Effects of long-term training on the progression of chronic renal failure in rats

The Effects of Exercise Training on Recovery of Biochemical and Hematological Outcomes in Patients Surviving COVID-19: A Randomized Controlled Assessor-Blinded Trial

BACKGROUND

No previous research has investigated the direct effects of exercise interventions on COVID-19 outcomes. The aim is to investigate the effect of 8 weeks of home-based moderate-intensity continuous training (MICT), resistance training (RT), and combined aerobic and resistance training (CET) on biochemical and hematologic markers associated with COVID-19 symptoms and severity in COVID-19 survivors.

METHODS

A total of 547 male and female COVID-19 survivors were screened, and 296 (aged 20-93 years) were randomly assigned in a 1:1:1:1 ratio to one of four groups: MICT (n = 74), RT (n = 74), CET (n = 74), or non-exercise (NON-EX, n = 74). Blood samples were taken at baseline, at week 4, and week 8 after training.

RESULTS

After the intervention, compared with the NON-EX group, all 3 MICT, RT, and CET interventions caused significant improvements in the levels of creatine kinase (CK), lactate dehydrogenase (LDH), C-reactive protein (CRP), troponin-I, d-dimer, creatinine, urea, potassium (K), sodium (Na), white blood cell (WBC), neutrophils, lymphocytes, red blood cells (RBC), platelets, hemoglobin, and hematocrit concentrations (P < 0.05). CET was effectively superior to MICT and RT in the improvements in the biochemical and hematological variables studied (P < 0.05).

CONCLUSIONS

Overall, the present study demonstrates that long-term MICT plus RT interventions have a synergistic effect in accelerating and enhancing the recovery in patients surviving COVID-19. Trial registration IRCT20160605028270N3, 6 September 2020.

Oxidative stress and the antioxidant system in salivary glands of rats with experimental chronic kidney disease

OBJECTIVE

This study aims to analyze the presence of oxidative stress and activity of the antioxidant system in the parotid and submandibular salivary glands of rats with Chronic Kidney Disease (CKD).

DESIGN

Sixteen male wistar rats were divided into two groups (n = 8, each): control rats and rats with CKD. CKD was induced by 5/6 nephrectomy. Blood urea nitrogen and serum creatinine clearance were quantified. Malondialdehyde, superoxide dismutase, glutathione peroxidase, glutathione reductase, catalase, total antioxidant status, ascorbic acid, α-tocopherol, superoxide anion, and hydrogen peroxide concentrations were assessed.

RESULTS

In CKD rats, blood urea nitrogen, serum creatinine, and proteinuria concentrations were increased, while creatinine clearance was reduced. In the submandibular gland, superoxide anion concentration was increased significantly (p < 0.05). Hydrogen peroxide and superoxide anion concentrations were reduced in the parotid gland. CKD rats presented increased malondialdehyde concentration, total antioxidant status, superoxide dismutase, and glutathione reductase activities only in the parotid gland (p < 0.05).

CONCLUSION

Oxidative stress and changes in the antioxidant system were found in the parotid and submandibular salivary glands in an experimental model of CKD induced by 5/6 nephrectomy.

Resistance training downregulates macrophages infiltration in the kidney of 5/6 nephrectomized rats

INTRODUCTION

Chronic kidney disease (CKD) is considered a significant world health problem with elevated mortality rates. Patients with CKD are restricted to mild physical activity, present chronic inflammatory state and loss of muscle strength. Currently, the influence of resistance exercise (RE) on the progression of renal disease has not being fully elucidated.

PURPOSE

To evaluate the effects of RE on the progression of CKD in a remnant kidney model (5/6Nx) in rats.

METHODS

Eight-week-old Wistar rats were submitted to 5/6 nephrectomy and were divided into four groups: Sham sedentary (Sham SD); Sham RE (Sham RE); 5/6Nx SD and 5/6Nx RE. The animals were trained for 8 weeks in a vertical climbing ladder for 3 days per week, on non-consecutive days.

RESULTS

As expected, 5/6Nx SD group presented a markedly loss of renal function, increased plasma inflammatory cytokines and increased oxidative stress with a reduced activity of nitric oxide. The higher macrophage infiltration and fibrosis confirmed these conditions. RE attenuated systolic blood pressure and renal function decrease and also improved serum lipid parameters in 5/6 Nx animals. It was evident the increase of muscle strength and mass in the trained groups while the sedentary group showed reduced muscle weight and strength compared to Sham SD.

CONCLUSIONS

RE implemented following 5/6Nx retard the progression of chronic kidney injury while simultaneously allowed the maintenance of skeletal muscle strength.

The effects of aerobic exercise on eGFR, blood pressure and VO2peak in patients with chronic kidney disease stages 3-4: A systematic review and meta-analysis

BACKGROUND

CKD is associated with several comorbidities, cardiovascular disease being the most significant. Aerobic training has a beneficial effect on cardiovascular health in healthy and some well-defined non-healthy populations. However, the effect of aerobic training on glomerular filtration rate in patients with CKD stages 3-4 is unclear.

OBJECTIVE

To review the effects of aerobic exercise training on kidney and cardiovascular function in patients with chronic kidney disease (CKD) stages 3-4.

