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.

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.

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.

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.

Measures of Loop Diuretic Efficiency and Prognosis in Chronic Kidney Disease

BACKGROUND

The evolution and prognostic impact of loop diuretic efficiency according to chronic kidney disease (CKD) severity is unclear.

METHODS

This retrospective cohort study includes 783 CKD patients on oral loop diuretic therapy with a 24-h urine collection available. Acute kidney injury and history of renal replacement therapy were exclusion criteria. Patients were stratified according to Kidney Disease Improving Global Outcomes (KDIGO) glomerular filtration rate class. Loop diuretic efficiency was calculated as urine output, natriuresis, and chloruresis, each adjusted for loop diuretic dose, and compared among strata. Risk for onset of dialysis and all-cause mortality was evaluated.

RESULTS

Loop diuretic efficiency metrics decreased from KDIGO class IIIB to IV in furosemide users and from KDIGO class IV to V with all loop diuretics (p value <0.05 for all comparisons). The correlation between loop diuretic efficiency and creatinine clearance was moderate at best (Spearman's ρ 0.298-0.436; p value <0.001 for all correlations). During median follow-up of 45 months, 457 patients died (58%) and 63 received kidney transplantation (8%), while dialysis was started before in 328 (42%). All loop diuretic efficiency metrics were significantly and independently associated with both the risk for dialysis and all-cause mortality. In KDIGO class IV/V patients, low loop diuretic efficiency (i.e., urine output adjusted for loop diuretic dose ≤1,000 mL) shortened median time to dialysis with 24 months and median time to all-cause mortality with 23 months.

CONCLUSION

Low loop diuretic efficiency is independently associated with a shorter time to dialysis initiation and a higher risk for all-cause mortality in CKD.

Elevated plasma endothelin-1 is related to low natriuresis, clinical signs of congestion, and poor outcome in acute heart failure

AIMS

Endothelin-1 (ET-1) is a potent vasoconstrictor, which regulates renal and vascular function. We aimed to relate plasma levels of ET-1 with the clinical picture and outcomes in acute heart failure (AHF).

METHODS AND RESULTS

We studied 113 patients with AHF [mean age 65 ± 13 (years), median (upper and lower quartiles) N-terminal pro-B-type natriuretic peptide, 5422 (2689; 8582) (pg/mL)], in whom plasma levels of ET-1 were serially measured at admission (10.8 ± 5.2), Day 1 (9.5 ± 3.4), and Day 2 (8.9 ± 3.8) (pg/mL). The population was divided into tertiles across baseline ET-1 levels. Patients in the highest ET-1 tertile had predominant clinical signs of peripheral congestion; however, no difference was observed in pulmonary congestion and severity of dyspnoea. They also presented lower spot urine sodium at admission (75 ± 35 vs. 99 ± 43 vs. 108 ± 30), 6 h (84 ± 34 vs. 106 ± 43 vs. 106 ± 35), and Day 1 (75 ± 38 vs. 96 ± 36 vs. 100 ± 35) (mmol/L), when compared with the second and first tertile, respectively (all P < 0.05); furthermore, they received higher doses of intravenous furosemide from Day 2 and had longer intravenous diuretics, as median switch to oral furosemide was 4 (3; 4) vs. 3 (2; 4) vs. 2 (2; 3) (days), respectively, P < 0.05. There was no difference in serum creatinine, urea, and renal injury biomarkers (kidney injury molecule-1, serum cystatin C, and urine neutrophil gelatinase-associated lipocalin) between the ET-1 tertiles. Higher values of ET-1 measured at each time point were related with a higher risk of 1 year mortality.

CONCLUSIONS

Elevation of ET-1 is related to clinical signs of peripheral congestion, low urine sodium excretion, and poor outcome in AHF.

The value of urinary sodium assessment in acute heart failure

Acute heart failure (AHF) is a frequent medical condition that needs immediate evaluation and appropriate treatment. Patients with signs and symptoms of volume overload mostly require intravenous loop diuretics in the first hours of hospitalization. Some patients may develop diuretic resistance, resulting in insufficient and delayed decongestion, with increased mortality and morbidity. Urinary sodium measurement at baseline and/or during treatment has been proposed as a useful parameter to tailor diuretic therapy in these patients. This systematic review discusses the current sum of evidence regarding urinary sodium assessment to evaluate diuretic efficacy in AHF. We searched Medline, Embase, and Cochrane Clinical Trials Register for published studies that tested urinary sodium assessment in patients with AHF.

Sodium-glucose co-transporter-2 inhibitors: peculiar "hybrid" diuretics that protect from target organ damage and cardiovascular events

AIMS

Sodium-glucose co-transporter-2 inhibitors (SGLT2i) have been proven to lead to relevant cardiovascular benefits, regardless of glycemic control function. SGLT2i have on the one hand led to reduction in cardiovascular events such as heart failure and on the other hand to renal protection. Blood pressure reduction and kidney function play a central role in these outcomes. This focused review describes the main mechanisms and clinical aspects of SGLT2i.

DATA SYNTHESIS

These drugs act on the proximal renal tubule and behave as diuretics with a "hybrid" mechanism, as they can favour both natriuresis and enhanced diuresis due to an osmotic effect dependent on glycosuria, resulting in blood pressure decrease. The exclusive peculiarity of these "diuretics", which distinguishes them from loop and thiazide diuretics, lies also in the activation of the tubule-glomerular feedback.

