Quantifying the integrated physiological effects of endothelin-1 on cardiovascular and renal function in healthy subjects: a mathematical modeling analysis.

Endothelin-1 (ET-1) is a potent vasoconstrictor with strong anti-natriuretic and anti-diuretic effects. While many experimental studies have elucidated the mechanisms of ET-1 through its two receptors, ETA and ETB, the complexity of responses and sometimes conflicting data make it challenging to understand the effects of ET-1, as well as potential therapeutic antagonism of ET-1 receptors, on human physiology. In this study, we aimed to develop an integrated and quantitative description of ET-1 effects on cardiovascular and renal function in healthy humans by coupling existing experimental data with a mathematical model of ET-1 kinetics and an existing mathematical model of cardiorenal function. Using a novel agnostic and iterative approach to incorporating and testing potential mechanisms, we identified a minimal set of physiological actions of endothelin-1 through ETA and ETB receptors by fitting the physiological responses (changes in blood pressure, renal blood flow, glomerular filtration rate (GFR), and sodium/water excretion) to ET-1 infusion, with and without ETA/ETB antagonism. The identified mechanisms align with previous experimental studies on ET-1 and offer novel insights into the relative magnitude and significance of endothelin's effects. This model serves as a foundation for further investigating the mechanisms of ET-1 and its antagonists.

Post-diuretic spot urine sodium assessment in acute heart failure: a retrospective analysis.

AIMS: To provide real-world data on post-diuretic spot urine sodium concentration (UNa) assessment in acute heart failure (AHF) and its implications for treatment. METHODS AND RESULTS: Automated query of the electronic medical record identified patients admitted to the cardiac intensive care unit of a single tertiary care hospital between November 2018 and December 2021, who received intravenous loop diuretics. Detailed manual chart review confirmed the AHF diagnosis. Stratification was performed based on whether post-diuretic UNa was assessed within 24 h of admission. AHF was confirmed in 340/380 identified patients. Post-diuretic UNa was assessed in 117 (34%), more frequently when ejection fraction was reduced and heart failure more advanced. Patients with versus without post-diuretic UNa assessment received higher doses of intravenous loop diuretics and more frequently acetazolamide and thiazide-like diuretics (p < 0.001 for all), resulting in similar urine output despite more advanced heart failure [2,488 mL (1,740-4,033 mL) vs. 2,400 mL (1,553-3,250 mL), respectively; p = 0.170]. Diuretic therapy remained more intense at discharge in the post-diuretic UNa group, with also a higher prescription rate of angiotensin-neprilysin inhibitors (p = 0.021). Serum creatinine increases/decreases were similarly frequent irrespectively from UNa assessment, with more dynamic changes observed in patients with UNa ≤ 80 mmol/L versus ≥ 81 mmol/L. After adjustments for baseline characteristics, the risk for death or heart failure readmission was similar in patients with versus without UNa assessment [HR (95%CI) = 1.43 (0.88-2.32); p = 0.150]. CONCLUSION: Post-diuretic UNa assessment in AHF was associated with more intense diuretic regimens, preserving urine output despite its use in a sicker population.

Evaluation of Diuretic Activity of Aqueous and Hydro Methanolic Crude Extracts and Solvent Fraction of the Hydromethanolic Flower Extract of Erica Arborea L. (Ericaceae) in Swiss Albino Mice.

Purpose: To evaluate the diuretic effects of aqueous (AQ) and hydromethanolic crude extract (HM) the as well as the solvent fractions of the HM extract from Erica arborea flowers in mice. Methods: Mice were administered AQ and HM crude extracts, along with solvent fractions of HM extracts of E. arborea flowers, including HXF (n-hexane fraction), EAF (ethyl acetate fraction), and AQF (aqueous fraction), at doses ranging from 100 to 400 mg/kg orally. The effects of these extracts and solvent fractions on urine and salt excretion over 5 hours were compared to the effects of the solvent used for reconstitution and a standard drug (furosemide 10 mg/kg), as well as to each other. Results: The HM crude extract at a lower dose (100 mg/kg) significantly increased urine volume and salt excretion starting from the 3rd h compared to the AQ crude extract. Similar effects were observed for EAF. Notably, the HM extract and its EAF at 400 mg/kg showed comparable urine and salt excretion profiles to the standard drug. Conclusion: This study demonstrated that HM extract and EAF promote better diuresis, likely due to their saluretic properties. Furthermore, it confirms the diuretic activity of Erica arborea flowers.

