Inappropriate activity of local renin-angiotensin-aldosterone system during high salt intake: impact on the cardio-renal axis

Modulation of Angiotensin-II and Angiotensin 1-7 Levels Influences Cardiac Function in Myocardial Ischemia-reperfusion Injury

The angiotensin-converting enzyme-2 (ACE-2) alters the pathophysiology of various fatal cardiovascular diseases, including ischemic heart disease, whereas angiotensin 1-7 (Ang 1-7) exerts a wide range of actions. The effects of ischemia-reperfusion (IR) injury include damage to myocardial tissue that initiates protease action, causing cardiac cell death. Angiotensin- II (Ang-II) contributes through the renin-angiotensin system (RAS) to the IR injury, whereas Ang 1-7 paradoxically exerts a protective effect through the same. Thus, the myocardial ischemic reperfusion injury (MIRI) may be altered by the RAS of the heart. This review paper focuses on ACE-2, angiotensin-converting enzyme (ACE), and Ang 1-7 regulation in the RAS of the heart in the pathophysiology of MIRI. The treatment in such conditions using ACE-2 activator, ACE inhibitor, and Ang-II antagonists may promote vascular functions as well as cardio- protection.

A traditional Korean fermented food, Gochujang exerts anti-hypertensive effects, regardless of its high salt content by regulating renin-angiotensin-aldosterone system in SD rats

The current study aimed to investigate the distinct outcomes of table salt and salt in Gochujang on blood pressure (BP). Animals were divided into 3 groups, including normal diet (NS, 0.5 % NaCl), high-salt diet (HS, normal diet with 8 % NaCl), or high-salt Gochujang diet (HSG, normal diet with Gochujang containing 8 % NaCl). Compared to the NS groups, the HS group showed significantly increased systolic blood pressure (SBP), while the HSG group did not elevate SBP. The HS group had lower serum angiotensin II and aldosterone levels than the NS group, while the HSG group showed higher levels of those parameters than the HS group. The renal mRNA expression related to the renin-angiotensin-aldosterone system (RAAS) was significantly higher in the HS group than the NS group, while the HSG group had markedly lower expression of those markers. The urinary and fecal Na+/K+ proportion was higher in both HS and HSG groups relative to the NS group, but the HSG group showed a decreased Na+/K+ ratio in urine and feces compared to the HS group. Moreover, the HS group had a significantly upregulated mRNA level of Na+/HCO3- co-transporter (Slc4a4) in the kidney than the NS group, whereas the HSG group showed downregulated mRNA expression of Slc4a4 compared to the HS group. This study demonstrates that Gochujang has anti-hypertensive effects regardless of its high salt content and provide the evidence regarding the distinct impacts between salt in Gochujang and the table salt.

Renin-Angiotensin-Aldosterone System: From History to Practice of a Secular Topic

Renin-angiotensin-aldosterone system (RAAS) inhibitors are standard care in patients with hypertension, heart failure or chronic kidney disease (CKD). Although we have studied the RAAS for decades, there are still circumstances that remain unclear. In this review, we describe the evolution of the RAAS and pose the question of whether this survival trait is still necessary to humankind in the present age. We elucidate the benefits on cardiovascular health and kidney disease of RAAS inhibition and present promising novel medications. Furthermore, we address why more studies are needed to establish a new standard of care away from generally prescribing ACEi or ARB toward an improved approach to combine drugs tailored to the needs of individual patients.