CONCLUSIONS

This mechanism, resulting in modulation of arterioles' tone and renin secretion, contributes to the favorable outcomes, suggesting a wider use of SGLT2i in internal medicine, nephrology and cardiology.

Utility of Urine Biomarkers and Electrolytes for the Management of Heart Failure

PURPOSE OF REVIEW

To provide insight into the role of urine biomarkers and electrolytes for the management of heart failure.

RECENT FINDINGS

The age-dependent decrease in glomerular filtration rate due to loss of functional nephrons occurs at a faster pace in heart failure, potentially exacerbated by episodes of acute kidney injury. Urine biomarkers have not convincingly demonstrated to improve detection of irreversible renal damage and predict long-term renal trajectories, compared with serial creatinine measurements. Recent data show that natriuresis and diuretic response track poorly with glomerular filtration, but strongly with prognosis. Urine sodium concentration > 50-70 mmol/L was recently put forward through expert consensus as an adequate diuretic response. The value of urine biomarkers to detect structural renal damage in heart failure remains unsure and the latter is probably uncommon, especially over short-term follow-up. Urine electrolytes on the other hand predict diuretic response accurately and may allow better diuretic titration.

Overlap between nocturnal polyuria, diurnal polyuria, and 24-h polyuria among men with nocturia

PURPOSE

A recent update in International Continence Society (ICS) terminology now recognizes nocturnal polyuria (NP) and diurnal polyuria (DP) as related subcategories of "Polyuria (global symptom)". This study determines the real-world clinical overlap between NP, DP, and 24-h polyuria (24hP) among men with nocturia.

METHODS

Analysis of frequency-volume charts from men ≥ 18 years with ≥ 1 nocturnal void(s). Three separate analyses were performed using different rate criteria for NP, DP, and 24hP: (1) urine production > 90 mL/h (extrapolated from a proposed definition for NP); (2) > 125 mL/h (extrapolated from a proposed definition for 24hP [3000 mL/24 h]); and (3) > 1.67 mL/kg/h (extrapolated from the current ICS definition for 24hP [> 40 mL/kg/24 h]). Subjects were categorized as having one of five mathematically permissible phenotypic combinations: (1) isolated NP, (2) isolated DP, (3) NP + 24hP, (4) DP + 24hP, and (5) NP + DP + 24hP.

RESULTS

167, 95, and 61 patients were included at criteria 1, 2, and 3, respectively, with 56%, 43%, and 30% of patients demonstrating overlapping phenotypes (i.e., phenotypic combinations 3-5) at cut-offs 1-3, respectively. The prevalence of NP was similar across cut-offs (81-87%), but the prevalence of NP without 24hP was highly threshold-dependent (43-73%).

CONCLUSION

Consistent with current ICS terminology, there exists a substantial overlap between NP, DP, and 24hP. As demonstrated in the current study, absolute volume-based criteria for NP/DP/24hP are indeed conducive to the diagnosis of concurrent NP + 24hP, and may be preferred over proportion-based NP criteria when both NP + 24hP are suspected.

Clinical importance of urinary sodium excretion in acute heart failure

Aims

Urinary sodium assessment has recently been proposed as a target for loop diuretic therapy in acute heart failure (AHF). We aimed to investigate the time course, clinical correlates and prognostic importance of urinary sodium excretion in AHF.

Methods and results

In a prospective cohort of 175 consecutive patients with an admission for AHF we evaluated urinary sodium excretion 6 h after initiation of loop diuretic therapy. Clinical outcome was all‐cause mortality or heart failure rehospitalization. Mean age was 71 ± 14 years, and 44% were female. Median urinary sodium excretion was 130 (67–229) mmol at 6 h, 347 (211–526) mmol at 24 h, and decreased from day 2 to day 4. Lower urinary sodium excretion was independently associated with male gender, younger age, renal dysfunction and pre‐admission loop diuretic use. There was a strong association between urinary sodium excretion at 6 h and 24 h urine volume (beta = 0.702, P < 0.001). Urinary sodium excretion after 6 h was a strong predictor of all‐cause mortality after a median follow‐up of 257 days (hazard ratio 3.81, 95% confidence interval 1.92–7.57; P < 0.001 for the lowest vs. the highest tertile of urinary sodium excretion) independent of established risk factors and urinary volume. Urinary sodium excretion was not associated with heart failure rehospitalization.

Conclusion

In a modern, unselected, contemporary AHF population, low urinary sodium excretion during the first 6 h after initiation of loop diuretic therapy is associated with lower urine output in the first day and independently associated with all‐cause mortality.

Cerebral Salt Wasting in Traumatic Brain Injury Is Associated with Increased Morbidity and Mortality

INTRODUCTION

In the setting of cerebral injury, cerebral salt wasting (CSW) is a potential cause of hyponatremia, which contributes to adverse effects and mortality.

OBJECTIVE

The primary objective of this study was to evaluate the clinical outcomes of severe traumatic brain injury (TBI) patients complicated by CSW.

METHODS

A retrospective data analysis was performed on data collected from patients with TBI with an abbreviated injury scale (AIS) greater than 3. Data was divided into 2 groups of patients with CSW and those without. The primary endpoint was incidence of adverse effects of CSW in regard to injury severity score (ISS), hospital length of stay (HLOS), ventilator days, ICU length of stay (ICU LOS) and survival to discharge. Data was analyzed using a one-way analysis of variance (ANOVA).