How can inhibition of glucose and sodium transport in the early proximal tubule protect the cardiorenal system?

What mechanisms can link the inhibition of SGLT2-mediated Na+-coupled glucose reabsorption in early proximal tubules to kidney and heart protection in patients with and without type 2 diabetes? Due to physical and functional coupling of SGLT2 to other sodium and metabolite transporters in the early proximal tubule (including NHE3, URAT1), inhibitors of SGLT2 (SGLT2i) reduce reabsorption not only of glucose, inducing osmotic diuresis, but of other metabolites plus of a larger amount of sodium than expected based on SGLT2 inhibition alone, thereby reducing volume retention, hypertension, and hyperuricemia. Metabolic adaptations to SGLT2i include a fasting-like response, with enhanced lipolysis and formation of ketone bodies that serve as additional fuel for kidneys and heart. Making use of the physiology of tubulo-glomerular communication, SGLT2i functionally lower glomerular capillary pressure and filtration rate, thereby reducing physical stress on the glomerular filtration barrier, tubular exposure to albumin and nephrotoxic compounds, and the oxygen demand for reabsorbing the filtered load. Together with reduced gluco-toxicity in the early proximal tubule and better distribution of transport work along the nephron, SGLT2i can preserve tubular integrity and transport function and, thereby, GFR in the long-term. By shifting transport downstream, SGLT2 inhibitors may simulate systemic hypoxia at the oxygen sensors in the deep cortex/outer medulla, which stimulates erythropoiesis and, together with osmotic diuresis, enhances hematocrit and thereby improves oxygen delivery to all organs. The described SGLT2-dependent effects may be complemented by off-target effects of SGLT2i on the heart itself and on the microbiome formation of cardiovascular-effective uremic toxins.

Transforming Diabetes Care: The Molecular Pathways through Which GLP1-RAs Impact the Kidneys in Diabetic Kidney Disease.

Diabetic kidney disease (DKD) is a substantial complication of type 2 diabetes (T2D), presenting challenges in chronic kidney disease (CKD) management. In addition to traditional and recent therapies, including angiotensin, converting enzyme (ACE) inhibitors, angiotensin receptor blockers, sodium-glucose cotransporter 2 (SGLT2) inhibitors, and mineralocorticoid receptor antagonists, the evolution of antihyperglycemic treatments has introduced a promising agent, glucagon-like peptide-1 receptor agonist (GLP-1RA) for the management of DKD. GLP-1RAs enhance insulin release and reduce glucagon release, offering a novel approach to DKD management. This review analyzes the molecular pathways through which GLP1-RAs confer renal protection in T2D and DKD, which are complex and multifaceted. They include modulation of renal hemodynamics, antioxidative and anti-inflammatory actions, metabolic regulation, and direct cellular effects. These mechanisms highlight GLP1-RA's potential as a therapeutic option for glycemic control and direct or indirect renal function protection in diabetic patients, emphasizing the potentiality of GLP-1RAs for dual therapy, with cardiovascular and renal protection as a holistic approach. Clinical evidence supports GLP-1RAs in reducing albuminuria and enhancing kidney outcomes, highlighting their value in a comprehensive DKD management strategy.

Prognostic Impact of Induced Natriuresis in Acute Decompensated Heart Failure and Its Association with Intraabdominal Pressure and Other Congestion Markers: A Multimodal Approach to Congestion Assessment.