Assessing Sarcocornia as a Salt Substitute: Effects on Lipid Profile and Gelatinase Activity

Sodium, although essential for life, is a key factor in changes in vascular function and cardiovascular disease when consumed in excess. Sarcocornia spp., a halophyte plant with many nutritional benefits, presents itself as a promising substitute for the consumption of purified salt. Matrix metalloproteinases (MMPs) 2 and 9 are widely studied due to their action in physiological processes and as biomarkers at the diagnostic level due to their increased expression in inflammatory processes. This study aimed to evaluate whether replacing salt with Sarcocornia perennis (S. perennis) powder in healthy young people leads to an improvement in biochemical profiles and the attenuation of MMP-2 and MMP-9 activity. In the present study, 30 participants were randomized into a control group that consumed salt and an intervention group that replaced salt with powdered S. perennis. The evaluation of the biochemical parameters was carried out by the spectrophotometry method, and the evaluation of MMP activity was carried out by zymography. A significant decrease was observed in the intervention group in total cholesterol, high-density lipoprotein cholesterol (HDL-c), and creatinine (p-value ≤ 0.05), along with lower but not significantly different mean values of triglycerides. Regarding MMP activity after the intervention, a lower mean value was observed for MMP-9 activity, with there being higher mean values for MMP-2 activity, both with p-values ≥ 0.05. The results confirmed that the consumption of S. perennis is a beneficial choice for health regarding the lipid profile. The evaluation of MMP activity indicated the potential of S. perennis in the regulation of MMP-9 activity in healthy individuals, along with the need for the further study of these proteases in individuals with pathologies.

Comparison of saline infusion test and captopril challenge test in the diagnosis of Chinese with primary aldosteronism in different age groups

Background

To explore the diagnostic accuracy and the optimal cutoff value between the saline infusion test (SIT) and captopril challenge test (CCT) [including the value and suppression of plasma aldosterone concentration (PAC)] for primary aldosteronism (PA) diagnosing.

Methods

A total of 318 patients with hypertension were consecutively enrolled, including 126 patients with PA and 192 patients with essential hypertension (EH), in this observational study. The characteristics of patients and laboratory examinations were collected and compared. The comparison between SIT and CCT was carried by drawing the receiver operator characteristic curve (ROC) and calculating the area under the curve (AUC) to explore the diagnostic accuracy and the optimal cutoff value.

Results

The average age was 51.59 ± 10.43 in the PA group and 45.72 ± 12.44 in the EH group (p<0.05). The optimal cutoff value was 10.7 ng/dL for post-CCT PAC, 6.8 ng/dL for post-SIT PAC, and 26.9% for suppression of post-CCT PAC. The diagnostic value of post-CCT PAC was the highest with 0.831 for the AUC and 0.552 for the Youden index. The optimal cutoff value for patients who were <50 years old was 11.5 ng/dL for post-CCT PAC and 8.4 ng/dL for post-SIT PAC. The suppression of post-CCT PAC turned to 18.2% for those of age 50 or older.

Conclusion

Compared with SIT, CCT had a higher diagnostic value when post-CCT PAC was used as the diagnostic criterion in Chinese people, while the selection of diagnostic thresholds depended on patient age.

Effect of Angiotensin receptor blockade on Plasma Osmolality and Neurohumoral Responses to High Environmental Temperature in Rats Fed a High Salt Diet

Plasma osmolality (pOsmol) and neurohumoral signals play important roles in the pathophysiology of cardiovascular diseases. Our study investigated the effect of high environmental temperature (HET) on neurohumoral responses and pOsmol in rats fed a high salt diet (HSD), with and without angiotensin II receptor blockade (ARB), using telmisartan.  Fifty-six male 8-week old Sprague-Dawley rats (95-110g) were randomly assigned into seven groups of 8 rats. These included control rats (I) fed with 0.3% NaCl diet (normal diet, ND); salt-loaded rats (II) fed with 8% NaCl (high salt) diet; ND rats (III) exposed to HET (38.5±0.5oC ) 4 hours daily per week; rats (IV) fed with 8% NaCl diet and exposed to HET daily. Others included rats (V) fed with 8% NaCl diet and treated with telmisartan (30mg/kg); ND rats (VI) exposed to HET and treated with telmisartan; rats (VI) fed with 8% NaCl diet, exposed to HET and treated with telmisartan. Plasma angiotensin II, aldosterone, vasopressin and norepinephrine (NE) concentrations were determined by ELISA technique; pOsmol from plasma K+, Na+ and Urea. HSD combined with HET in rats synergistically increased pOsmol (P<0.001) with an associated non-synergistic rise in fluid intake (P<0.001), fluid balance (P<0.001), plasma angiotensin II (P<0.01) and aldosterone (P<0.05), NE (P<0.001) and vasopressin (P<0.05) concentrations compared to control. Telmisartan did not alter pOsmol in all the treated-rats, but normalized fluid intake levels and plasma vasopressin in the rats exposed to either HSD or HEt alone. Prolonged exposure of rats to hot environment exacerbated the effect of excess dietary salt on pOsmol, with no effect on angiotensin II-mediated neurohumoral responses.