METHODS

A random-effects meta-analysis was performed to analyse published randomized controlled trials through February 2018 on the effect of aerobic training on estimated glomerular filtration rate, blood pressure and exercise tolerance in patients with CKD stages 3-4. Web of Science, PubMed and Embase databases were searched for eligible studies.

RESULTS

11 randomized controlled trials were selected including 362 participants in total. Favourable effects were observed on estimated glomerular filtration rate (+2.16 ml/min per 1.73m2; [0.18; 4.13]) and exercise tolerance (+2.39 ml/kg/min; [0.99; 3.79]) following an on average 35-week aerobic training program when compared to standard care. No difference in change in blood pressure was found.

CONCLUSIONS

There is a small beneficial effect of aerobic training on estimated glomerular filtration rate and exercise tolerance, but not on blood pressure, in patients with CKD stages 3-4. However, data are limited and pooled findings were rated as of low to moderate quality.

Effect of cardiac rehabilitation on the renal function in chronic kidney disease - Analysis using serum cystatin-C based glomerular filtration rate

Background

Whether an individually determined appropriate level of cardiac rehabilitation (CR) has a favorable effect on the renal function still remains unclarified. The aim of this study was to confirm the effect of CR on the estimated glomerular filtration rate (eGFR) using cystatin C, which is known to be unaffected by physical exercise.

Methods

The study population was comprised of 86 patients (61 males; average age 74 y/o) with a lower-moderate level of chronic kidney disease (CKD) who was admitted to our hospital for treatment of cardiovascular disease (CVD) and who participated in our 3-month CR program. The exercise capacity was assessed by cardiopulmonary exercise testing (CPX) and the eGFR was measured by a formula based on the serum cystatin C concentration (eGFRcys) in each patient both at the beginning and end of the CR.

Results

In the CVD patients with CKD, both the peak oxygen uptake (VO₂) and peak work rate (WR) improved significantly after CR (15.0 ± 3 to 15.8 ± 3 ml/min/kg, p = 0.002. 65.5 ± 21 to 70.2 ± 25 W, p = 0.001). Regarding the renal function, the eGFRcys improved (45.2 ± 11 to 47.3 ± 13 ml/min/1.73 m², p = 0.023), however, the eGFR assessed by the serum creatinine (eGFRcr) did not improve after CR (45.1 ± 12 to 44.9 ± 13 ml/min/1.73 m², p = 0.834).

Conclusions

In CVD patients, a novel CR program significantly improved the exercise capacity. Further, CR was shown to have a favorable effect on the renal function when it was estimated by the eGFRcys.

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Cardiac rehabilitation improved the renal function using serum cystatin C.

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Cardiac rehabilitation didn't change the renal function using serum creatinine.

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Cardiac rehabilitation is most effective on moderate to severe CKD patients.

Exercise in patients with hypertension and chronic kidney disease: a randomized controlled trial

Hypertension and chronic kidney disease (CKD) are global public health problems, both associated with higher risk of cardiovascular (CV) and renal events. This trial randomized non-diabetic adult patients with hypertension and CKD stages 2-4 to 16 weeks of aerobic and resistance training or usual care. The primary outcome was the change in estimated glomerular filtration rate (eGFR). Secondary outcomes included changes in systolic and diastolic blood pressure (BP), body weight, fasting blood glucose, lipid profile, high-sensitivity C-reactive protein (hs-CRP), and functional capacity. The analysis was performed by intention-to-treat, using linear mixed-effects models for repeated measures over time. A hundred fifty patients were included in the intervention (76) or control (74) groups. No difference was found in eGFR, BP, body weight, or lipid profile changes between the groups. However, there were significant decreases in hs-CRP [-6.7(-11.7 to -1.8) mg/L] and fasting blood glucose [-11.3(-20.0 to -1.8) mg/dL], and an increase in functional capacity [2' Step Test 33.9 (17.7-50.0); 30″ Stand Test 2.3 (0.9-3.7)] in exercise group compared with control group. The results of this RCT show that combined aerobic and resistance training could reduce inflammation and insulin resistance in hypertensive patients with earlier stages of CKD, without a significant effect on kidney disease progression. Clinical trials.gov NCT01155128.

Effects of Physical Exercise in Patients with End Stage Renal Failure, on Dialysis and Renal Transplantation: Current Status and Recommendations

There is increasing evidence about the benefits of regular physical activity in the chronically ill. Patients with chronic renal failure prior to and after renal transplant are one of the target groups in which increased controlled physical activity is highly recommended. Significant atrophy and increased non-contractile tissue are present in the muscle of predialytic and patients on hemodialysis, which is associated with poor physical performance and poor outcome of renal disease. Thus, interventions to increase physical activity or otherwise address atrophy may improve performance and quality of life in these patients. Other abnormalities in these patients, such as metabolic impairments, anemia, and hormonal changes, especially insulin resistance and lipid disorders, could be also modulated by certain therapeutic agents and physical activity. Increasing activity levels in this target group could be particularly important since it is well established that controlled physical exercise reduces the risk of cardiovascular disease in the general population. Patients who participate in regular physical activity following transplant will have higher health-related fitness and quality of life compared to those who remain inactive. The potential risk of physical activity can be reduced by medical evaluation, risk stratification, careful supervision, and education

