (pro)renin receptor in the remnant kidneys of 5/6 nephrectomized rats

Recent studies have revealed that (pro)renin receptor ((P)RR), a newly identified member of the renin–angiotensin system, is associated with renal organ damage. However, there is little information regarding the regulation of (P)RR expression in various pathophysiological conditions. We therefore examined the expression of (P)RR in the remnant kidneys of rats with renal mass ablation due to 5/6 nephrectomy by quantitative RT-PCR, Western blot analysis and immunohistochemistry. Expression levels of (P)RR mRNA were significantly increased in the remnant kidneys at day 56 after nephrectomy, when compared with sham operation (about 1.6-fold, P = 0.001). Western blot analysis showed that expression levels of (P)RR protein were greatly increased in the remnant kidneys at day 56, compared with sham operation (about 7.9-fold, P = 0.02). The renal tubular cells were immunostained with anti-(P)RR antibody in both 5/6 nephrectomized rats and sham operated rats. The glomeruli were sporadically immunostained in 5/6 nephrectomized rats, but not in sham operated rats. These findings indicate that the intra-renal (P)RR expression is increased in the remnant kidneys of 5/6 nephrectomized rats, and suggest that (P)RR may contribute to the renal injury.     

The Impacts of Albuminuria and Low eGFR on the Risk of Cardiovascular Death,All-Cause Mortality,and Renal Events in Diabetic Patients: Meta-Analysis

Background

Precise effects of albuminuria and low estimated glomerular filtration rate (eGFR) on cardiovascular mortality, all-cause mortality, and renal events in diabetic patients are uncertain.

Materials and Methods

A systematic review was conducted of the literature through MEDLINE, EMBASE, and CINHAL from 1950 to December 2010. Cohort studies of diabetic patients providing adjusted relative risk (RR) of albuminuria and eGFR for risks of cardiovascular mortality, all-cause mortality, and renal events were selected. Two reviewers screened abstracts and full papers of each study using standardized protocol.

Results

We identified 31 studies fulfilling the criteria from 6546 abstracts. With regard to the risk of cardiovascular mortality, microalbuminuria (RR 1.76, 95%CI 1.38–2.25) and macroalbuminuria (RR 2.96 95%CI 2.44–3.60) were significant risk factors compared to normoalbuminuria. The same trends were seen in microalbuminuria (RR 1.60, 95%CI 1.42–1.81), and macroalbuminuria (RR 2.64, 95%CI 2.13–3.27) for the risk of all-cause mortality, and also in microalbuminuria (RR 3.21, 95%CI 2.05–5.02) and macroalbuminuria (RR 11.63, 95%CI 5.68–23.83) for the risk of renal events. The magnitudes of relative risks associated with low eGFR along with albuminuria were almost equal to multiplying each risk rate of low eGFR and albuminuria. No significant factors were found by investigating potential sources of heterogeneity using subgroup analysis.

Conclusions

High albuminuria and low eGFR are relevant risk factors in diabetic patients. Albuminuria and low eGFR may be independent of each other. To evaluate the effects of low eGFR, intervention, or race, appropriately designed studies are needed.     

Asymmetrical (ADMA) and symmetrical dimethylarginine (SDMA) as potential risk factors for cardiovascular and renal outcome in chronic kidney disease – possible candidates for paradoxical epidemiology?