RESULTS

A total of 310 consecutive patients with severe head injury (anatomic injury score 3 or greater) were evaluated over a 3-year period. A total of 125 of the 310 patients (40%) were diagnosed with cerebral salt wasting as defined by hyponatremia with appropriate urinary output and salt replacement. Patients with CSW had poorer outcomes in regard to ISS (21.8 vs 14.2, p<0.0001), HLOS (14.1 vs 3.5, p<0.0001), ventilator days (5.0 vs 0.45, p<0.0001), ICU LOS (8.5 vs 1.6, p<0.0001), and survival to discharge (88% vs 99%, p<0.0001).

DISCUSSION

Common adverse effects of CSW were noted in this study. Patients with TBI have a predilection towards development of CSW and consequently have poorer outcomes including increased morbidity and mortality. Data is sparse on the duration of CSW and degree of hyponatremia over time. Larger, comparative studies need to be performed to investigate the hyponatremic patient population and the clinical outcomes of those who present with CSW.

Kidney Is Essential for Blood Pressure Modulation by Dietary Potassium

Eating more potassium may reduce blood pressure and the occurrence of other cardiovascular diseases by actions on various systems, including the vasculature, the sympathetic nervous system, systemic metabolism, and body fluid volume. Among these, the kidney plays a major role in the potassium-rich diet-mediated blood pressure reduction. PURPOSE OF REVIEW: To provide an overview of recent discoveries about the mechanisms by which a potassium-rich diet leads to natriuresis. RECENT FINDINGS: Although the distal convoluted tubule (DCT) is a short part of the nephron that reabsorbs salt, via the sodium-chloride cotransporter (NCC), it is highly sensitive to changes in plasma potassium concentration. Activation or inhibition of NCC raises or lowers blood pressure. Recent work suggests that extracellular potassium concentration is sensed by the DCT via intracellular chloride concentration which regulates WNK kinases in the DCT. High-potassium diet targets NCC in the DCT, resulting in natriuresis and fluid volume reduction, which are protective from hypertension and other cardiovascular problems.

Vasopressin receptor subtypes and renal sodium transport

In mammals, three subtypes of V-receptors have been identified in the kidney. The effects of vasopressin, a hormone synthesized in the hypothalamus, are triggered by three distinct receptor isoforms: V2, V1a, and V1b. Stimulation of V2-receptors regulates urine osmotic concentration by increasing sodium reabsorption in the thick ascending limb of the loop of Henle and enhancing osmotic permeability of the epithelium cells in the collecting duct. Stimulation of V1a-receptors inhibits renal sodium reabsorption and induces natriuresis, comparable to the effect of the diuretic furosemide, in the thick ascending limb of the loop of Henle. Stimulation of V1b-receptors induces potassium secretion in the final parts of the distal segments and initial parts of the collecting ducts. In this review, we discuss the role of vasopressin and its interaction with V-receptor subtypes in natriuresis and for stabilizing the physicochemical parameters of the internal environment and water-salt homeostasis in humans. A better understanding of these systems and their regulation is necessary to facilitate identification of additional system components and mechanisms, clarify their contribution during various normal and pathological functional states, and suggest novel strategies for the development of therapeutic interventions.

Azilsartan causes natriuresis due to its sympatholytic action in kidney disease

The sympathoinhibitory mechanism of azilsartan was investigated in an adenine-induced chronic renal failure model. Azilsartan exerted an antihypertensive effect, though BP elevation induced by adenine was marginal. The creatinine value was significantly lower in the azilsartan group (AZ) than in the vehicle group (VEH); furthermore, proteinuria was suppressed, and sodium excretion was augmented in the AZ group. The low frequency (LF) of systolic BP was suppressed (VEH: 4.07 ± 2.67 mmHg² vs. AZ: 3.32 ± 1.93 mmHg² P < 0.001), and the spontaneous baroreflex gain (sBRG) was augmented (VEH: 1.04 ± 0.62ms/mmHg vs. AZ: 1.38 ± 0.69 ms/mmHg, P < 0.001) in AZ. There were no significant differences in ACE1 and ACE2 expression between the groups, which indicated that the action of azilsartan on these components of the intrarenal renin-angiotensin-aldosterone system was comparatively small. Although NHE3, NKCC, and ENaC expression was similar between the groups, NaCl cotransporter (NCC) expression was markedly suppressed by azilsartan (P < 0.05). Thus, in a mild chronic kidney disease (CKD) model with slight BP elevation, the sympatholytic effect of ARB might be expected, and azilsartan might exert its natriuretic effect by NCC suppression achieved by sympathoinhibitory activity.

Acetazolamide to increase natriuresis in congestive heart failure at high risk for diuretic resistance

AIMS

To investigate the effects of acetazolamide on natriuresis, decongestion, kidney function and neurohumoral activation in acute heart failure (AHF).

