Sodium balance, circadian BP rhythm, heart rate variability, and intrarenal renin-angiotensin-aldosterone and dopaminergic systems in acute phase of ARB therapy

Renal denervation inhibits the renin-angiotensin-aldosterone system in spontaneously hypertensive rats

This study was conducted to explore the effect of renal denervation (RDN) on the renin-angiotensin-aldosterone system (RAAS) in spontaneously hypertensive rats (SHRs). Our experimental rats were randomly divided into the RDN group conducted by painting 10% phenol on the bilateral renal nerves (RDNX), the shamoperation group simply painting with saline (Sham), and the normotension control group (WKY) following all the animal blood and tissues of kidney, hypothalamus, and adrenal gland collected and examined 2 weeks after RDN operation. We found that the aldosterone (ALD) levels in serum and tissues all decreased in the RDNX group compared with the Sham group (p < .05). Meantime, the expression of angiotensin II type1 receptor (AT1R) mRNA also exhibited significantly reduced by 2.22-fold in the RDNX group compared to the Sham group identical to the expression of AT1R protein in the renal cortex and outer stripe of the outer medulla (OSOM) subjected to denervation surgery, which manifested the lower ATIR protein expression than the Sham group (p < .05). Besides, the expression of angiotensin II (Ang II) protein in the cortex , OSOM, and inner stripe of the outer medulla were all attenuated by RDN in comparison with the Sham group (p < .05). RDN reduced intrarenal RAAS and circulating RAAS to lower blood pressure and repair renal function.

Systematic Review and Meta-Analysis of Renin-Angiotensin-Aldosterone System Blocker Effects on the Development of Cardiovascular Disease in Patients With Chronic Kidney Disease

Background: Cardiovascular events are one of the most serious complications that increase the risk of mortality and morbidity in pre-dialysis and on-dialysis chronic kidney disease (CKD) patients. Activation of the renin-angiotensin-aldosterone system (RAAS) is considered to contribute to the development of cardiovascular events in these populations. Therefore, several kinds of RAAS blockers have been frequently prescribed to prevent cardiovascular events in patients with CKD; however, their effectiveness remains controversial. This systematic review focuses on whether RAAS blockers prevent cardiovascular events in patients with CKD. Method: PubMed were searched to retrieve reference lists of eligible trials and related reviews. Randomized prospective controlled trials that investigated the effects on cardiovascular events in CKD patients that were published in English from 2010 to 2020 were included. Results: Among 167 identified studies, 11 eligible studies (n = 8,322 subjects) were included in the meta-analysis. The meta-analysis showed that RAAS blockers significantly reduced cardiovascular events in on-dialysis patients with CKD [three studies; odds ratio (OR), 0.52; 95% confidence interval (CI), 0.36 to 0.74; p = 0.0003], but there was no significant difference in pre-dialysis patients with CKD because of the heterogeneity in each study (eight studies). We also investigated the effects of each kind of RAAS blocker on cardiovascular events in CKD patients. Among the RAAS blockers, mineralocorticoid receptor antagonists significantly decreased cardiovascular events in pre-dialysis or on-dialysis patients with CKD (four studies; OR, 0.60; 95%CI, 0.50 to 0.73, p < 0.0001). However, angiotensin receptor blockers did not show significant effects (four studies; OR, 0.65; 95%CI, 0.42 to 1.01; p = 0.0529). The effects of angiotensin converting enzyme inhibitors and direct renin inhibitors on cardiovascular events in patients with CKD could not be analyzed because there were too few studies. Conclusion: Mineralocorticoid receptor antagonists may decrease cardiovascular events in pre-dialysis or on-dialysis patients with CKD.