BACKGROUND: Congestion is an essential issue in patients with heart failure (HF). Standard treatments do not usually achieve decongestion, and various strategies have been proposed to guide treatment, such as determination of natriuresis. After starting treatment with loop diuretics, we postulate that initial natriuresis might help treatment titration, decongestion, and improve prognosis. METHODS: It was a prospective and observational study. Patients admitted with the diagnosis of HF decompensation were eligible. An assessment of congestion was performed during the first 48 h. RESULTS: A total of 113 patients were included. A poor diuretic response was observed in 39.8%. After the first 48 h, patients with a greater diuretic response on admission (NaU > 80 mmol/L) showed fewer pulmonary b lines (12 vs. 15; p = 0.084), a lower IVC diameter (18 mm vs. 22 mm; p = 0.009), and lower IAP figures (11 mmHg vs. 13 mmHg; p = 0.041). Survival analysis tests demonstrated significant differences showing a higher proportion of all-cause mortality (ACM) and HF rehospitalization in the poor-diuretic-response group (log-rank test = 0.020). CONCLUSIONS: Up to 40% of the patients presented a poorer diuretic response at baseline, translating into worse outcomes. Patients with an optimal diuretic response showed significantly higher abdominal decongestion at 48 h and a better prognosis regarding ACM and/or HF rehospitalizations.

Naringen's Effects on Diuresis and Prevention of Urolithiasis in Hypertensive Rats.

This research demonstrates the diuretic effect of naringenin, a flavanone aglycone found in citrus, on spontaneously hypertensive female and male rats (SHR). The data reinforces existing literature findings that male SHR exhibits higher systolic blood pressure than age-matched females. Urine volume assessed over 8 hours was lower when obtained from SHR males than females. When these animals were orally treated with different doses of naringenin (0.1-1 mg/kg), this increased urinary volume in both genders at the highest dose tested. In contrast, the lowest dose promoted a significant natriuretic effect. The other electrolytes analyzed in urine were not significantly altered, except potassium excretion, which was shown to be increased in the urine of SHR males. Furthermore, naringenin showed promise in reducing calcium oxalate (CaOx) crystal formation in an in vitro model, presenting potential advantages in lithiasis prevention.

Anti-hypertensive effect of a novel angiotensin II receptor neprilysin inhibitor (ARNi) -S086 in DSS rat model.

Introduction: Angiotensin receptor-neprilysin inhibitor (ARNi), comprised of an angiotensin receptor blocker (ARB) and a neprilysin inhibitor (NEPi), has established itself as a safe and effective intervention for hypertension. S086 is a novel ARNi cocrystal developed by Salubris for the treatment of heart failure and hypertension. Methods: Dahl Salt Sensitive (DSS) hypertensive rat model and telemetry system were employed in this study to investigate the anti-hypertensive efficacy of S086 and compare it with the first ARNi-LCZ696. Results and discussion: The study showed that oral administration of S086 dose-dependently lowered blood pressure (P < 0.001). The middle dosage of S086 (23 mg/kg) exhibited efficacy comparable to LCZ696 (68 mg/kg), while also demonstrating superiority at specific time points (P < 0.05). Notably, water consumption slightly decreased post-treatment compared to the vehicle group. Furthermore, there were significant increases in natriuresis and diuresis observed on the first day of treatment with 23 mg/kg and 68 mg/kg S086 (P < 0.001). However, over the course of treatment, the effects in all treatment groups gradually diminished. This study demonstrates the anti-hypertensive efficacy of S086 in DSS hypertensive rat model, offering promising avenues for the clinical development of S086 as a hypertension treatment.

The impact of GLP-1 receptor agonist liraglutide on blood pressure profile, hydration, natriuresis in diabetic patients with severely impaired kidney function.

Chronic treatment with GLP-1R agonists may moderately lower blood pressure due to increased natriuresis and RAAS inhibition. Short-term effect of these drugs on blood pressure may be opposite and its mechanism remains unclear. We investigated the effect of a single dose of liraglutide on diurnal blood pressure profile, natriuresis, hydration and serum concentration of renin, aldosterone and atrial natriuretic peptide (ANP) in diabetic kidney disease (DKD). 17 patients with eGFR < 30 ml/min/1.73 m2 and 17 with > 60 ml/min/1.73 m2 received in a random order a single subcutaneous dose 1.2 mg liraglutide and placebo with subsequent 24 h blood pressure and natriuresis monitoring. Before and after each medication thoracic fluid index and plasma renin, aldosterone and ANP were also assessed. The blood pressure load in the daytime and nighttime were significantly increased after liraglutide compared to placebo in patients with eGFR < 30 ml/min/1.73 m2. In patients with eGFR > 60 ml/min/1.73 m2 the changes of arterial pressure were comparable, while the morning surge was significantly reduced after liraglutide compared to placebo. After liraglutide 24 h urine sodium excretion increased in both groups vs. placebo (p < 0.001), the effect was greatest in subjects with eGFR > 60 ml/min/1.73 m2. Plasma ANP increased after liraglutide in both groups, most in patients with eGFR < 30 ml/min/1.73 m2 group. Plasma aldosterone (p = 0.013) and thoracic fluid index (p = 0.01) decreased after liraglutide compared to placebo (p = 0.013 and p + 0.01, respectively. Plasma renin concentration remained unchanged. In severe chronic kidney disease liraglutide induces a transient increase of blood pressure due to reduced natriuresis. The natriuretic effect of liraglutide in DKD may be related to increased ANP and decreased aldosterone secretion.