METHODS AND RESULTS

This prospective, two-centre study included 34 AHF patients on loop diuretics with volume overload. All had a serum sodium concentration < 135 mmol/L and/or serum urea/creatinine ratio > 50 and/or an admission serum creatinine increase of > 0.3 mg/dL compared to baseline. Patients were randomised towards acetazolamide 250-500 mg daily plus bumetanide 1-2 mg bid vs. high-dose loop diuretics (bumetanide bid with daily dose twice the oral maintenance dose). The primary endpoint was natriuresis after 24 h. Natriuresis after 24 h was similar in the combinational treatment vs. loop diuretic only arm (264 ± 126 vs. 234 ± 133 mmol; P = 0.515). Loop diuretic efficiency, defined as natriuresis corrected for loop diuretic dose, was higher in the group receiving acetazolamide (84 ± 46 vs. 52 ± 42 mmol/mg bumetanide; P = 0.048). More patients in the combinational treatment arm had an increase in serum creatinine levels > 0.3 mg/dL (P = 0.046). N-terminal pro-B-type natriuretic peptide reduction and peak neurohumoral activation within 72 h were comparable among treatment arms. There was a non-significant trend towards lower all-cause mortality or heart failure readmissions in the group receiving acetazolamide with low-dose loop diuretics vs. high-dose loop diuretic monotherapy (P = 0.098).

CONCLUSION

Addition of acetazolamide increases the natriuretic response to loop diuretics compared to an increase in loop diuretic dose in AHF at high risk for diuretic resistance.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01973335.

Effect of intracerebroventricular epinephrine microinjection on blood pressure and urinary sodium handling in gestational protein-restricted male adult rat offspring

In this study, we hypothesized that blunting of the natriuresis response to intracerebroventricularly (ICV) microinjected adrenergic agonists is involved in the development of hypertension in maternal low-protein intake (LP) offspring. A stainless steel cannula was stereotaxically implanted into the right lateral ventricle (LV), then we evaluated the ICV administration of adrenergic agonists at increasing concentrations, and of α1 and α2-adrenoceptor antagonists on blood pressure and urinary sodium handling in LP offspring relative to an age-matched normal-protein intake (NP) group. We confirmed that epinephrine (Epi) microinjected into the LV of conscious NP rats leads to enhanced natriuresis followed by a reduction in arterial pressure. This response is associated with increased proximal and post-proximal sodium excretion accompanied by an unchanged glomerular filtration rate. The current study showed, in both NP and LP offspring, that the natriuretic effect of Epi injection into the LV was abolished by prior local microinjection of an α1-adrenoceptor antagonist (prazosin). Conversely, LV α2-adrenoceptor antagonist (yohimbine) administration potentiated the action of Epi. The LV yohimbine pretreatment normalized urinary sodium excretion and reduced the blood pressure in LP compared with age-matched NP offspring. These are, as far as we are aware, the first results showing the role of central adrenergic receptors’ interaction on hypertension pathogenesis in maternal LP fetal-programming offspring. This study also provides good evidence for the existence of central nervous system adrenergic mechanisms consisting of α1 and α2-adrenoceptors, which work reciprocally on the control of renal sodium excretion and blood pressure. Although the precise mechanism of the different natriuretic response of NP and LP rats is still uncertain, these results lead us to speculate that inappropriate neural adrenergic pathways might have significant effects on tubule sodium transport, resulting in the inability of the kidneys to control hydrosaline balance and, consequently, an increase in blood pressure.

Summary: We evaluated the effect of intracerebroventricular microinjections of adrenergic agonists at increasing concentrations, and μ1 and μ2-adrenergic receptors antagonists on blood pressure and urinary sodium in hypertensive low- and normal-protein rat offdpring.

Molecular mechanisms for the regulation of blood pressure by potassium

It has been well documented that the amount of potassium in the diet is associated with blood pressure levels in the population: the higher the potassium consumption, the lower the blood pressure and the cardiovascular mortality. In the last few years certain mechanisms for potassium regulation of salt reabsorption in the kidney have been elucidated at the molecular level. In this work we discuss the evidence demonstrating the relationship between potassium intake and blood pressure levels in human populations and in animal models, as well as the experimental data that reveal the effects of potassium on transepithelial Na⁺ reabsorption in different nephron segments. We also discuss the physiological relevance of K⁺-induced natriuresis, and finally, we focus on the molecular mechanisms by which extracellular potassium modulates the activity of the renal NaCl cotransporter, which is the mechanism that has been best dissected so far.

An iso-osmolar oral supplement increases natriuresis and does not increase stomal output in patients with an ileostomy: A randomised, double-blinded, active comparator, crossover intervention study

BACKGROUND

Patients with an ileostomy often experience fluid and electrolyte depletion because of gastrointestinal loss. This study aimed to compare how an iso-osmolar and a hyperosmolar oral supplement affect ileostomy output, urine production, and natriuresis as proxy measurements of water-electrolyte balance.

METHODS

In a randomised, double-blinded, active comparator, crossover intervention study, we included eight adult ileostomy patients who were independent of parenteral support. We investigated how an iso-osmolar (279 mOsm/kg) and a hyperosmolar (681 mOsm/kg) oral supplement affected ileostomy output mass, urine volume, and natriuresis. In addition to their habitual diet, each participant ingested 800 mL/day of either the iso-osmolar or hyperosmolar supplement in each of two study periods. Each period started with 24-hour baseline measurements, and the supplements were ingested during the following 48 h. All measurements were repeated in the last 24 h.

RESULTS

No statistically significant changes in ileostomy output were detected following the intake of either oral supplement (median (range) 67 (-728 to 290) g/day, p = 0.25) despite increased fluid intake. Compared with the hyperosmolar supplement, the iso-osmolar supplement induced a statistically significant increase in urine volume (470 (0-780) mL/day, p = 0.02) and natriuresis (36 (0-66) mmol/day, p = 0.02).