Effect of Mineral-Balanced Deep-Sea Water on Kidney Function and Renal Oxidative Stress Markers in Rats Fed a High-Salt Diet

This study investigated the effect of mineral-balanced deep-sea water (DSW) on kidney health using an animal model of kidney injury due to a high-sodium diet. High magnesium/low sodium (HMLS) and high magnesium/high calcium (HMHC) DSW samples with different mineral contents were prepared. Sprague–Dawley rats were fed an 8% sodium chloride (NaCl) diet for four weeks to induce kidney injury, and each group was supplied with purified water or mineral water. Kidney injury was observed in the NaCl group according to increased kidney injury markers and malondialdehydes, providing evidence of oxidative stress. However, the kidney injury was repaired by the intake of mineral-balanced DSW. It was confirmed that the HMLS and HMHC groups showed improved Na⁺ excretion through the urine. Kidney injury markers in urine decreased and upregulation of low-density lipoprotein receptor-related protein2 mRNA expression was observed in the HMLS and HMHC groups. In addition, superoxide dismutase activity was increased in the HMHC groups. The gene expression patterns of the RNA sequencing were similar between the CON and HMLS groups. These results suggest that DSW has beneficial effects on kidney health due to the balanced magnesium and calcium levels in models of kidney injury caused by excessive sodium intake.

Visceral adiposity index is positively associated with blood pressure: A systematic review

PURPOSE

This systematic review aimed to investigate the association between VAI and blood pressure.

METHODS

The study was according to the PRISMA standards and the bibliographic search in the PubMed, EMBASE and Cochrane Library databases.

RESULTS

This review included 32 articles, with 60,482 individuals - children to elderly people between 7 and 102 years old - of different age groups, most of them female (54.9%; n = 26,478). The year of publication ranged from 2010 to 2020, indicating that it is a recent theme, applied in almost all continents (America, Europe, Africa and Asia). The authors used data as continuous or into quantiles; blood pressure data also varied, with different cutoff points for the classification of arterial hypertension or continuously. The vast majority of studies have shown a positive association between VAI and blood pressure, both the sexes, in different age groups. The evaluation of the quality of the articles used by the Tool of the Joanna Briggs Institute according to their design.

CONCLUSION

Individuals with increased VAI have higher blood pressure levels. Registration (PROSPERO: CRD42020205965).

Identification of the toxic threshold of 3-hydroxybutyrate-sodium supplementation in septic mice

BACKGROUND

In septic mice, supplementing parenteral nutrition with 150 mg/day 3-hydroxybutyrate-sodium-salt (3HB-Na) has previously shown to prevent muscle weakness without obvious toxicity. The main objective of this study was to identify the toxic threshold of 3HB-Na supplementation in septic mice, prior to translation of this promising intervention to human use.

METHODS

In a centrally-catheterized, antibiotic-treated, fluid-resuscitated, parenterally fed mouse model of prolonged sepsis, we compared with placebo the effects of stepwise escalating doses starting from 150 mg/day 3HB-Na on illness severity and mortality (n = 103). For 5-day survivors, also the impact on ex-vivo-measured muscle force, blood electrolytes, and markers of vital organ inflammation/damage was documented.