Summary. Background: Asymmetrical dimethylarginine (ADMA) is an inhibitor of nitric-oxide synthase. It has been linked to atherosclerotic risk in the general population as well as in end-stage renal disease patients (ESRD), whereas symmetrical dimethylarginine (SDMA) is thought to be biological inactive. Prospective data concerning the role of both dimethylarginines are rare in patients with chronic kidney disease. Methods: 200 patients with chronic kidney disease (mean age 57.6 ± 13.0 years, 69 female, 131 male); 82 with chronic renal failure (CRF), 81 on maintenance haemodialysis (HD) and 37 renal transplant recipients (RTR) were prospectively followed for 24 months. ADMA and SDMA were measured by HPLC. The relation of plasma levels of ADMA and SDMA together with conventional risk factors for the cardiovascular and renal outcome was investigated with Cox proportional hazards model. Results: Mean serum levels of SDMA were significantly increased in all groups compared to the control group (P ≤ 0.0005), ADMA was increased only in HD and RTR (P ≤ 0.004). Forty-seven cardiovascular events (CVE) occurred during follow-up, 35 patients died, and 39 patients reached ESRD. Multivariate analysis showed diabetes (RR 3.072, P = 0.01), ESRD (RR 11.915, P < 0.0005), elevated CRP levels (RR 3.916, P < 0.0005) and surprisingly a lower ADMA level (RR 0.271, P = 0.008) as independent risk factors for CVE. Serum creatinine (RR 11.378, P = 0.001), haemoglobin (RR 0.710, P = 0.038 for an increment of 1 mmol/l), and SDMA levels (RR 1.633, P = 0.006, per 1 μmol/l increment) were predictors for the progression to ESRD. Conclusions: Data from a heterogeneous group of patients with chronic kidney disease provide evidence that conventional risk factors seem to play a more important role than elevated serum levels of ADMA or SDMA for cardiovascular events. Increasing serum SDMA concentration seems to play an additive role for the renal outcome besides serum creatinine and haemoglobin levels. Whether ADMA might possibly be a candidate for the phenomenon of “paradoxical epidemiology” in chronic kidney disease needs further investigation.     

The Dose-Dependent Effect of Nesiritide on Renal Function in Patients with Acute Decompensated Heart Failure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Conflicting renal effects of nesiritide have been reported in patients with acute decompensated heart failure. To answer this controversy, we performed a meta-analysis of randomized controlled trials to evaluate the influence of nesiritide on renal function in patients with acute decompensated heart failure.

Methods

Articles were obtained from PubMed, Medline, Cochrane Library and reference review. Randomized controlled studies that investigated the effects of continuous infusion of nesiritide on renal function in adult patients with acute decompensated heart failure were included and analyzed. Fixed-effect model was used to estimate relative risk (RR) and weight mean difference (WMD). The quality assessment of each study, subgroup, sensitivity, and publication bias analyses were performed.

Results

Fifteen randomized controlled trials were eligible for inclusion. Most of included studies had relatively high quality and no publication bias was found. Overall, compared to control therapies, nesiritide might increase the risk of worsening renal function in patients with acute decompensated heart failure (RR 1.08, 95% CI 1.01–1.15, P = 0.023). In subgroup analysis, high-dose nesiritide strongly associated with renal dysfunction (RR 1.54, 95% CI 1.19-2.00, P = 0.001), but no statistical differences were observed in standard-dose (RR 1.04, 95% CI 0.98-1.12, P = 0.213), low-dose groups (RR 1.01, 95% CI 0.74-1.37, P = 0.968) and same results were identified in the subgroup analysis of placebo controlled trials. Peak mean change of serum creatinine from baseline was no significant difference (WMD -2.54, 95% CI -5.76-0.67, P = 0.121).

Conclusions

In our meta-analysis, nesiritide may have a dose-dependent effect on renal function in patients with acute decompensated heart failure. High-dose nesiritide is likely to increase the risk of worsening renal function, but standard-dose and low-dose nesiritide probably have no impact on renal function. These findings could be helpful to optimize the use of nesiritide in clinical practice.     

Hemoglobin Targets for Chronic Kidney Disease Patients with Anemia: A Systematic Review and Meta-analysis

Background

Numerous studies have identified a relationship between hemoglobin (Hb) levels and mortality in patients with chronic kidney disease (CKD), which have raised concerns about the optimal Hb targets in correction of anemia. Our study is designed to investigate the potential effects of targeted Hb levels, aiming to give some evidence for therapy of renal anemia.

Methodology/Principal Findings

A comprehensive search of Medline, Embase and the Cochrane Database of Systematic Reviews was performed in December 2011 and updated in February 2012 for any new trials. Randomized trials designed to evaluate effects of high (generally the Hb about 13.0 g/dL) and low Hb (generally the Hb about 10.0 g/dL) targets on clinical outcomes in CKD patients with anemia were collected. All statistical analysis was calculated using the RevMan software available free from the Cochrane Collaboration. 24 trials involving 10361 patients were identified. Our findings demonstrated a statistically significant increased risk of mortality in the high Hb levels (RR 1.18; 95% CI 1.02 to 1.37) while the high and low Hb groups were both treated with ESAs. Overall, compared with low Hb levels, high Hb levels are associated with increased risk of hypertension (RR 1.40; 95% CI 1.11 to 1.75), stroke (RR 1.73; 95% CI 1.31 to 2.29), and hospitalizations (RR 1.07; 95% CI 1.01 to 1.14). However, there are no significant differences in the risk of non-fatal myocardial infarction (RR 1. 13; 95% CI 0.79 to 1.61) and renal replacement therapy (RR 1. 00; 95% CI 0.85 to 1.18).

