Sodium Reabsorption Research Articles

Abstract 13298: Impact of Finerenone on Cardiac Biomarkers in Patients With T2D and Chronic Kidney Disease

Introduction: Finerenone is a non-steroidal, selective antagonist of the mineralocorticoid receptor (MR), which blocks MR-mediated sodium reabsorption and MR overactivation. In this biomarker substudy to FIDELITY, a pooled, pre-specified analysis of FIGARO-DKD and FIDELIO-DKD, NT-proBNP and cardiac troponin T (cTnT) levels were assessed to explore the effect of finerenone on cardiac markers. FIGARO-DKD and FIDELIO-DKD were two phase III trials investigating efficacy and safety of finerenone vs. placebo (PLC) on cardiorenal outcomes, in patients with T2D and CKD. Hypothesis: Finerenone impacts the levels of major cardiac biomarkers. Methods: Samples were collected prospectively from non-selected patients who consented to the biomarker study. At baseline (BL), this study included 1037 subjects with cTnT data and 1592 subjects with NT-proBNP data from 13 and 24 countries, respectively. Samples were analyzed at BL, 4, 12, 24, 36 and 48 months follow-up on treatment with finerenone or PLC. Treatment effects on biomarkers were computed by a linear mixed model, adjusted for age, gender, screening eGFR and UACR, history of CVD, BL biomarker levels and geographical region. Results: Both, NT-proBNP and cTnT increased over time in both arms, yet, the increase was significantly lower in the active arm compared to PLC, even though finerenone temporarily reduces eGFR. The maximum ratio (finerenone to PLC) was 0.82 (95% CI: 0.76 to 0.90) at month 4 for NT-proBNP, and 0.94 (95% CI: 0.892 to 0.995) for cTnT at month 36. Median levels of biomarkers at BL were 177 pg/mL (NT-proBNP, IQR: 74-426) or 18 pg/mL (cTnI, IQR: 7-27). Conclusions: In patients with T2D and CKD, finerenone, on top of maximum tolerated labelled RAS inhibition and standard of care co-medication, reduced plasma NT-proBNP and cTnT, biomarkers usually associated with cardiac stress and injury, and indicative of poor prognosis. Our findings are in line with outcome data from FIDELITY showing a 22% risk reduction for HF hospitalization1 and other findings suggestive of reduced adverse cardiac remodeling. This data provides supportive mechanistic insights for benefits on cardiorenal outcomes in FIDELITY, confirming preclinical findings as well as clinical data on short-term treatment effects on NT-proBNP.

Glomerular and tubular effects of dapagliflozin, eplerenone and their combination in patients with chronic kidney disease: A post-hoc analysis of the ROTATE-3 study.

Sodium-glucose co-transporter 2 inhibitors and mineralocorticoid receptor antagonists reduce albuminuria and the risk of kidney failure. The aim of this study was to investigate the effects of both agents alone and in combination on markers of the glomerular endothelial glycocalyx and tubular function. This post-hoc analysis utilized data of the ROTATE-3 study, a randomized cross-over study in 46 adults with chronic kidney disease and urinary albumin excretion ≥100 mg/24 h, who were treated for 4 weeks with dapagliflozin, eplerenone or its combination. The effects of dapagliflozin, eplerenone and the combination on outcome measures such as heparan sulphate, neuro-hormonal markers and tubular sodium handling were assessed with mixed repeated measures models. The mean percentage change from baseline in heparan sulphate after 4 weeks treatment with dapagliflozin, eplerenone or dapagliflozin-eplerenone was -34.8% (95% CI -52.2, -10.9), -5.9% (95% CI -32.5, 31.3) and -28.1% (95% CI -48.4, 0.1) respectively. The mean percentage change from baseline in plasma aldosterone was larger with eplerenone [38.9% (95% CI 2.8, 87.7)] and dapagliflozin-eplerenone [32.2% (95% CI -1.5, 77.4)], compared with dapagliflozin [-12.5% (95% CI -35.0, 17.8)], respectively. Mean percentage change from baseline in copeptin with dapagliflozin, eplerenone or dapagliflozin-eplerenone was 28.4% (95% CI 10.7, 49.0), 4.2% (95% CI -10.6, 21.4) and 23.8% (95% CI 6.6, 43.9) respectively. Dapagliflozin decreased proximal absolute sodium reabsorption rate by 455.9 mmol/min (95% CI -879.2, -32.6), while eplerenone decreased distal absolute sodium reabsorption rate by 523.1 mmol/min (95% CI -926.1, -120.0). Dapagliflozin-eplerenone decreased proximal absolute sodium reabsorption [-971.0 mmol/min (95% CI -1411.0, -531.0)], but did not affect distal absolute sodium reabsorption [-9.2 mmol/min (95% CI -402.0, 383.6)]. Dapagliflozin and eplerenone exert different effects on markers of glomerular and tubular function supporting the hypothesis that different mechanistic pathways may account for their kidney protective effects.