Aerobic exercise training rescues protein quality control disruption on white skeletal muscle induced by chronic kidney disease in rats

We tested whether aerobic exercise training (AET) would modulate the skeletal muscle protein quality control (PQC) in a model of chronic kidney disease (CKD) in rats. Adult Wistar rats were evaluated in four groups: control (CS) or trained (CE), and 5/6 nephrectomy sedentary (5/6NxS) or trained (5/6NxE). Exercised rats were submitted to treadmill exercise (60 min., five times/wk for 2 months). We evaluated motor performance (tolerance to exercise on the treadmill and rotarod), cross-sectional area (CSA), gene and protein levels related to the unfolded protein response (UPR), protein synthesis/survive and apoptosis signalling, accumulated misfolded proteins, chymotrypsin-like proteasome activity (UPS activity), redox balance and heat-shock protein (HSP) levels in the tibialis anterior. 5/6NxS presented a trend towards to atrophy, with a reduction in motor performance, down-regulation of protein synthesis and up-regulation of apoptosis signalling; increases in UPS activity, misfolded proteins, GRP78, derlin, HSP27 and HSP70 protein levels, ATF4 and GRP78 genes; and increase in oxidative damage compared to CS group. In 5/6NxE, we observed a restoration in exercise tolerance, accumulated misfolded proteins, UPS activity, protein synthesis/apoptosis signalling, derlin, HSPs protein levels as well as increase in ATF4, GRP78 genes and ATF6α protein levels accompanied by a decrease in oxidative damage and increased catalase and glutathione peroxidase activities. The results suggest a disruption of PQC in white muscle fibres of CKD rats previous to the atrophy. AET can rescue this disruption for the UPR, prevent accumulated misfolded proteins and reduce oxidative damage, HSPs protein levels and exercise tolerance.

Salivary Alterations in Rats with Experimental Chronic Kidney Disease

Objective

This study aimed to analyze changes in saliva composition and salivary secretion process of rats with chronic kidney disease induced by 5/6 nephrectomy to set the foundation for salivary studies related to CKD.

Methods

CKD was induced in Wistar rats via 5/6 nephrectomy. Blood and saliva samples were collected from Control, Sham and CKD groups at 8 and 12 weeks after the surgery. Salivation was stimulated via intraperitoneal injections of pilocarpine (1.0 mg/Kg body weight) or isoproterenol (5.0 mg/Kg body weight). Saliva was collected and immediately stored at -80°C until analysis. The salivary flow rate, total protein, amylase and peroxidase activities, and urea concentrations were measured. The blood urea nitrogen (BUN) and serum creatinine concentrations were also evaluated.

Results

Increases in BUN and serum creatinine concentrations were observed in the CKD groups. Amylase activity was significantly reduced in response to both stimuli in the CKD groups at 8 weeks and increased in the CKD groups at 12 weeks in response to isoproterenol stimulus. The peroxidase activities of the CKD groups were significantly reduced in response to isoproterenol stimulation and were increased at 12 weeks in response to pilocarpine stimulation. Salivary urea was significantly increased in the CKD groups at 8 weeks in response to the isoproterenol stimuli and at 12 weeks in response to both salivary agonists.

Conclusions

The pattern of alterations observed in this experimental model is similar to those observed in patients and clearly demonstrates the viability of 5/6 nephrectomy as an experimental model in future studies to understand the alterations in salivary compositions and in salivary glands that are elicited by CKD.

Regular aquatic exercise for chronic kidney disease patients: a 10-year follow-up study

Chronic kidney disease (CKD) patients not yet in dialysis can benefit from increased physical activity; however, the safety and outcomes of aquatic exercise have not been investigated in observational studies. The aim of this study was to analyze association of 10 years of regularly performed aquatic exercise with the study endpoint--that is, all-cause death or start of dialysis. Consecutive CKD patients were included in the study in January 2002. The exercise group (n=7) exercised regularly under the supervision of physiotherapist for 10 years; the control group (n=9), matched in terms of age and clinical parameters, remained sedentary. Low-intensity aerobic aquatic exercise was performed regularly twice a week; 32 weeks or more of exercise therapy sessions were conducted annually. None of the members of the aquatic exercise group reached dialysis or died in 10 years. In the sedentary control group, 55% reached the study endpoint--renal replacement therapy (n=2) or all-cause death (n=3). Occurrence of the study endpoint, compared using the exact multinomial test with unconditional margins, was statistically significantly different (P-value: 0.037) between the study groups. Regular supervised aquatic exercise arrested CKD progression. There was a statistically significant difference between the sedentary group and the exercise group in reaching renal replacement therapy or all-cause death in a follow-up time of 10 years.