Conclusions/Significances

Targeting low Hb levels are beneficial to CKD patients especially in the predialysis population. The optimal Hb targets to aim for in CKD patients and at what Hb level the risks of adverse events begin to increase remain elusive. Future studies are still needed to elucidate these questions.     

Regulation of the (pro)renin-renin receptor in cardiac remodelling

The (pro)renin-renin receptor [(P)RR] was discovered as an important novel component of the renin-angiotensin system (RAS). The functional significance of (P)RR is widely studied in renal and vascular pathologies and has sparked interest for a potential role in cardiovascular disease. To investigate the role of (P)RR in cardiac pathophysiology, we aimed to assess (P)RR regulation in adverse cardiac remodelling of the failing heart. In particular, we evaluated the expression of (P)RR in different models of heart failure and across different species. Significantly increased levels of (P)RR mRNA were found in post-myocardial infarcted (MI) hearts of rats (1.6-fold, P < 0.05) and mice (5-fold, P < 0.01), as well as in transgenic rats with overexpression of the mouse renin gene (Ren2) (2.2-fold, P < 0.01). Moreover, we observed a strong increase of (P)RR expression in hearts of dilated cardiomyopathy (DCM) patients (5.3-fold, P < 0.001). Because none of the tested commercially available antibodies appeared to detect endogenous (P)RR, a (P)RR-specific polyclonal antibody was generated to study (P)RR protein levels. (P)RR protein levels were significantly increased in the post-MI rat heart (1.4-fold, P < 0.05) as compared to controls. Most interestingly in DCM patients, a significant 8.7-fold (P < 0.05) increase was observed. Thus, protein expression paralleled gene expression. These results demonstrate that (P)RR expression is strongly up-regulated both in rodent models of heart failure and in the failing human heart, hinting to a potential role for (P)RR in cardiac pathophysiology.     

Receptor-mediated nonproteolytic activation of prorenin and induction of TGF-β1 and PAI-1 expression in renal mesangial cells

While elevated plasma prorenin levels are commonly found in diabetic patients and correlate with diabetic nephropathy, the pathological role of prorenin, if any, remains unclear. Prorenin binding to the (pro)renin receptor [(p)RR] unmasks prorenin catalytic activity. We asked whether elevated prorenin could be activated at the site of renal mesangial cells (MCs) through receptor binding without being proteolytically converted to renin. Recombinant inactive rat prorenin and a mutant prorenin that is noncleavable, i.e., cannot be activated proteolytically, are produced in 293 cells. After MCs were incubated with 10(-7) M native or mutant prorenin for 6 h, cultured supernatant acquired the ability to generate angiotensin I (ANG I) from angiotensinogen, indicating both prorenins were activated. Small interfering RNA (siRNA) against the (p)RR blocked their activation. Furthermore, either native or mutant rat prorenin at 10(-7) M alone similarly and significantly induced transforming growth factor-β(1), plasminogen activator inhibitor-1 (PAI-1), and fibronectin mRNA expression, and these effects were blocked by (p)RR siRNA, but not by the ANG II receptor antagonist, saralasin. When angiotensinogen was also added to cultured MCs with inactive native or mutant prorenin, PAI-1 and fibronectin were further increased significantly compared with prorenin or mutant prorenin alone. This effect was blocked partially by treatment with (p)RR siRNA or saralasin. We conclude that prorenin binds the (p)RR on renal MCs and is activated nonproteolytically. This activation leads to increased expression of PAI-1 and transforming growth factor-β(1) via ANG II-independent and ANG II-dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may play a role in the development of diabetic nephropathy.     

