Increase In Excretion Research Articles

Glucosuria as a major mechanism-associated effect of sodium-glucose cotransporter 2 inhibitors: Is there cause for concern?

Introduction. One of the main mechanisms of action of SGLT2 inhibitors is an increase in renal excretion of glucose and sodium, development of glucosuria against the background of decreased levels of daily glycemia. The frequency of glucosuria development in patients without DM/prediabetes, receiving SGLT2 inhibitors for the treatment of CHD or CKD, as a consequence of the mechanism of action of SGLT2 inhibitors inhibitors is poorly studied and seems to be very interesting.Aim. To evaluate in real clinical practice the frequency of the development and severity of glucosuria in patients with CHF treated with inhibitors of SGLT2 inhibitors both on the background of concomitant DM2 and without type 2 DM.Materials and methods. Within the framework of a one-stage, prospective, observational study we evaluated the frequency of development and severity of glucosuria in patients with CHF, receiving SGLT2 inhibitors inhibitors, who were in the cardiology department of V.P. Demikhov State Clinical Hospital of Moscow. A total of 230 patients were included in the analysis.Results. The mean age of the patients was 74 [66; 83] years. Median LVEF was 36 [29; 44] %, NTproBNP 1019 [423; 2355] pg/ml. Heart failure with reduced ejection fraction (HFrEF) was recorded in 64.81% of patients, 17.13% had HF with mildly reduced ejection fraction and 18.06% had a СHF preserved ejection fraction. DM2 was present in 38.7 percent of patients with СHF. Among patients with CHF, the ‘glucosuria phenomenon’ due to the administration of SGLT2 inhibitors was observed in 31.16% of those without DM2, and in 52.27% of СHF patients with concomitant DM2.Conclusion. In patients with CHF receiving SGLT2 inhibitors therapy, the ‘glucosuria phenomenon’ developed in one in three patients without overt carbohydrate metabolism abnormalities and one in two with DM2. The findings suggest that the glucosuria effect of SGLT2 inhibitors is not a required event even in patients with DM2, which may influence the incidence of adverse events in general clinical practice. And the cardioprotective benefits of SGLT2 inhibitors may be due to other mechanisms unrelated to glucose excretion, which, according to recent studies, is considered a surrogate predictor of favorable prognosis concerning CHF and renal outcomes. Nevertheless, additional clinical and experimental studies are required to determine the cardioprotective mechanisms of SGLT2 inhibitors and the predictive value of drug-induced glucosuria.

Dysregulation of sympathoadrenal system activity in patients with microvascular angina

Abstract Introduction Recent studies have highlighted that a significant proportion of patients (up to 47%) undergoing coronary angiography due to clinical indications do not exhibit significant stenosis in epicardial vessels. Among these patients, up to 50% may suffer from microvascular angina (MVA). Despite the absence of intramural coronary artery lesions typically associated with atherosclerosis, the occurrence of transient myocardial ischemia and cardiac pain syndrome raises interest due to the incomplete understanding of their underlying mechanisms. Objective This study aims to comprehensively investigate sympathoadrenal system activity in patients with microvascular angina. Materials and Methods A total of 40 patients diagnosed with MVA, aged 35-76 years, including 11 (27.5%) men and 29 (72.5%) women, were enrolled, along with 20 healthy individuals. Assessment of sympathoadrenal system (SAS) activity involved determining daily urinary excretion levels of free and conjugated catecholamine fractions (CA) using solid-phase enzyme immunoassay: adrenaline (A), noradrenaline (NA), dopamine (DA), and DOFA. Additionally, catecholamine deamination enzyme activity—monoamine oxidase (MAO)—was determined using solid-phase EIA. Results Patients with MVA exhibited a significant increase in the excretion of all CA fractions. Specifically, adrenaline (A) excretion increased by 56.7%, surpassing the control by 1.7 times (p<0.001). Noradrenaline (NA) levels were elevated by 59.5% in MVA patients, which was 1.6 times higher than the control group (p<0.001). Dopamine (DA) levels in MVA patients increased by 31.0%, surpassing control values by 1.36 times (p<0.001). Moderate elevation in DOFA levels by 19.7% was observed, which was 1.23 times higher than the control (p<0.01). Ratios of CA sulfocatecholamine formation processes indicated pronounced deviations from normal. Gender differences revealed marked changes in sympathoadrenal activity, particularly in women (p<0.001). Studies of MAO activity on the first day identified a moderate decrease in its activity in MVA patients—0.03±0.002 units/ext. (p<0.01), while healthy individuals exhibited an activity level of 0.07±0.001 units/ext. Conclusion The findings underscore the crucial pathogenetic role of SAS in the development of MVA. The study demonstrates that the severity of ischemia correlates with disruptions in SAS components. Notably, these disruptions are pronounced in MVA, indicating an overload of the sympathoadrenal system—a critical component of organismal homeostasis. Under conditions of SAS overload, the pivotal enzyme in biogenic amine oxidation, MAO, undergoes significant transformation, leading to reduced activity towards monoamines. These findings were consistent with our clinical investigation.

Gastrointestinal permeability and kidney injury risk during hyperthermia in young and older adults.