CONCLUSION

Intake of the two oral supplements did not affect ileostomy output during this short intervention. Natriuresis increased following intake of the iso-osmolar supplement compared to that after ingesting the hyperosmolar supplement, indicating that patients with an ileostomy may benefit from increasing their ingestion of iso-osmolar fluids. ClinicalTrials.gov identifier:NCT03348709.

The effect of sodium nitrite infusion on renal function, brachial and central blood pressure during enzyme inhibition by allopurinol, enalapril or acetazolamide in healthy subjects: a randomized, double-blinded, placebo-controlled, crossover study

Background

Sodium nitrite (NaNO₂) causes vasodilation, presumably by enzymatic conversion to nitric oxide (NO). Several enzymes with nitrite reducing capabilities have been discovered in vitro, but their relative importance in vivo has not been investigated. We aimed to examine the effects of NaNO₂ on blood pressure, fractional sodium excretion (FE_Na), free water clearance (C_H2O) and GFR, after pre-inhibition of xanthine oxidase, carbonic anhydrase, and angiotensin-converting enzyme. The latter as an approach to upregulate endothelial NO synthase activity.

Methods

In a double-blinded, placebo-controlled, crossover study, 16 healthy subjects were treated, in a randomized order, with placebo, allopurinol 150 mg twice daily (TD), enalapril 5 mg TD, or acetazolamide 250 mg TD. After 4 days of treatment and standardized diet, the subjects were examined at our lab. During intravenous infusion of 240 μg NaNO₂/kg/hour for 2 h, we measured changes in brachial and central blood pressure (BP), plasma cyclic guanosine monophosphate (P-cGMP), plasma and urine osmolality, GFR by ⁵¹Cr-EDTA clearance, FE_Na and urinary excretion rate of cGMP (U-cGMP) and nitrite and nitrate (U-NO_x). Subjects were supine and orally water-loaded throughout the examination day.

Results

Irrespective of pretreatment, we observed an increase in FE_Na, heart rate, U-NO_x, and a decrease in C_H2O and brachial systolic BP during NaNO₂ infusion. P-cGMP and U-cGMP did not change during infusion. We observed a consistent trend towards a reduction in central systolic BP, which was only significant after allopurinol.

Conclusion

This study showed a robust BP lowering, natriuretic and anti-aquaretic effect of intravenous NaNO₂ regardless of preceding enzyme inhibition. None of the three enzyme inhibitors used convincingly modified the pharmacological effects of NaNO₂. The steady cGMP indicates little or no conversion of nitrite to NO. Thus the effect of NaNO₂ may not be mediated by NO generation.

Trial registration

EU Clinical Trials Register, 2013-003404-39. Registered December 3 2013.

Pharmacodynamic assessment of diuretic efficacy and braking in a furosemide continuous infusion model

INTRODUCTION

Diuretic failure is a potential life-ending event but is unpredictable and poorly understood. The objectives of this study were to evaluate pharmacodynamic markers of furosemide-induced diuresis and to investigate mechanisms of diuretic braking in dogs receiving constant rate infusion (CRI) of furosemide.

ANIMALS

Six healthy male dogs.

METHODS

Raw data and stored samples from one arm of a previously published study were further analyzed to mechanistically investigate causes of diuretic braking in these dogs. Urine volume was recorded hourly during a 5-h furosemide CRI. Urine and blood samples were collected hourly to measure serum and urine electrolytes, urine aldosterone, and plasma and urine furosemide. Serum electrolyte fractional excretion was calculated. Urine sodium concentration was indexed to urine potassium (uNa:uK) and urine furosemide (uNa:uFur) concentrations, plasma furosemide concentration was indexed to urine furosemide concentration (pFur:uFur), and urine aldosterone was indexed to urine creatinine (UAldo:C). Temporal change and the relationship to urine volume were evaluated for these measured and calculated variables.

RESULTS

Urine volume was significantly correlated with urine electrolyte amounts and with uNa:uK. The ratio of pFur:uFur decreased during the infusion, whereas furosemide excretion was unchanged.

CONCLUSIONS

There was a strong relationship between urine volume and absolute urine electrolyte excretion. Urine volume was strongly correlated to uNa:uK, giving it potential as a spot indicator of urine production during diuresis. The decrease in uNa:uK over time during the infusion is consistent with mineralocorticoid modification of urinary electrolyte excretion, supporting renin-angiotensin-aldosterone activation as a cause of diuretic braking in this model.

SGLT-2 Inhibitors in Heart Failure: Implications for the Kidneys

PURPOSE OF REVIEW

This review aims to summarize the renal effects of sodium-glucose transporter-2 (SGLT-2) inhibitors and their potential implications in heart failure pathophysiology.

RECENT FINDINGS

In patients with diabetes and established atherosclerosis, the SGLT-2 inhibitor empagliflozin versus placebo significantly reduced the rate of heart failure admissions with 35%. Moreover, empagliflozin slowed kidney disease progression and reduced the need for renal replacement therapy. SGLT-2 inhibitors inhibit proximal tubular sodium and chloride reabsorption, leading to increased nephron flux throughout the distal renal tubules, most notably at the level of the macula densa. Afferent arteriolar vasoconstriction is promoted through tubulo-glomerular feedback and reduces glomerular capillary hydrostatic pressure, relieving podocyte stress and explaining renal preservation. Further, plasma volume is contracted and natriuresis promoted without inducing neurohumoral activation. Finally, SGLT-2 inhibitors may improve endothelial function and energy metabolism efficiency. Together, these promising features place them as a potential novel treatment for heart failure.