Cardiac function is preserved following 4 weeks of voluntary wheel running in a rodent model of chronic kidney disease

The purpose of this investigation was to determine the effect of 4 wk of voluntary wheel running on cardiac performance in the 5/6 ablation-infarction (AI) rat model of chronic kidney disease (CKD). We hypothesized that voluntary wheel running would be effective in preserving cardiac function in AI. Male Sprague-Dawley rats were divided into three study groups: 1) sham, sedentary nondiseased control; 2) AI-SED, sedentary AI; and 3) AI-WR, wheel-running AI. Animals were maintained over a total period of 8 wk following AI and sham surgery. The 8-wk period included 4 wk of disease development followed by a 4-wk voluntary wheel-running intervention/sedentary control period. Cardiac performance was assessed using an isolated working heart preparation. Left ventricular (LV) tissue was used for biochemical tissue analysis. In addition, soleus muscle citrate synthase activity was measured. AI-WR rats performed a low volume of exercise, running an average of 13 ± 2 km, which resulted in citrate synthase activity not different from that in sham animals. Isolated AI-SED hearts demonstrated impaired cardiac performance at baseline and in response to preload/afterload manipulations. Conversely, cardiac function was preserved in AI-WR vs. sham hearts. LV nitrite + nitrate and expression of LV nitric oxide (NO) synthase isoforms 2 and 3 in AI-WR were not different from those of sham rats. In addition, LV H2O2 in AI-WR was similar to that of sham and associated with increased expression of LV superoxide-dismutase-2 and glutathione peroxidase-1/2. The findings of the current study suggest that a low-volume exercise intervention is sufficient to maintain cardiac performance in rats with CKD, potentially through a mechanism related to improved redox homeostasis and increased NO.

Exercise in kidney disease and diabetes: time for action

Physical inactivity is well recognised as a major health issue in today's society. Regular exercise is important in maintaining health and preventing chronic disease, it is increasingly accepted as a valuable therapeutic intervention in many long-term conditions. Unfortunately the role of physical activity in renal disease has been largely overlooked and provision of exercise advice and rehabilitation programmes for kidney patients lags well behind that of cardiology and pulmonary services. Research indicates that exercise can impact positively upon many of the health issues associated with declining renal function and renal replacement therapy, as concluded by a recent Cochrane review on the topic. As exercise should be integral to the management of diabetes, the issue is particularly relevant for patients with diabetic kidney disease. This paper summarises what is known about the main effects of exercise training in chronic kidney disease and diabetic kidney disease, and suggests how adaptations in the attitudes and approaches of the multidisciplinary renal and diabetes healthcare teams can help patients to enjoy the diverse benefits of an appropriately active lifestyle.

Exercise attenuates renal dysfunction with preservation of myocardial function in chronic kidney disease

Previous studies have suggested that exercise improves renal and cardiac functions in patients with chronic kidney disease. The aim of this study was to evaluate the effects of long-term aerobic swimming exercise with overload on renal and cardiac function in rats with 5/6 nefrectomy (5/6Nx). Eight Wistar rats were placed into 4 groups: Control (C), Control+Exercise (E), Sedentary 5/6Nx (NxS) and 5/6Nx+Exercise (NxE). The rats were subjected to swimming exercise sessions with overload for 30 min five days per week for five weeks. Exercise reduced the effect of 5/6Nx on creatinine clearance compared to the NxS group. In addition, exercise minimized the increase in mean proteinuria compared to the NxS group (96.9±10.0 vs. 51.4±9.9 mg/24 h; p<0.05). Blood pressure was higher in the NxS and NxE groups compared to the C and E groups (216±4 and 178±3 vs. 123±2 and 124±2 mm Hg, p<0.05). In the 200 glomeruli that were evaluated, the NxS group had a higher sclerosis index than did the NxE group (16% vs. 2%, p<0.05). Echocardiography demonstrated a higher anterior wall of the left ventricle (LV) in diastole in the NxS group compared with the C, E and NxE groups. The NxS group also had a higher LV posterior wall in diastole and systole compared with the E group. The developed isometric tension in Lmax of the heart papillary muscle was lower in the NxS group compared with the C, E and NxE groups. These results suggested that exercise in 5/6Nx animals might reduce the progression of renal disease and lessen the cardiovascular impact of a reduction in renal mass.

Previous exercise training has a beneficial effect on renal and cardiovascular function in a model of diabetes

Exercise training (ET) is an important intervention for chronic diseases such as diabetes mellitus (DM). However, it is not known whether previous exercise training intervention alters the physiological and medical complications of these diseases. We investigated the effects of previous ET on the progression of renal disease and cardiovascular autonomic control in rats with streptozotocin (STZ)-induced DM. Male Wistar rats were divided into five groups. All groups were followed for 15 weeks. Trained control and trained diabetic rats underwent 10 weeks of exercise training, whereas previously trained diabetic rats underwent 14 weeks of exercise training. Renal function, proteinuria, renal sympathetic nerve activity (RSNA) and the echocardiographic parameters autonomic modulation and baroreflex sensitivity (BRS) were evaluated. In the previously trained group, the urinary albumin/creatinine ratio was reduced compared with the sedentary diabetic and trained diabetic groups (p<0.05). Additionally, RSNA was normalized in the trained diabetic and previously trained diabetic animals (p<0.05). The ejection fraction was increased in the previously trained diabetic animals compared with the diabetic and trained diabetic groups (p<0.05), and the myocardial performance index was improved in the previously trained diabetic group compared with the diabetic and trained diabetic groups (p<0.05). In addition, the previously trained rats had improved heart rate variability and BRS in the tachycardic response and bradycardic response in relation to the diabetic group (p<0.05). This study demonstrates that previous ET improves the functional damage that affects DM. Additionally, our findings suggest that the development of renal and cardiac dysfunction can be minimized by 4 weeks of ET before the induction of DM by STZ.

