Resistance exercise training ameliorates chronic kidney disease outcomes in a 5/6 nephrectomy model

Association of aerobic and muscle-strengthening physical activity with chronic kidney disease in participants with hypertension

BACKGROUND

In Korea, chronic kidney disease (CKD) is increasingly prevalent among adults with hypertension, of which approximately 30% of the population is affected. Despite the recognized benefits of adherence to physical activity (PA) recommendations, including aerobic and muscle-strengthening activities (MSA), the impact of such adherence on the prevalence of CKD in individuals with hypertension has not been extensively studied. This study aimed to investigate the association between aerobic PA and MSA levels, and the prevalence of CKD in individuals with hypertension.

METHODS

This study included 5,078 individuals with hypertension using data from the Korean National Health and Nutrition Examination Survey (2019-2021). PA levels were measured as min/week of moderate-to-vigorous PA (MVPA) based on self-reports, and MSA was quantified as the number of days per week. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m². Logistic regression analysis evaluated the association between meeting PA guidelines and CKD after adjusting for potential confounders. Additionally, a joint analysis was conducted to assess the combined effects of MVPA and MSA on CKD.

RESULTS

After adjusting for all covariates, higher MVPA was associated with a lower prevalence of CKD. Compared to the group with inactive, the group with MVPA 1-149 min/week had an odds ratio (OR) of 0.80 (95% confidence interval [CI], 0.61-1.05), the group that met the MVPA 150-299 min/week criteria had an OR of 0.85 (95% CI, 0.62-1.17), and the group that met the MVPA ≥ 300 min/week criteria had an OR of 0.53 (95% CI, 0.37-0.76). MSA alone did not show a significant association with CKD. In the joint analysis, the group that met the MVPA and MSA guidelines had the lowest OR of 0.54 (95% CI, 0.34-0.86), compared to the group that did not meet either.

CONCLUSIONS

MVPA was associated with the prevalence of CKD in participants with hypertension but not in those with MSA alone. However, compared with the group that did not meet both guidelines, the group that met both guidelines showed the lowest prevalence of CKD.

Establishment and application of a new 4/6 infarct nephrectomy rat model for moderate chronic kidney disease

PURPOSE

To develop a new 4/6 infarct nephrectomy (INx) model rat mimicking moderate chronic kidney disease (CKD) and to evaluate its application.

METHODS

We modified the conventional 5/6 INx rat model to create the 4/6 INx model by ligating the renal artery branch to induce infarction of one-third of the left kidney after right kidney removal and compared biochemically and histologically both models. To demonstrate the application of the 4/6 INx model, the effects of a supplementary compound containing calcium carbonate, chitosan, palm shell activated charcoal etc., that is effective for both CKD and its complications, were compared between both models.

RESULTS

Impairment of renal function in the 4/6 INx group was significantly more moderate than in the 5/6 INx group (P < 0.05). The 4/6 INx group showed less histological damage in kidney than in the 5/6 INx group. The supplementary compound did not improve CKD in the 5/6 INx group, but ameliorated elevation of blood urea nitrogen in the 4/6 INx group.

CONCLUSIONS

We developed the 4/6 INx model, which is more moderate than the conventional 5/6 INx model. This model could potentially demonstrate the effectiveness of drugs and supplements intended to prevent CKD and its progression.

The effect of periodic resistance training on obese patients with type 2 diabetic nephropathy

Resistance training is an exercise against resistance designed to train the endurance and strength of muscle. To observe the effect of intervention of periodic resistance training on obese patients with type 2 diabetic nephropathy. A total of 60 obese patients with type 2 diabetic nephropathy were randomized into resistance training group and aerobic exercise group (30 patients each group) for observing the changes of blood glucose, body weight, blood lipid, insulin resistance, serum creatinine (Scr), urinary microalbumin, urinary albumin excretion rate (UAER) calculated by urinary creatinine, and glomerular filtration rate (GFR) after 12 weeks of intervention, and relevant significance as well. The number of patients with hypoglycemia during the intervention was also recorded. After 12 weeks of intervention, the weight, Body mass index (BMI), Waist, Triglyceride (TG), Cholesterol (TC), Low-density lipoprotein cholesterol (LDL), Fasting glucose (FBG), Fasting insulin (FINS), Glycosylated hemoglobin (HbA1c) and urine Albumin-Creatinine Ratio (uACR) were decreased and GFR was increased in both groups (P < 0.05), but the effect was more significant in the resistance training group. GFR was increased from 92.21 ± 10.67 mL/(min·1.73 m2) to 100.13 ± 12.99 mL/(min·1.73 m2) in resistance training group (P < 0.05). In the aerobic exercise group, GFR was increased from 89.98 ± 9.48 mL/(min·1.73 m2) to 92.51 ± 11.35 mL/(min·1.73 m2) (P > 0.05). Periodic resistance training can not only control the weight, blood sugar and blood lipid of obese patients with type 2 diabetic nephropathy, but also improve the urinary albumin excretion rate and glomerular filtration rate of early obese patients with type 2 diabetic nephropathy, and delay the progression of diabetic nephropathy. It is an effective non-drug intervention.

