Renoprotective effects of voluntary running exercise training on aldosterone-induced renal injury in human L-FABP chromosomal transgenic mice

Elevated urinary angiotensinogen excretion links central and renal hemodynamic alterations

Inappropriate activation of intrarenal renin-angiotensin system (RAS) may contribute to the pathogenesis of cardio-renal syndrome (CRS). We aimed to examine the cross-sectional associations of urinary angiotensinogen (AGT) excretion, a biomarker of intrarenal RAS activity, with central (aortic) and renal hemodynamic parameters in middle-aged and older adults, including patients with chronic kidney disease. Aortic and renal hemodynamic parameters were measured using applanation tonometry and duplex ultrasonography in 282 participants. Urinary AGT, liver-type fatty acid-binding protein (L-FABP), and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured for each participant. Multiple linear regression analyses demonstrated that urinary AGT levels were associated with aortic blood pressures, pulsatile measures of renal blood flow, plasma NT-proBNP and urinary L-FABP levels after adjusting for potential covariates, including age, sex, body mass index, estimated glomerular filtration rate (GFR), and medication use. Additionally, when classified based on GFR stages and urinary AGT levels, plasma NT-proBNP and urinary L-FABP levels increased in participants with lower GFR and higher AGT groups. Our findings suggest that urinary AGT excretion is a shared determinant of central (aortic) and renal hemodynamics in middle-aged and older adults, providing clinical evidence for the potential role of intrarenal RAS activity in the development of CRS.

The effects of exercise on kidney injury: the role of SIRT1

In patients with kidney injury, muscle mass and strength decrease with altered muscle protein synthesis and degradation along with complications such as inflammation and low physical activity. A treatment strategy to maintain muscle metabolism in kidney injury is important. One of the proposed strategies in this regard is exercise, which in addition to inducing muscle hypertrophy, reducing plasma creatinine and urea and decreasing the severity of tubal injuries, can boost immune function and has anti-inflammatory effects. One of the molecules that have been considered as a target in the treatment of many diseases is silent information regulator 1 (SIRT1). Exercise increases the expression of SIRT1 and improves its activity. Therefore, studies that examined the effect of exercise on kidney injury considering the role of SIRT1 in this effect were reviewed to determine the direction of kidney injury research in future regarding to its prevalence, especially following diabetes, and lack of definitive treatment. In this review, we found that SIRT1 can be one of renoprotective target pathways of exercise. However, further studies are needed to determine the role of SIRT1 in different kidney injuries following exercise according to the type and severity of exercise, and the type of kidney injury.

Endurance exercise training-attenuated diabetic kidney disease with muscle weakness in spontaneously diabetic Torii fatty rats

Background The aim of this study was to evaluate protective effects of endurance exercise training against diabetic kidney disease (DKD) with muscle weakness by using male spontaneously diabetic Torii (SDT) fatty rats as type 2 diabetic animal models with obesity, hypertension, and hyperlipidemia. Methods Eight-week-old SDT fatty rats (n = 12) and Sprague-Dawley (SD) rats (n = 10) were randomly divided into exercise (Ex; SDT-Ex: n = 6, SD-Ex: n = 5) and sedentary groups (SDT-Cont: n = 6, SD-Cont: n = 5), respectively. Each group underwent regular treadmill exercise four times a week from ages 8 to 16 weeks. Results The exercise attenuated hypertension and hyperlipidemia and prevented increases in renal parameter levels without affecting blood glucose levels. In the SDT fatty rats, it prevented induction of renal morphological abnormalities in the interstitium of the superficial and intermediate layers of the cortex. Downregulated expression of endothelial nitric oxide synthase in the glomerulus of the SDT fatty rats was significantly upregulated by the exercise. The exercise upregulated the renal expressions of both medium-chain acyl-CoA dehydrogenase and peroxisome proliferator-activated receptor γ coactivator-1α related to fatty acid metabolism. It increased muscle strength and both muscle weight and cross-sectional area of type IIb muscle fibers in the extensor digitorum longus muscle in the SDT fatty rats. Conclusion Endurance exercise training in type 2 diabetes ameliorates DKD by improving endothelial abnormality and enhancing fatty acid metabolism in addition to attenuated hypertension, hyperlipidemia, and muscle weakness independently of blood glucose levels.