Swimming exercise prevents fibrogenesis in chronic kidney disease by inhibiting the myofibroblast transdifferentiation

Background

The renal function of chronic kidney disease (CKD) patients may be improved by a number of rehabilitative mechanisms. Swimming exercise training was supposed to be beneficial to its recovery.

Methodology/Principal Findings

Doxorubicin-induced CKD (DRCKD) rat model was performed. Swimming training was programmed three days per week, 30 or 60 min per day for a total period of 11 weeks. Serum biochemical and pathological parameters were examined. In DRCKD, hyperlipidemia was observed. Active mesangial cell activation was evidenced by overexpression of PDGFR, P-PDGFR, MMP-2, MMP-9, α-SMA, and CD34 with a huge amount collagen deposition. Apparent myofibroblast transdifferentiation implicating fibrogenesis in the glomerular mesangium, glomerulonephritis and glomeruloscelorosis was observed with highly elevated proteinuria and urinary BUN excretion. The 60-min swimming exercise but not the 30 min equivalent rescued most of the symptoms. To quantify the effectiveness of exercise training, a physical parameter, i.e. “the strenuosity coefficient” or “the myokine releasing coefficient”, was estimated to be 7.154×10⁻³ pg/mL-J.

Conclusions

The 60-min swimming exercise may ameliorate DRCKD by inhibiting the transdifferentiation of myofibroblasts in the glomerular mesangium. Moreover, rehabilitative exercise training to rescue CKD is a personalized remedy. Benefits depend on the duration and strength of exercise, and more importantly, on the individual physiological condition.

Angiotensin II receptor blocker pretreatment of rats undergoing sudden renal ablation

BACKGROUND

Subtotal nephrectomy (N) in rats results in progressive hypertension, proteinuria and renal lesions. Renin-angiotensin system blockade initiated at N prevents these changes; treatments failing to reduce hypertension and proteinuria do not.

METHODS

Ten Munich-Wistar rats underwent 1&frac12; surgical N; eight littermates were pretreated with losartan (L) only for 6 weeks prior to 1&frac12; N (N + L). Pretreated (n = 8; C + L) and untreated controls (C; n = 8) had sham operations.

RESULTS

Over 6 months, N and N + L rats developed ∼80% increase in glomerular filtration rate per nephron over C and C + L, P < 0.001). Hypertension (intra-arterial mean blood pressure 116 ± 6.8 mmHg in N rats versus 102 ± 3.2 in C, 104 ± 8.4 in C + L, and 104 ± 8.4 in N + L rats, P < 0.001 for all) and proteinuria (120 ± 20 mg/day in N versus 39 ± 10 in C, 34 ± 8 in C + L and 35 ± 8 in N + L, P < 0.001 for all) developed only in N. Focal segmental glomerulosclerosis (FSGS) (%) at 6 months was 20 ± 8 in N and 17.5 ± 8 in N + L (ns) and <1 in C and C + L (P < 0.001 versus N and N + L). Interstitial fractional volume (Vv), 4.0 ± 1.7% in C and 4.4 ± 1.6% in C + L (ns), was similarly increased to 7.5 ± 2.5% in N and 9.0 ± 3.9% in N+L (P < 0.04 versus C and C + L). Atrophic tubule Vv was increased by >300% in N and N + L over C and C + L (P < 0.02 for all). Glomerular volume doubled in N and N + L (P < 0.001). Podocyte foot process effacement was greater in N and NL than in C or C + L (P ≤ 0.02 for all). Thus, L given for 6 weeks prior to 1&frac12; N prevented hypertension and proteinuria over the subsequent 6 months without reducing glomerular hypertrophy, hyperfiltration or interstitial, tubular or FSGS lesions or foot process effacement.

CONCLUSIONS

These studies dissociated systemic hypertension and proteinuria from the renal lesions in this model. Durable effects of losartan on blood pressure and proteinuria likely represent epigenetic processes.

Aerobic exercise in obese diabetic patients with chronic kidney disease: a randomized and controlled pilot study

Background

Patients with obesity, diabetes, and chronic kidney disease (CKD) are generally physically inactive, have a high mortality rate, and may benefit from an exercise program.

Methods

We performed a 24-week randomized controlled feasibility study comparing aerobic exercise plus optimal medical management to medical management alone in patients with type 2 diabetes, obesity (body mass index [BMI] > 30 kg/m²), and stage 2-4 CKD (estimated glomerular filtration rate [eGFR] 15-90 mL/min/1.73 m² with persistent proteinuria). Subjects randomized to exercise underwent thrice weekly aerobic training for 6 followed by 18 weeks of supervised home exercise. The primary outcome variable was change in proteinuria.

Results

Seven subjects randomized to exercise and 4 control subjects completed the study. Exercise training resulted in an increase in exercise duration during treadmill testing, which was accompanied by slight but insignificant decreases in resting systolic blood pressure and 24-hour proteinuria. Exercise did not alter GFR, hemoglobin, glycated hemoglobin, serum lipids, or C-reactive protein (CRP). Caloric intake and body weight and composition also did not change with exercise training.