Herbal medicine (Oryeongsan) for fluid and sodium balance in renal cortex of spontaneously hypertensive rats.

Background: Herbal medicine Oryeongsan (ORS), also known as Wulingsan in Chinesehas been used for the treatment of impaired body fluid balance. However, the mechanisms involved are not clearly defined. The purpose of the present study was to identify the actions of ORS on the renal excretory function and blood pressure (BP) and to define the mechanisms involved in association with renin-angiotensin system (RAS) and natriuretic peptide system (NPS) in spontaneously hypertensive rats (SHR), an animal model of human essential hypertension. Methods: Changes in urine volume (UV), excretion of electrolytes including Na+ (urinary excretion of Na+ (UNaV)) were measured. RT-PCR was performed to trace the changes in expression of RAS, NPS and sodium (Na+)-hydrogen (H+) exchanger 3 (NHE3) in the renal cortex. Results: In the SHR treated with vehicle (SHR-V) group, UV and UNaV were suppressed and the Na+ balance was maintained at the higher levels leading to an increase in BP compared to WKY-V group. These were accompanied by an increase in NHE3 expression with an accentuation of angiotensin I converting enzyme-angiotensin II type 1 (ACE-AT1) receptor and concurrent suppression of angiotensin II type 2 (AT2) receptor/ACE2-Mas receptor expression in the renal cortex. Chronic treatment with ORS increased UV and UNaV, and decreased the Na+ and water balance with a decrease in BP in the ORS-treated SHR-ORS group compared to SHR-V. These were accompanied by a decrease in NHE3 expression with a suppression of ACE-AT1 receptor and concurrent accentuation of AT2/ACE2-Mas receptor. Conclusion: The present study shows that ORS reduced BP with a decrease in Na+ and water retention by a suppression of NHE3 expression via modulation of RAS and NPS in SHR. The present study provides pharmacological rationale for the treatment of hypertension with ORS in SHR.

Protocolized Natriuresis-Guided Decongestion Improves Diuretic Response: The Multicenter ENACT-HF Study.

BACKGROUND: The use of urinary sodium to guide diuretics in acute heart failure is recommended by experts and the most recent European Society of Cardiology guidelines. However, there are limited data to support this recommendation. The ENACT-HF study (Efficacy of a Standardized Diuretic Protocol in Acute Heart Failure) investigated the feasibility and efficacy of a standardized natriuresis-guided diuretic protocol in patients with acute heart failure and signs of volume overload. METHODS: ENACT-HF was an international, multicenter, open-label, pragmatic, 2-phase study, comparing the current standard of care of each center with a standardized diuretic protocol, including urinary sodium to guide therapy. The primary end point was natriuresis after 1 day. Secondary end points included cumulative natriuresis and diuresis after 2 days of treatment, length of stay, and in-hospital mortality. All end points were adjusted for baseline differences between both treatment arms. RESULTS: Four hundred one patients from 29 centers in 18 countries worldwide were included in the study. The natriuresis after 1 day was significantly higher in the protocol arm compared with the standard of care arm (282 versus 174 mmol; adjusted mean ratio, 1.64; P<0.001). After 2 days, the natriuresis remained higher in the protocol arm (538 versus 365 mmol; adjusted mean ratio, 1.52; P<0.001), with a significantly higher diuresis (5776 versus 4381 mL; adjusted mean ratio, 1.33; P<0.001). The protocol arm had a shorter length of stay (5.8 versus 7.0 days; adjusted mean ratio, 0.87; P=0.036). In-hospital mortality was low and did not significantly differ between the 2 arms (1.4% versus 2.0%; P=0.852). CONCLUSIONS: A standardized natriuresis-guided diuretic protocol to guide decongestion in acute heart failure was feasible, safe, and resulted in higher natriuresis and diuresis, as well as a shorter length of stay.

