Basal natriuresis as a predictor of diuretic resistance and clinical evolution in acute heart failure

BACKGROUND

Some clinical guidelines recommend serial measurement of natriuresis to detect diuretic resistance (DR) in acute heart failure (AHF) patients, but it adds complexity to the management.

OBJECTIVES

To correlate a single measurement of basal natriuresis (BN) on admission with the development of DR and clinical evolution in AHF hospitalized patients.

METHODS

Prospective and multicenter study included AHF hospitalized patients, without shock or creatinine >2.5mg%. Patients received 40mg of intravenous furosemide on admission, then BN was measured, and diuretic treatment was guided by protocol. BN was considered low if <70 meq/L. DR was defined as the need of furosemide >240mg/day, tubular blockade (TB), hypertonic saline solution (HSS) or renal replacement therapy (RRT). In-hospital cardiovascular (CV) mortality, CV mortality and AHF readmissions at 60-day post-discharge were evaluated.

RESULTS

157 patients were included. BN was low in 22%. DR was development in 19% (12.7% furosemide >240mg/day, 8% TB, 4% RRT). Low NB was associated with DR (44% vs 12%; p 0.0001), persistence of congestion (26.5% vs 11.4%; p 0.05), furosemide >240 mg/day (29% vs 8%; p 0.003), higher cumulative furosemide dose at 72 hours (220 vs 160mg; p 0.0001), TB (20.6 vs 4.9%; p 0.008), RRT (11.8 vs 1.6%; p 0.02), worsening of AHF (27% vs 9%; p 0.01), inotropes use (21% vs 7%; p 0.48), respiratory assistance (12% vs 2%; p 0.02) and a higher in-hospital CV mortality (12% vs 4%; p 0.1). No association was demonstrated with post-discharge endpoints.

CONCLUSIONS

In AHF patients, low BN was associated with DR, persistent congestion, need for aggressive decongestion strategies, and worse in-hospital evolution.

Renal function in PUSH-AHF: a summary of newly released data from the 2024 Annual Congress of the Heart Failure Association of the ESC

The Pragmatic Urinary Sodium-based algoritHm in Acute Heart Failure (PUSH-AHF) study, published in August of 2023, was the first randomized clinical trial to compare natriuresis-guided decongestion (based on spot urinary sodium measurement) to standard of care in patients with acute heart failure with congestion receiving loop diuretic therapy. Based on results from their trial, the authors concluded that natriuresis-guided loop diuretic treatment was safe and improved natriuresis and diuresis without impacting long-term clinical outcomes. The original PUSH-AHF trial included limited information about renal outcomes and left clinicians with important questions about how natriuresis-guided decongestion might affect their patients' renal function. On May 12, 2024, however, at the 2024 Annual Congress of the HFA-ESC, Dr. Kevin Damman provided an in-depth exploration of renal outcomes from the trial when he presented a pre-specified, secondary analysis, renal function in the PUSH-AHF trial. This review puts the sub-study findings into context by considering the history of the original trial from which they came from and explaining the need for a close study of its renal outcomes particularly. It highlights the potential impact of renal function in PUSH-AHF on clinical practice and future directions that should be considered by the cardiology research community.

Osmolality in oral supplements drives ileostomy output: Defining the Goldilocks zone

BACKGROUND

Patients with an ileostomy often have impaired quality of life, sodium depletion, secondary hyperaldosteronism, and other organ-specific pathologies. The osmolality of oral supplements influences ileostomy output and increases sodium loss. We hypothesized the existence of an osmolality range in which fluid absorption and secondary natriuresis are optimal.

METHODS

This was a single-center, quasi-randomized crossover intervention study, including patients with an ileostomy and no home parenteral support. After an 8-h fasting period, each patient ingested 500 mL of 3-18 different oral supplements and a standardized meal during the various intervention periods, followed by a 6-h collection of ileostomy and urine outputs. The primary outcome was 6-h ileostomy output.

RESULTS

A total of 14 ileostomy patients with a median age of 65 years (interquartile range 38-70 years) were included. The association between osmolalities (range 5-1352 mOsm/kg) and ileostomy output forecasted an S-curve. A linear association between osmolality of oral supplements (range 290-600 mOsm/kg) and ileostomy output was identified and assessed with a mixed-effects model. Ileostomy output increased by 57 g/6 h (95% confidence interval (CI) 21-94) when the oral supplement osmolality increased by 100 mOsm/kg (p = 0.005).

CONCLUSION

Osmolality in oral supplements correlated with ileostomy output. Our results indicate that patients with an ileostomy may benefit from increased ingestion of oral supplements with osmolalities between 100 and 290 mOsm/kg. We define this range as the Goldilocks zone, equivalent to optimal fluid and electrolyte absorption.