Conclusion

Exercise training in obese diabetic patients with CKD is feasible and may have clinical benefits. A large-scale randomized controlled trial to determine the effects of exercise on renal functions, cardiovascular fitness, inflammation, and oxidative stress in diabetic patients with CKD is planned.

Combination of chronic exercise and antihypertensive therapy enhances renoprotective effects in rats with renal ablation

BACKGROUND

We assessed the renal protective effects of treatment with moderate exercise (EX), with EX plus olmesartan (OLS), with EX plus azelnidipine (AZN), and with the three together in a rat model of chronic renal failure (CRF).

METHODS

Male 5/6-nephrectomized Wistar Kyoto (WKY) rats were divided into six groups according to the following treatments for: (i) no EX (C); (ii) moderate EX with treadmill running (20 m/min for 60 min/day, 5 days/week) (EX); (iii) EX+OLS (10 mg/kg/day); (iv) EX+AZN (3 mg/kg/day); (v) EX+OLS (5 mg/kg/day)+AZN (1.5 mg/kg/day); and (vi) sham operation (S). The rats were then treated for 12 weeks.

RESULTS

EX, EX+OLS, EX+AZN, and EX+OLS+AZN showed decreases in the serum creatinine (Scr), an index of glomerular sclerosis (IGS), the relative interstitial volume of the renal cortex (RIV), the number of ED-1 (monoclonal antibody) positive cells (ED1(+)) and the glomerular expression score of alpha-smooth muscle actin (alpha-SMA(+)). EX+OLS, EX+AZN, and EX+OLS+AZN blocked the development of hypertension, increased the number of Wilms' tumor-1 (WT-1) positive cells (WT1(+)); EX+OLS and EX+OLS+AZN blunted the increases in proteinuria. In particular, blood urea nitrogen (BUN), ED1(+), alpha-SMA(+), WT1(+), IGS, and RIV in the EX+OLS+AZN were the lowest among all the nephrectomized groups.

CONCLUSIONS

In the results, simultaneous treatment of EX, OLS, and AZN showed renal protective effects in this rat model suggesting that the treatment may affect the macrophage infiltration to the glomerulus, the fibroblast accumulation in the glomerulus, the mesangial activation, and the podocyte differentiation.

Chronic renal failure induces genetic instability in multiple organs of Wistar rats

BACKGROUND

Taking into consideration the strong evidence for a relationship between DNA damage and carcinogenesis, the aim of this study was to investigate whether blood, liver, heart, kidney and brain are particularly sensitive organs for DNA damaging during chronic renal disease by the single-cell gel (comet) assay to predict genetic instability induced by this pathological condition.

METHODS

A total of 18 male Wistar rats were divided into two groups: negative control (n = 8) and experimental (n = 10), in which was submitted to the 5/6 renal mass ablation by ligation of two or three branches of the left renal artery and total right nephrectomy during 8 weeks.

RESULTS

The results showed that chronic renal disease was able to induce genetic damage in blood, heart, liver and kidney cells as depicted by the mean tail moment. No genetic damage was induced in brain cells, i.e. no significant statistically differences (P > 0.05) were noticed when compared to negative control.

CONCLUSION

In conclusion, our results suggest that chronic renal failure could contribute to the damage of DNA at all organs evaluated, except to the brain cells. As DNA damage is an important step in events leading to carcinogenesis, this study represents a relevant contribution to the correct evaluation of the potential health risks associated with kidney disease.

A comparison of aerobic exercise and resistance training in patients with and without chronic kidney disease

The morbidity and mortality associated with chronic kidney disease (CKD) are primarily caused by atherosclerosis and cardiovascular disease, which may be in part caused by inflammation and oxidative stress. Aerobic exercise and resistance training have been proposed as measures to combat obesity, inflammation, endothelial dysfunction, oxidative stress, insulin resistance, and progression of CKD. In non-CKD patients, aerobic exercise reduces inflammation, increases insulin sensitivity, decreases microalbuminuria, facilitates weight loss, decreases leptins, and protects against oxidative injury. In nondialysis CKD, aerobic exercise decreases microalbuminuria, protects from oxidative stress, and may increase the glomerular filtration rate (GFR). Aerobic exercise in hemodialysis patients has been reported to enhance insulin sensitivity, improve lipid profile, increase hemoglobin, increase strength, decrease blood pressure, and improve quality of life. Resistance training, in the general population, decreases C-reactive protein, increases insulin sensitivity, decreases body fat content, increases insulin-like growth factor-1 (IGF-1), and decreases microalbuminuria. In the nondialysis CKD population, resistance training has been reported to reduce inflammation, increase serum albumin, maintain body weight, increase muscle strength, increase IGF-1, and increase GFR. Resistance training in hemodialysis increases muscle strength, increases physical functionality, and improves IGF-1 status. Combined aerobic exercise and resistance training during dialysis improves muscle strength, work output, cardiac fitness, and possibly dialysis adequacy. There is a need for more investigation on the role of exercise in CKD. If the benefits of aerobic exercise and strength training in non-CKD populations can be shown to apply to CKD patients as well, renal rehabilitation will begin to play an important role in the approach to the treatment, prevention, and slowed progression of CKD.