Remedial role of exercise training to deep-fried oil-induced metabolic and histological changes in Wistar rats

Exercise training is a well-known lifestyle to maintain good health. The present study was conducted to explore the effect of regular exercise training (for 15 min) on biochemical, physiological, and histological changes in fried oil intake (5 g/kg body weight, for 5 weeks) with or without raw oil supplementation. Liver disease and heart muscle injury were accounted for by significant (p < .05) increase in liver and heart biomarker enzymes in serum. Creatinine and urea level were also significantly increased in the fried oil-fed group as a sign of kidney injury. But all the biological markers including triglycerides, low-density lipoprotein cholesterol (LDL-C) was decreased significantly (p < .05) in the exercise-trained rat group. These metabolic changes were substantiated by the histological study of respective organs. Therefore, people should avoid repeatedly deep-fried oil consumption rather than fresh ones though regular exercise training has been found to resolve these metabolic abnormalities. PRACTICAL APPLICATIONS: Exercise training is a common practice to reduce the onset of some metabolic abnormalities for example cardiovascular disease, non-alcoholic fatty liver disease, chronic kidney disease, and also prevents various cell and tissue damages. Repeated frying of vegetable oil not only reduces its nutritional value but also produce free fatty acids and other toxic compounds. The present study revealed that repeatedly heated vegetable oil consumption causes injuries in the heart, liver, kidney, and small intestine by the oxidative products. As a result, the level of biomarkers of these responsive organs was found to be elevated. But regular exercise training ameliorated these detrimental effects. So, in terms of public health concern, regular exercise is one of the best ways to keep the body fit especially those who are consuming deep-fried oil.

Incremental short maximal exercise increases urinary liver-type fatty acid-binding protein in adults without CKD

Exercise-induced redistribution of tissue blood flow decreases the renal blood flow in an exercise intensity-dependent manner. However, the acute effects of incremental short maximal exercise on renal tubular conditions remain unknown. The purpose of this study was to investigate the acute effects of incremental short maximal exercise on the urinary liver-type fatty acid-binding protein, which is a highly sensitive tubular biomarker that correlates excellently with peritubular capillary blood flow. A total of 116 adults (aged 24-83 years) without chronic kidney disease performed the incremental short maximal exercise using a cycling ergometer, wherein the exercise sequence consisted of commencing with a 2-min workout period at 20 W (as a warm-up period) and then followed by a 10-20 W increase every 1 minute until termination criteria were reached. Urinary samples were gathered before and immediately after the exercise to evaluate the concentrations of urinary creatinine, albumin, and liver-type fatty acid-binding protein. Urinary excretion levels of albumin and liver-type fatty acid-binding protein were significantly increased post-exercise (P < .001 and P = .008, respectively). Furthermore, the % change in urinary liver-type fatty acid-binding protein levels after exercise was found to correlate independently with age, estimated glomerular filtration rate at baseline, and the % change in urinary albumin (Model R²  = 0.451, P < .001). Our findings suggest that incremental short maximal exercise may lead to acute slightly adverse effects on tubular conditions, especially in young adults or adults with lower renal function, even without chronic kidney disease.

Relationship between Urinary Liver-Type Fatty Acid-Binding Protein (L-FABP) and Sarcopenia in Spontaneously Diabetic Torii Fatty Rats

BACKGROUND

Type 2 diabetes (T2D) is a known risk factor for diabetic kidney disease (DKD) and sarcopenia in older patients. Because there may be an interaction between DKD and sarcopenia, the aim of the present study is to investigate the relationship between urinary levels of liver-type fatty acid-binding protein (L-FABP) and sarcopenia using a novel rat model of T2D.

METHODS

Male spontaneously diabetic Torii (SDT) fatty rats (n = 5) at 16 weeks of age were used as an animal model of T2D. Age- and sex-matched Sprague-Dawley (SD) rats (n = 7) were used as controls. Urine samples were obtained from the rats, and muscle strength was evaluated with the use of the forelimb grip test at 16, 20, and 24 weeks of age. Serum, kidney, soleus, and extensor digitorum longus (EDL) muscle samples were collected at 24 weeks of age. Urinary L-FABP levels were measured using dedicated enzyme-linked immunosorbent assays.

RESULTS

Increased urinary L-FABP levels, focal glomerular sclerosis, moderate interstitial inflammation and fibrosis, and accumulation of renal oxidative proteins were significantly observed in the SDT fatty rats, compared to the SD rats. Muscle weight, muscle strength, cross-sectional areas of both type I and type IIb muscle fibers, and increasing rate of muscle strength were significantly decreased in the SDT fatty rats compared to the SD rats at 24 weeks. Urinary L-FABP levels at 20 and 24 weeks were significantly negatively correlated with muscle strength. Urinary L-FABP levels at 16 weeks were significantly negatively correlated with the increasing rate of muscle strength.

CONCLUSIONS

Urinary L-FABP reflects the degree of muscle strength and weight, as well as cross-sectional areas of muscle fibers. Although further clinical study is needed, urinary L-FABP may be useful to monitor the progression of sarcopenia and DKD in T2D patients.