Renal function and natriuresis-guided diuretic therapy - a pre-specified analysis from the PUSH-AHF trial

AIM

In a randomized controlled trial, we recently showed that a natriuresis-guided diuretic approach improved natriuresis and diuresis in patients with acute heart failure (HF). In this pre-specified analysis, we investigated the association between (worsening) renal function, outcomes and the effect of intensive natriuresis-guided loop diuretic therapy as compared with standard of care.

METHODS AND RESULTS

The Pragmatic Urinary Sodium-based algoritHm in Acute Heart Failure (PUSH-AHF) trial randomized patients to natriuresis-guided diuretic therapy or standard of care. Serum creatinine and estimated glomerular filtration rate (eGFR) were assessed at fixed timepoints, and worsening renal function (WRF) was assessed at 72 h. The primary outcome was the interaction between randomized treatment allocation, baseline eGFR and the dual primary outcome of PUSH-AHF: total natriuresis at 24 h and time to all-cause mortality or HF rehospitalization at 180 days. In 309 patients, median baseline eGFR was 53 (35-73) ml/min/1.73 m2, and 58% had eGFR <60 ml/min/1.73 m2. Baseline eGFR did not significantly modify the treatment effect of natriuresis-guided diuretic therapy on natriuresis at 24 h (p for interaction = 0.730). However, baseline eGFR significantly modified the effect on all-cause mortality and HF rehospitalization (p for interaction = 0.017): the risk of this second primary outcome was lower in patients with lower eGFR who were randomized to the natriuresis-guided group. In the natriuresis-guided arm, eGFR decreased more (-11.0 vs. -6.91 ml/min/1.73 m2; p = 0.002) during the first 3 days, but this effect was attenuated at discharge (-10.3 vs. -8.69 ml/min/1.73 m2; p = 0.38). WRF was more frequently observed in patients randomized to natriuresis-guided treatment, but was not associated with worse clinical outcomes.

CONCLUSIONS

Natriuresis-guided diuretic treatment improved diuresis and natriuresis irrespective of baseline eGFR and occurrence of WRF, was effective even in patients with low eGFR, and the observed effect on eGFR was transient and not associated with worse clinical outcomes.

Augmentation of nitric oxide deficient hypertension by high salt diet is associated with reduced TNF-α receptor type 1 expression in the kidneys

BACKGROUND

High salt (HS) intake induces an augmented hypertensive response to nitric oxide (NO) inhibition, though it causes minimal changes in blood pressure (BP) in NO intact condition. The cause of such augmentation is not known. HS induces tumor necrosis factor-alpha (TNFα) production that causes natriuresis via activation of its' receptor type 1 (TNFR1). We hypothesized that NO deficiency reduces renal TNFR1 activity, leading to enhanced sodium retention and hypertension.

METHODS

We examined the changes in renal TNFR1 protein expression (Immunohistochemistry analyses) after HS (4% NaCl) intake in wild-type mice (WT, C57BL6) treated with a NO synthase (NOS) inhibitor, nitro-L-arginine methyl ester (L-NAME; 0.05 mg/min/g; osmotic mini-pump), as well as in endothelial NOS knockout mice (eNOSKO) and compared the responses in WT mice with normal salt (NS; 0.3% NaCl) intake. BP was measured with tail-cuff plethysmography and 24-hour urine collections were made using metabolic cages.

RESULTS

HS alone did not alter mean BP in untreated mice (76±3 to 77±1 mmHg) but induced an augmented response in L-NAME treated (106±1 vs 97±2 mmHg) and in eNOSKO (107±2 vs 89±3 mmHg) mice. The percentage area of TNFR1 expression in renal tissue was higher in WT+HS (4.1 + 0.5%) than in WT+NS mice (2.7±0.6%). However, TNFR1 expression was significantly lower in L-NAME treated WT+NS (0.9±0.1%) and in eNOSKO+NS (1.4±0.2%) than in both WT+NS and WT+HS mice.

CONCLUSION

These data indicate that TNFR1 activity is downregulated in NO deficient conditions, which facilitates salt retention leading to augmented hypertension during HS intake.

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.

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.

Impact of vasodilators on diuretic response in patients with congestive heart failure: A mechanistic trial of cimlanod (BMS-986231)

AIM

To investigate the effects of Cimlanod, a nitroxyl donor with vasodilator properties, on water and salt excretion after an administration of an intravenos bolus of furosemide.