Genetic Factors Associated with Hypertension: A Comprehensive Review

Recent scientific findings indicate that hypertension is a largely genetically driven condition; one of today’s leading global health issues. There are many identified gene mutations associated with different aspects involving blood pressure control that lead to hypertension. More recently, certain specific genetic variants related to blood pressure control have been found using the modern techniques of genetic analysis that may assist in developing custom strategies to prevent and treat hypertension. The aim of this article is to highlight genetic aspects of hypertension and use them to establish individual therapy. It looks at the influence of genetic diversity on sodium resorption, skeletal muscle contraction, and drug pharmacokinetics. These studies indicate that GWAS has identified some genetic variants for hypertension and developed some genetic risk score (GRS) which can be used for prediction purpose. Therefore, genetic contribution is significant in establishing as well as sustaining high blood pressure. Knowledge about genetics regarding hypertension may change the way it is addressed on a person-by-person basis. Nevertheless, research needs to tackle the challenge of validating associations among diverse populations while developing a mechanism for translating genetic findings into clinical practice. Thus, we would enhance preventive, diagnostic and therapeutic measures for many people globally. Keywords: Hypertension; Genetic factors; Blood pressure regulation; Genome-wide association studies (GWAS); Personalized medicine approaches.

Resveratrol Inhibits Proximal Tubular Sodium Reabsorption and Suppresses the Progression of Renal Injury

Resveratrol Inhibits Proximal Tubular Sodium Reabsorption and Suppresses the Progression of Renal Injury

Novel insights into perfluorinated compound-induced hepatotoxicity: Chronic dietary restriction exacerbates the effects of PFBS on hepatic lipid metabolism in mice

Perfluorobutane sulfonates (PFBS) have garnered extensive utilization because of their distinctive physicochemical properties. The liver acts as a key target organ for toxicity within the body and is vital for regulating metabolic processes, particularly lipid metabolism. However, there is currently a significant research gap regarding the influences of PFBS on hepatic lipid metabolism, especially in individuals with different dietary statuses. Here, the objective of this research was to examine the effects of PFBS on hepatic function under different dietary conditions. The results suggested that the levels of liver injury biomarkers were significantly upregulated, e.g., transaminase (GPT, GOT), while liver lipid levels were downregulated after exposure to PFBS at concentration of 50 μg/L for 42 days. Moreover, restricted diet further intensified the adverse effects of PFBS on the liver. Metabolomics analysis identified significant alterations in lipid-related metabolites in PFBS-induced hepatotoxicity, PFBS exposure induced a decrease in lysophosphatidylethanolamine and lysophosphatidylcholine. PFBS exposure caused an increase in aldosterone and prostaglandin f2alpha under restricted diet. In PFBS treatment group, histidine metabolism, beta-alanine metabolism, and arginine biosynthesis were the main pathway for PFBS toxicity. Aldosterone-regulated sodium reabsorption as a vital factor in inducing PFBS toxicity in the RD-PFBS treatment group. The analysis of 16S rRNA sequencing revealed that exposure to PFBS resulted in imbalance of gut microbial communities. PFBS exposure induced a decrease in Akkermansia and Lactobacillus, but an increase in Enterococcus. PFBS exposure caused the abundance of Lachnospiraceae_NK4A136_group was significantly elevated under restricted diet. Additionally, disruptions in the expression of genes involved in lipid production and consumption may significantly contribute to lipid imbalance in the liver. This study underscores the importance of recognizing the harmful impact of PFBS on liver function, along with the biotoxicity of contaminant influenced by dietary habits.

THU474 Primary Hyperaldosteronism As A Cause Of PTH Elevation After Parathyroid Surgery

Abstract Disclosure: W. Thi: None. A. Rao: None. Background: Primary hyperaldosteronism can cause hypercalciuria, parathyroid hormone (PTH) elevation due to secondary hyperparathyroidism, and reduce bone mineral density. Screening for primary hyperaldosteronism can be done with serum aldosterone-renin ratio (ARR). We report a case of recurrent hyperparathyroidism after parathyroid surgery. Workup identified primary hyperaldosteronism as the cause of recurrent hyperparathyroidism. Treatment with spironolactone normalized PTH levels. Case Presentation: A 59-year-old African-American female in the Columbia VA Health Care System presented with hypertension, hypokalemia, bone density loss, and elevated PTH with normal calcium, one year after resection of a right inferior parathyroid adenoma to treat primary hyperparathyroidism. The patient had uncontrolled hypertension with hypokalemia while on losartan and amlodipine. Serum calcium was 9.4mg/dl(8.4-10.2mg/dl), PTH 89.4 pg/ml(29.2-79.9pg/ml), albumin 3.8g/dl(3.5-5G/dl), vitamin D 34 ng/ml(>28.9ng/ml), aldosterone 9ng/dl(</=28ng/dl), plasma renin activity 0.28ng/ml/h(0.25-5.82ng/ml/h), ARR 32. Treatment of the patient with potassium supplements corrected the hypokalemia to 3.7mmol/L (5-5.1mm/l), and ARR was 94 with aldosterone 17 ng/dl and PRA 0.18 ng/ml/h and 24-hour urine calcium 304mg/24h(35-250mg/24h). Based on the laboratory values, and the absence of adrenal nodules during a CT scan, a diagnosis of primary hyperaldosteronism due to idiopathic hyperplasia of the adrenal was made. Spironolactone was started and PTH levels dropped down to 64.8pg/ml and serum calcium remained normal 5 months after treatment was initiated. Discussion: Primary Hyperaldosteronism causes extravascular fluid volume expansion with a reduction in proximal tubular sodium and calcium reabsorption. Increased calcium and sodium delivery to distal segments of the nephron leads to sodium reabsorption by mineralocorticoids without reabsorbing calcium, resulting in hypocalcemia with concomitant secondary hyperparathyroidism. Bone loss results from direct mineralocorticoid receptor-mediated effects of aldosterone on osteoblasts and osteoclasts and indirectly from high PTH levels to promote bone resorption. Treatment of primary hyperaldosteronism can reverse bone loss and reduce fracture risk rate within 18-36 months. This case suggests that primary hyperaldosteronism be considered a cause of secondary hyperparathyroidism and successfully treated with mineralocorticoid receptor antagonists. Presentation: Thursday, June 15, 2023