We tested whether older adults, compared with young adults, exhibit greater gastrointestinal permeability and kidney injury during heat stress. Nine young (32±3 years) and nine older (72±3 years) participants were heated using a model of controlled hyperthermia (increasing core temperature by 2°C via a water-perfused suit). Gastrointestinal permeability was assessed using a multi-sugar drink test containing lactulose, sucrose and rhamnose. Blood and urine samples were assayed for markers of intestinal barrier injury [plasma intestinal fatty acid binding protein (I-FABP), plasma lipopolysaccharide binding protein (LBP) and plasma soluble cluster of differentiation 14 (sCD14)], inflammation (serum cytokines), kidney function (plasma creatinine and cystatin C) and kidney injury [urine arithmetic product of IGFBP7 and TIMP-2 (TIMP-2 × IGFBP7), neutrophil gelatinase-associated lipocalin and kidney injury molecule-1]. The lactulose-to-rhamnose ratio was increased in both young and older adults (group-wide: Δ0.11±0.11), but the excretion of sucrose was increased only in older adults (Δ1.7±1.5). Young and older adults showed similar increases in plasma LBP (group-wide: Δ0.65±0.89µg/mL), but no changes were observed for I-FABP or sCD14. Heat stress caused similar increases in plasma creatinine (group-wide: Δ0.08±0.07mg/dL), cystatin C (group-wide: Δ0.16±0.18mg/L) and urinary IGFBP7×TIMP-2 [group-wide: Δ0.64±0.95 (pg/min)2] in young and older adults. Thus, the level of heat stress used herein caused modest increases in gastrointestinal permeability, resulting in a mild inflammatory response in young and older adults. Furthermore, our data indicate that older adults might be more at risk for increases in gastroduodenal permeability, as evidenced by the larger increases in sucrose excretion in response to heat stress. Finally, our findings show that heat stress impairs kidney function and elevates markers of kidney injury; however, these responses are not modulated by age.

8034 Putting the Pieces Together: Carney Complex, A Hyper-Rare Congenital Neoplastic Syndrome

Abstract Disclosure: G. Fontanazza: None. A.R. Conforti: None. K. Bird: None. M. Caplan: None. Intro: Carney complex (CNC) is an autosomal dominant disorder characterized by multisystem neoplasia that primarily affects the thyroid, pituitary, and adrenal glands. Its prevalence is not well established, as only 750 cases have been reported worldwide. This condition arises when an inactivating PRKAR1A gene mutation results in dysregulated cell proliferation and tumorigenesis. Complications include the potential for malignant transformation and systemic manifestations, necessitating comprehensive management and ongoing surveillance of disease progression. Case: The patient is a 58-year-old woman who initially presented as a teenager with complaints of hirsutism, truncal obesity, and violaceous abdominal striae. Initial workup revealed a low-dose dexamethasone suppression test that resulted in a non-suppressed cortisol levels. She also had undetectable adrenocorticotropic hormone (ACTH) levels. Imaging revealed no pituitary masses and demonstrated slight bilateral adrenal enlargement without adenomas. Despite these results, she was empirically treated for presumed pituitary-dependent Cushing's disease and received external beam radiation. Despite treatment, she continued to have episodes of hypercortisolism that were apparent clinically and biochemically. Over time, she developed a cardiac myxoma with six cerebrovascular accidents and multiple benign tumors. As an adult, she underwent extensive endocrine evaluation, which revealed urine cortisol excretion that paradoxically rose in response to dexamethasone. ACTH levels were always undetectable, even when she was significantly hypercortisolemic. Genetic testing revealed a homozygous mutation in the melanocortin-2 receptor (MC2R). Accordingly, she elected to have a bilateral adrenalectomy and was started on hydrocortisone and fludrocortisone. Discussion: The patient exhibited ACTH-independent micronodular adrenal hyperplasia and its most frequent variant, primary pigmented nodular adrenocortical disease. Bilateral pigmented nodular hyperplasia is a finding which can occur in association with CNC and cause episodic hypercortisolism. These patients have been shown to respond to dexamethasone with a paradoxical increase in glucocorticoid excretion. While management requires ongoing surveillance, this patient had not been diagnosed until later in life and did not have regular screening. When speculating on the late detection, her story reflects the parable of the blind men and the elephant: endocrinology managed Cushing's disease, cardiology managed atrial myxoma, and oncology managed osteochondromyxomas. Limited perspective with specialized management and an inability to see the whole picture led to prolonged diagnosis with unfortunate sequelae. This report encourages physicians to develop perspective awareness and to consider the entire picture when treating patients. Presentation: 6/2/2024

