Effect of nebivolol on renal nitric oxide availability and tubular function in patients with essential hypertension

The effect of orally administered nitrate on renal function and blood pressure in a randomized, placebo-controlled, crossover study in healthy subjects

BACKGROUND

Several studies have shown inorganic nitrate/nitrite to reduce blood pressure in both healthy subjects and hypertensive patients. An effect presumably caused through bioconversion to nitric oxide. However, studies on inorganic nitrate/nitrite have shown inconsistent results on renal functions such as GFR and sodium excretion. The current study investigated whether orally administered nitrate would decrease blood pressure and increase GFR and urinary sodium excretion.

METHODS

In a randomized, placebo-controlled, double-blinded, crossover study, 18 healthy subjects received a daily dose of 24 mmol potassium nitrate and placebo (potassium chloride) during 4 days in a randomized order. Subjects also ingested a standardized diet and completed a 24-h urine collection. GFR was determined by the constant infusion technique and during GFR measurement, brachial blood pressure (BP) and central blood pressure (cBP), heart rate, and arterial stiffness were measured every half hour using the Mobil-O-Graph®. Blood samples was analyzed for nitrate, nitrite, cGMP, vasoactive hormones and electrolytes. Urine was analyzed for nitrate, nitrite, cGMP, electrolytes, ENaC_γ, NCC, CrCl, C_H2O and UO.

RESULTS

No differences in GFR, blood pressure or sodium excretion were found between the treatments with potassium nitrate and placebo. However, both nitrate and nitrite levels in plasma and urine were significantly increased by potassium nitrate intake and the 24-h urinary excretion of sodium and potassium were stable, showing adherence to the standardized diet and the study medication.

CONCLUSION

We found no decrease in blood pressure or increase in GFR and sodium excretion of 24 mmol potassium nitrate capsules as compared to placebo after 4 days of treatment. Healthy subjects may be able to compensate the effects of nitrate supplementation during steady state conditions. Future research should focus on long-term studies on the difference in response between healthy subjects and patients with cardiac or renal disease.

Prediction of Renal Function Damage in Patients with Essential Hypertension Based on Stepwise Regression Equation Scanning by AASI

Detection of arterial stiffness is an important method to predict the occurrence of hypertension complications and to screen patients with high cardiovascular risk. In order to predict the damage of AASI to the renal function of patients with essential hypertension, the prediction of AASI based on stepwise Regression equation scanning for renal function damage in patients with essential hypertension is proposed. Measure the 24 h ambulatory blood pressure of the selected subjects, establish a linear Regression equation scanning, and calculate the slope of the straight line, and finally, the slope is AASI. According to the quartiles, AASI is divided into four parts: group I < 0.53 (n = 49); 0.53 ≤ group II < 0.60 (n = 51); 0.60 ≤ group III < 0.69 (n = 48); group IV ≥ 0.69 (n = 44). Experiment result shows the following: with the increase of AASI, cystatin (CysC) also increased significantly, while CysC-eGFR decreased significantly (P < 0.05). Compared with groups I, II, and III, Scr and CysC in group IV increased (P < 0.05), and Ccr, CysC-eGFR, and (CKD-EPI)-eGFR all decreased (P < 0.05). AASI is positively correlated with CysC performance, and the correlation coefficient r is 0.637. It is negatively correlated with Ccr performance, and r is -0.361. It is negatively correlated with CysC-eGFR, and r is -0.698. And it is negatively correlated with (CKD-EPI)-eGFR, and r is -0.331. Age and 24 h PP also showed an increasing trend with the increase of AASI, and it suggests that age may be an influencing factor that promotes kidney damage caused by hypertension; it also suggests that AASI can be used as a new indicator of arterial compliance; AASI is linearly related to various indicators of renal damage and can be used as a predictive indicator of renal damage caused by essential hypertension; cystatin C and the estimated glomerular filtration rate CysC-eGFR based on cystatin C are better than other indicators reflecting glomerular filtration rate, more sensitively assess the degree of early renal damage. Obesity may also be a factor that promotes kidney damage caused by hypertension.

Effect of furosemide on body composition and urinary proteins that mediate tubular sodium and sodium transport-A randomized controlled trial

Background

Furosemide inhibits the sodium potassium chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle and increases urinary water and sodium excretion. This study investigates the effect of furosemide on body composition estimated with multifrequency bioimpedance spectroscopy (BIS) technique and urinary proteins from NKCC2.