THU598 Pseudohypoaldosteronism Type 2: A New Variant Of A Rare Disease

Abstract Disclosure: T.L. Cater: None. L. Borges Espinosa: None. Introduction: Familial hyperkalemia and hypertension syndrome or pseudohypoaldosteronism type 2 (PH2) is a rare monogenic hypertension resulting from WNK1, WNK4, KLHL3, or CUL3 gene mutation. Subsequent interference at the Na-Cl co-symporter, epithelial Na, or ROMK channel results in metabolic acidosis, hyperkalemia, and hypertension responsive to thiazide treatment. This case demonstrates PH2 resulting from a KLHL3 gene variant not previously described. Mutations to KLHL3 decrease Na-Cl cotransporter expression in the distal convoluted tubule leading to increased sodium and chloride reabsorption, volume expansion, hypertension, and, therefore, less sodium available for potassium exchange in the collecting duct. Case Description: A 30-year-old female G1P0 with twin gestation was admitted at 33 weeks for preeclampsia with severe features. PMH was unremarkable. She underwent C-section and was discharged home with healthy twin daughters. BMP during admission showed hyperkalemia with peak potassium 5.2 mmol/L which improved to 4.6 mmol/L by discharge. Essential hypertension was diagnosed 3 months later (BP 130/90, 78 bpm, RR 16, BMI 30.0 kg/m2). Labetalol 50 mg BID was initiated. BMP obtained showed hyperkalemia as high as 6.4 mmol/L. Further workup showed undetectable renin with normal aldosterone, hyperchloremic metabolic acidosis with chloride 111 mmol/L and bicarbonate 20 mmol/L, and normal EKG. She was managed in the ED where her potassium improved to 5.1 mmol/L with persistent hyperchloremic metabolic acidosis. A diagnosis of pseudohyperkalemia was presumed initially. Labetalol was discontinued in favor of hydrochlorothiazide 12.5 mg daily. Lost to follow-up, she presented 10 years later to Endocrinology at age 41 for chronic hyperkalemia and hyperchloremic metabolic acidosis. Labs showed potassium 6.5 mmol/L, chloride 108 mmol/L, and bicarbonate 23 mmol/L. Exam showed BP 133/98, BMI 26.63 kg/m2. She recounted several ER visits over the past decade for hyperkalemia with highest reported potassium of 7.8. She had stopped her thiazide due to dizziness, palpitations, and fatigue. Family history was now notable for hyperkalemia in her father, two brothers, and fraternal niece but no genetic testing was available. We resumed hydrochlorothiazide 12.5 mg every other day; follow-up labs showed improved potassium 5.2 mmol/L. Genetic testing revealed heterozygosity in the KLHL3 gene for the c.1064T &gt G sequence, a variant that has not been reported in the literature or large population database. Conclusion: Hypertension in PH2, distinct in its presentation with hyperkalemia and metabolic acidosis, requires a detailed family history and hormonal evaluation to make the diagnosis. Genetic testing in our case patient revealed a variant at the KLHL3 gene not previously described, underscoring the utility of genetic testing in understanding this rare condition. Presentation: Thursday, June 15, 2023

Diabetes and Cardiorenal Complications: A Clinical Review of Existing Therapies and Novel Combinations, Focusing on SGLT2 Inhibitors.