Skeletal muscle atrophy in clinical and preclinical models of chronic kidney disease: A systematic review and meta-analysis

Patients with chronic kidney disease (CKD) are often regarded as experiencing wasting of muscle mass and declining muscle strength and function, collectively termed sarcopenia. The extent of skeletal muscle wasting in clinical and preclinical CKD populations is unclear. We evaluated skeletal muscle atrophy in preclinical and clinical models of CKD, with multiple sub-analyses for muscle mass assessment methods, CKD severity, sex and across the different preclinical models of CKD. We performed a systematic literature review of clinical and preclinical studies that measured muscle mass/size using the following databases: Ovid Medline, Embase and Scopus. A random effects meta-analysis was utilized to determine standard mean difference (SMD; Hedges' g) between healthy and CKD. Heterogeneity was evaluated using the I2 statistic. Preclinical study quality was assessed via the Systematic Review Centre for Laboratory Animal Experimentation and clinical studies quality was assessed via the Newcastle-Ottawa Scale. This study was registered in PROSPERO (CRD42020180737) prior to initiation of the search. A total of 111 studies were included in this analysis using the following subgroups: 106 studies in the primary CKD analysis, 18 studies that accounted for diabetes and 7 kidney transplant studies. Significant atrophy was demonstrated in 78% of the preclinical studies and 49% of the clinical studies. The random effects model demonstrated a medium overall SMD (SMD = 0.58, 95% CI = 0.52-0.64) when combining clinical and preclinical studies, a medium SMD for the clinical population (SMD = 0.48, 95% CI = 0.42-0.55; all stages) and a large SMD for preclinical CKD (SMD = 0.95, 95% CI = 0.76-1.14). Further sub-analyses were performed based upon assessment methods, disease status and animal model. Muscle atrophy was reported in 49% of the clinical studies, paired with small mean differences. Preclinical studies reported significant atrophy in 78% of studies, with large mean differences. Across multiple clinical sub-analyses such as severity of CKD, dialysis modality and diabetes, a medium mean difference was found. Sub-analyses in both clinical and preclinical studies found a large mean difference for males and medium for females suggesting sex-specific implications. Muscle atrophy differences varied based upon assessment method for clinical and preclinical studies. Limitations in study design prevented conclusions to be made about the extent of muscle loss with disease progression, or the impact of dialysis. Future work would benefit from the use of standardized measurement methods and consistent clinical staging to improve our understanding of atrophy changes in CKD progression, and analysis of biological sex differences.

Effects of bisphosphonates and treadmill exercise on bone and kidney in adenine-induced chronic kidney disease rats

INTRODUCTION

The increasing prevalence of osteoporosis and chronic kidney disease (CKD) due to the aging of society has highlighted the need for development of effective treatments for elderly patients. This study examined whether the combination of treadmill exercise therapy and alendronate (ALN) can improve bone mineral density (BMD) and bone strength without worsening renal function in adenine-induced CKD model rats.

MATERIALS AND METHODS

8-week-old male Wistar rats (n = 70) were divided into experimental groups based on the treatment protocol, i.e., non-CKD (control), vehicle only (CKD), ALN only, exercise only, and combined ALN plus exercise. A 0.75% adenine diet was used to induce CKD. Groups were killed at either 20 or 30 weeks of age. Comprehensive assessments included serum and urine biochemistry tests, renal histology, bone histomorphometry, BMD measurement, micro-computed tomography examinations, and biomechanical testing.