20 Trace metal homeostasis in growing cattle

Abstract Apparent trace metal absorption and tissue retention upon incremental levels of supplemental Zn, Cu, and Mn were studied in growing cattle. A total of 60 Holstein bulls were enrolled for the study and fed for 28 d a diet consisting of barley straw (15%), molasses (10%) and pelleted concentrate (75%; Zn = 78 ppm, Cu = 15 ppm, Mn = 91 ppm). Thereafter, 20 bulls were randomly selected and slaughtered for determination of baseline tissue trace metal composition. The remaining 40 bulls [body weight (BW) = 394 ± 20 kg] were then blocked based on BW in 8 blocks of 5 bulls each. Bulls within a block were randomly assigned one of the diets differing in supplemental levels of Zn, Cu, and Mn (all from sulfate form) with the following dietary contents of Zn, Cu and Mn, respectively: No supplement (38, 7, and 47 ppm), Dose 1 (61, 11, and 68 ppm), Dose 2 (78, 15 and 91 ppm), Dose 3 (123, 26, 136 ppm) or Dose 4 (195, 43, and 214 ppm). These diets were fed for 12 wk, and complete collection of feces and urine were performed on wk 4, 8 and 12 for assessment of trace metals balance and apparent absorption. Gastrointestinal tissues, whole organs (heart, liver, spleen, and kidney), bile, cervical vertebra, and tibia were collected at slaughterhouse from all bulls. All samples were dried, ground, and analyzed for minerals. Data were processed using dietary treatment as a continuous variable and also as categorial variable. Both approaches adjusted for the fixed effect of block (Proc Mixed, SAS 9.4). Whole-body Zn, Cu and Mn balance quadratically increased (P < 0.05) with supplementation, with a significantly higher values for Dose 4 compared with all other dietary treatment (Figure 1, P < 0.05). Dose 4 also led to a 2-fold increase in urinary Zn and Cu excretions (P < 0.05), and a 4-fold increase in urinary Mn excretion (P < 0.01). Although magnitudes of change were moderate (8 to 15%), increasing dietary Zn supply linearly increased spleen Zn content (P = 0.03), and tended to increase ruminal and hepatic Zn content (P < 0.10). Hepatic Cu linearly increased from 264 to 667 mg/kg DM with increasing dietary Cu supply (P < 0.01), whereas Cu concentration in bile only increased at Doses 4 and 5 (P < 0.01). Increasing Mn supply resulted in quadratic increase of ruminal and biliary Mn content from 340 to 1140 mg/kg DM, and from 0.32 to 1.38 mg/L, respectively. Small intestine and cecum Mn concentrations linearly and quadratically increased (about 2-fold increase, P < 0.05) with incremental supply of Mn. Homeostatic regulation mechanisms were apparently overwhelmed at the greatest Zn, Cu and Mn supplementation levels evaluated in this study.

Abstract P300: Modulation of Osmolyte Levels by ACE Inhibitors and SGLT-2 Inhibitors in Normotensive Rats

Hypertension is associated with disturbances in the water-electrolyte balance, leading to changes in osmotic pressure. Osmolytes, such as taurine among other compounds, play a critical role in maintaining cellular integrity under osmotic stress. This study evaluated the effects of ACE inhibitors (ACE-I) and SGLT-2 inhibitors (SGLT2i) on osmolyte homeostasis. Twelve-week-old male Sprague-Dawley (SD, n = 38) rats were divided into five groups: control (water), low and high doses of canagliflozin, and low and high doses of captopril. Metabolic studies were conducted in metabolic cages. Using liquid chromatography coupled with mass spectrometry (LC-MS), we measured osmolyte concentrations in blood, urine, kidney, liver and heart tissues. The obtained results demonstrated significant increases in liver taurine concentrations (13.34 ± 1.39 vs. 10.49 ± 1.45, p=0.029) and urinary taurine excretion (25.08 ± 2.81 vs. 16.54 ± 3.77, p=0.001) in the high-dose canagliflozin group compared to controls. Both treatments enhanced the total urinary excretion of L-alanine, β-alanine, choline, glycine, taurine, and carnitine. Additionally, canagliflozin increased the excretion of betaine and glycerophosphorylcholine (GPC). A reduction in serum β-alanine was noted in the captopril-treated rats. These findings highlight the novel effects of SGLT-2 inhibitors and ACE-I on osmolyte levels in normotensive rats, suggesting potential mechanisms contributing to their cardioprotective effects. Further research is required to elucidate the clinical significance of osmolyte changes in enhancing the protective effects of these drug classes.

Bone and vascular effects of magnesium supplements in CKD patients (the MagicalBone Pilot Study).

The progression of chronic kidney disease (CKD) involves the development of alterations in mineral metabolism that are closely related to cardiovascular outcomes and bone disease. Hypomagnesemia is associated with more rapid progression of CKD and other comorbidities. Our objective was to analyze in CKD patients stages 3-4 the impact of the administration of magnesium (Mg) carbonate on bone mineral density (BMD) and hemodynamic changes associated with by vascular calcification (VC). Patients with CKD stages 3-4 were randomized into controls (n=12) or intervention (n=7) group receiving 360mg of Mg carbonate daily during a 15-month period. Parameters related to mineral metabolism, BMD, VC, and pulse wave velocity (PWV) were evaluated. Supplementation with Mg produced an increase in the urinary excretion of Mg while serum Mg levels remained stable and no episodes of hypermagnesemia were reported. In addition, no significant changes were found in the degree of VC assessed by Adragao index, however, both serum and urine Mg were significantly associated with a decrease in PWV, suggesting an increase in vascular compliance. Likewise, BMD did not change following treatment, but serum Mg significantly correlated with the levels of N-terminal propeptide of collagen alpha-1(I) chain (PINP), a marker of bone synthesis. In sum, these results suggest a possible beneficial effect of Mg on vascular compliance with no detrimental effects on bone status. In addition, our results highlight the need to consider monitorization of urinary Mg status in CKD patients.