Type 2 diabetes mellitus (T2DM) is a set of metabolic disorders specified by hyperglycemia as a result of abnormalities in insulin secretion or sensitivity. Chronic kidney disease (CKD) and cardiovascular disease (CVD) are the widespread co-morbidities of T2DM and share risk factors for onset and progression. Despite numerous mono- and combination therapies exist, the progression of diabetes complications remains a global health concern. Treatment options for diabetic- CKD and CVD include drugs targeting hyperglycemia, hypertension, albuminuria, hyperlipidemia and the renin-angiotensin aldosterone system (RAAS). The sodium-glucose co-transporter 2 channel (SGLT2) is abundantly present in proximal tubules of the kidney and its capacity to recover glucose and sodium from the glomerular filtrate limits urinary glucose and sodium excretion. SGLT2 inhibitors (SGLT2i) reduce sodium and glucose reabsorption in the proximal and thus increase urinary glucose excretion in T2DM. SGLT2i monotherapy can improve but dual SGLT2/RAAS inhibition or SGLT2i along with other classes of drugs are more effective in protecting the kidneys and the cardiovascular system in patients with and without diabetes. Combinations such as empagliflozin and linagliptin, ertugliflozin and metolazone, dapagliflozin and sacubitril- valsartan and many more show promising results. Here, we have reviewed the ongoing and completed clinical trials, addressed current theories, and discussed necessary future research to explain the possible risks and benefits of using an SGLT2i alone and in combination with existing antidiabetic drugs and drugs acting on the cardiovascular system.

Efficacy of Flavonoid Apigenin on Hemodynamic indices, Baroreflex Function, Cardiac and Kidney Remodeling and Vasoactive-Inflammatory Biomarkers in Experimental Renal Hypertension

The hypothesis stated here that, the long-term prevention by natural flavonoid phenolic compound, for example apigenin (Apg), improves baroreflex sensitivity and vascular resistance and occurs beneficial action for attenuation the renal hypertension (RH). One-kidney, 1-clip rats (1K1C) were treated with Apg for 2 weeks after 1 week of surgical intervention. At the end of the study in the control RH group the blood pressure (BP) increased on average by 43.5%, decreased in heart period (HP) by 9.8%, cardiochronotropic (vagal) component of baroreflex sensitivity (BRS) by 50%, and adrenergic component by 34%. Thus, in 1K1C experimental model of hypertension, provides switching to parasympathetic component and accompanied with proportionally nearly two-fold increase in epinephrine (EPN) and norepinephrine (NE) without changes in EPN/NE ratio. Morphometric changes in the kidney and heart confirmed the development of kidney and cardiac hypertrophy and renal functioning disturbances (blood urea nitrogen (BUN) increased in more than two-fold) and markers of sodium reabsorption in proximal tubule, total trans-EETs, decreased in 1.6-fold. The pronounced increased proinflammatory cytokines, interleukin 1b (IL1 b), endothelin -1 (ET-1) and tumor necrosis factor (TNF)-a confirmed the formation of “sterile inflammation” which strengthening by the nearly two-fold decreasing in the level of anti-inflammatory (vasodilatory) mediators, prostaglandin E2 (PGE2). Preventive long-term regime treatment with Apg (5mg/kg i.p./daily) in RH rats significantly decreased BP by 18.6%, increased parasympathetic component of BRS by 38.5% without marked altered its sympathetic component. Such deremodeling in BRS sensitivity associated with significant decreased in heart and kidney hypertrophy and functional activity of kidney, normalization of BUN and total EETs, reducing in circulating plasma level of catecholamines, and markedly attenuated progression of inflammation, decreased of proinflammatory levels of cytokines. Thus, Apg provides preventive beneficial pluripotent action in RH rats by exerting antihypertensive, cardio- and renoprotective effects and attenuation of “sterile inflammation”.

B-192 An LC-MS/MS Method using the Xevo TQ Absolute Mass Spectrometer for the Combined Analysis of Aldosterone and Plasma Renin Activity in Plasma for Clinical Research

Abstract Background Primary aldosteronism (PA) is a common cause of hypertension, whereby uncontrollable amounts of aldosterone are produced by a benign tumour or hyperplasia of the adrenal glands. Excess aldosterone results in significant sodium reabsorption in the kidneys, increasing water retention and blood volume, thereby causing hypertension. The renin-angiotensin-aldosterone system (RAAS) regulates the production of aldosterone and in this system, renin and aldosterone should move in synchronicity with each other throughout the day. Therefore, these two components are used to assess the status of the RAAS, particularly in the evaluation of new therapies in clinical research studies. Historically, the assessments of aldosterone and plasma renin activity (PRA) have been performed using separate methods using immunoassay or more recently liquid chromatography - tandem mass spectrometry (LC-MS/MS) platforms. One of the benefits of using LC-MS/MS for clinical research is the ability to measure multiple analytes across the proteome and metabolome using the same system and even in the same analysis to provide more information in less time and save costs. Here we evaluate a single LC-MS/MS method for the combined measurement of plasma aldosterone and renin activity for clinical research purposes. Methods Aldosterone certified reference material (Merck, UK) and Angiotensin I (Cambridge BioScience, UK) were used to create calibrators in 2% Bovine Serum Albumin (BSA) in Phosphate Buffered Saline (PBS). In-house QC material prepared in both 2% BSA in PBS and K2EDTA plasma (BioIVT, UK), were used to evaluate method precision. Plasma samples were analyzed using the newly developed method and the quantified results were compared to separate independent LC-MS/MS methods for aldosterone and plasma renin activity. Plasma samples were treated with generation buffer (Sodium acetate, EDTA, acetic acid, SBTI and PMSF) and mixed for three hours at 37 °C. Samples were precipitated, diluted and centrifuged prior to SPE. Sample supernatant was transferred to a Waters Oasis™ µElution 96 Well Plate, followed by a wash and elution. Using an ACQUITY™ UPLC™ I-Class System, samples were injected onto a Waters XBridge™ C8, 2.5 µm, 2.1 × 50 mm Column using a water/methanol/ammonium fluoride gradient elution profile and quantified with a Waters Xevo™ TQ Absolute Mass Spectrometer. Results The method demonstrated no significant carryover or matrix effects and was shown to be linear from 10 - 2500 pg/mL for aldosterone and 0.1–25 ng/mL/h for PRA. Analytical sensitivity investigations indicate the analytical sensitivity of this method would allow precise quantification (<20%) at 10 pg/mL and 0.1 ng/mL/h, for aldosterone and PRA, respectively. Coefficients of variation (CV) for total precision and repeatability on 5 analytical runs for low, mid and high QCs were all <10% (n = 25) for aldosterone and PRA. Comparison with samples previously analyzed by an independent LC-MS/MS method demonstrated good agreement for aldosterone and PRA. Conclusions We have successfully quantified aldosterone and renin activity in plasma in a single method using an SPE protocol with LC-MS/MS analysis, for clinical research purposes. The method demonstrates excellent linearity and precision, with minimal matrix effects. For Research Use Only. Not for Use in Diagnostic Procedures.

