Background: Arterial hypertension (AH) is associated with heart and chronic kidney disease (CKD). However, the precise mechanisms of myocardial remodeling (MR) in the settings of CKD remain elusive. We hypothesized that TRPC6, calcineurin/NFAT, and Wnt/β-catenin signaling pathways are involved in the development of MR in the background of CKD and AH. Methods: Early CKD was induced by performing a 5/6 nephrectomy (5/6NE) in spontaneously hypertensive rats (SHR-NE). Sham-operated (SO) SHR (SHR-SO) and Wistar Kyoto (WKY-SO) rats served as controls. Systolic blood pressure (SBP), heart rate, myocardial mass index (MMI), serum creatinine, cardiomyocyte diameter (dCM), myocardial fibrosis (MF), serum and kidney α-Klotho levels, myocardial expression of calcineurin (CaN), TRPC6, and β-catenin were measured two months after 5/6NE or SO. Results: NE-induced kidney dysfunction corresponded to mild-to-moderate human CKD and was associated with an increase in FGF23 and a decrease in renal α-Klotho. The levels of SBP, MMI, dCM, and MF were higher in SHRs compared to WKY-SO as well as in SHR-NE vs. SHR-SO. The MR was associated with increased cardiomyocyte expression of CaN/NFAT and β-catenin along with its intracellular re-distribution. TRPC6 protein levels were substantially elevated in both SHR groups with higher Trpc6 mRNA expression in SHR-NE. Conclusions: The Wnt/β-catenin and TRPC6/CaN/NFAT hypertrophic signaling pathways seem to be involved in myocardial remodeling in the settings of AH and CKD and might be mediated by FGF23 and α-Klotho axis.
Aim. To assess the significance of the serum uromodulin (Tamm-Horsfall protein - THP) concentration (Sumo) as an early biomarker of tubular atrophy (TA) and interstitial renal fibrosis (IF) in patients with glomerulopathies. Materials and methods. 84 patients with glomerulopathy and 11 practically healthy persons (control) were examined. Uromodulin concentrations in serum and urine (Uumo) were measured, renal excretion of this protein and the estimated glomerular filtration rate (eGFR) were established. A semi-quantitative assessment of nephrobioptates was performed. Results and discussion. Sumo decreases with a minimum expression of tubular atrophy (TA) or interstitial fibrosis (IF), when the values of eGFR still remain normal. Variations of such excretory parameters of THP as Uumo, daily excretion, and ratio: urinary uromodulin / urinary creatinine, did not manifest a similar trend. Conclusion. Sumo is promising as an early biomarker of fibrotic and atrophic renal damage. The parameters of renal excretion of THP do not seem to have this property. The reason for the delay in the decline of Uumo in the progression of CKD as compared to the decrease in Sumo seems to be the need to maintain a sufficient Uumo to counteract urinary tract infection and stone formation.
INTRODUCTION.It is suggested that fibroblast growth factor 23 (FGF23) and its co-receptor Klotho are probably associatedwith changes in calcium metabolism in chronic kidney disease (CKD) due to ability to regulate intracellular Ca transport bymodulating the cationic channels TRPV5 and TRPV6.THE AIMis to investigate the association between Klotho, FGF23 and renal excretion of Ca in the initial stages of experimental CKD.MATERIAL AND METHODS.The experimental models of chronic kidney injury were resection of the renal tissue in spontaneously hypertensive rats (SHR). Serum concentrations of intact FGF23 and PTH were determined by ELISA, renal Klotho protein expression by IHC. The indices of Ca excretion were calculated.RESULTS.Serum creatinine concentration, creatinine clearance and the severity of interstitial fibrosis in experimental models corresponded to the initial stages of chronic kidney disease. UCa24 and FECa were higher, Klotho protein expression was lower in groups with more severe renal dysfunction, without significant differences in FGF23 and PTH levels. Multiple regression analysis showed that FECa and UCa24 were not associated with FGF23, Klotho, and PTH.CONCLUSION.Renal excretion of Ca in initial stages of experimental kidney damage is not associated with Klotho and FGF23 levels.
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