Renal and Cardiovascular Effects of sodium-glucose cotransporter 2 (SGLT2) inhibition in combination with loop Diuretics in diabetic patients with Chronic Heart Failure (RECEDE-CHF): protocol for a randomised controlled double-blind cross-over trial

INTRODUCTION

Type 2 diabetes (T2D) and heart failure (HF) are a frequent combination, where treatment options remain limited. There has been increasing interest around the sodium-glucose cotransporter 2 (SGLT2) inhibitors and their use in patients with HF. Data on the effect of SGLT2 inhibitor use with diuretics are limited. We hypothesise that SGLT2 inhibition may augment the effects of loop diuretics and the benefits of SGLT2 inhibitors may extend beyond those of their metabolic (glycaemic parameters and weight loss) and haemodynamic parameters. The effects of SGLT2 inhibitors as an osmotic diuretic and on natriuresis may underlie the cardiovascular and renal benefits demonstrated in the recent EMPA-REG study.

METHODS AND ANALYSIS

To assess the effect of SGLT2 inhibitors when used in combination with a loop diuretic, the RECEDE-CHF (Renal and Cardiovascular Effects of SGLT2 inhibition in combination with loop Diuretics in diabetic patients with Chronic Heart Failure) trial is a single-centre, randomised, double-blind, placebo-controlled, cross-over trial conducted in a secondary care setting within NHS Tayside, Scotland. 34 eligible participants, aged between 18 and 80 years, with stable T2D and CHF will be recruited. Renal physiological testing will be performed at two points (week 1 and week 6) on each arm to assess the effect of 25 mg empagliflozin, on the primary and secondary outcomes. Participants will be enrolled in the trial for a total period between 14 and 16 weeks. The primary outcome will assess the effect of empagliflozin versus placebo on urine output. The secondary outcomes are to assess the effect of empagliflozin on glomerular filtration rate, cystatin C, urinary sodium excretion, urinary protein/creatinine ratio and urinary albumin/creatinine ratio when compared with placebo.

ETHICS AND DISSEMINATION

Ethics approval was obtained by the East of Scotland Research Ethics Service. Results of the trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03226457; Pre-results.

Hyponatremia in Traumatic Brain Injury: A Practical Management Protocol

BACKGROUND

Hyponatremia (defined as serum sodium <135 mEq/L) is the most common electrolyte abnormality in traumatic brain injury (TBI) and is also an independent predictor of poor neurologic outcome. The reported incidence of hyponatremia varies widely in literature reports, and there is continuing difficulty in clearly differentiating between the 2 common causes of hyponatremia with natriuresis: the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW). We encounter hyponatremia frequently in our practice, and we therefore decided to review data from our center to estimate the incidence of hyponatremia and the results of our management strategies, and attempt to formulate simple guidelines for the correction of hyponatremia in TBI.

METHODS

A retrospective analysis of 1500 consecutively admitted patients with TBI was performed by the use of electronic records and radiographic review. Hyponatremia was defined as serum sodium <135 mEq/L, and natriuresis as a urine spot sodium of more than >40 mEq/L. The incidence of TBI, its management, and the effect of fludrocortisone were evaluated.

RESULTS

The incidence of hyponatremia was 13.2%. Early therapy with fludrocortisone significantly reduced the duration of hospital stay (P < 0.05). Traumatic subarachnoid hemorrhage was the most common abnormality on the admission computed tomographic scan in patients who experienced hyponatremia.

CONCLUSION

Early initiation of fludrocortisone in the setting of hyponatremia with natriuresis decreases the hospital stay. This protocol is probably safer in a tropical country where fluid restriction might be harmful. It also eliminates the need to differentiate between SIADH and CSW.

Blood Pressure and the Renal Actions of AT2 Receptors

Angiotensin type-2 receptors (AT2Rs) in the renal proximal tubule inhibit sodium (Na+) reabsorption by inducing renal cyclic GMP formation and internalizing and inhibiting major Na+ transporters Na+-H+ exchanger-3 (NHE-3) and Na+/K+ATPase (NKA). Instead of angiotensin II (Ang II), angiotensin III (Ang III) is the predominant endogenous agonist for this response. Exogenous non-peptide AT2R agonist Compound-21 induces natriuresis and lowers blood pressure (BP) in normal and Ang II-infused hypertensive rodents. Spontaneously hypertensive rats (SHR; both pre-hypertensive and hypertensive) have defective natriuretic responses to Ang III, suggesting a defect in AT2R-mediated natriuresis in SHR that leads to hypertension. The mechanisms of deficient AT2R-mediated natriuresis in SHR are unknown but could involve either pre-receptor or receptor/post-receptor defects.

Diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats: Role of muscarinic acetylcholine receptors

BACKGROUND

Luteolin is a very common phenolic compound found in a wide variety of natural products. Although several biological properties have already been described regarding the beneficial effect of luteolin in the cardiovascular and renal system, no scientific research explored its potential effect as a diuretic agent in experimental trials.