THE EFFECT OF HIGH FLUORIDE INTAKE ON SODIUM, AND POTASSIUM AND CALCIUM LEVELS IN SHEEP BLOOD SERUM

This experiment was carried out to investigate levels of sodium, potassium and calcium in ovine blood serum for 12 weeks during which fluoride (100 ppm) was added to the ration. The rams remained physically in good condition and there were no lesions in the teeth, gums and joints. With the exception of an increase in sodium at the end of the first week, sodium and potassium levels were not influenced. This finding could point out to the possibility of failure of the added fluoride to induce significant changes in kidney and aldosterone functions regarding regulation of these two ions in blood. There was a general tendency of the total calcium level to decrease which reached statistical significance in samples of three weeks. Such decrease could be due to a decline in calcium intestinal absorption and an increase in bone deposition and excretion with urine.

Role of Arthrospira Platensis in Preventing and Treating High-Fat Diet-Induced Hypercholesterolemia in Adult Rats.

Hyperlipidaemia is a recognised risk factor for cardiovascular disease. In this study, the antihyperlipidaemic properties of spirulina (Arthrospira platensis, strain S2 from Serbia) were tested in adult Wistar rats before and after induction of hypercholesterolaemia by a high-fat diet (HFD) to compare the preventive with the curative effect. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), alanine transaminase (ALT) and aspartate transaminase (AST) levels were measured in the blood samples. The chemical composition (lipids, proteins and cholesterol) and the content of bile acids in the faeces of the animals were also analysed. Feeding rats with an atherogenic diet for 10 weeks led to the successful development of hyperlipidaemia, as serum TC and LDL-C levels as well as lipids, cholesterol and bile acids in the animals' faeces were significantly increased. Pre- and post-treatment with spirulina led to a reduction in serum LDL, TC and ALT levels. Administration of spirulina resulted in both a significant increase in primary bile acids excretion and a decrease in bile acids metabolism, with pre-treatment being more effective than post-treatment in some cases. These results suggest that increased excretion of bile acids as well as an effect on the gut microbiota may be the mechanism responsible for the anti-hyperlipidaemic activity of the tested spirulina strain.

Renal handling of albumin in rats with early stage diabetes: A theoretical analysis.

In early diabetic nephropathy (DN), recent studies have shown that albuminuria stems mostly from alterations in tubular function rather than from glomerular damage. Several factors in DN, including hyperfiltration, hypertrophy and reduced abundance of the albumin receptors megalin and cubilin, affect albumin endocytosis in the proximal tubule (PT). To assess their respective contribution, we developed a model of albumin handling in the rat PT that couples the transport of albumin to that of water and solutes. Our simulations suggest that, under basal conditions, ∼75% of albumin is retrieved in the S1segment. The model predicts negligible uptake in S3, as observed experimentally. It also accurately predicts the impact of acute hyperglycaemia on urinary albumin excretion. Simulations reproduce observed increases in albumin excretion in early DN by considering the combined effects of increased glomerular filtration rate (GFR), osmotic diuresis, hypertrophy, and megalin and cubilin downregulation, without stipulating changes in glomerular permselectivity. The results indicate that in isolation, glucose-elicited osmotic diuresis and glucose transporter upregulation raise albumin excretion only slightly. Enlargement of PT diameter not only augments uptake via surface area expansion, but also reduces fluid velocity and thus shear stress-induced stimulation of endocytosis. Overall, our model predicts that downregulation of megalin and cubilin and hyperfiltration both contribute significantly to increasing albumin excretion in rats with early-stage diabetes. The results also suggest that acute sodium-glucose cotransporter 2 inhibition lowers albumin excretion only if GFR decreases sufficiently, and that angiotensin II receptor blockers mitigate urinary albumin loss in early DN in large part by upregulating albumin receptor abundance. KEY POINTS: The urinary excretion of albumin is increased in early diabetic nephropathy (DN). It is difficult to experimentally disentangle the multiple factors that affect the renal handling of albumin in DN. We developed a mathematical model of albumin transport in the rat proximal tubule (PT) to examine the impact of elevated plasma glucose, hyperfiltration, PT hypertrophy and reduced abundance of albumin receptors on albumin uptake and excretion in DN. Our model predicts that glucose-elicited osmotic diuresis per se raises albumin excretion only slightly. Conversely, increases in PT diameter and length favour reduced albumin excretion. Our results suggest that downregulation of the receptors megalin and cubilin in PT cells and hyperfiltration both contribute significantly to increasing albumin excretion in DN. The model helps to better understand the mechanisms underlying urinary loss of albumin in early-stage diabetes, and the impact of specific treatments thereupon.

FLAVONOIDS FOR ANTI-HYPERURICEMIA: A LITERATURE REVIEW

Background: Hyperuricemia is a condition on the level of uric acid in the blood increases, it is more than 6.0 mg/dL in women and more than 7.0 mg/dL in men and is currently a public health problem because of its increasing prevalence. Hyperuricemia is believed to have contributed to an increased risk of mortality and morbidity associated with various diseases such as metabolic syndrome, kidney disease, cardiovascular disease, etc. Flavonoids in plants can be used to help treat hyperuricemia due to it is believed to have low side effects. Objective: The aim of this article was to review the effect of flavonoids on plants as anti-hyperuricemia. Design: The design used in preparing this manuscript is an integrative review by reviewing articles on the impact of flavonoids as anti-hyperuricemia. Data Sources: Sources of information were obtained from research articles from 2004-2023 which were accessed through PubMed, Scopus, Sciendirect, SpringerLink, and Google Scholar. Review Methods: In the process of selecting articles to ensure the quality of the articles used in preparing this article, the authors used the PRISMA method. Results: In this article, 15 in vivo studies related to the effect of plants containing flavonoids (kaemferol, luteolin, apigenin, rutin quercetin, morin, butein, vitexin, etc.) on reducing uric acid levels by various mechanisms from previous studies. Conclusion: Based on several studies reported that flavonoids have an effect on lowering uric acid levels by inhibiting xanthine oxidase (XO) activity, affecting the expression of uric acid transporters in the kidneys which contribute to the increase of excretion of uric acid in urine.