Терапия ксеногенным протеомным комплексом из эмбриональных клеток головного мозга тормозит прогрессирование экспериментально вызванной хронической почечной недостаточности.

Introduction. In previously published experimental studies, we have shown that in rats with pre-modeled acute post-ischemic renal failure, therapy with a proteomic complex isolated from brain cells of pig embryos has a pronounced therapeutic effect, reducing the severity of functional and histological disorders and preventing the transition of the pathological process into chronic kidney insuffiency. The aim of this study is to evaluate the effectiveness of this therapy for the course of artificially induced chronic renal failure (CRF) in rats. Material and methods. Experiments were carried out on 45 white mongrel male rats weighing 200-240 g. CRF was modeled by unilateral nephrectomy and resection of both poles of the remaining kidney, which reduced the mass of the functioning parenchyma by 80%. In the 1-st series of experiments no therapy was performed. In the 2-nd - 4-th series the animals were intraperitoneally injected with a fractionated xenogenic proteomic complex (secretom) from pig brain stem and progenitor cells (SSPC) at a daily dose of 0.1 ml in different modes: two 10-days courses with a 10-days break between them (2nd series); prolongation of the 1st course up to 20 days and a repeated 10-days course after 10 days (3rd series); continuous SSPC therapy for 30 days (4-th series). 5th series – intact animals. The effectiveness of therapy was evaluated based on the severity of the development of compensatory renal hypertrophy, the dynamics of biochemical parameters of kidney function, the activity of enzymes (ALT, AST, LDH, alkaline phosphatase) in blood and urine and the level of uremic neurotoxins 3-indoxyl sulfate and ptolyl sulfate in the blood. Results. SSPC therapy in all variants contributed to a more pronounced compensatory hypertrophy of the remaining kidney, as well as a decrease in the severity of the main functional indicators after 30 and 60 days: the severity of polyuria decreased, the concentration of urea in the blood decreased to a greater extent, and the glomerular filtration rate and tubular reabsorption of sodium and calcium approached normal values, which was not observed in the control series. The severity of the therapeutic effect was more pronounced with continuous 30-day therapy. There was also a less pronounced increase in the activity of enzymes in the blood and their excretion in the urine, which indicated the cytoprotective effect of SSPC therapy. If in the control series of experiments, the deterioration of the studied indicators were noted with an increase in the observation period from 30 to 60 days, whereas in all experimental series they remained at a subnormal level. SSPC therapy also contributed to a lower accumulation of uremic toxins (3-indoxyl sulfate and p-tolyl sulfate) in the blood. Conclusion. Prolonged therapy of SSPC prevents the progression of CRF by stimulating compensatory hypertrophy of the kidney and cytoprotective effect and promotes more effective elimination of uremic toxins, preventing their accumulation in the blood.

O-Linked GlcNAcylation mediates the inhibition of proximal tubule (Na++K+)ATPase activity in the early stage of diabetes mellitus

BackgroundDiabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). It has been proposed that modifications in the function of proximal tubule epithelial cells (PTECs) precede glomerular damage during the onset of DKD. This study aimed to identify modifications in renal sodium handling in the early stage of DM and its molecular mechanism. MethodsStreptozotocin (STZ)-induced diabetic BALB/c mice (STZ group) and LLC-PK1 cells, a model of PTECs, were used. All parameters were assessed in the 4th week after an initial injection of STZ. ResultsEarly stage of DKD was characterized by hyperfiltration and PTEC dysfunction. STZ group exhibited increased urinary sodium excretion due to impairment of tubular sodium reabsorption. This was correlated to a decrease in cortical (Na++K+)ATPase (NKA) α1 subunit expression and enzyme activity and an increase in O-GlcNAcylation. RNAseq analysis of patients with DKD revealed an increase in expression of the glutamine-fructose aminotransferase (GFAT) gene, a rate-limiting step of hexosamine biosynthetic pathway, and a decrease in NKA expression. Incubation of LLC-PK1 cells with 10 μM thiamet G, an inhibitor of O-GlcNAcase, reduced the expression and activity of NKA and increased O-GlcNAcylation. Furthermore, 6-diazo-5-oxo-L-norleucine (DON), a GFAT inhibitor, or dapagliflozin, an SGLT2 inhibitor, avoided the inhibitory effect of HG on expression and activity of NKA associated with the decrease in O-GlcNAcylation. ConclusionOur results show that the impairment of tubular sodium reabsorption, in the early stage of DM, is due to SGLT2-mediated HG influx in PTECs, increase in O-GlcNAcylation and reduction in NKA expression and activity.

Abstract 098: Collecting Duct-derived (pro)renin Receptor Contributes To 2-kidney, 1-clip-induced Renovascular Hypertension And Ischemic Nephropathy In Mice

The 2-kidney, 1-clip (2K1C) Goldblatt model features overactivation of the systemic renin-angiotensin-aldosterone system (RAAS) due to increased renin release from juxtaglomerular cells. However, no prior study functionally evaluates possible involvement of the intrarenal RAAS in this model. Within the kidney, (pro)renin receptor (PRR) is predominantly expressed in the collecting duct (CD) implicated in regulation of the intrarenal RAAS under physio-pathological conditions. In the present study, we employed a mouse model of CD-specific deletion of PRR (CD PRR KO) to examine the role of CD PRR in pathogenesis of 2K1C-induced renovascular hypertension and ischemic nephropathy and to further explore the underlying mechanism. Floxed and CD PRR KO mice were subjected to sham-operation or 2K1C procedure, followed by analysis of blood pressure, renal injury, and indices of the RAAS, as well as the expression of subunits of ENaC. Clipping-induced hypertension and renal injury were both attenuated in CD PRR KO mice as compared with floxed controls (MAP on day24: Floxed/2K1C 148.2±3.9 mm Hg vs. CD PRR KO/2K1C 136.9±2.5 mm Hg, n=6, p < 0.05) (urinary albumin/creatinine: Floxed/2K1C 67.5±6.4 mg/g vs. CD PRR KO/2K1C 30.9±3.5 mg/g, n=6, p < 0.01). Of note, the reductions of clipping-induced protein abundance of fibronectin and α-SMA in CD PRR KO mice were 70% and 55%, respectively. Similarly, clipping induced paralleled increases in renal mRNA expression of IL-1β, TNF-α, MCP-1 and TGF-β1 in floxed mice, which were all blunted in CD PRR KO mice. The protective phenotype of the null mice was paralleled with suppressed intrarenal renin and aldosterone (Aldo) levels. In contrast, clipping-induced enhancement of circulating renin and Aldo remained unchanged between the genotypes. Moreover, renal medullary α-ENaC mRNA and protein expression was elevated by clipping in floxed mice, which was respectively blunted 52% and 54% in CD PRR KO mice. Together, these results suggest that the activation of CD PRR stimulates components of the intrarenal RAAS and renal medullary α-ENaC, which result in increased tubular sodium reabsorption and thus contribute to 2K1C-induced renovascular hypertension and ischemic nephropathy.

Potentiating-antibiotic activity and absorption, distribution, metabolism, excretion and toxicity properties (ADMET) analysis of synthetic thiadiazines against multi-drug resistant (MDR) strains.

Thiadiazines are heterocyclic compounds that contain two nitrogen atoms and one sulfur atom in their structure. These synthetic molecules have several relevant pharmacological activities, such as antifungal, antibacterial, and antiparasitic. The present study aimed to evaluate the possible in vitro and in silico interactions of compounds derived from thiadiazines. The compounds were initially synthesized, purified, and confirmed through HPLC methodology. Multi-drug resistant bacterial strains of Staphylococcus aureus 10 and Pseudomonas aeruginosa 24 were used to evaluate the direct and modifying antibiotic activity of thiadiazine derivatives. ADMET assays (absorption, distribution, metabolism, excretion, and toxicity) were conducted, which evaluated the influence of the compounds against thousands of macromolecules considered as bioactive targets. There were modifications in the chemical synthesis in carbon 4 or 3 in one of the aromatic rings of the structure where different ions were added, ensuring a variability of products. It was possible to observe results that indicate the possibility of these compounds acting through the cyclooxygenase 2 mechanism, which, in addition to being involved in inflammatory responses, also acts by helping sodium reabsorption. The amine group present in thiadiazine analogs confers hydrophilic characteristics to the substances, but this primary characteristic has been altered due to alterations and insertions of other ligands. The characteristics of the analogs generally allow easy intestinal absorption, reduce possible hepatic toxic effects, and enable possible neurological and anti-inflammatory action. The antibacterial activity tests showed a slight direct action, mainly of the IJ23 analog. Some compounds were able to modify the action of the antibiotics gentamicin and norfloxacin against multi-drug resistant strains, indicating a possible synergistic action. Among all the results obtained in the study, the relevance of thiadiazine analogs as possible coadjuvant drugs in the antibacterial, anti-inflammatory, and neurological action with low toxicity is clear. Need for further studies to verify these effects in living organisms is not ruled out.