Renin release responses to in vitro prostaglandin challenge in the summer-active ground squirrel, Spermophilus lateralis

1. Using a renal cortical slice preparation from the summer-active ground squirrel, Spermophilus lateralis, resting renin release (RR) and tissue cyclic AMP content (TcAMPC) levels were found to be significantly higher and lower, respectively, than those previously reported for its hibernating counterpart. 2. At a 10(-5) M dose, PGE2 but not PGE1, PGF2-alpha or PGA1, significantly stimulated RR in the summer-active ground squirrel (SAGS). 3. Addition of agents which normally increase TcAMPC significantly potentiated the effect of PGE1, while preventing that of PGE2, on RR and TcAMPC. 4. Opposite TcAMPC changes may mediate the in vitro RR responses to PGE1 and PGE2 administration in the SAGS.     

The Association between Fish Consumption and Risk of Renal Cancer: A Meta-Analysis of Observational Studies

Background

Several case-control studies and cohort studies have investigated the association between fish intake and renal cancer risk, however, they yielded conflicting results. To our knowledge, a comprehensive assessment of the association between fish consumption and risk of renal cancer has not been reported. Hence, we conducted a systematic literature search and meta-analysis to quantify the association between fish consumption and renal cancer.

Methods

A systematic search was performed using the PubMed, Embase, and Cochrane Library Central database for case-control and cohort studies that assessed fish intake and risk of renal cancer. Two authors independently assessed eligibility and extracted data. Fixed-effect and random-effect models were used to estimate summary relative risks (RR) and the corresponding 95% confidence intervals (CIs). Subgroup analyses, sensitivity analysis and cumulative meta-analysis were also performed.

Results

A total of 12 case-control studies and three cohort studies published between 1990 and 2011 were included in the meta-analysis, involving 9,324 renal cancer cases and 608,753 participants. Meta-analysis showed that fish consumption did not significantly affect the risk of renal cancer (RR=0.99, 95% CI [0.92,1.07]). In our subgroup analyses, the results were not substantially affected by study design, region, gender, and confounder adjustments. Furthermore, sensitivity analysis confirmed the stability of results.

Conclusions

The present meta-analysis suggested that there was no significant association between fish consumption and risk of renal cancer. More in-depth studies are warranted to report more detailed results, including stratified results by fish type, preparation method, and gender.     

Adherence with Dosing Guideline in Patients with Impaired Renal Function at Hospital Discharge

Objectives

To determine the prevalence, determinants, and potential clinical relevance of adherence with the Dutch dosing guideline in patients with impaired renal function at hospital discharge.

Design

Retrospective cohort study between January 2007 and July 2011.

Setting

Academic teaching hospital in the Netherlands.

Subjects

Patients with an estimated glomerular filtration rate (eGFR) between 10-50 ml/min/1.73m² at discharge and prescribed one or more medicines of which the dose is renal function dependent.

Main Outcome Measures

The prevalence of adherence with the Dutch renal dosing guideline was investigated, and the influence of possible determinants, such as reporting the eGFR and severity of renal impairment (severe: eGFR<30 and moderate: eGFR 30-50 ml/min/1.73m²). Furthermore, the potential clinical relevance of non-adherence was assessed.

Results

1327 patients were included, mean age 67 years, mean eGFR 38 ml/min/1.73m². Adherence with the guideline was present in 53.9% (n=715) of patients. Reporting the eGFR, which was incorporated since April 2009, resulted in more adherence with the guideline: 50.7% vs. 57.0%, RR 1.12 (95% CI 1.02-1.25). Adherence was less in patients with severe renal impairment (46.0%), compared to patients with moderate renal impairment (58.1%, RR 0.79; 95% CI 0.70-0.89). 71.4% of the cases of non-adherence had the potential to cause moderate to severe harm.

Conclusion

Required dosage adjustments in case of impaired renal function are often not performed at hospital discharge, which may cause harm to the majority of patients. Reporting the eGFR can be a small and simple first step to improve adherence with dosing guidelines.     

Adjunctive Medical Therapy with α-Blocker after Extracorporeal Shock Wave Lithotripsy of Renal and Ureteral Stones: A Meta-Analysis

Background

Although some trials assessed the efficacy and safety of the α-blocker in facilitating renal and ureteral stones expulsion after extracorporeal shock wave lithotripsy (ESWL), the role of the α-blocker in facilitating upper urinary calculi expulsion after ESWL remain controversial.

Aims

To determine the efficacy and safety of the α-blocker in facilitating renal and ureteral stones expulsion after ESWL.

Methods

A literature search was carried out using the PubMed database, EMBASE and the Cochrane Library database to identify relevant studies. Two reviewers independently extracted data and assessed methodological quality. Pooled effect estimates were obtained using a fixed- and random-effects meta-analysis.