Methods

This study is a randomized, placebo‐controlled, crossover study where healthy subjects received either placebo or 40 mg furosemide on two separate occasions, where body composition with BIS, renal function, proteins from tubular proteins that mediate sodium and water transport, and plasma concentrations of vasoactive hormones were measured before and after intervention.

Results

We observed an expected increased diuresis with a subsequent reduction in bodyweight of (−1.51 ± 0.36 kg, p < .001) and extracellular water (ECW; −1.14 ± 0.23 L, p < .001) after furosemide. We found a positive correlation between the decrease in ECW and a decrease in bodyweight and a negative correlation between the decrease in ECW and the increase in urinary output. Intracellular water (ICW) increased (0.47 ± 0.28 L, p < .001). Urinary excretion of NKCC2 increased after furosemide and the increase in NKCC2 correlated with an increase in urine output and a decrease in ECW.

Conclusion

We found BIS can detect acute changes in body water content but the method may be limited to estimation of ECW. BIS demonstrated that furosemide increases ICW which might be explained by an extracellular sodium loss. Finally, urinary proteins from NKCC2 increases after furosemide with a good correlation with diuresis end the decrease in ECW.

The renin-angiotensin system in COVID-19: Why ACE2 targeting by coronaviruses produces higher mortality in elderly hypertensive patients?

This renin‐angiotensin system (RAS) interpretation is focused on differences in tissue dependence on RAS and on the topological hierarchy that allows mediators to act only on downstream tissues.

Dependence of tissues on RAS: Tested by expectation maximization clustering of the RNA human tissue expression (https://biogps.org/). ACE and vasoconstrictive AT1R clustered with the prorenin receptor. ACE2 and dilatory MAS1 clustered with nine RAS‐related genes, highly expressed in: Liver; Cardiac_Myocytes; Skeletal_Muscle; Uterus; Kidney; Lung; Small_Intestine; Smooth_Muscle.

RAS and stress accumulation: While prorenin is active after binding to its receptor, binding of soluble renin increases its enzymatic activity several times. Increased renin secretion multiplies the overall capacity for producing Ang I, leading to hypertension and increased vascular resistance.

Coronavirus infection and comorbidities: Cardiorespiratory failure during infection is linked to the previously altered RAS role in lungs and myocardium. Reduced vasodilation by ACE2 lead to vasoconstriction and suboptimal tissue perfusion patterns. Also see the video abstract here https://www.youtube.com/watch?v=Jf0Iped-Mws

Effect of 3% saline and furosemide on biomarkers of kidney injury and renal tubular function and GFR in healthy subjects - a randomized controlled trial

Background

Chloride is speculated to have nephrotoxic properties. In healthy subjects we tested the hypothesis that acute chloride loading with 3% saline would induce kidney injury, which could be prevented with the loop-diuretic furosemide.

Methods

The study was designed as a randomized, placebo-controlled, crossover study. Subjects were given 3% saline accompanied by either placebo or furosemide. Before, during and after infusion of 3% saline we measured glomerular filtration rate (GFR), fractional excretion of sodium (FE_Na), urinary chloride excretion (u-Cl), urinary excretions of aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaC_γ), neutrophil gelatinase-associated lipocalin (u-NGAL) and kidney injury molecule-1 (u-KIM-1) as marker of kidney injury and vasoactive hormones: renin (PRC), angiotensin II (p-AngII), aldosterone (p-Aldo) and arginine vasopressin (p-AVP). Four days prior to each of the two examinations subjects were given a standardized fluid and diet intake.

Results

After 3% saline infusion u-NGAL and KIM-1 excretion increased slightly (u-NGAL: 17 ± 24 during placebo vs. -7 ± 23 ng/min during furosemide, p = 0.039, u-KIM-1: 0.21 ± 0.23 vs − 0.06 ± 0.14 ng/ml, p <  0.001). The increase in u-NGAL was absent when furosemide was given simultaneously, and the responses in u-NGAL were not significantly different from placebo control. Furosemide changed responses in u-KIM-1 where a delayed increase was observed. GFR was increased by 3% saline but decreased when furosemide accompanied the infusion. U-Na, FE_Na, u-Cl, and u-osmolality increased in response to saline, and the increase was markedly pronounced when furosemide was added. FE_K decreased slightly during 3% saline infusion, but simultaneously furosemide increased FE_K. U-AQP2 increased after 3% saline and placebo, and the response was further increased by furosemide. U-ENaC_γ decreased to the same extent after 3% saline infusion in the two groups. 3% saline significantly reduced PRC, p-AngII and p-Aldo, and responses were attenuated by furosemide. p-AVP was increased by 3% saline, with a larger increase during furosemide.