Serial evaluation of loop diuretic efficiency following left ventricular assist device implantation.

More than 50% of heart failure (HF) patients require diuretic therapy after left ventricular assist device (LVAD). Although few data related to diuretic response (DR) exist in stage D patients, tubular sodium reabsorption may be clinically prognostic independent of estimated glomerular filtration rate (eGFR) and proteinuria within this cohort. We aimed to characterize DR serially before and after LVAD implantation in a stage D population. We conducted a prospective, observational cohort study of HF patients receiving diuretics with plans to undergo LVAD implantation. We measured urine sodium (UNa) and creatinine (UCr) at three points after diuretic therapy: pre-LVAD, post-LVAD prior to discharge, and as an outpatient. Prior to LVAD, patients (N = 19) had an average eGFR of 54.0 ± 18.0 mL/min/1.73 m2, spot UNa of 74.8 ± 28.0 mmol/L, and fractional excretion of sodium (FENa) of 3.1 ± 2.7%. Pre-LVAD, eGFR did not correlate with spot UNa nor FENa (p > 0.05 for both). LVAD implantation did not improve DR post-LVAD (mean change FENa per 40 mg IV furosemide 0.5 ± 1.0%; p = 0.84), and 90% of patients required loop diuretics at 90 days post-surgery. Improved hemodynamics following LVAD may not improve DR or tubular function; larger studies are needed to confirm our results and assess the utility of DR to predict post-LVAD outcomes.

Aldosterone Antagonism Is More Effective at Reducing Blood Pressure and Excessive Renal ENaC Activity in AngII-Infused Female Rats Than in Males.

AngII (angiotensin II)-dependent hypertension causes comparable elevations of blood pressure (BP), aldosterone levels, and renal ENaC (epithelial Na+ channel) activity in male and female rodents. Mineralocorticoid receptor (MR) antagonism has a limited antihypertensive effect associated with insufficient suppression of renal ENaC in male rodents with AngII-hypertension. While MR blockade effectively reduces BP in female mice with salt-sensitive and leptin-induced hypertension, MR antagonism has not been studied in female rodents with AngII-hypertension. We hypothesize that overstimulation of renal MR signaling drives redundant ENaC-mediated Na+ reabsorption and BP increase in female rats with AngII-hypertension. We employ a combination of physiological, pharmacological, biochemical, and biophysical approaches to compare the effect of MR inhibitors on BP and ENaC activity in AngII-infused male and female Sprague Dawley rats. MR blockade markedly attenuates AngII-hypertension in female rats but has only a marginal effect in males. Spironolactone increases urinary sodium excretion and urinary sodium-to-potassium ratio in AngII-infused female, but not male, rats. The expression of renal MR and HSD11β2 (11β-hydroxysteroid dehydrogenase type 2) that determines the availability of MR to aldosterone is significantly higher in AngII-infused female rats than in males. ENaC activity is ≈2× lower in spironolactone-treated AngII-infused female rats than in males. Reduced ENaC activity in AngII-infused female rats on spironolactone correlates with increased interaction with ubiquitin ligase Nedd4-2 (neural precursor cell expressed developmentally down-regulated protein 4-2), targeting ENaC for degradation. MR-ENaC axis is the primary determinant of excessive renal sodium reabsorption and an attractive antihypertensive target in female rats with AngII-hypertension, but not in males.

Real-time laser speckle contrast imaging measurement during normothermic machine perfusion in pretransplant kidney assessment.

Normothermic machine perfusion (NMP) provides a platform for pre-transplant kidney quality assessment that is essential for the use of marginal donor kidneys. Laser speckle contrast imaging (LSCI) presents distinct advantages as a real-time and noncontact imaging technique for measuring microcirculation. In this study, we aimed to assess the value of LSCI in visualizing renal cortical perfusion and investigate the additional value of dual-side LSCI measurements compared to single aspect measurement during NMP. Porcine kidneys were obtained from a slaughterhouse and then underwent NMP. LSCI was used to measure one-sided cortical perfusion in the first 100 min of NMP. Thereafter, the inferior renal artery branch was occluded to induce partial ischemia and LSCI measurements on both ventral and dorsal sides were performed. LSCI fluxes correlated linearly with the renal blood flow (R2 = 0.90, p < 0.001). After renal artery branch occlusion, absence of renal cortical perfusion could be visualized and semiquantified by LSCI. The overall ischemic area percentage of the ventral and dorsal sides was comparable (medianinterquartile range[IQR], 38 [24-43]% vs. 29 [17-46]%, p = 0.43), but heterogenous patterns between the two aspects were observed. There was a significant difference in oxygen consumption (mean ± standard deviation [SD], 2.57 ± 0.63 vs. 1.83 ± 0.49 mLO2 /min/100 g, p < 0.001), urine output (median [IQR], 1.3 [1.1-1.7] vs. 0.8 [0.6-1.3] mL/min, p < 0.05), lactate dehydrogenase (mean ± SD, 768 ± 370 vs. 905 ± 401 U/L, p < 0.05) and AST (mean ± SD, 352 ± 285 vs. 462 ± 383 U/L, p < 0.01) before and after renal artery occlusion, while no significant difference was found in creatinine clearance, fractional excretion of sodium, total sodium reabsorption and histological damage. LSCI fluxes correlated linearly with renal blood flow during NMP. Renal cortical microcirculation and absent perfusion can be visualized and semiquantified by LSCI. It provides a relative understanding of perfusion levels, allowing for a qualitative comparison between regions in the kidney. Dual-side LSCI measurements are of added value compared to single aspect measurement and renal function markers.