METHODS AND RESULTS

In this randomized, double-blind, mechanistic, crossover trial, 21 patients with left ventricular ejection fraction <45%, increased plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and receiving loop diuretics were given, on separate study days, either an 8 h intravenous (IV) infusion of cimlanod (12 μg/kg/min) or placebo. Furosemide was given as a 40 mg IV bolus four hours after the start of infusion. The primary endpoint was urine volume in the 4 h after the bolus of furosemide during infusion of cimlanod compared with placebo. Median NT-proBNP at baseline was 1487 (interquartile range: 847-2665) ng/L. Infusion of cimlanod increased cardiac output and reduced blood pressure without affecting cardiac power index consistent with its vasodilator effects. Urine volume in the 4 h post-furosemide was lower with cimlanod (1032 ± 393 ml) versus placebo (1481 ± 560 ml) (p = 0.002), as were total sodium excretion (p = 0.004), fractional sodium excretion (p = 0.016), systolic blood pressure (p < 0.001), estimated glomerular filtration rate (p = 0.012), and haemoglobin (p = 0.010), an index of plasma volume expansion.

CONCLUSIONS

For patients with heart failure and congestion, vasodilatation with agents such as cimlanod reduces the response to diuretic agents, which may offset any benefit from acute reductions in cardiac preload and afterload.

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

BACKGROUND

Diabetic 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.

METHODS

Streptozotocin (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.

RESULTS

Early 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.

CONCLUSION

Our 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.

Endothelin mediates sex-differences in acclimation to high salt diet in rats

INTRODUCTION

Current understanding of sodium (Na+) handling is based on studies done primarily in males. Contrary to the gradual increase in high salt (HS) induced natriuresis over 3-5 days in males, female Sprague Dawley (SD) rats have a robust natriuresis after 1 day of HS. Renal endothelin-1 (ET-1) signaling, through ET receptor A and B, is an important natriuretic pathway and was implicated in our previous dietary salt acclimation studies, however, the contribution of ET receptors to sex-differences in acclimation to dietary Na+ challenges has yet to be clarified. We hypothesized that ET receptors mediate the augmented natriuretic capacity of female rats in response to a HS diet.

METHODS

To test our hypothesis, male and female SD rats were implanted with telemeters and randomly assigned to treatment with A-182086, a dual ETA and ETB receptor antagonist, or control. 24-h urine samples were collected and assessed for electrolytes and ET-1. Studies were performed on a normal salt (NS, 0.3% NaCl) diet and after challenging rats with HS (4% NaCl) diet for 1 day.

RESULTS

We found that A-182086 increased blood pressure in male and female SD rats fed either diet. Importantly, A-182086 eliminated sex-differences in natriuresis on NS and HS. In particular, A-182086 promotes HS-induced natriuresis in male rats rather than attenuating the natriuretic capacity of females. Further, the sex-difference in urinary ET-1 excretion in NS-fed rats was eliminated by A-182086.

CONCLUSION

In conclusion, ET receptors are crucial for mediating sex-difference in the natriuretic capacity primarily through their actions in male rats.

Sodium-glucose cotransporter-2 inhibitors in heart failure: Potential decongestive mechanisms and current clinical studies

Congestion is a key pathophysiological feature of heart failure (HF) syndrome that drives most of the clinical manifestations of acute HF and is related with poor quality of life and outcomes. Therefore, safe and effective decongestion is an important therapeutic target in the management of acute HF and despite the use of guideline-recommended loop diuretics, adequate decongestion is not always achieved in patients with acute HF. Recently, sodium-glucose cotransporter-2 (SGLT-2) inhibitors have been shown to provide clinical benefits across a broad spectrum of patients with HF, including consistent reduction in the risk of acute HF episodes. While the exact mechanisms underlying these benefits remain a matter of debate, a growing body of evidence suggests that effective decongestion may be partly responsible, especially in the setting of acute HF. In this review, we discuss the potential decongestive mechanisms of SGLT-2 inhibitors, such as osmotic diuresis, natriuresis, preservation of glomerular filtration and facilitation of interstitial drainage, which can collectively translate into effective and safe decongestion. Furthermore, we provide a comprehensive review of up-to-date clinical data of SGLT-2 inhibitor use in the acute HF population.

Intrarenal Mechanisms of Sodium-Glucose Cotransporter-2 Inhibitors on Tubuloglomerular Feedback and Natriuresis