Dietary Cholest-4-en-3-one, a Cholesterol Metabolite of Gut Microbiota, Alleviates Hyperlipidemia, Hepatic Cholesterol Accumulation, and Hyperinsulinemia in Obese, Diabetic db/db Mice.

Previous studies have shown that dietary cholest-4-en-3-one (4-cholestenone, 4-STN) exerts anti-obesity and lipid-lowering effects in mice. However, its underlying mechanisms are not fully understood. In the present study, we evaluated whether 4-STN supplementation would protect obese diabetic db/db mice from obesity-related metabolic disorders. After four weeks of feeding of a 0.25% 4-STN-containing diet, dietary 4-STN was found to have significantly alleviated hyperlipidemia, hepatic cholesterol accumulation, and hyperinsulinemia; however, the effect was not sufficient to improve hepatic triglyceride accumulation or obesity. Further analysis demonstrated that dietary 4-STN significantly increased the content of free fatty acids and neutral steroids in the feces of db/db mice, indicating that the alleviation of hyperlipidemia by 4-STN was due to an increase in lipid excretion. In addition, dietary 4-STN significantly reduced the levels of desmosterol, a cholesterol precursor, in the plasma but not in the liver, suggesting that normalization of cholesterol metabolism by 4-STN is partly attributable to the suppression of cholesterol synthesis in extrahepatic tissues. In addition, dietary 4-STN increased the plasma and hepatic levels of 4-STN metabolites cholestanol (5α-cholestan-3β-ol) and coprostanol (5β-cholestan-3β-ol). Our results show that dietary 4-STN alleviates obesity-related metabolic disorders, such as hyperlipidemia, hepatic cholesterol accumulation, and hyperinsulinemia, in db/db mice.

Injection of luteinizing hormone or human chorionic gonadotropin increases calcium excretion and serum PTH in males

Animal and human studies have suggested that sex steroids have calciotropic actions, and it has been proposed that follicle-stimulating hormone (FSH) may exert direct effects on bone. Here, we demonstrate the expression of the receptor for Luteinizing hormone (LH) and human choriogonadotropin (hCG), LHCGR, in human kidney tissue, suggesting a potential influence on calcium homeostasis. To investigate the role of LHCGR agonist on calcium homeostasis in vivo, we conducted studies in male mice and human subjects. Male mice were treated with luteinizing hormone (LH), and human extrapolation was achieved by injecting 5000 IU hCG once to healthy men or men with hypergonadotropic or hypogonadotropic hypogonadism. In mice, LH treatment significantly increased urinary calcium excretion and induced a secondary increase in serum parathyroid hormone (PTH). Similarly, hCG treatment in healthy men led to a significant increase in urinary calcium excretion, serum PTH levels, and 1,25 (OH)2D3, while calcitonin, and albumin levels were reduced, possibly to avoid development of persistent hypocalcemia. Still, the rapid initial decline in ionized calcium coincided with a significant prolongation of the cardiac QTc-interval that normalized over time. The observed effects may be attributed to LH/hCG-receptor (LHCGR) activation, considering the presence of LHCGR expression in human kidney tissue, and the increase in sex steroids occurred several hours after the changes in calcium homeostasis. Our translational study shed light on the intricate relationship between gonadotropins, sex hormones and calcium, suggesting that LHCGR may be influencing calcium homeostasis directly or indirectly.

#1610 FGF23-mediated hypertension via augmented calcium entry in vascular smooth muscle cells