The Value of Heart Rhythm Complexity in Identifying High-Risk Pulmonary Hypertension Patients

Pulmonary hypertension (PH) is a fatal disease—even with state-of-the-art medical treatment. Non-invasive clinical tools for risk stratification are still lacking. The aim of this study was to investigate the clinical utility of heart rhythm complexity in risk stratification for PH patients. We prospectively enrolled 54 PH patients, including 20 high-risk patients (group A; defined as WHO functional class IV or class III with severely compromised hemodynamics), and 34 low-risk patients (group B). Both linear and non-linear heart rate variability (HRV) variables, including detrended fluctuation analysis (DFA) and multiscale entropy (MSE), were analyzed. In linear and non-linear HRV analysis, low frequency and high frequency ratio, DFAα1, MSE slope 5, scale 5, and area 6–20 were significantly lower in group A. Among all HRV variables, MSE scale 5 (AUC: 0.758) had the best predictive power to discriminate the two groups. In multivariable analysis, MSE scale 5 (p = 0.010) was the only significantly predictor of severe PH in all HRV variables. In conclusion, the patients with severe PH had worse heart rhythm complexity. MSE parameters, especially scale 5, can help to identify high-risk PH patients.

Relationship between saline infusion and blood pressure variability in non-critically patients with hypertension: A retrospective study

Saline is a commonly used intravenous solvent, however, its excessive infusion may increase drug-induced sodium intake. To investigate the effects of saline infusion on blood pressure variability (BPV) in patients with hypertension, a retrospective study was performed in 1010 patients with hypertension. The patients who received saline infusion before surgery for continuous 3 to 5 days were divided into 2 groups according to the saline infusion volume during the hospitalization, which are >500 mL per day group and <500 mL per day group. The overall incidence of abnormal BPV was 11.58%. As for the incidence of abnormal BPV in the <500 mL per day group with 698 patients was 9.17%, while that in the >500 mL per day group with 312 patients was as high as 16.99%. Additionally, >500 mL of daily saline infusion for continuous 3 to 5 days (P for trend = .004, odds ratio [OR] = 1.911, 95% confidence interval [CI] for OR 1.226-2.977), medical history of diabetes mellitus (P < .001, OR = 4.856, 95% CI for OR 3.118-7.563) and cardiovascular diseases (P < .001, OR = 2.498, 95% CI for OR 1.549-4.029) may be risk factors of abnormal BPV; while anti-hypertensive therapy with diuretics (P < .001, OR = 0.055, 95% CI for OR 0.024-0.125) may be the protective factor. Our study suggests that >500 mL of daily saline infusion for continuous 3 to 5 days may have disadvantages in the blood pressure control for hypertensive patients, especially for the patients with diabetes mellitus and cardiovascular diseases.

The angiotensin II type 1 receptor blocker azilsartan can overwhelm the sympathetic nerve activation stimulated by coadministration of calcium channel blockers

Objective:

In our recent study, non-Gaussianity of heart rate variability (λ_25s), an indicator of sympathetic nerve activity, did not change during two-day treatment with the angiotensin II type 1 receptor blocker (ARB) azilsartan. Coadministration of calcium channel blockers (CCBs) might affect the study results.

Methods:

In this subanalysis, 20 patients with chronic kidney disease (14 men; age 61±15 years) were divided into three groups: patients with coadministration of L-type CCB, patients without coadministration of CCB, and patients with coadministration of sympathoinhibitory (L/T- or L/T/N-type) CCB. λ_25s was calculated separately in daytime and nighttime.

Results:

Daytime λ_25s at baseline was higher in patients with L-type CCB coadministration (0.62±0.18, n = 5) compared with those without CCB (0.49±0.13, n = 11) and those with sympathoinhibitory CCB (0.46±0.06, n = 4). The relationship between the changes in daytime λ_25s and systolic blood pressure was positive in patients with L-type CCB coadministration, whereas the relationship was inverse in the other two groups. A larger decrease in daytime λ_25s was shown in patients with L-type CCB coadministration compared with those in the other two groups.

Conclusions:

CCBs, as well as diuretics, are recommended as second-line antihypertensive agents. Our results suggested that ARBs can overwhelm the activation of sympathetic nerve activity stimulated by coadministration of L-type CCBs.