Skeletal muscle dysfunction in chronic renal failure: effects of exercise

A number of chronic illnesses such as renal failure (CRF), obstructive pulmonary disease, and congestive heart failure result in a significant decrease in exercise tolerance. There is an increasing awareness that prescribed exercise, designed to restore some level of physical performance and quality of life, can be beneficial in these conditions. In CRF patients, muscle function can be affected by a number of direct and indirect mechanisms caused by renal disease as well as various treatment modalities. The aims of this review are twofold: first, to briefly discuss the mechanisms by which CRF negatively impacts skeletal muscle and, therefore, exercise capacity, and, second, to discuss the available data on the effects of programmed exercise on muscle function, exercise capacity, and various other parameters in CRF.

Obesity, Smoking, and Physical Inactivity as Risk Factors for CKD: Are Men More Vulnerable?

BACKGROUND

The incidence of end-stage renal disease is especially high in men, and some studies indicated that smoking is a risk factor for men only. We investigated associations between obesity, smoking, and physical inactivity and chronic kidney disease (CKD) in the general population and whether risk for CKD was restricted to men.

METHODS

This was a cross-sectional health survey of the entire adult population of Nord-Trondelag County, Norway, 1995 to 1997, with a 70.6% participation rate. Glomerular filtration rate (GFR) was estimated in all subjects 20 years and older from calibrated serum creatinine levels by using the simplified Modification of Diet in Renal Disease Study formula, and CKD cases are defined as those with a GFR less than 45 mL/min/1.73 m2 (< 0.75 mL/s).

RESULTS

A total of 30,485 men and 34,708 women were included, and prevalences of GFR less than 45 mL/min/1.73 m2 (< 0.75 mL/s) were 0.8% and 1.1%, respectively. Age- and sex-adjusted logistic regression analyses showed dose-response relations for body mass index, smoking history, and physical activity. Relative risks were 1.77 (95% confidence interval [CI], 1.47 to 2.14) for obesity (body mass index > or = 30 kg/m2), 1.52 (95% CI, 1.13 to 2.06) for smoking (> 25 pack-years), and 2.14 (95% CI, 1.39 to 3.30) for physical inactivity (no or some physical activity in leisure time). For subjects with all these risk factors, relative risk was 5.10 (95% CI, 2.36 to 11.01). These results remained significant after adjusting for other known risk factors. No biological interactions between sex and obesity, smoking, or physical activity were found.

CONCLUSION

Obesity, smoking, and physical inactivity were associated significantly with CKD. Men were not more susceptible to these risk factors than women.

Voluntary Exercise during Chronic Renal Failure in Rats

PURPOSE

Chronic renal failure (CRF) patients often experience a significant degradation in quality of life that is associated with decreased physical fitness. Previous animal studies have used forced running or swimming as modalities to investigate the interactions between exercise and CRF. These modalities generally include stress responses unrelated to the exercise itself. The purpose of the current work was to determine whether, and to what extent, rats experiencing the onset of CRF would participate in voluntary wheel running exercise. An additional objective was to examine physiological parameters related to skeletal muscle and cardiovascular adaptation in the context of CRF and exercise.

METHODS

Groups of rats were assigned to sham-operated or 5/6 nephrectomy groups, and further divided into running or nonrunning subgroups. Blood, heart, and muscle tissues were collected 30 d after the exercise groups were returned to running wheel-equipped cages.

RESULTS

The results demonstrated that rats experiencing the early stages of CRF will voluntarily exercise to the same extent as sham-operated animals (e.g., sham, 7.2+/-0.8 vs CRF, 6.8+/-0.7 km.d). CRF resulted in increased systolic blood pressure that was not normalized by exercise. CRF induced a decrease in hemoglobin concentration that was prevented by exercise. Voluntary running resulted in an apparently nonpathological left ventricular hypertrophy in both the sham-operated and CRF rats. In locomotor skeletal muscles, CRF resulted in a 31% decrease in citrate synthase activity that was completely blunted by voluntary running activity.

CONCLUSION

Rats experiencing the onset of CRF will run voluntarily. This exercise appears to provide some potentially palliative effects on the skeletal muscle and cardiovascular responses to CRF.

The effect of reactive oxidant generation in acute exercise-induced proteinuria in trained and untrained rats