Sodium-glucose linked transporter 2 inhibitors in liver cirrhosis: Beyond their antidiabetic use.

Type 2 diabetes mellitus (T2DM) and liver cirrhosis are clinical entities that frequently coexist, but glucose-lowering medication options are limited in cirrhotic patients. Sodium-glucose linked transporter 2 (SGLT2) inhibitors are a class of glucose-lowering medication that act independently of insulin, by causing glycosuria in the proximal convoluted tubule. In this review, we aimed to briefly present the main data and to provide insight into the pathophysiology and potential usefulness of SGLT2 inhibitors in cirrhotic patients with or without T2DM. SGLT2 inhibitors have been proven useful as antidiabetic treatment in patients with metabolic liver disease, with most robust data from patients with metabolic dysfunction-associated steatotic liver disease (MASLD), where they also showed improvement in liver function parameters. Moreover, it has been suggested that SGLT2 inhibitors may have effects beyond their antidiabetic action. Accordingly, they have exhibited cardioprotective effects, expanding their indication in patients with heart failure without T2DM. Since decompensated liver cirrhosis and congestive heart failure share common pathophysiological features, namely renin-angiotensin-aldosterone axis and sympathetic nervous system activation as well as vasopressin secretion, SGLT2 inhibitors could also be beneficial in patients with decompensated cirrhosis, even in the absence of T2DM.

Unlocking the Potential of Acetazolamide: A Literature Review of an Adjunctive Approach in Heart Failure Management.

Background: Heart failure (HF) patients often experience persistent fluid overload despite standard diuretic therapy. The adjunctive use of acetazolamide, a carbonic anhydrase inhibitor, in combination with loop diuretics has shown promise in improving decongestion and diuretic efficacy. This literature review aims to analyze six studies evaluating the effectiveness of acetazolamide as an additive treatment for acute decompensated heart failure (ADHF) and its impact on various outcomes. Methods: We searched the PubMed database using the terms "acetazolamide heart failure". We refined our search with specific filters (as shown our PRISMA flow diagram) and exclusion criteria, narrowing down our results to five studies. We included an extra study via expert recommendation, ultimately including six studies for comprehensive analysis. Results: The review highlights the positive effects of acetazolamide on decongestion, natriuresis, and diuresis in HF patients. However, it also showcases the limitations of these trials. Discussion: While the reviewed studies demonstrate the potential benefits of acetazolamide in enhancing decongestion and diuretic efficiency, there are limitations to consider, including small sample sizes, lack of blinding, and limited external validity. Further research is needed to confirm these findings, compare acetazolamide with other diuretic combinations, and explore its effects in a broader population of heart failure patients, including those in the United States. The use of acetazolamide in HF management warrants continued investigation to optimize its role in improving decongestion and patient outcomes.

3-Demethyl-2-geranyl-4-prenylbellidifoline, a natural xanthone with diuretic and kidney protective properties.

OBJECTIVES: The diuretic and kidney protective effect of the 3-demethyl-2-geranyl-4-prenylbellidifoline (DGP) were evaluated in rats. METHODS: The normotensive (NTR) and spontaneously hypertensive rats (SHR) received, once a day for 7 days, oral treatment with DGP (0.1 mg/kg), hydrochlorothiazide (10 mg/kg), or vehicle (10 ml/kg). Urine, blood, and kidney samples were collected for further analysis. KEY FINDINGS: The urine and Na+ elimination content were significantly higher in the groups that received DGP. Furthermore, a Ca2+-sparing action was detected in the urine of DGP-treated groups, which was consistent with the reduction in calcium oxalate crystal formation. Relevantly, the treatment did not change the parameters examined in the blood. Concerning the renal analyses, DGP treatment recovered the morphological damages of the kidney corpuscle area of SHR. In addition to the differences observed between the NTR and SHR vehicle groups, DGP augmented the amount of reduced glutathione and the activity of glutathione S-transferase GST while reducing the catalase and N-acetyl-ß-D-glucosaminidase activity and nitrite levels. CONCLUSION: Together, this study displayed the prolonged diuretic action of DGP and its natriuretic, Ca2+-sparing, and antiurolytic effects. The antioxidative and anti-inflammatory effects of DGP were evidenced in SHR kidneys, opening perspectives for further studies regarding the benefits of this xanthone.