When sodium-glucose cotransporter-2 (SGLT2) inhibitors were first introduced a decade ago, no one expected them to have substantial effects beyond their known glucose-lowering effects, until the emergence of evidence of their robust renal and cardiovascular benefits showing that they could attenuate progression of kidney disease, irrespective of diabetes, as well as prevent the development of acute kidney injury. Still, the precise and elaborate mechanisms underlying the major organ protection of SGLT2 inhibitors remain unclear. SGLT2 inhibitors inhibit the reabsorption of sodium and glucose in the proximal tubule of the kidney and then recovers tubuloglomerular feedback, whereby SGLT2 inhibitors reduce glomerular hyperfiltration. This simple demonstration of their beneficial effects has perplexed experts in seeking more plausible and as yet undisclosed explanations for the whole effects of SGLT2 inhibitors, including metabolism reprogramming and the modulation of hypoxia, inflammation, and oxidative stress. Given that the renal benefits of SGLT2 inhibitors in patients with kidney disease but without diabetes were comparable to those seen in patients with diabetes, it may be reasonable to keep the emphasis on their hemodynamic actions. In this context, the aim of the present review is to provide a comprehensive overview of renal hemodynamics in individuals with diabetes who are treated with SGLT2 inhibitors, with a focus on natriuresis associated with the regulation of tubuloglomerular feedback and potential aquaresis. Throughout the discussion of alterations in renal sodium and water transports, particular attention will be given to the potential enhancement of adenosine and its receptors following SGLT2 inhibition.

Pre-treatment bicarbonate levels and decongestion by acetazolamide: the ADVOR trial

AIMS

Acetazolamide inhibits proximal tubular sodium and bicarbonate re-absorption and improved decongestive response in acute heart failure in the ADVOR trial. It is unknown whether bicarbonate levels alter the decongestive response to acetazolamide.

METHODS AND RESULTS

This is a sub-analysis of the randomized, double-blind, placebo-controlled ADVOR trial that randomized 519 patients with acute heart failure and volume overload in a 1:1 ratio to intravenous acetazolamide (500 mg/day) or matching placebo on top of standardized intravenous loop diuretics (dose equivalent of twice oral maintenance dose). The primary endpoint was complete decongestion after 3 days of treatment (morning of day 4). Impact of baseline HCO3 levels on the treatment effect of acetazolamide was assessed. : Of the 519 enrolled patients, 516 (99.4%) had a baseline HCO3 measurement. Continuous HCO3 modelling illustrated a higher proportional treatment effect for acetazolamide if baseline HCO3 ≥ 27 mmol/l. A total of 234 (45%) had a baseline HCO3 ≥ 27 mmol/l. Randomization towards acetazolamide improved decongestive response over the entire range of baseline HCO3- levels (P = 0.004); however, patients with elevated baseline HCO3 exhibited a significant higher response to acetazolamide [primary endpoint: no vs. elevated HCO3; OR 1.37 (0.79-2.37) vs. OR 2.39 (1.35-4.22), P-interaction = 0.065), with higher proportional diuretic and natriuretic response (both P-interaction < 0.001), greater reduction in congestion score on consecutive days (treatment × time by HCO3-interaction <0.001) and length of stay (P-interaction = 0.019). The larger proportional treatment effect was mainly explained by the development of diminished decongestive response in the placebo arm (loop diuretics only), both with regard to reaching the primary endpoint of decongestion as well as reduction in congestion score. Development of elevated HCO3 further worsened decongestive response in the placebo arm (P-interaction = 0.041). A loop diuretic only strategy was associated with an increase in the HCO3 during the treatment phase which was prevented by acetazolamide (day 3: placebo 74.8% vs. acetazolamide 41.3%, P < 0.001).

CONCLUSION

Acetazolamide improves decongestive response over the entire range of HCO3- levels; however, the treatment response is magnified in patients with baseline or loop diuretic-induced elevated HCO3 (marker of proximal nephron NaHCO3 retention) by specifically counteracting this component of diuretic resistance.

Spot Urinary Sodium Measurements: the Future Direction of the Treatment and Follow-up of Patients with Heart Failure

PURPOSE OF REVIEW

Heart failure is characterized by episodes of congestion with need for hospitalization. The current metrics lack the accuracy to predict and prevent episodes of congestion and to guide diuretic titration to reach euvolemia in case of decompensation. This article aims to provide answers to the role of urinary sodium measurements in acute and chronic heart failure.

RECENT FINDINGS

In acute heart failure, urinary sodium concentrations at the moment of admission and after diuretic administration are correlated with short- and long-term outcome. As this is a reflection of the degree of sodium retention, it can be used as a guide in the diuretic titration. In chronic heart failure, it might be used to predict and consequently prevent episodes of decompensation. Urinary sodium measurements hold great promises to be a novel diagnostic and therapeutic parameter in patients with acute and chronic heart failure. However, more research is needed.