Abstract Background and Objectives Ongoing studies are shedding light on the potential connection between FGF23 and hypertension. In experimental settings, the administration of recombinant FGF23 in mice has been demonstrated to induce hypertension by elevating serum sodium, along with an increase in NCC receptors in the kidney. Clinical evidences further supports pro-hypertensive effects of high circulating levels of FGF23. Our group has previously demonstrated a direct influence of FGF23 on increased arterial stiffness by inducing a phenotypic transition in vascular smooth muscle cells (VSMCs) from a contractile to a synthetic phenotype. This study aimed comprehensively to evaluate, both in vivo and in vitro, whether FGF23 directly leads to hypertension through the stimulation of intracellular calcium entry in vascular cells. Methods To ascertain whether FGF23 contributes to hypertension through a direct impact on blood vessels, recombinant FGF23 (15 µg/day) was administered for 28 days via Alzet pumps. Blood pressure was meticulously measured in these animals, and we investigated alterations in vascular remodeling and calcium channels, as well as proteins associated with vascular contraction such as Orai1, STIM1, PKD1, SERCA2a, and AGTR1. In vitro experiments included the evaluation of the effect of elevated levels of recombinant FGF23 (2 ng/ml) over 9 days on intracellular calcium entry stimulated by Ang2 (100 nM) or Thapsigargin (2.5 µM). We used the FURA method to conduct these experiments. To elucidate the in vitro pro-hypertensive mechanisms of FGF23, studies were conducted with the administration of inhibitors targeting FGF Receptors 1-3 (AZD4547, 150 nM), FGF Receptor-4 (BLU9931, 10 nM), and Erk1/2 phosphorylation (PD98059, 10 μM). Additionally, changes in Orai1, STIM1, PKD1, SERCA2a, and AGTR1 were also evaluated in these VSMCs. Results After 28 days of recombinant FGF23 treatment, no significant differences were observed in serum sodium levels, yet there was a marked increase in urinary phosphorus excretion. Systolic and diastolic blood pressure values showed a progressive significant elevation in animals exposed to high levels of FGF23. The expression of AGTR1 and PKD1 levels significantly increased after FGF23 administration for 28 days (Figure). However, Orai1 and STIM1 in the thoracic aorta exhibited no significant differences following FGF23 treatment. In VSMCs, the exposure to recombinant FGF23 for 9 days resulted in increased calcium entry upon Ang2 stimulation (Figure). This effect was markedly diminished after inhibiting FGFR1-3 receptors and Erk1/2 phosphorylation (Figure). Notably, the inhibition of FGF23 receptor 4 (FGFR4) had no impact on the calcium entry induced by FGF23 (Figure). While Orai1, STIM1, IP3R, and TRPV5 in VSMCs remained unaffected by recombinant FGF23 administration, PKD1, SERCA2, and AGTR1 levels were significantly elevated compared to control cells (Figure). The addition of Thapsigargin in a Ca2+-free culture medium to VSMCs incubated with recombinant FGF23 for 9 days led to increased Ca2+ efflux from endoplasmic reticulum. Conclusion Elevated levels of FGF23 directly enhanced calcium entry in VSMCs. This effect is mediated by FGFR1-3 receptors, Erk1/2 phosphorylation, and the upregulation of related protein to cell contraction such as SERCA2a, PKD1 or AGTR1. These modifications could be responsible of FGF23-associated hypertension in the experimental model.

The Puzzle of Aspirin and Iron Deficiency: The Vital Missing Link of the Iron-Chelating Metabolites.

Acetylsalicylic acid or aspirin is the most commonly used drug in the world and is taken daily by millions of people. There is increasing evidence that chronic administration of low-dose aspirin of about 75-100 mg/day can cause iron deficiency anaemia (IDA) in the absence of major gastric bleeding; this is found in a large number of about 20% otherwise healthy elderly (>65 years) individuals. The mechanisms of the cause of IDA in this category of individuals are still largely unknown. Evidence is presented suggesting that a likely cause of IDA in this category of aspirin users is the chelation activity and increased excretion of iron caused by aspirin chelating metabolites (ACMs). It is estimated that 90% of oral aspirin is metabolized into about 70% of the ACMs salicyluric acid, salicylic acid, 2,5-dihydroxybenzoic acid, and 2,3-dihydroxybenzoic acid. All ACMs have a high affinity for binding iron and ability to mobilize iron from different iron pools, causing an overall net increase in iron excretion and altering iron balance. Interestingly, 2,3-dihydroxybenzoic acid has been previously tested in iron-loaded thalassaemia patients, leading to substantial increases in iron excretion. The daily administration of low-dose aspirin for long-term periods is likely to enhance the overall iron excretion in small increments each time due to the combined iron mobilization effect of the ACM. In particular, IDA is likely to occur mainly in populations such as elderly vegetarian adults with meals low in iron content. Furthermore, IDA may be exacerbated by the combinations of ACM with other dietary components, which can prevent iron absorption and enhance iron excretion. Overall, aspirin is acting as a chelating pro-drug similar to dexrazoxane, and the ACM as combination chelation therapy. Iron balance, pharmacological, and other studies on the interaction of iron and aspirin, as well as ACM, are likely to shed more light on the mechanism of IDA. Similar mechanisms of iron chelation through ACM may also be implicated in patient improvements observed in cancer, neurodegenerative, and other disease categories when treated long-term with daily aspirin. In particular, the role of aspirin and ACM in iron metabolism and free radical pathology includes ferroptosis, and may identify other missing links in the therapeutic effects of aspirin in many more diseases. It is suggested that aspirin is the first non-chelating drug described to cause IDA through its ACM metabolites. The therapeutic, pharmacological, toxicological and other implications of aspirin are incomplete without taking into consideration the iron binding and other effects of the ACM.

Preventive effects of vasohibin-2-targeting peptide vaccine for diabetic nephropathy.