RESULTS

Blood biochemistry tests, urine analyses and histological evaluations of the kidney demonstrated that ALN treatment did not worsen renal function or kidney fibrosis in moderate-stage CKD model rats. Both ALN and treadmill exercise significantly suppressed bone resorption (p < 0.05-p < 0.01). Moreover, ALN monotherapy and combined ALN and treadmill exercise significantly improved BMD of the lumbar spine and femur, bone microstructure, and trabecular bone strength (p < 0.05-p < 0.01). Treadmill exercise was also shown to decrease cortical porosity at the mid-diaphysis of the femur and improve kidney fibrosis.

CONCLUSION

The combination of ALN and treadmill exercise is effective in improving BMD, the microstructure of trabecular and cortical bone, and bone strength, without compromising renal function in adenine-induced CKD model rats.

The role of exercise in improving hyperlipidemia-renal injuries induced by a high-fat diet: a literature review

A diet that is high in sugar and fat is a precursor to various chronic diseases, especially hyperlipidemia. Patients with hyperlipidemia have increased levels of plasma free fatty acids and an ectopic accumulation of lipids. The kidney is one of the main organs affected by this disease and, recently, there have been more studies conducted on renal injury caused by hyperlipidemia. The main pathological mechanism is closely related to renal lipotoxicity. However, in different kidney cells, the reaction mechanism varies due to the different affinities of the lipid receptors. At present, it is believed that in addition to lipotoxicity, hyperlipidemia induced-renal injury is also closely related to oxidative stress, endoplasmic reticulum stress, and inflammatory reactions, which are the result of multiple factors. Exercise plays an important role in the prevention of various chronic diseases and recently emerging researches indicated its positive effects to renal injury caused by hyperlipidemia. However, there are few studies summarizing the effects of exercise on this disease and the specific mechanisms need to be further explored. This article summarizes the mechanisms of hyperlipidemia induced-renal injury at the cellular level and discusses the ways in which exercise may regulate it. The results provide theoretical support and novel approaches for identifying the intervention target to treat hyperlipidemia induced-renal injury.

Aerobic exercise inhibits renal EMT by promoting irisin expression in SHR

To determine the effect of aerobic exercise in different intensities on renal injury and epithelial-mesenchymal transformation (EMT) in the kidney of spontaneously hypertensive rats (SHR) and explore possible mechanisms, we subjected SHR to different levels of 14-week aerobic treadmill training. We tested the effects of aerobic exercise on irisin level, renal function, and EMT modulators in the kidney. We also treated angiotensin II-induced HK-2 cells with irisin and tested the changes in EMT levels. The data showed low and moderate aerobic exercise improved renal function and inhibited EMT through promoting irisin expression in SHR. However, high-intensity exercise training had no effect on renal injury and EMT in SHR but did significantly activate STAT3 phosphorylation in the kidney. These results clarify the mechanisms of exercise in improving hypertension-related renal injury and suggest that irisin might be a therapeutic target for patients with kidney injury.

Comparison of the Surgical Resection and Infarct 5/6 Nephrectomy Rat Models of Chronic Kidney Disease

The 5/6 nephrectomy rat remnant kidney model is commonly employed to study chronic kidney disease (CKD). This model requires removal of one whole kidney and two-thirds of the other. The two most common ways of producing the remnant kidney are surgical resection of poles, known as the polectomy (Pol) model, or ligation of upper and lower renal arterial branches, resulting in pole infarction (Inf). These models have much in common, but also major phenotypic differences, and thus respectively model unique aspects of human CKD. The purpose of this review is to summarize phenotypic similarities and differences between these two models and their relation to human CKD, while emphasizing their vascular phenotype. In this article we review studies that have evaluated arterial blood pressure, the renin-angiotensin-aldosterone-system (RAAS), autoregulation, nitric oxide, single nephron physiology, angiogenic and anti-angiogenic factors, and capillary rarefaction in these two models. Phenotypic similarities: both models spontaneously develop hallmarks of human CKD including uremia, fibrosis, capillary rarefaction, and progressive renal function decline. They both undergo whole-organ hypertrophy, hyperfiltration of functional nephrons, reduced renal expression of angiogenic factor VEGF, increased renal expression of the anti-angiogenic thrombospondin-1, impaired renal autoregulation, and abnormal vascular nitric oxide physiology. Key phenotypic differences: the Inf model develops rapid-onset, moderate-to-severe systemic hypertension, and the Pol model early normotension followed by mild-to-moderate hypertension. The Inf rat has a markedly more active renin-angiotensin-aldosterone-system. Comparison of these two models facilitates understanding of how they can be utilized for studying CKD pathophysiology (e.g., RAAS dependent or independent pathology).