METHODS

Groups of male normotensive (NTR) and spontaneously hypertensive rats (SHR) were orally treated with vehicle, hydrochlorothiazide or luteolin. In another experimental set, in order to verify the possible mechanisms of luteolin-induced diuresis, NTR were treated with vehicle, hydrochlorothiazide, amiloride, L-NAME, indomethacin or atropine, 1h before receiving luteolin. The cumulative urine volume, electrolytes excretion, pH and osmolality were measured at the end of the experiment (after 8h).

RESULTS

Luteolin, at dose of 3mg/kg, was able to induce both diuretic and natriuretic effect in NTR and SHR groups, without interfering with urinary pH, K⁺ or Cl^- levels. While Ca²⁺ content remained unchanged in urine from luteolin-treated group of NTR, luteolin reduced Ca²⁺ excretion in urine from SHR. The treatment with HCTZ and amiloride intensified luteolin-induced diuresis and natriuresis, with an interesting potassium-sparing effect, in addition to an increase in urinary osmolality levels. Moreover, the diuretic and natriuretic action of luteolin was fully avoided in the presence of atropine, a non-selective muscarinic receptor antagonist.

CONCLUSIONS

This study revealed the diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats. Our data also showed the involvement of muscarinic acetylcholine receptors for the renal effects of luteolin.

Evidence of the role of the vagal nerves as a monitor in the gastrointestinal-renal axis of natriuresis in human: Effects of vagotomy

This study aimed to investigate the mechanism of gastrointestinal regulation of natriuresis. Sixteen subjects without (group I) and sixteen subjects with a truncal vagotomy (group II), were given a daily diet of 18mmol of sodium for 5days (D1-D5). The sodium deficit for this period was calculated for each subject and on the morning of day-6 (D6), their cumulative deficit (E) was given as 3% NaCl. In both groups the subjects were divided to receive the hypertonic saline either orally (Ior, IIor) or intravenously (Iiv, IIiv). During the period of low sodium diet when compared to group II subjects of group I (1) had a greater weight loss (p<0.005), (2) demonstrated a larger drop in pulse pressure (p<0.005), (3) achieved a positive sodium equilibrium later (D5 vs D4) and (4) developed a greater sodium deficit (p<0.005). During the two 12h periods of D6, both Ior and Iiv exhibited greater natriuresis during the first 12h period (p<0.0001) whereas both IIor and IIiv did so during the second 12h period (p<0.0001). On D6 Ior excreted the greatest percentage of E (E%; 35.63%±3.12%, p<0.0001) compared to Iiv (17.06%±1.78%), IIor (16.03%±3.54%) and IIiv (15.39%±2.77%) whereas E% was not different between the other subgroups. These results indicate that the differential natriuresis between oral and intravenous sodium loading in previously sodium deprived subjects, is due to a mechanism in which the vagal nerves play a significant role as part of neural reflex or via a natriuretic hormone.

Effects of cardiotonic steroids on isolated perfused kidney and NHE3 activity in renal proximal tubules

Cardiotonic steroids (CS) are known as modulators of sodium and water homeostasis. These compounds contribute to the excretion of sodium under overload conditions due to its natriuretic property related to the inhibition of the renal Na⁺/K⁺-ATPase (NKA) pump α1 isoform. NHE3, the main route for Na⁺ reabsorption in the proximal tubule, depends on the Na⁺ gradient generated by the NKA pump. In the present study we aimed to investigate the effects of marinobufagin (MBG) and telocinobufagin (TBG) on the renal function of isolated perfused rat kidney and on the inhibition of NKA activity. Furthermore, we investigated the mechanisms for the cardiotonic steroid-mediated natriuretic effect, by evaluating and comparing the effects of bufalin (BUF), ouabain (OUA), MBG and TBG on NHE3 activity in the renal proximal tubule in vivo. TBG significantly increased GFR, UF, natriuresis and kaliuresis in isolated perfused rat kidney, and inhibits the activity of NKA at a much higher rate than MBG. By stationary microperfusion technique, the perfusion with BUF, OUA, TBG or MBG promoted an inhibitory effect on NHE3 activity, whereas BUF was the most effective agent, and demonstrated a dose-dependent response, with maximal inhibition at 50nM. Furthermore, our data showed the role of NKA-Src kinase pathway in the inhibition of NHE3 by CS. Finally, a downstream step, MEK1/2-ERK1/2 was also investigated, and, similar to Src inhibition, the MEK1/2 inhibitor (U0126) suppressed the BUF effect. Our findings indicate the involvement of NKA-SRc-Kinase-Ras-Raf-ERK1/2 pathway in the downregulation of NHE3 by cardiotonic steroids in the renal proximal tubule, promoting a reduction of proximal sodium reabsorption and natriuresis.

Differential Effects of Dapagliflozin on Cardiovascular Risk Factors at Varying Degrees of Renal Function

BACKGROUND AND OBJECTIVE

Sodium glucose cotransporter 2 inhibition with dapagliflozin decreases hemoglobin A1c (HbA1c), body weight, BP, and albuminuria (urinary albumin-to-creatinine ratio). Dapagliflozin also modestly increases hematocrit, likely related to osmotic diuresis/natriuresis. Prior studies suggest that the HbA1c-lowering effects of dapagliflozin attenuate at lower eGFR. However, effects on other cardiovascular risk factors at different eGFR levels are incompletely understood.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This pooled analysis of 11 phase 3 clinical trials assessed changes in HbA1c, body weight, BP, hematocrit, and urinary albumin-to-creatinine ratio with placebo (n=2178) or dapagliflozin 10 mg (n=2226) over 24 weeks in patients with type 2 diabetes according to baseline eGFR (eGFR≥45 to <60 ml/min per 1.73 m2, eGFR≥60 to <90 ml/min per 1.73 m2, and eGFR≥90 ml/min per 1.73 m2).