Diabetic nephropathy remains the leading cause of end-stage kidney disease in many countries, and additional therapeutic targets are needed to prevent its development and progression. Some angiogenic factors are involved in the pathogenesis of diabetic nephropathy. Vasohibin-2 (VASH2) is a novel proangiogenic factor, and our previous study showed that glomerular damage is inhibited in diabetic Vash2 homozygous knockout mice. Therefore, we established a VASH2-targeting peptide vaccine as a tool for anti-VASH2 therapy in diabetic nephropathy. In this study, the preventive effects of the VASH2-targeting peptide vaccine against glomerular injury were examined in a streptozotocin (STZ)-induced diabetic mouse model. The mice were subcutaneously injected with the vaccine at two doses 2 wk apart and then intraperitoneally injected with 50 mg/kg STZ for 5 consecutive days. Glomerular injury was evaluated 20 wk after the first vaccination. Treatment with the VASH2-targeting peptide vaccine successfully induced circulating anti-VASH2 antibody without inflammation in major organs. Although the vaccination did not affect blood glucose levels, it significantly prevented hyperglycemia-induced increases in urinary albumin excretion and glomerular volume. The vaccination did not affect increased VASH2 expression but significantly inhibited renal angiopoietin-2 (Angpt2) expression in the diabetic mice. Furthermore, it significantly prevented glomerular macrophage infiltration. The preventive effects of vaccination on glomerular injury were also confirmed in db/db mice. Taken together, the results of this study suggest that the VASH2-targeting peptide vaccine may prevent diabetic glomerular injury in mice by inhibiting Angpt2-mediated microinflammation.NEW & NOTEWORTHY This study demonstrated preventive effects of VASH2-targeting peptide vaccine therapy on albuminuria and glomerular microinflammation in STZ-induced diabetic mouse model by inhibiting renal Angpt2 expression. The vaccination was also effective in db/db mice. The results highlight the importance of VASH2 in the pathogenesis of early-stage diabetic nephropathy and the practicability of anti-VASH2 strategy as a vaccine therapy.

Adrenal circadian clock protein BMAL1 regulates aldosterone and renal excretory function in a sex- and time-dependent manner

BMAL1 is a core circadian clock protein that is important for circadian rhythms of physiological function, as well as maintaining physiological homeostasis, including aspects of kidney function. Global Bmal1 knockout (KO) male mice exhibit loss of diurnal rhythm of renal sodium (Na) excretion in response to a normal or high salt diet. However, renal Na excretion rhythm remained intact in kidney-specific Bmal1 KO male mice. The adrenal gland synthesizes hormones, such as aldosterone, which influence renal electrolyte handling. The role of adrenal BMAL1 in the regulation of renal function remains unknown. The study objective was to test the hypothesis that adrenal BMAL1 is required for normal rhythms of aldosterone and renal Na handling. Male and female adrenal-specific aldosterone synthase Cre positive (AS) Bmal1 KO and littermate Cre negative, floxed control mice ( n=5-9/genotype) were acclimated to metabolic cages for 3 days then samples were collected for three days with mice on a normal salt diet followed by 7 days on a low salt diet to challenge the mice to stimulate aldosterone production. Twelve-hour food intake was measured, and urine samples were collected to measure night/day patterns in renal Na balance. Urinary aldosterone excretion was measured by ELISA. Both day and night urinary aldosterone excretion were increased following a low salt diet in control and KO male mice (ANOVA main effect of diet, p<0.05). Male AS Bmal1 KO mice displayed a significant increase in day urinary aldosterone excretion following a normal and low salt diet (ANOVA main effect of genotype, p=0.0230), with a trend for an increase in night urinary aldosterone excretion ( p=0.0571). Interestingly, these genotype effects were not seen in female AS Bmal1 KO mice. Urinary aldosterone was increased following a low salt diet in female mice, but only during the nighttime in control and KO mice ( p=0.0205). Sex differences were also observed in renal Na balance, where Na balance was more positive during the day in male, but not female, AS Bmal1 KO vs. control mice (ANOVA main effect of genotype, p=0.0282). Together, these data suggest adrenal BMAL1 is required for normal rhythms of aldosterone and renal Na balance in a sex-dependent manner. Future work will investigate whether the changes in aldosterone contribute to changes in renal Na balance. This work was supported by the American Heart Association (Postdoctoral FellowshipP0240441 to H.C.; Established Investigator Award 19EIA34660135 to M.G), theRobert and Mary Cade Professorship in Physiology (to M.G.) and the NIH(F32DK121424 to G.R.C.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluation of different ratios of neutral detergent-soluble carbohydrate fractions on performance, ingestive behavior, and nitrogen balance in dairy goats.

Cell components soluble in neutral detergent are a diverse group, both compositionally and nutritionally. The present study aimed to evaluate production responses, behavior (eating, ruminating, and idling), and nitrogen balance of dairy goats fed different ratios of neutral detergent-soluble carbohydrate fractions. Five multiparous Alpine does with mean ± SD initial body mass of 49.5 ± 7.9kg and 60days of lactation were randomly assigned in a 5 × 5 Latin square design. The treatments were the ratios of starch (starch associated with soluble sugar [StSS]) to neutral detergent-soluble fiber (NDSF) (StSS:NDSF): 0.89, 1.05, 1.24, 1.73, and 2.92. No effect was observed (P > 0.05) of StSS:NDSF on the intakes of neutral detergent fiber (NDF) and NDSC. However, DM intake showed a quadratic behavior (P = 0.049). The ingestive behavior was affected by StSS:NDSF linearly increased (P = 0.002) the feeding efficiency. The increase in StSS:NDSF caused a linear increase in fecal (P = 0.011), urinary (P < 0.001), and milk nitrogen excretion (P = 0.024). The increase in StSS:NDSF affected (P = 0.048) milk yield and net energy lactation (P = 0.036). In conclusion, dairy goats experience reduced dry matter intake and milk yield when subjected to high-NDSC diets, specifically those above 1.24 StSS:NDSF ratio. Elevated NDSC levels in the diets lead to decreased feeding time, whereas rumination remains unaffected. Nitrogen losses in goats increase linearly with high-NDSC diets, and a significant impact on nitrogen balance.