Results

The meta-analysis included 23 RCTs, α-blocker significantly enhanced expulsion rate of upper urinary tract calculi after ESWL (P<0.00001; RR 1.21; 95% CI 1.12–1.31), significantly promoted steinstrasse expulsion (P=0.03; RR 1.25; 95% CI 1.03–1.53), significantly shortened the discharge time of upper urinary tract calculi (P=0.0001; MD -2.12; 95% CI -3.20–-1.04), significantly reduced the patient''s pain VAS score (P=0.001; RR -1.0; 95% CI -1.61–-0.39). Compared with the control group, dizziness (P=0.002; RR 5.48; 95% CI 1.91–15.77), anejaculation (P=0.02; RR 12.17; 95% CI 1.61–91.99) and headache (P=0.04; RR 4.03; 95% CI 1.04–15.72) in the α-blocker group was associated with a higher incidence.

Conclusions

Treatment with α-blocker after ESWL appears to be effective in enhancing expulsion rate of upper urinary tract calculi, shortening the discharge time of upper urinary tract calculi, reducing the patient''s pain. The side effects of α-blocker were light and few.     

Intravascular Administration of Mannitol for Acute Kidney Injury Prevention: A Systematic Review and Meta-Analysis

Background

The effects of mannitol administration on acute kidney injury (AKI) prevention remain uncertain, as the results from clinical studies were conflicting. Due to the lack of strong evidence, the KDIGO Guideline for AKI did not propose completely evidence-based recommendations on this issue.

Methods

We searched PubMed, EMBASE, clinicaltrials.gov and Cochrane Controlled Trials Register. Randomized controlled trials on adult patients at increased risk of AKI were considered on the condition that they compared the effects of intravascular administration of mannitol plus expansion of intravascular volume with expansion of intravascular volume alone. We calculated pooled risk ratios, numbers needed to treat and mean differences with 95% confidence intervals for dichotomous data and continuous data, respectively.

Results

Nine trials involving 626 patients were identified. Compared with expansion of intravascular volume alone, mannitol infusion for AKI prevention in high-risk patients can not reduce the serum creatinine level (MD 1.63, 95% CI −6.02 to 9.28). Subgroup analyses demonstrated that serum creatinine level is negatively affected by the use of mannitol in patients undergoing an injection of radiocontrast agents (MD 17.90, 95% CI 8.56 to 27.24). Mannitol administration may reduce the incidence of acute renal failure or the need of dialysis in recipients of renal transplantation (RR 0.34, 95% CI 0.21 to 0.57, NNT 3.03, 95% CI 2.17 to 5.00). But similar effects were not found in patients at high AKI risk, without receiving renal transplantation (RR 0.29, 95% CI 0.01 to 6.60).

Conclusions

Intravascular administration of mannitol does not convey additional beneficial effects beyond adequate hydration in the patients at increased risk of AKI. For contrast-induced nephropathy, the use of mannitol is even detrimental. Further research evaluating the efficiency of mannitol infusions in the recipients of renal allograft should be undertaken.     

Resonance Raman studies of lactoperoxidase

Resonance Raman (RR) spectra obtained at three excitation wavelengths are reported for various ferric, ferrous, and ferryl derivatives of bovine lactoperoxidase. The RR spectra of the ferric derivatives show the full complement of the vinyl stretching and scissor modes indicating that the two vinyls in the protoporphyrin IX prosthetic group are present in unmodified forms. The cysteine thiol complex exhibits a RR spectrum identical to that of the native enzyme, an observation which strongly suggests a nonheme binding site for the thiol substrates. The different ferrous complexes of lactoperoxidase which result from heme reduction at slightly alkaline and acidic pH gave identical low-frequency RR spectra. Differences are observed, however, in the high-frequency region. Reduction in the presence of cyanide, however, yields two time-resolved complexes. Changes in the ligand field during the conversion to the final form of the cyanoferrous complex are proposed based on the changes observed in the low-frequency vibrational spectrum. Comparisons are made between the low-frequency RR spectra of the limiting form of the cyanoferrous and the nitric oxide lactoperoxidase complexes. The similarity between the RR spectra of these two complexes in the 150-500 cm-1 region supports the assignment of structures for these complexes where the six-coordinate heme iron is displaced from the heme plane and away from the proximal histidine ligand.     