RESULTS

By doubling the reference dose of 150 mg/day to 300 mg/day 3HB-Na, illness severity scores doubled (p = 0.004) and mortality increased from 30.4 to 87.5 % (p = 0.002). De-escalating this dose to 225 mg still increased mortality (p ≤ 0.03) and reducing the dose to 180 mg/day still increased illness severity (p ≤ 0.04). Doses of 180 mg/day and higher caused more pronounced metabolic alkalosis and hypernatremia (p ≤ 0.04) and increased markers of kidney damage (p ≤ 0.05). Doses of 225 mg/day 3HB-Na and higher caused dehydration of brain and lungs (p ≤ 0.05) and increased markers of hippocampal neuronal damage and inflammation (p ≤ 0.02). Among survivors, 150 mg/day and 180 mg/day increased muscle force compared with placebo (p ≤ 0.05) up to healthy control levels (p ≥ 0.3).

CONCLUSIONS

This study indicates that 150 mg/day 3HB-Na supplementation prevented sepsis-induced muscle weakness in mice. However, this dose appeared maximally effective though close to the toxic threshold, possibly in part explained by excessive Na+ intake with 3HB-Na. Although lower doses were not tested and thus might still hold therapeutic potential, the current results point towards a low toxic threshold for the clinical use of ketone salts in human critically ill patients. Whether 3HB-esters are equally effective and less toxic should be investigated.

Perindopril Reduces Arterial Pressure and Does Not Inhibit Exercise-Induced Angiogenesis in Spontaneously Hypertensive Rats

ABSTRACT

Sympathetic activity, arteriolar structure, and angiogenesis are important mechanisms modulating hypertension and this study aimed to analyze the effects of perindopril treatment, associated or not with exercise training, on the mechanisms that control blood pressure (BP) in hypertensive rats. Spontaneously hypertensive rats (SHR) were allocated into 4 groups: 1/sedentary (S); 2/perindopril (P, 3.0 mg/kg/d); 3/trained (T); and 4/trained + perindopril (TP). Wistar rats were used as normotensive sedentary control group. SHR were assigned to undergo a treadmill training (T) or were kept sedentary. Heart rate, BP, sympathetic activity to the vessels (LF-SBP), and skeletal muscle and myocardial morphometric analyses were performed. BP was significantly lower after all 3 strategies, compared with S and was accompanied by lower LF-SBP (-76%, -53%, and -44%, for P, T, and TP, respectively). Arteriolar vessel wall cross-sectional area was lower after treatments (-56%, -52%, and -56%, for P, T, and TP, respectively), and only TP presented higher arteriolar lumen area. Capillary rarefaction was present in soleus muscle and myocardium in S group and both trained groups presented higher vessel density, although perindopril attenuated this increase in soleus muscle. Although myocyte diameter was not different between groups, myocardial collagen deposition area, higher in S group, was lower after 3 strategies. In conclusion, we may suggest that perindopril could be an option for the hypertensive people who practice exercise and need a specific pharmacological treatment to reach a better BP control, mainly because training-induced angiogenesis is an important response to facilitate blood flow perfusion and oxygen uptake and perindopril did not attenuate this response.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of SPH3127: A Phase I, Randomized, Double-Blind, Placebo-Controlled Trial

PURPOSE

To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of single- and multiple-dose SPH3127 in healthy individuals.

METHODS

This was a randomized, double-blind, placebo-controlled, Phase I dose-escalation study.