Dapagliflozin Stimulates Renal Ammonia Excretion in Rats

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are drugs that induce glycosuria and are used to treat type 2 diabetes mellitus, moreover it has also been used in other conditions such as heart failure and atherosclerosis. However, little is known about the effects of these drugs on renal function. Considering that the maintenance of acid-base balance is closely related to renal physiology, in this study we evaluated the influence of chronic use of dapagliflozin on global renal function and urinary excretion of ammonia and titratable acids. Objective: To evaluate global renal function and urinary acid excretion (ammonia and titratable acid) in male Wistar rats chronically treated with dapagliflozin. Methods: 3-month-old male Wistar rats were randomized to control (C) and dapagliflozin (D) groups. Animals in group D received dapagliflozin (3 mg/kg, gavage) for 4 weeks. All animals were given food and water ad libitum throughout the experimental protocol. At 4 months of age, animals were placed in metabolic cages for 24-hour urine collection followed by blood sampling. Plasma concentrations of creatinine, sodium, potassium, urea, pH, pCO2, and bicarbonate were evaluated. The following were also evaluated: body weight, water intake, urine flow, and excretion of ammonia, titratable acids, glucose, and protein. Protocol approved by CEUA-UNIFESP number: 5985180423. Values expressed as mean ± standard error; number of animals per group: 6. Results: No significant changes were observed in blood gas parameters: pH (C: 7.33±0.043; D: 7.36±0.027), pCO2 (C: 53.30±2.40; D: 52.67±3.63 mmHg) and HCO3− (C: 27.07±1.31; D: 29.75±1.72 mEq/L) and no significant changes in plasma creatinine concentration (C: 0.41±0.04; D: 0.40±0.04mg/dl), Na+ (C: 144±0.47; D: 137±2.04 mmol/l) and K+ (C: 4.30±0.21; D: 4.16±0.20 mmol/l). We observed a significant increase in urine flow (C: 0.027±0.006; D: 0.068±0.005 mL/min/kg), possibly associated with intense glycosuria (C: 0.017±0.005; D: 8.97±0.51 g/24h). The significant increase in plasma urea concentration (C: 39.17±2.57; D: 48.83±1.27 mg/dL) and proteinuria (C: 11.04±0.30; D: 15.79±0.56 mg/24h) may indicate some renal impairment. Considering the marked increase in urinary excretion of ammonia (C: 0.65±0.05; D: 3.49±2.31 mEq/24h) and titratable acids (C: 0.180±0.036; D: 0.628±0.078 mEq/24h), we can conclude that the drug-induced glycosuria may lead to biochemical adaptations to maintain blood glucose levels within the normal range, at the expense of increased metabolic acid production. However, further experiments are needed to confirm this hypothesis. CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Central Inhibition of Antidiuretic Hormone by the Kappa Opioid Receptor Agonist Nalfurafine Prevents and Reverses Loop Diuretic Resistance

PURPOSE: Diuretic resistance is a failure to achieve a therapeutically desired increase in the renal excretion of sodium and water and reduction in edema despite a full dose of a loop diuretic. High levels of antidiuretic hormone (ADH) have been associated with reduced urine output in heart failure patients. However, ADH’s contribution to the development of diuretic resistance is not known. Assuming that ADH may be released in response to the diuresis produced by loop diuretics, we tested the premise that co-treatment of rats with nalfurafine, a centrally acting kappa opioid (KOR) agonist that inhibits the release of ADH would prevent and/or reverse diuretic resistance to the loop diuretic furosemide. METHODS: Changes in 5-hr urine output (metabolic cages; no water access during collection), urinary Na/K excretion, and osmolality were measured in male Sprague-Dawley rats administered twice-daily i.p. injections (9:00am, 2:00pm; n=6/group) for 11 days with 1) furosemide only (F, 10mg/kg, i.p.; days 1-11), 2) furosemide + nalfurafine (F+N, 10ug/kg, i.p.; days 1-11) or 3) F (days 1-5) followed by F+N (days 6-11). 5-hr urine collection was measured in between the morning and afternoon drug injections and rats were returned to home cages. Control 5-hr urine samples (saline, i.p.) were collected 2 days prior to beginning drug treatments. SUMMARY: Initial treatment (day 1) of rats with F alone and F+N markedly increased urine output. However, over days 6-10, urine output was significantly reduced (diuretic resistance) in rats that continued to receive F alone. Daily co-treatment of F+N beginning day 1 maintained a marked 5-hrdiuresis for all 11 days. Further, delaying addition of nalfurafine co-administration with F until day 6 reversed established diuretic resistance as noted by a marked increase in diuresis over days 6-10 with F+N cotreatment. Initial treatment (day 1) of rats with furosemide also produced a marked natriuresis and kaliuresis. However, on subsequent days (2-11) there was a significant decrease in the renal excretion of sodium and potassium that remained lower in all 3 treatment groups. In contrast, nalfurafine co-treatment beginning either day 1 (Group 2) or day 6 (Group 3) increased free-water clearance as compared to furosemide alone (Group 1). CONCLUSIONS: These results demonstrate that co-administration of the KOR agonist nalfurafine prevented and reversed diuretic resistance to furosemide without worsening electrolyte excretion. Further, these findings support the premise that in response to fluid loss caused by repeated loop diuretic administration, a compensatory release and renal action of ADH plays an important role in mediating loop diuretic resistance. NIH P30GM106392 (DK) LSUHSC REP243 (DK). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.