Cooperative block of the plant endomembrane ion channel by ruthenium red.

Effects of ruthenium red (RR) on the slow Ca(2+)-activated Ca(2+)-permeable vacuolar channel have been studied by patch-clamp technique. Applied to the cytosolic side of isolated membrane patches, RR at concentrations of 0.1-5 microM produced two distinct effects on single channel kinetics, long lasting closures and a flickering block of the open state. The first effect was largely irreversible, whereas the second one could be washed out. The extent of flickering block steeply increased (zdelta = approximately 1.35) with the increase of cytosol-positive voltage, dragging RR into the channel pore. At least two RR ions are involved in the block according to Hill coefficient n = approximately 1.30 for the dose response curves. The on-rate rate of the drug binding linearly depended on the RR concentration, implying that one RR ion already plugged the pore. The blocked state was further stabilized by binding of the second RR. This stabilization was in excess of that predicted by independent binding as the dependence of unblocking rate on RR concentration revealed. A cooperative model was therefore employed to describe the kinetic behavior of RR binding. At zero voltage the half-blocking RR concentration of 36 microM and the bimolecular on-rate constant of 1.8 x 10(8) M(-1) s(-1) were estimated.     

Building interacting partner predictors using co-varying residue pairs between histidine kinase and response regulator pairs of 48 bacterial two-component systems

The two‐component system (TCS) is a signal transduction system that involves a histidine kinase (HK) and a response regulator (RR). Although up to hundreds of TCSs may operate in parallel in a bacterial cell, the high‐fidelity of a TCS signaling is well maintained, minimizing irrelevant crosstalk between TCSs. When a HK gene and a RR gene in a given TCS system exist in neighboring positions, it is almost certain that their protein products (i.e., HK and RR) are interacting partners. However, large bacterial genomes often have multiple HK genes and/or cognate RR genes that are not neighboring positions. In many partially assembled genomes, some HK genes and RR genes belong to different contigs. In these cases, it is not clear which HK(s) and RR(s) interact. By combining information‐theoretic and graph‐theoretic approaches, we developed a computational method identifying co‐evolving residue pairs between HKs and cognate RRs and predicting the interacting HK:RR pairs for each TCS. In addition, we built a TCSppWWW webserver ( http://compath.org/platcom/tcs ) that takes query sequences of pairing candidates and predicts their HK:RR pairing using precomputed models. The current release of TCSppWWW provides predictors for 48 TCSs using over 20,000 protein sequences from about 900 bacterial genomes. Three different types of predictors using Random Forest, RBF Network, and Naïve Bayes are provided. Once a set of HK and RR candidate sequences are submitted, TCSppWWW aligns query sequences to the precomputed multiple sequence alignment of HK:RR pairs, extracts co‐evolving column positions, then returns prediction results with prediction margin and additional information. Proteins 2011. © 2010 Wiley‐Liss, Inc.     

Growth performance,carcass and noncarcass traits and meat quality of Barbarine lambs fed rosemary distillation residues

The aim of this experiment was to study the effect of total replacement of oat hay by rosemary distillation residues (RR) on growth, carcass characteristics and meat quality of Barbarine lambs. A total of 21 lambs were divided into three groups. The control group (C) was offered 600 g of oat hay; the RR87 and RR60 groups received 600 g of pellets containing 87% and 60% of RR, respectively. The CP content was 9% and 14% for RR87 and RR60, respectively. All animals were supplemented by 600 g of concentrate. After 77 days of fattening, lambs were slaughtered. The DM and CP intakes were significantly increased with RR diets. The average daily gain was higher (P<0.001), while the feed conversion rate was lower for RR60 and RR87 than C group. The dressing percentage was similar for all groups. The tissular (muscle, fat and bone) and the regional (leg, shoulder, etc.) carcass composition did not differ among groups. The bony organs and gut weights were similar among groups, while functional ones (skin, liver, kidney and testicles) were significantly heavier for both RR groups than control. The ultimate pH, water cooking loss and color variables were similar among groups and the chemical composition (protein, fat, myoglobin, collagen and iron) did not differ also among groups. These results revealed the opportunity of RR use in fattening lambs without adverse effects on carcass and meat characteristics. Moreover, 9% CP in RR pellets are enough given the same growth performance recorded as that of RR with 14% CP.