FINDINGS

SPH3127 exposure, expressed as C_max, AUC_0-t, and AUC_0-∞, was proportionally increased with dose for a range of 25-800 mg (single ascending dose [SAD]) and 100-400 mg daily (multiple ascending doses [MADs]). In an SAD, the C_max values with 25, 50, 100, 200, 400, and 800 mg of SPH3127 were 90.67, 344.50, 523.50, 1239.50, 2445.00, and 5753.33 ng/mL, respectively. The corresponding AUC_0-t values were 294.48, 843.62, 1109.33, 2858.56, 6697.50, and 13057.83 h × ng/mL. In MADs, after the first dose of SPH3127, the C_max values with 100, 200, and 400 mg of SPH3127 were 421.50, 969.00, and 2468.33 ng/mL, respectively. The corresponding AUC_0-t values were 1279.28, 2275.77, and 5934.26 h × ng/mL. At steady state, the C_max values with 100, 200, and 400 mg of SPH3127 were 514.67, 1419.17, and 2513.33 ng/mL, respectively. The corresponding AUC_0-24 values were 1638.14, 3096.20, and 7577.70 h × ng/mL. The median T_max range from 0.33 to 1.0 h and the median t_1/2 from 3 to 4 h. In an SAD, when the dose was >100 mg, plasma renin activity inhibition of up to 90% lasted up to 24 h. In MADs, renin activity was continuously inhibited by up to 90% in each group for 24 h after the last administration. Treatment-emergent adverse events (AEs) were reported in 29.2% of individuals receiving the SAD and 33.3% of those receiving MADs. Only mild adverse events occurred.

IMPLICATIONS

SPH3127 was well tolerated and had robust and sustained suppression of plasma renin activity. CLINICALTRIALS.

GOV IDENTIFIERS

NCT03128138 (SAD study) and NCT03255993 (MAD study).

Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature

Acute viral respiratory infections are the main infectious disease in the world. In 2020, a new disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), coronavirus disease 2019 (COVID-19), became a global pandemic. The immune response to the virus depends on factors such as genetics, age and physical state, and its main input receptor is the angiotensin-converting enzyme 2. The practice of physical exercises acts as a modulator of the immune system. During and after physical exercise, pro- and anti-inflammatory cytokines are released, lymphocyte circulation increases, as well as cell recruitment. Such practice has an effect on the lower incidence, intensity of symptoms and mortality in viral infections observed in people who practice physical activity regularly, and its correct execution must be considered to avoid damage. The initial response is given mainly by type I interferons (IFN-I), which drive the action macrophages and lymphocytes, followed by lymphocyte action. A suppression of the IFN-I response has been noted in COVID-19. Severe conditions have been associated with storms of pro-inflammatory cytokines and lymphopenia, as well as circulatory changes and virus dispersion to other organs. The practice of physical activities strengthens the immune system, suggesting a benefit in the response to viral communicable diseases. Thus, regular practice of adequate intensity is suggested as an auxiliary tool in strengthening and preparing the immune system for COVID-19. Further studies are needed to associate physical exercise with SARS-CoV-2 infection.

Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature

Acute viral respiratory infections are the main infectious disease in the world. In 2020, a new disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), coronavirus disease 2019 (COVID-19), became a global pandemic. The immune response to the virus depends on factors such as genetics, age and physical state, and its main input receptor is the angiotensin-converting enzyme 2. The practice of physical exercises acts as a modulator of the immune system. During and after physical exercise, pro- and anti-inflammatory cytokines are released, lymphocyte circulation increases, as well as cell recruitment. Such practice has an effect on the lower incidence, intensity of symptoms and mortality in viral infections observed in people who practice physical activity regularly, and its correct execution must be considered to avoid damage. The initial response is given mainly by type I interferons (IFN-I), which drive the action macrophages and lymphocytes, followed by lymphocyte action. A suppression of the IFN-I response has been noted in COVID-19. Severe conditions have been associated with storms of pro-inflammatory cytokines and lymphopenia, as well as circulatory changes and virus dispersion to other organs. The practice of physical activities strengthens the immune system, suggesting a benefit in the response to viral communicable diseases. Thus, regular practice of adequate intensity is suggested as an auxiliary tool in strengthening and preparing the immune system for COVID-19. Further studies are needed to associate physical exercise with SARS-CoV-2 infection.