Effectiveness of Chrono-Pharmacotherapy Depending on the Salt Sensitivity of Patients with Arterial Hypertension and Diabetes Mellitus Type 2

Aim. To study the effect of two regimens of combined antihypertensive therapy during the day on daily monitoring of arterial pressure, central aortic pressure, and arterial stiffness, depending on the salt sensitivity of hypertensive patients with diabetes mellitus type 2. Material and methods. 130 hypertensive patients with type 2 diabetes mellitus were included into the study. They were divided into 2 subgroups: salt-sensitive (group 1) and salt-resistant (group 2), and then randomized to subgroups A and B of ongoing therapy: in the morning ramipril and indapamide retard, bedtime – amlodipine (subgroup 1A and 2A); or in the morning amlodipine and indapamide retard, bedtime – ramipril (subgroup 1B and 2B). Initially and after 24 weeks of antihypertensive therapy, 24-hour blood pressure monitoring was performed, the indices of central aortic pressure and arterial stiffness were determined. Results. After 24 weeks, in all subgroups, there was a significant positive dynamics of the parameters of 24-hour blood pressure monitoring, central aortic pressure and arterial stiffness indices. In the subgroup 1В, it was registered a significant improvement in the majority of parameters of 24-hour blood pressure monitoring (decrease in 24-hours systolic BP by 24.4%, 24-hours diastolic BP by 22.1%; p<0.05), central aortic pressure (decrease in aortal systolic BP by 15.9%, aortal diastolic BP by 20.8%; p<0.05) and vascular wall stiffness parameters (decrease in pulse wave velocity by 13.8%; p<0.05) in comparison with group 1A (decrease in 24-hours systolic BP by 17.5%, 24-hours diastolic BP by 14.6%, aortal systolic BP by 12.7%, aortal diastolic BP by 9.7%, pulse wave velocity by 9.2%; p<0.05 in comparison with the group 1B). In the case of salt-resistant patients, there were comparable positive changes in the parameters of 24-hour blood pressure monitoring, central aortic pressure and arterial stiffness indices against the background of both dosing regimens during the day. Conclusion. In the study, it was demonstrated the more pronounced antihypertensive and vasoprotective efficacy of the combination of thiazide-like diuretic with calcium channel blocker in the morning and ACE inhibitor in bedtime compared to the alternative regimen of prescribed pharmacotherapy in salt-sensitive patients, and comparable efficacy of both regimens in salt-resistant hypertensive patients with diabetes mellitus type 2.

Fiend and friend in the renin angiotensin system: An insight on acute kidney injury

Besides assisting the maintenance of blood pressure and sodium homeostasis, the renin-angiotensin system (RAS) plays a pivotal role in pathogenesis of acute kidney injury (AKI). The RAS is equipped with two arms i) the pressor arm composed of Angiotensin II (Ang II)/Angiotensin converting enzyme (ACE)/Angiotensin II type 1 receptor (AT1R) also called conventional RAS, and ii) the depressor arm consisting of Angiotensin (1-7) (Ang 1-7)/Angiotensin converting enzyme 2 (ACE2)/MasR known as non-conventional RAS. Activation of conventional RAS triggers oxidative stress, inflammatory, hypertrophic, apoptotic, and pro-fibrotic signaling cascades which promote AKI. The preclinical and clinical studies have reported beneficial as well as deleterious effects of RAS blockage either by angiotensin receptor blocker or ACE inhibitor in AKI. On the contrary, the depressor arm opposes the conventional RAS, has beneficial effects on the kidney but has been less explored in pathogenesis of AKI. This review focuses on significance of RAS in pathogenesis of AKI and provides better understanding of novel and possible therapeutic approaches to combat AKI.