Activation of TRPV1 improves natriuresis and salt sensitivity in high-fat diet fed mice

Western diet (WD) intake increases morbidity of obesity and salt-sensitive hypertension albeit mechanisms are largely unknown. We investigated the role of transient receptor potential vanilloid 1 (TRPV1) in WD intake-induced hypertension. TRPV1^-/- and wild-type (WT) mice were fed a normal (CON) or Western diet (WD) for 16-18 weeks. Mean arterial pressure (MAP) after normal sodium glucose (NSG) loading with or without L-NAME (a NO synthase inhibitor) or N-oleoyldopamine (OLDA, a TRPV1agonist) was not different between the two strains on CON.WT or TRPV1^-/- mice fed WD had increased MAP after NSG, with a greater magnitude in TRPV1^-/- mice. OLDA decreased while L-NAME increased MAP in WT-WD but not in TRPV1^-/--WD mice. The urinary nitrates plus nitrites excretion (UNOx), an indicator of renal NO production, was increased in both strains on CON after NSG. TRPV1 ablation with WD intake abolished NSG-induced increment in UNOx. OLDA further increased while L-NAME prevented NSG-induced increment in UNOx in WT-WD mice. Urinary sodium excretion was increased in both strains on CON and in WT-WD mice but not in TRPV1^-/--WD mice after NSG. OLDA further increased while L-NAME prevented NSG-induced increases in sodium excretion in WT-WD but not in TRPV1^-/--WD mice. Thus, TRPV1 ablation increases salt sensitivity during WD intake possibly via impaired renal NO production and sodium excretion. Activation of TRPV1 enhances renal NO production and sodium excretion, resulting in prevention of increased salt sensitivity during WD intake.

PPAR-α knockout leads to elevated blood pressure response to angiotensin II infusion associated with an increase in renal α-1 Na+/K+ ATPase protein expression and activity

Peroxisome proliferator activated receptor alpha (PPAR-α) deletion has been shown to increase blood pressure (BP). We hypothesized that the BP increase in PPAR-α KO mice was mediated by increased expression and activity of basolateral Na+/K+ ATPase (NKA) pump. To address this hypothesis, we treated wild-type (WT) and PPAR-α knockout (KO) mice with a slow-pressor dose of angiotensin II (400 ng/kg·min) for 12 days by osmotic minipump. Radiotelemetry showed no significant differences in baseline mean arterial pressure (MAP) between WT and PPAR-α KO mice; however, by day 12 of infusion, MAP was significantly higher in PPAR-α KO mice (156 ± 16) compared to WT mice (138 ± 11 mmHg). NKA activity and protein expression (α1 subunit) were significantly higher in PPAR-α KO mice compared to WT mice. There was no significant difference in NKA mRNA levels. Angiotensin II further increased the expression and activity of the NKA in both genotypes along with the water channel, aquaporin 1 (Aqp1). In contrast, angiotensin II decreased the expression (64-97% reduction in band density) of sodium‑hydrogen exchanger-3 (NHE3), NHE regulatory factor-1 (NHERF1, Slc9a3r1), sodium‑potassium-2-chloride cotransporter (NKCC2), and epithelial sodium channel (ENaC) β- and γ- subunits in the renal cortex of both WT and PPAR-α KO mice, with no difference between genotypes. The sodium-chloride cotransporter (NCC) was also decreased by angiotensin II, but significantly more in PPAR-α KO (59% WT versus 77% KO reduction from their respective vehicle-treated mice). Our results suggest that PPAR-α attenuates angiotensin II-mediated increased blood pressure potentially via reducing expression and activity of the NKA.

Correlation between kidney sodium and potassium handling and the renin-angiotensin-aldosterone system in children with hypertensive disorders

BACKGROUND

Urine sodium and potassium are used as surrogate markers for dietary consumption in adults with hypertension, but their role in youth with hypertension and their association with components of the renin-angiotensin-aldosterone system (RAAS) are incompletely characterized. Some individuals with hypertension may have an abnormal RAAS response to dietary sodium and potassium intake, though this is incompletely described. Our objective was to investigate if plasma renin activity and serum aldosterone are associated with urine sodium and potassium in youth referred for hypertensive disorders.

METHODS

This pilot study was a cross-sectional analysis of baseline data from 44 youth evaluated for hypertensive disorders in a Hypertension Clinic. We recorded urine sodium and potassium concentrations normalized to urine creatinine, plasma renin activity, and serum aldosterone and calculated the sodium/potassium (UNaK) and aldosterone/renin ratios. We used multivariable generalized linear models to estimate the associations of renin and aldosterone with urine sodium and potassium.

RESULTS

Our cohort was diverse (37% non-Hispanic Black, 14% Hispanic), 66% were male, and median age was 15.3 years; 77% had obesity and 9% had a secondary etiology. Aldosterone was associated inversely with urine sodium/creatinine (β: -0.34, 95% CI -0.62 to -0.06) and UNaK (β: -0.09, 95% CI -0.16 to -0.03), and adjusted for estimated glomerular filtration rate and serum potassium.

CONCLUSIONS

Higher serum aldosterone levels, but not plasma renin activity, were associated with lower urine sodium/creatinine and UNaK at baseline in youth referred for hypertensive disorders. Further characterization of the RAAS could help define hypertension phenotypes and guide management. A higher resolution version of the Graphical abstract is available as supplementary information.