Primary Role of the Kidney in Pathogenesis of Hypertension.

Previous transplantation studies and the concept of 'nephron underdosing' support the idea that the kidney plays a crucial role in the development of essential hypertension. This suggests that there are genetic factors in the kidney that can either elevate or decrease blood pressure. The kidney normally maintains arterial pressure within a narrow range by employing the mechanism of pressure-natriuresis. Hypertension is induced when the pressure-natriuresis mechanism fails due to both subtle and overt kidney abnormalities. The inheritance of hypertension is believed to be polygenic, and essential hypertension may result from a combination of genetic variants that code for renal tubular sodium transporters or proteins involved in regulatory pathways. The renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system (SNS) are the major regulators of renal sodium reabsorption. Hyperactivity of either the RAAS or SNS leads to a rightward shift in the pressure-natriuresis curve. In other words, hypertension is induced when the activity of RAAS and SNS is not suppressed despite increased salt intake. Sodium overload, caused by increased intake and/or reduced renal excretion, not only leads to an expansion of plasma volume but also to an increase in systemic vascular resistance. Endothelial dysfunction is caused by an increased intracellular Na+ concentration, which inhibits endothelial nitric oxide (NO) synthase and reduces NO production. The stiffness of vascular smooth muscle cells is increased by the accumulation of intracellular Na+ and subsequent elevation of cytoplasmic Ca++ concentration. In contrast to the hemodynamic effects of osmotically active Na+, osmotically inactive Na+ stimulates immune cells and produces proinflammatory cytokines, which contribute to hypertension. When this occurs in the gut, the microbiota may become imbalanced, leading to intestinal inflammation and systemic hypertension. In conclusion, the primary cause of hypertension is sodium overload resulting from kidney dysregulation.

Decongestion in Acute Heart Failure-Time to Rethink and Standardize Current Clinical Practice?

Most episodes of acute heart failure (AHF) are characterized by increasing signs and symptoms of congestion, manifested by edema, pleura effusion and/or ascites. Immediately and repeatedly administered intravenous (IV) loop diuretics currently represent the mainstay of initial therapy aiming to achieve adequate diuresis/natriuresis and euvolemia. Despite these efforts, a significant proportion of patients have residual congestion at discharge, which is associated with a poor prognosis. Therefore, a standardized approach is needed. The door to diuretic time should not exceed 60 min. As a general rule, the starting IV dose is 20-40 mg furosemide equivalents in loop diuretic naïve patients or double the preexisting oral home dose to be administered via IV. Monitoring responses within the following first hours are key issues. (1) After 2 h, spot urinary sodium should be ≥50-70 mmol/L. (2) After 6 h, the urine output should be ≥100-150 mL/hour. If these target measures are not reached, the guidelines currently recommend a doubling of the original dose to a maximum of 400-600 mg furosemide per day and in patients with severely impaired kidney function up to 1000 mg per day. Continuous infusion of loop diuretics offers no benefit over intermittent boluses (DOSE trial). Emerging evidence by recent randomized trials (ADVOR, CLOROTIC) supports the concept of an early combination diuretic therapy, by adding either acetazolamide (500 mg IV once daily) or hydrochlorothiazide. Acetazolamide is particularly useful in the presence of a baseline bicarbonate level of ≥27 mmol/L and remains effective in the presence of preexisting/worsening renal dysfunction but should be used only in the first three days to prevent severe metabolic disturbances. Patients should not leave the hospital when they are still congested and/or before optimized long-term guideline-directed medical therapy has been initiated. Special attention should be paid to AHF patients during the vulnerable post-discharge period, with an early follow-up visit focusing on up-titrate treatments of recommended doses within 2 weeks (STRONG-HF).