Inhibition of the P2X7 receptor improves renal function via renin-angiotensin system and nitric oxide on diabetic nephropathy in rats

AIM

To evaluate the effects of P2X₇ receptor blockade on renin-angiotensin system (RAS) in rats with diabetic nephropathy (DN).

MAIN METHODS

Wistar rats were unilaterally nephrectomized and received streptozotocin for diabetes mellitus (DM) induction; control animals (CTL) received the drug vehicle. The animals were submitted to P2X₇ receptor silencing, forming the group (DM + siRNA). The animals were placed in metabolic cages for data collection and evaluation of renal function; at the end of the protocol, the kidney was removed for analysis of P2X₇, renin, angiotensin-converting enzyme (ACE), ACE2, angiotensin, thiobarbituric acid reactive substance levels (TBARS), nitric oxide (NO) and qualitative histological.

KEY FINDINGS

The metabolic profile was attenuated in DM + siRNA vs. DM and there was a significant improvement in creatinine, urea and proteinuria levels in the same group. Renin expression was significantly decreased in DM + siRNA vs. DM. ACE and ACE2 were significantly reduced in DM + siRNA vs. DM. TBARS levels were decreased and NO showed an increase in DM + siRNA vs. DM, both significant. All histological alterations were improved in DM + siRNA vs. DM.

SIGNIFICANCE

Data have shown that although silencing of the P2X₇ receptor did not decrease fasting glucose, it promoted an improvement in the metabolic profile and a significant recovery of renal function, revealing a protective action by the inhibition of this receptor. This effect must have occurred due to the inhibition of RAS and the increase of NO, suggesting that the use of P2X₇ receptors inhibitors could be used as adjuvant therapy against DN progression.

High-Salt Loading Downregulates Nrf2 Expression in a Sodium-Dependent Manner in Renal Collecting Duct Cells

Background

High salt intake is associated with both oxidative stress and chronic kidney disease (CKD) progression. Nuclear factor E2-related factor 2 (Nrf2) is a transcriptional factor regulating the antioxidant and detoxifying genes to potently antagonize oxidative stress. This study examined the effect of high salt loading on the expression of Nrf2 in kidney.

Methods

Mice were treated with acute salt loading, and Nrf2 expression in the kidney was detected by Western blotting and immunostaining. Reactive oxygen species (ROS) levels in the kidney were measured using dihydroethidium (DHE) staining. In vitro, mpkCCD cells were cultured in high osmolality medium by adding sodium chloride (NaCl), sodium gluconate (Na-Glu), choline chloride (Choline-Cl), or mannitol. Then, Nrf2 and its target genes were measured.

Results

Nrf2 protein in renal cortex and medulla tissue lysates was significantly downregulated after acute salt loading. Immunofluorescence data showed that Nrf2 was mainly located in collecting duct principal cells evidenced by co-staining of Nrf2 with AQP2. Contrasting to the reduced Nrf2 expression, ROS levels in the kidney were significantly increased after salt loading. In vitro, the Nrf2 protein level was downregulated in mpkCCD cells after NaCl treatment for 24 h. Interestingly, sodium gluconate had a similar effect on downregulating Nrf2 expression as NaCl, whereas neither Choline-Cl nor mannitol changed Nrf2 expression. Meanwhile, the mRNA levels of Nrf2 target genes were downregulated by NaCl and/or sodium gluconate, while some of them were also regulated by Choline-Cl, indicating a more complex regulation of these genes under a high salt condition. Finally, we found that the downregulation of Nrf2 caused by NaCl was not affected by N-acetylcysteine (NAC), spironolactone, or NS-398, suggesting other mechanisms mediating Nrf2 downregulation caused by high salt challenge.

Conclusion

High salt downregulated Nrf2 mainly via a sodium-dependent manner in kidney collecting duct cells, which might contribute to the excessive renal oxidative stress and CKD progression.