RESULTS

Compared with placebo, reductions in HbA1c with dapagliflozin were 0.6%, 0.5%, and 0.3%, respectively, for each consecutive lower eGFR subgroup (P value interaction <0.001). Effects of dapagliflozin on hematocrit, body weight, and BP were similar regardless of baseline eGFR, suggesting that effects potentially related to volume and natriuresis are eGFR independent. Moreover, among individuals with baseline urinary albumin-to-creatinine ratio ≥30 mg/g, placebo-adjusted reductions in urinary albumin-to-creatinine ratio were larger in the lowest eGFR subgroup (P value interaction <0.001). Adverse events occurred more frequently in the lowest eGFR subgroup; this was true for both dapagliflozin- and placebo-treated patients.

CONCLUSIONS

The HbA1c-lowering effects of dapagliflozin decrease as renal function declines. However, dapagliflozin consistently decreases body weight, BP, and urinary albumin-to-creatinine ratio regardless of eGFR. These effects in conjunction with the finding of similar effects on hematocrit, a proxy for volume contraction, suggest that the effects of dapagliflozin are partly mediated via nonglucosuric-dependent mechanisms.

Evaluation of the diuretic activity of the aqueous and 80% methanol extracts of the root of Euclea divinorum Hiern (Ebenaceae) in Sprague Dawley rats

BACKGROUND

Diuretics are drugs that increase the formation of urine and are important for the treatment of various diseases including hypertension and edema. The root decoction of Euclea divinorum has been used as a diuretic agent in the traditional medicine. Therefore, this study was aimed to evaluate the diuretic activity of the crude extracts of the roots of Euclea divinorum in Sprague Dawley rats.

METHODS

The aqueous extract (AE) and 80% methanol extract (80ME) of the plant were prepared using decoction and maceration, respectively. Vehicle (distilled water, 10ml/kg), standard drug (hydrochlorothiazide, 10mg/kg) and three doses (100mg/kg, 200mg/kg and 400mg/kg) of the AE and 80ME were given to male rats by oral gavage. Parameters like urine volume (for 5h), electrolyte concentration and pH were measured (at 5^th h) and analyzed. Data were analyzed using one way analysis of variance (ANOVA) followed by Tukey post hoc test. Linear regression was also applied to show the dose dependency nature of the diuretic effect.

RESULTS

The result indicated that the 80ME of the plant significantly (p<0.05) produced diuresis at 200mg/kg and 400mg/kg. Furthermore, the AE produced significant diuresis (p<0.05) at all doses. With regard to the electrolyte excretion, the AE produced significant natriuresis and kaliuresis at all tested doses (p<0.001), while the 80ME showed significant natriuresis and kaliuresis at 200mg/kg (p<0.01) and 400mg/kg (p<0.001). Preliminary phytochemical screening revealed the presence of secondary metabolites, including saponins, flavonoids, glycosides, steroids, tannins and terpinoids in both extracts. These constituents might be responsible for the diuretic activity of Euclea divinorum. Both extracts were also found to be safe at 2000mg/kg on the acute toxicity study.

CONCLUSION

This finding provides a scientific support for the acclaimed traditional use of the roots of Euclea divinorum as a diuretic agent.

Mechanisms underlying the diuretic effect of Gomphrena celosioides Mart. (Amaranthaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Gomphrena celosioides (Amaranthaceae) is a native medicinal plant found in Mato Grosso do Sul State that is used for treating urinary tract and kidney stones. This study aimed to evaluate the diuretic effects of ethanolic extract from G. celosioides (EEGC) on acute and extended diuresis to provide a pharmacological basis for its use in traditional medicine.

AIM OF THE STUDY

To evaluate the diuretic and natriuretic activity of EEGC and its mechanism of action in an animal model.

MATERIALS AND METHODS

EEGC (30, 100 and 300mg/kg) was orally administered in male Wistar rats, and urinary excretion was measured at intervals of up to 8h after administration. To evaluate participation of the nitric oxide (NO), prostaglandin and bradykinin pathways in its effect, respective inhibitors were also administered together with effectives doses of EEGC and compared with control groups. A 7-day model with daily administration and urine measurement was also carried out.

RESULTS

Oral administration of doses of 100 and 300 significantly increased urine output after 8h compared to the control group. It was observed this effect is dependent on the NO, prostaglandin and bradykinin pathways because their inhibitors reduced the diuretic effects of EEGC. Moreover, after 7 days of treatment, the effect was sustained and a decrease in serum aldosterone was observed in the extract group.

CONCLUSION

According to the results, G. celosioides extract showed diuretic and natriuretic effects associated with more than one mechanism of action. Considering that all diuretic drugs are currently available for the treatment of volume and electrolyte disturbances, especially hypertensive status, the present results may have clinical relevance and open new possibilities for the development of new natural diuretics from G. celosioides.