The Relationship between the Intrarenal Dopamine System and Intrarenal Renin-angiotensin System Depending on the Renal Function

Objective The mechanisms underlying the intrarenal renin-angiotensin system (RAS) activation depend on the conditions of kidney diseases. In angiotensin II (AngII) infusion models, the circulating AngII is filtered into the renal tubular lumens, activating intrarenal RAS. However, in the chronic kidney disease (CKD) models, plasma angiotensinogen (AGT) is filtered into the tubular lumens because of glomerular injury, activating intrarenal RAS. The intrarenal dopamine system activation reduces intrarenal AGT expression and suppresses the intrarenal RAS activity in AngII infusion models. However, the relationship between the intrarenal dopamine system and intrarenal RAS has not been elucidated. Therefore, this study was conducted to determine that relationship in CKD patients. Methods We recruited 46 CKD patients (age: 51.1±20.0 years; 16 men; causes of CKD: chronic glomerulonephritis, 34; diabetic nephropathy, 2; nephrosclerosis, 4; and others, 6) not undergoing dialysis or taking RAS blockers. The urinary dopamine (U-DOPA) level, an indicator of intrarenal dopamine activity, and the urinary AGT (U-AGT) level, a surrogate marker of intrarenal RAS activity, were measured. Results As the CKD stages progressed, the U-DOPA levels decreased while the U-AGT levels increased. The U-DOPA levels were significantly and negatively correlated with the U-AGT levels but significantly and positively correlated with the estimated glomerular filtration rate (eGFR). A multiple regression analysis revealed that the U-DOPA levels were associated with the U-AGT levels after adjusting for age, sex, body mass index, and blood pressure (β=-0.38, p=0.045). However, no correlation was observed when eGFR was also adjusted (β=-0.17, p=0.29). Conclusion The negative correlation between the intrarenal dopamine system and intrarenal RAS in CKD patients may be affected by the renal function.

Sodium balance, circadian BP rhythm, heart rate variability, and intrarenal renin-angiotensin-aldosterone and dopaminergic systems in acute phase of ARB therapy

We have revealed that even in humans, activated intrarenal renin–angiotensin–aldosterone system (RAAS) enhances tubular sodium reabsorption to facilitate salt sensitivity and nondipper rhythm of blood pressure (BP), and that angiotensin receptor blocker (ARB) could increase daytime urinary sodium excretion rate (U_NaV) to produce lower sodium balance and restore nondipper rhythm. However, the sympathetic nervous system and intrarenal dopaminergic system can also contribute to renal sodium handling. A total of 20 patients with chronic kidney disease (61 ± 15 years) underwent 24‐h ambulatory BP monitoring before and during two‐day treatment with ARB, azilsartan. Urinary angiotensinogen excretion rate (U_AGTV, μg/gCre) was measured as intrarenal RAAS; urinary dopamine excretion rate (U_DAV, pg/gCre) as intrarenal dopaminergic system; heart rate variabilities (HRV, calculated from 24‐h Holter‐ECG) of non‐Gaussianity index λ_25s as sympathetic nerve activity; and power of high‐frequency (HF) component or deceleration capacity (DC) as parasympathetic nerve activity. At baseline, glomerular filtration rate correlated inversely with U_AGTV (r = −0.47, P = 0.04) and positively with U_DAV (r = 0.58, P = 0.009). HF was a determinant of night/day BP ratio (β = −0.50, F = 5.8), rather than DC or λ_25s. During the acute phase of ARB treatment, a lower steady sodium balance was not achieved. Increase in daytime U_NaV preceded restoration of BP rhythm, accompanied by decreased U_AGTV (r = −0.88, P = 0.05) and increased U_DAV (r = 0.87, P = 0.05), but with no changes in HRVs. Diminished sodium excretion can cause nondipper BP rhythm. This was attributable to intrarenal RAAS and dopaminergic system and impaired parasympathetic nerve activity. During the acute phase of ARB treatment, cooperative effects of ARB and intrarenal dopaminergic system exert natriuresis to restore circadian BP rhythm.