Distinct renin/aldosterone activity profiles correlate with renal function, natriuretic response, decongestive ability and prognosis in acute heart failure

BACKGROUND

Although renin-angiotensin-aldosterone system (RAAS) activation is believed to be the major driver of acute heart failure (AHF) episodes our understanding of its prevalence and clinical relevance in contemporary settings is incomplete.

METHODS

Serum renin and aldosterone were measured at day-1 and at discharge in patients (n = 211) that were hospitalized between 2016 and 2017 for AHF in a single cardiology center. The population was profiled based on upper limits of normal (ULN) of both biomarkers assessed at day-1 and linked with the clinical course and outcomes.

RESULTS

The study population constituted of three profiles: RAAS-/- (n = 121 [57%]); RAAS+/- (n = 60 [28%]); and RAAS+/+ (n = 30 [14%]). The RAAS+/+ profile had the lowest blood pressure and serum sodium at admission, day-2 and discharge compared to the other profiles (p < 0.001). The RAAS+/+ patients had significantly lower urine Na+ at admission (57.8 ± 36.7 vs 97.3 ± 31.3 and 86.4 ± 35.0), day-1 (52.7 ± 32.7 vs 85.3 ± 36.3 and 75.5 ± 33.9) mmol/l, vs RAAS-/- and RAAS+/- profiles, respectively, all p < 0.001. There was also a gradual decrease of renal function across increasing RAAS profiles. The RAAS+/+ profile received higher dose of furosemide at discharge 120 [80-160] vs the other profiles 80 [40-120] mg, p < 0.01. The risks of one year mortality or HF rehospitalization increased across the RAAS profiles (p < 0.001). The trajectory of renin or aldosterone change during hospitalization was not related to outcomes.

CONCLUSIONS

The RAAS overactivity is not essential for development of AHF. However, elevated RAAS is a marker of more advanced stages of heart failure, is related to low natriuresis and adverse clinical outcomes.

Tagetes erecta L. flowers, a medicinal plant traditionally used to promote diuresis, induced diuretic and natriuretic effects in normotensive and hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tagetes erecta L., known as marigold, belongs to the Asteraceae family and is mainly found in South America. Despite reports that T. erecta flowers are used in folk medicine to treat cardiovascular and renal diseases, there is no study regarding its diuretic effect.

AIM

This study aimed to evaluate the chemical composition and the diuretic efficacy of the hydroethanolic extract from T. erecta (HETE) in normotensive (NTR) and hypertensive (SHR) rats.

MATERIAL AND METHODS

The HETE was analyzed by liquid chromatography coupled to diode array detector and mass spectrometry (LC-DAD-MS). Female and male NTR and SHR received the treatment with vehicle, HETE (0.01 mg/kg, 0.1 mg/kg, and 1 mg/kg) or hydrochlorothiazide (HCTZ; 5 mg/kg) orally. The urinary parameters were measured at the end of the 8-h experiment.

RESULTS

From HETE, saccharides and triterpenes were the main annotated compounds, such as erythrodiol and β-amyrin. The urine volume was significantly increased in the groups treated with HETE, in both male and female NTR and SHR rats, compared to the respective vehicle-treated groups. Regarding electrolytes elimination, the treatment with HETE did not reveal significant changes in the urine levels of K⁺ or Cl^-, but it showed a natriuretic and Ca²⁺-sparing effects. The HETE beneficial result in reducing Ca²⁺ excretion was confirmed through the protective effect found in front of the urinary calcium oxalate precipitation and crystallization. The combination with HCTZ, a classic diuretic and saluretic medicine, significantly enhanced HETE-induced diuresis, natriuresis, and the Ca²⁺-sparing effect. On the other hand, the K⁺-sparing action was improved in the combination of HETE with amiloride, a standard K⁺-sparing diuretic. In contrast, the combination of HETE with atropine (a non-selective muscarinic receptor antagonist) and indomethacin (an inhibitor of the cyclooxygenase enzyme), promoted an important reduction in urinary volume, but interestingly the natriuretic effect was maintained.

CONCLUSION

This study contributed to the preclinical validation of the diuretic efficacy of T. erecta, highlighting this species as promising for the development of new pharmacological strategies for the management of kidney disorders.