The Integral Role of Chloride & With-No-Lysine Kinases in Cell Volume Regulation & Hypertension.

Chloride anions are the most abundant in humans. For many years, it has been believed that chloride is simply a counterion of all other cations, ensuring the electroneutrality of the extracellular space. Recent data suggests that chloride anions possess a broad spectrum of important activities that regulate vital cellular functions. It is now evident that, apart from its contribution to the electroneutrality of the extracellular space, it acts as an osmole and contributes to extracellular and intracellular volume regulation. Its anionic charge also contributes to the generation of cell membrane potential. The most interesting action of chloride anions is their ability to regulate the activity of with-no-lysine kinases, which in turn regulate the activity of sodium chloride and potassium chloride cotransporters and govern the reabsorption of salt and excretion of potassium by nephron epithelia. Chloride anions seem to play a crucial role in cell functions, such as cell volume regulation, sodium reabsorption in the distal nephron, potassium balance, and sodium sensitivity, which lead to hypertension. All of these functions are accomplished on a molecular level via complicated metabolic pathways, many of which remain poorly defined. We attempted to elucidate some of these pathways in light of recent advances in our knowledge, obtained mainly from experimental studies.

Nonatherosclerotic Renovascular Hypertension.

Renovascular hypertension (RVH) is a secondary form of high blood pressure resulting from impaired blood flow to the kidneys with subsequent activation of the renin-angiotensin-aldosterone system. Often, this occurs due to abnormally small, narrowed, or blocked blood vessels supplying one or both kidneys (ie: renal artery occlusive disease) and is correctable. Juxtaglomerular cells release renin in response to decreased pressure, which in turn catalyzes the cleavage of circulating angiotensinogen synthesized by the liver to the decapeptide angiotensin I. Angiotensin-converting enzyme then cleaves angiotensin I to form the octapeptide angiotensin II, a potent vasopressor and the primary effector of renin-induced hypertension. The effects of angiotensin II are mediated by signaling downstream of its receptors. Angiotensin receptor type 1 is a G-protein-coupled receptor that activates vasoconstrictor and mitogenic signaling pathways resulting in peripheral arteriolar vasoconstriction and increased renal tubular reabsorption of sodium and water which promotes intravascular volume expansion. Angiotensin II stimulates the adrenal cortical release of aldosterone, which promotes renal tubular sodium reabsorption, resulting in volume expansion. Angiotensin II acts on glial cells and regions of the brain responsible for blood pressure regulation increasing renal sympathetic activation. Angiotensin II simulates the release of vasopressin from the pituitary which stimulates thirst and water reabsorption from the kidney to expand the intravascular volume and cause peripheral vasoconstriction (increased sympathetic tone). All of these mechanisms coalesce to increase arterial pressure by way of arteriolar constriction, enhanced cardiac output, and the retention of sodium and water.

SGLT2: A PERSPECTIVE ON PATHOPHYSIOLOGY AND IMPACT OF SGLT2 INHIBITION ON RENAL FUNCTION

In individuals with diabetes, kidney size and glomerular filtration rate (GFR) tend to increase, and elevated GFR is a risk factor for diabetic kidney disease. Hyperfiltration occurs when high glucose levels in the glomerular filtrate causes increased reabsorption of glucose and sodium by the sodium-glucose cotransporters SGLT2 and SGLT1 in the proximal tubule. This hyperfiltration puts additional stress on the filtration barrier and increases the oxygen demand for reabsorption. Tubular growth is associated with a molecular signature that leads to inflammation and fibrosis. SGLT2 inhibitors play a significant role in mitigating hyperfiltration by reducing sodium and glucose reabsorption, normalizing feedback signals, and alleviating the physical stress on the filtration barrier. This tubule-centered model of diabetic kidney physiology explains the positive effects of SGLT2 inhibitors on renal outcomes, as demonstrated in large-scale clinical trials. Although these medications primarily target glucose reabsorption , patients with type 2 diabetes mellitus benefit from reduced blood glucose levels along with various other physiological advantages. Data support their use for modifying risk of kidney disease progression and acute kidney injury, not only in patients with type 2 diabetes at high cardiovascular risk, but also in patients with chronic kidney disease or heart failure irrespective of diabetes status, primary kidney disease, or kidney function.