Conclusion

This study shows minor increases in markers of kidney injury after 3% saline infusion Furosemide abolished the increase in NGAL and postponed the increase in u-KIM-1. The clinical importance of these findings needs further investigation.

Trial registration

(EU Clinical trials register number: 2015–002585-23, registered on 5th November 2015)

Effect of tolvaptan on renal handling of water and sodium, GFR and central hemodynamics in autosomal dominant polycystic kidney disease during inhibition of the nitric oxide system: a randomized, placebo-controlled, double blind, crossover study

BACKGROUND

Tolvaptan slows progression of autosomal dominant polycystic kidney disease (ADPKD) by antagonizing the vasopressin-cAMP axis. Nitric oxide (NO) stimulates natriuresis and diuresis, but its role is unknown during tolvaptan treatment in ADPKD.

METHODS

Eighteen patients with ADPKD received tolvaptan 60 mg or placebo in a randomized, placebo-controlled, double blind, crossover study. L-NMMA (L-NG-monomethyl-arginine) was given as a bolus followed by continuous infusion during 60 min. We measured: GFR, urine output (UO), free water clearance (C_H2O), fractional excretion of sodium (FE_Na), urinary excretion of aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensinII (p-AngII), aldosterone (p-Aldo), and central blood pressure (cBP).

RESULTS

During tolvaptan with NO-inhibition, a more pronounced decrease was measured in UO, C_H2O (61% vs 43%) and FE_Na (46% vs 41%) after placebo than after tolvaptan; GFR and u-AQP2 decreased to the same extent; p-AVP increased three fold, whereas u-ENaC_γ, PRC, p-AngII, and p-Aldo remained unchanged. After NO-inhibition, GFR increased after placebo and remained unchanged after tolvaptan (5% vs -6%). Central diastolic BP (CDBP) increased to a higher level after placebo than tolvaptan. Body weight fell during tolvaptan treatment.

CONCLUSIONS

During NO inhibition, tolvaptan antagonized both the antidiuretic and the antinatriuretic effect of L-NMMA, partly via an AVP-dependent mechanism. U-AQP2 was not changed by tolvaptan, presumeably due to a counteracting effect of elevated p-AVP. The reduced GFR during tolvaptan most likely is caused by the reduction in extracellular fluid volume and blood pressure.

TRIAL REGISTRATION

Clinical Trial no: NCT02527863 . Registered 18 February 2015.

Nebivolol Ameliorates Cisplatin-Induced Nephrotoxicity in Rats

Treatment with cisplatin is associated with dose-limiting side effects, mainly nephrotoxicity. On the other hand, nebivolol, a β1 -adrenoceptor antagonist, exhibits vasodilatory and antioxidative properties. This study aimed to determine whether nebivolol possesses a protective effect against cisplatin nephrotoxicity and explore many mechanisms underlying this potential effect. Nephrotoxicity was induced in Wistar rats by a single intraperitoneal injection of cisplatin (6 mg/kg) on day 2. Nebivolol (10 mg/kg) was administered orally for 7 consecutive days. Nebivolol showed a nephroprotective effect as demonstrated by the significant reduction in the elevated levels of serum creatinine and urea as well as renal levels of malondialdehyde, nitric oxide products (nitrite/nitrate), inducible nitric oxide synthase, tumour necrosis factor-alpha, caspase-3, angiotensin II and endothelin-1 with a concurrent increase in renal levels of reduced glutathione and endothelial nitric oxide synthase compared to untreated rats. Histopathological examination confirmed the nephroprotective effect of nebivolol. Pre-treatment with Nω -nitro-L-arginine methyl ester, the non-specific nitric oxide synthase inhibitor, partially altered the protection afforded by nebivolol. In conclusion, nebivolol protects rats against cisplatin-induced nephrotoxicity that is most likely through its antioxidant, anti-inflammatory and antiapoptotic effects as well as by abrogation of the augmented angiotensin II and endothelin-1 levels.