The diuretic effects of SGLT2 inhibitors: A comprehensive review of their specificities and their role in renal protection

Sodium-glucose cotransporter type 2 inhibitors (SGLT2is) are new oral glucose-lowering agents that provide cardiovascular and renal protection in both patients with and without type 2 diabetes. Because of their unique mechanism of action, increased glucosuria is associated with osmotic diuresis and some natriuresis, yet the latter seems mostly transient. The potential role of the diuretic effect in overall cardiovascular and renal protection by SGLT2is remains a matter of debate. Precise evaluation of the diuretic effect is not so easy and most studies relied upon indirect estimations that led to divergent results, presumably also explained by different study designs and population characteristics. Everybody agrees upon the fact that SGLT2is are different from other classical diuretics (thiazides and loop diuretics) as they present some favourable properties, i.e. reduced sympathetic activity, preserved potassium balance, lower risk of acute renal injury, decrease of serum uric acid level. The potential role of the diuretic effect of SGLT2is on renal outcomes is still unclear, yet their ability to reduce albuminuria and dampen the risk of heart failure may contribute to improve renal prognosis besides other complex underlying mechanisms. In this comprehensive review we first critically analyse the results obtained with indirect methods that assess a diuretic effect of SGLT2is, second we describe the specificities of the diuretic activity of SGLT2is compared with other classical diuretics, and third we discuss the potential mechanisms by which the diuretic effect of SGLT2is could contribute to the improvement of renal outcomes consistently reported with this innovative amazing pharmacological class.

Low sodium to potassium ratio in spot urine sample is associated with progression to acute kidney injury and mortality in hospitalized patients with cirrhosis

BACKGROUND

sodium to potassium ratio in spot urine sample (Na/K_ur) is a surrogate marker of sodium excretion that is recommended for the management of patients with ascites due to cirrhosis.

AIMS

to investigate Na/K_ur ratio and fractional excretion of sodium (FENa) in patients admitted with decompensated cirrhosis, evaluating its relationship with acute kidney injury (AKI) and prognosis.

METHODS

prospective cohort study included 225 adult subjects. Urine samples were obtained within 48 h of hospitalization.

RESULTS

AKI at admission was observed in 32.9% of patients and was associated with lower Na/K_ur ratio, but not FENa. Among 151 subjects initially without kidney dysfunction, AKI at some point during hospitalization occurred in 26.2% and was independently associated with low Na/K_ur ratio at admission. AKI was observed in 44% of the patients with Na/K_ur ratio < 1 and only in 8% when values ≥ 2. Na/K_ur ratio at admission was independently associated with 30-day mortality, with Kaplan-Meier survival probability of 78.8% for Na/K_ur ratio < 1 and 93.6% for values ≥ 1.

CONCLUSIONS

low Na/K_ur ratio in spot urine sample is associated with progression to AKI and lower short-term survival in patients hospitalized for decompensated cirrhosis.

Hypertension, cardiovascular disease, and nocturia: a systematic review of the pathophysiological mechanisms

Nocturia significantly impairs quality of life, especially in the elderly population, and urinary retention is a main target of treatment for urologists. In addition to nocturia, cardiovascular diseases are common in the elderly population, and a systematic review showed that hypertension and heart failure are often associated with nocturia. One possible pathogenic mechanism underlying the development of hypertension is an increase in blood pressure due to excessive salt intake in people with high-salt sensitivity. From Guyton's natriuretic curve, we can infer that salt-sensitive hypertensive patients who consume too much salt do not excrete salt during the daytime and are forced to excrete salt at night, resulting in increased urine production and nocturia. In patients with heart failure, the nocturnal supine position leads to an increase in central fluid volume due to an increase in venous return from the periphery, and the secretion of natriuretic peptide is stimulated by the stretching of the atria and ventricles. Thus, natriuresis due to hypertension and hydrodiuresis due to heart failure may cause nocturia, which can effectively be treated by the administration of thiazide diuretics and loop diuretics in the morning, respectively. Because cardiovascular diseases, such as hypertension and heart failure, can cause nocturia and because the treatment methods differ depending on the cause, it is necessary to pay close attention to nocturia in the management of lifestyle-related diseases, such as cardiovascular disease.

Diuretic response and effects of diuretic omission in ambulatory heart failure patients on chronic low-dose loop diuretic therapy

AIMS

To study loop diuretic response and effect of loop diuretic omission in ambulatory heart failure (HF) patients on chronic low-dose loop diuretics.

METHODS AND RESULTS

Urine collections were performed on two consecutive days in 40 ambulatory HF patients with 40-80 mg furosemide (day 1 with loop diuretic; day 2 without loop diuretic). Three phases were collected each day: (i) first 6 h; (ii) rest of the day; and (iii) night. On the day of loop diuretic intake, the total natriuresis was 125.9 (86.9-155.0) mmol/24 h and urine output was 1650 (1380-2025) mL/24 h. There was a clear loop diuretic response with a natriuresis of 9.4 (6.7-15.9) mmol/h and a urine output of 117 (83-167) mL/h during the first 6 h, followed by a significant drop in natriuresis and urine output during the rest of the day [2.6 (1.8-4.8) mmol/h and 55 (33-71) mL/h] and night [2.2 (1.6-3.5) mmol/h and 44 (34-73) mL/h]. On day 2, after loop diuretic omission, the natriuresis and urine output remained similarly low the entire day, resulting in a 50% reduction in natriuresis [55.1 (33.5-77.7) mmol/24 h; P < 0.001] and a 31% reduction in urine output [1035 (875-1425) mL/24 h; P < 0.001] compared with the day of loop diuretic intake.