Exercise-induced proteinuria is a common consequence of physical activity, although its mechanism is not clear. We investigated whether free radicals generated during exercise play a role in post-exercise proteinuria in sedentary and treadmill-running trained rats, separately. Sedentary and trained rats were randomly divided into four sub-groups: control, antioxidant treatment, exhaustive exercise and an exhaustive exercise plus antioxidant treatment group. Antioxidant therapy was applied by intragastric catheter for 4 weeks with vitamin C (ascorbic acid, 50 mg x kg(-1) x day(-1)) and vitamin E (alpha-tocopherol, 20 mg x kg(-1).day(-1)). Twenty-four-hour urine samples were used for measuring protein levels and protein electrophoresis. Thiobarbituric acid (TBARS) and glutathione (GSH) levels, superoxide dismutase (SOD) and catalase (CAT) activities were assayed in blood and tissues. Increased urinary protein levels and mixed type proteinuria in electrophoresis were identified after exhaustive exercise in sedentary rats. Erythrocyte, kidney and muscle TBARS levels were significantly elevated in this group. Antioxidant treatment prevented the increase in urinary protein levels, TBARS levels and the occurrence of mixed type proteinuria after exhaustive exercise in sedentary rats. Exhaustive exercise in trained rats resulted in elevation of urine protein levels and mixed type proteinuria although kidney TBARS levels were not changed compared to those of the trained controls. Antioxidant therapy in trained and exhausted-trained animals resulted in decreased TBARS levels in the kidney but it did not affect urinary-increased protein levels or electrophoresis in exhausted animals. This findings suggest that the exercise-induced oxidant stress may contribute to post-exercise proteinuria in sedentary rats. However, this mechanism may not be responsible for proteinuria in trained rats.

Beneficial effects of water-based exercise in patients with chronic kidney disease

The possible beneficial effect of regular aquatic exercise on cardiorespiratory, renal lipid parameters and oxidative stress status was studied in patients with mild to moderate renal failure. The exercise group did low-intensity aerobic exercise in the pool during a period of 12 weeks, twice a week, with sessions lasting for 30 min. Matched control participants remained sedentary. The results showed that in the exercise group all cardiorespiratory functional parameters improved and resting blood pressure lowered significantly. Proteinuria and cystatin-C were diminished significantly and glomerular filtration rate was enhanced. To evaluate the changes in oxidative stress status in the serum, products of lipid peroxidation (LPO) and serum glutathione values were measured. LPO was reduced significantly and reduced glutathione levels showed significant improvement after the exercise-conditioning programme. In the control group the data either remained the same or worsened in the same period of time. In conclusion, regular water-based exercise has beneficial effects on the cardiorespiratory, renal functional parameters and oxidative stress status in patients with moderate renal failure, and can be used in the complex rehabilitation of chronic renal failure patients, together with blood pressure control, dietary consultation, encouragement and education to prevent physical worsening and to postpone cardiovascular and renal atherosclerotic complications.

Renal protective effects of chronic exercise and antihypertensive therapy in hypertensive rats with chronic renal failure

OBJECTIVES

Patients with chronic renal failure are restricted to mild physical activity and tend to a lack of exercise. However, there have been few reports regarding the influence of chronic exercise on the progression of renal disease. Similarly, there are few animal models concerned with the effect of exercise training on improving renal function. Therefore, we assessed the renal effects of moderate chronic treadmill exercise in a remnant kidney model of spontaneously hypertensive rats (SHR) with chronic renal failure. We also assessed the effects of exercise and antihypertensive therapy on renal function.

DESIGN AND METHODS

Eight-week-old SHR were subjected to 5/6 nephrectomy by removal of the left kidney and excision of two-thirds of the right kidney. The rats were divided into four groups: (i) no exercise (Non-EX); (ii) moderate exercise with treadmill running (20 m/min, 0 grade incline for 60 min) (EX); (iii) EX with an angiotensin converting enzyme (ACE) inhibitor, enalapril (2 mg/kg per day, i.p.); and (iv) EX with an angiotensin receptor antagonist, losartan (5 mg/kg per day, i.p.), for 4 weeks.

RESULTS

Chronic EX significantly attenuated the increase in proteinuria (P < 0.01) and significantly protected against increases in the index of glomerular sclerosis (IGS). Both enalapril and losartan with EX significantly decreased blood pressure (P < 0.001), and further decreased the IGS. In the stepwise multiple regression analysis, only antihypertensive drug remained in the model as a significant predictor of IGS (P < 0.0001). In contrast, exercise, antihypertensive drug and mean systolic blood pressure (weeks 1-4) remained in the model as a significant predictors of mean proteinuria (weeks 1-4) (all P < 0.0001).

CONCLUSIONS

These results suggest that exercise does not worsen renal function and has renal-protective effects in this model of rats. Moreover, the antihypertensive therapy has additional renal-protective effects in this model of rats.

Safety of chronic exercise in a rat model of kidney disease

PURPOSE

The objective of this study was to determine the effect of treadmill running on polycystic kidney disease (PKD) progression and bone mineral density in Han:SPRD-cy rats, an animal model of PKD.

METHODS

Using a 2 x 2 design, normal and polycystic male rats were divided randomly into exercise and sedentary groups at 4 wk of age. The exercising group performed treadmill exercise (14 m x min(-1)) for 30 min 3 d x wk(-1) for 6 wk, whereas the control group remained sedentary. This 6-wk period represents the period of greatest cyst growth in this model.

RESULTS

Both exercised and sedentary polycystic animals had significantly greater kidney weights, as well as greater concentrations of serum urea nitrogen and serum creatinine than control animals. Exercise did not alter these parameters in either normal or polycystic animals. In addition, bone mineral density and bone mineral content, determined by dual-energy x-ray absorptiometry, were not altered by exercise in these animals. Bone mineral content, however, was marginally lower in polycystic animals.

CONCLUSIONS

These results support the safety of moderate exercise in PKD. Additional research in this area is needed since there may be other benefits that are derived from exercise in this population.