Decreased renal function increases the nighttime urine volume rate by carryover of salt excretion to the nighttime

Prognostic Value of Spot Urinary Creatinine Concentration and Its Relationship with Body Composition Parameters in HF Patients

BACKGROUND

Low 24-h urinary excretion of creatinine in patients with heart failure (HF) is believed to reflect muscle wasting and is associated with a poor prognosis. Recently, spot urinary creatinine concentration (SUCR) has been suggested as a useful prognostic factor in selected HF cohorts. This more practical and cheaper approach has never been tested in an unselected HF population. Moreover, neither the relation between SUCR and body composition markers nor the association of SUCR with the markers of volume overload, which are known to worsen clinical outcome, has been studied so far. The aim of the study was to check the prognostic value of SUCR in HF patients after adjusting for body composition and indirect markers of volume overload.

METHODS

In 911 HF patients, morning SUCR was determined and body composition scanning using dual X-ray absorptiometry (DEXA) was performed. Univariable and multivariable predictors of log SUCR were analyzed. All participants were divided into quartiles of SUCR.

RESULTS

In univariable analysis, SUCR weakly correlated with fat-free mass (R = 0.09, p = 0.01). Stronger correlations were shown between SUCR and loop diuretic dose (R = 0.16, p < 0.0001), NTproBNP (R = -0.15, p < 0.0001) and serum sodium (R = 0.16, p < 0.0001). During 3 years of follow-up, 353 (38.7%) patients died. Patients with lower SUCR were more frequently female, and their functional status was worse. The lowest mortality was observed in the top quartile of SUCR. In the unadjusted Cox regression analysis, the relative risk of death in all three lower quartiles of SUCR was higher by roughly 80% compared to the top SUCR quartile. Apart from lower SUCR, the significant predictors of death were age and malnutrition but not body composition. After adjustment for loop diuretic dose and percent of recommended dose of mineralocorticoid receptor antagonists, the difference in mortality vanished completely.

CONCLUSIONS

Lower SUCR levels in HF patients are associated with a worse outcome, but this effect is not correlated with fat-free mass. Fluid overload-driven effects may link lower SUCR with higher mortality in HF.

Catalpol Attenuates Oxidative Stress and Inflammation via Mechanisms Involving Sirtuin-1 Activation and NF-κB Inhibition in Experimentally-Induced Chronic Kidney Disease

Chronic kidney disease (CKD) is a stealthy disease, and its development is linked to mechanisms including inflammation and oxidative stress. Catalpol (CAT), an iridoid glucoside from the root of Rehmannia glutinosa, is reported to manifest anti-inflammatory, antioxidant, antiapoptotic and antifibrotic properties. Hence, we studied the possible nephroprotective effects of CAT and its mechanisms in an adenine-induced (0.2% w/w in feed for 4 weeks) murine model of CKD by administering 5 mg/kg CAT to BALB/c mice for the duration of 4 weeks except during weekends. Upon sacrifice, the kidney, plasma and urine were collected and various physiological, biochemical and histological endpoints were assessed. CAT significantly ameliorated the adenine-induced altered body and kidney weight, water intake, urine volume, and concentrations of urea and creatinine in plasma, as well as the creatinine clearance and the albumin and creatinine ratio. Moreover, CAT significantly ameliorated the effect of adenine-induced kidney injury by reducing the kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, cystatin C and adiponectin. Similarly, the augmented concentrations of markers of inflammation and oxidative stress in the adenine-treated group were markedly reduced with CAT pretreatment. Furthermore, CAT prevented adenine-induced deoxyribonucleic acid damage and apoptotic activity in the kidneys. Histologically, CAT significantly reduced the formation of tubular necrosis and dilation, as well as interstitial fibrosis in the kidney. In addition to that, CAT significantly decreased the adenine-induced increase in the phosphorylated NF-κB and reversed the reduced expression of sirtuin-1 in the kidney. In conclusion, CAT exhibits salutary effects against adenine-induced CKD in mice by mitigating inflammation, oxidative stress and fibrosis via mechanisms involving sirtuin-1 activation and NF-κB inhibition. Confirmatory studies are warranted in order to consider CAT as a potent nephroprotective agent against CKD.

Dietary salt with nitric oxide deficiency induces nocturnal polyuria in mice via hyperactivation of intrarenal angiotensin II-SPAK-NCC pathway

Nocturnal polyuria is the most frequent cause of nocturia, a common disease associated with a compromised quality of life and increased mortality. Its pathogenesis is complex, and the detailed underlying mechanism remains unknown. Herein, we report that concomitant intake of a high-salt diet and reduced nitric oxide (NO) production achieved through N^ω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) administration in mice resulted in nocturnal polyuria recapitulating the clinical features in humans. High salt intake under reduced NO production overactivated the angiotensin II-SPAK (STE20/SPS1-related proline–alanine-rich protein kinase)-NCC (sodium chloride co-transporter) pathway in the kidney, resulting in the insufficient excretion of sodium during the day and its excessive excretion at night. Excessive Na excretion at night in turn leads to nocturnal polyuria due to osmotic diuresis. Our study identified a central role for the intrarenal angiotensin II-SPAK-NCC pathway in the pathophysiology of nocturnal polyuria, highlighting its potential as a promising therapeutic target.

This study reports a mouse model of nocturnal polyuria - increased urine production at night that causes compromised quality of life and may impact mortality in older people. The authors identify a molecular pathway in the kidney that could prove to be a promising drug target for nocturnal polyuria.