CONCLUSION

Patients with HF on chronic loop diuretic treatment still have a clear diuretic response phase, while loop diuretic omission leads to a significant drop in natriuresis and urine output, arguing against routine cessation of low-dose loop diuretics.

Low-salt low-protein diet and blood pressure control in patients with advanced diabetic kidney disease and heavy proteinuria

PURPOSE

To assess the associations between effects of low salt, low protein diet supplemented with keto-analogues (sLPD)-on salt intake, blood pressure (BP) and cardiovascular events (CVEs) in patients with advanced diabetic kidney disease (DKD) and heavy proteinuria.

METHODS

Prospective, single-center study (total duration of 15 months), enrolling 92 patients with advanced DKD (median eGFR 11.7 ml/min) and heavy proteinuria (median 4.8 g/g creatininuria). The intervention consisted in a low salt-low protein (0.6 g/kg-day) diet (sLPD) under intensive nutritional counselling, and adjustment of antihypertensive therapy. The endpoints of this sub-analysis were a salt intake ≤ 5 g/day, a mean blood pressure (MAP) ≤ 97 mmHg, corresponding to KDIGO target of 130/80 mmHg, and the rate of CVEs.

RESULTS

Salt intake decreased with 2.5 g/day and the proportion of patients reaching the salt intake endpoint increased with 58%. A salt intake ≤ 5 g/day was associated with a reduced MAP, BMI, proteinuria, fractional excretion of sodium, and eGFR, suggesting a salt-related volume contraction but was not related to protein intake. Mean arterial pressure decreased with 13 mmHg. MAP ≤ 97 mmHg was associated with lower proteinuria, salt, and protein intake, but the contribution of salt intake cannot be differentiated from that of protein intake. CVEs occurred in 20% of patients and were independently related to a lower age and MAP, and increased comorbidities. eGFR only minimally declined and no renal adverse events were noted. sLPD was nutritionally safe.

CONCLUSIONS

The multifactorial personalized intervention allowed a stable MAP reduction to KDIGO recommended levels (≤ 97 mmHg), related to the decrease in salt and protein intake. However, BP lower than 130/80 mmHg increased the cardiovascular but not the renal risk in heavy proteinuric patients with advanced DKD.

TRIAL REGISTRATION NUMBER

0341507433: NCT03415074. Registered 02/02/2015 in US National Library of Medicine, ClinicalTrials.gov (NCT).

Renal profiling based on estimated glomerular filtration rate and spot urine sodium identifies high-risk acute heart failure patients

AIMS

In acute heart failure (AHF), assessment of renal function comprises estimation of glomerular filtration rate (eGFR), which does not provide any information about renal sodium/water handling. We describe the interactions between urinary sodium concentration and eGFR to better characterize AHF patients.

METHODS AND RESULTS

In 219 patients with AHF, spot urine sodium (UNa⁺ ) and eGFR were assessed on admission, day 1 and day 2 of hospitalization. We found no correlation between UNa⁺ and eGFR (calculated on each consecutive day, as an average of all three values, and as changes from baseline; all P > 0.05). The population was subsequently divided into four profiles based on eGFR (preserved vs. impaired; cutoff of 60 mL/min/1.73 m² ) and UNa⁺ (sodium excreter vs. non-excreter; cutoff of 60 mmol/L). At day 1, there were 70 (31.9%) patients classified as preserved eGFR/sodium excreter, 37 (16.8%) as impaired eGFR/sodium non-excreter, 72 (32.9%) as impaired eGFR/sodium excreter, and 40 (18%) as preserved eGFR/sodium non-excreter. Both sodium non-excreter profiles were associated with an increased risk of in-hospital heart failure worsening [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.3-6.4], inotrope use (OR 2.6, 95% CI 1.1-6.7) and rehospitalization due to AHF (OR 3.2, 95% CI 1.6-6.2; all P < 0.05). The preserved eGFR/sodium non-excreter profile was associated with highest 1-year mortality (52.5%) and remained an independent prognosticator after adjustment for other prognosticators (hazard ratio 2.9, 95% CI 1.7-5.2; P < 0.0005).

CONCLUSIONS

In AHF, values of spot UNa⁺ and eGFR are not interrelated. Concomitant assessment of eGFR and spot UNa⁺ may be useful for better clinical and therapeutic profiling of patients.