Blood pressure lowering efficacy of renin inhibitors for primary hypertension

Emerging production techniques and potential health promoting properties of plant and animal protein-derived bioactive peptides

Bioactive peptides (BPs) are short amino acid sequences that that are known to exhibit physiological characteristics such as antioxidant, antimicrobial, antihypertensive and antidiabetic properties, suggesting that they could be exploited as functional foods in the nutraceutical industry. These BPs can be derived from a variety of food sources, including milk, meat, marine, and plant proteins. In the past decade, various methods including in silico, in vitro, and in vivo techniques have been explored to unravel underlying mechanisms of BPs. To forecast interactions between peptides and their targets, in silico methods such as BIOPEP, molecular docking and Quantitative Structure-Activity Relationship modeling have been employed. Additionally, in vitro research has examined how BPs affect enzyme activities, protein expressions, and cell cultures. In vivo studies on the contrary have appraised the impact of BPs on animal models and human subjects. Hence, in the light of recent literature, this review examines the multifaceted aspects of BPs production from milk, meat, marine, and plant proteins and their potential bioactivities. We envisage that the various concepts discussed will contribute to a better understanding of the food derived BP production, which could pave a way for their potential applications in the nutraceutical industry.

Immunomodulatory properties of antihypertensive drugs and digitalis glycosides

INTRODUCTION

The role of chronic inflammatory process in the pathogenesis or exacerbation of hypertension has been already acknowledged.

AREAS COVERED

Therefore, one can speculate that hypotensive drugs may exert some of their therapeutic effects due to immunomodulatory properties. So far, this assumption has been tested in different studies, and the resulting knowledge is summarized in the current review article that is dedicated to different groups of antihypertensives, namely calcium channel blockers, beta blockers, as well as other less commonly used medications, such as hydralazine, agonists of alfa-2 receptor, diazoxide, doxazosin, aliskiren, and sodium nitroprusside. Articles were found in the Pubmed database by entering the name of a specific drug (or group of drugs) together with the words: immunology, cellular response, humoral response, inflammation, interleukin. The 2000-2021 range was used to search for all drugs except propranolol (1980-2021) and calcium blockers (1990-2021).

EXPERT OPINION

Observed decrease in serum/plasma concentration of proinflammatory cytokines, and CRP along with lower expression of adhesion molecules on immune cells strongly suggest that these drugs possess immunomodulatory properties, which seems to be crucial in the medical practice, especially in the therapy of hypertensive patients with other accompanying inflammatory-based diseases, such as type II diabetes, developed metabolic syndrome, allergies or autoimmunity.

Current and Emerging Classes of Pharmacological Agents for the Management of Hypertension

Cardiovascular disease accounts for more than 17 million deaths globally every year, of which complications of hypertension account for 9.4 million deaths worldwide. Early detection and management of hypertension can prevent costly interventions, including dialysis and cardiac surgery. Non-pharmacological approaches for managing hypertension commonly involve lifestyle modification, including exercise and dietary regulations such as reducing salt and fluid intake; however, a majority of patients will eventually require antihypertensive medications. In 2020, the International Society of Hypertension published worldwide guidelines in its efforts to reduce the global prevalence of raised blood pressure (BP) in adults aged 18 years or over. Currently, several classes of medications are used to control hypertension, either as mono- or combination therapy depending on the disease severity. These drug classes include those that target the renin-angiotensin-aldosterone system (RAAS) and adrenergic receptors, calcium channel blockers, diuretics and vasodilators. While some of these classes of medications have shown significant benefits in controlling BP and reducing cardiovascular mortality, the prevalence of hypertension remains high. Significant efforts have been made in developing new classes of drugs that lower BP; these medications exert their therapeutic benefits through different pathways and mechanism of actions. With several of these emerging classes in phase III clinical trials, it is hoped that the discovery of these novel therapeutic avenues will aid in reducing the global burden of hypertension.

Pharmacogenomics Informs Cardiovascular Pharmacotherapy

Precision medicine exemplifies the emergence of personalized treatment options which may benefit specific patient populations based upon their genetic makeup. Application of pharmacogenomics requires an understanding of how genetic variations impact pharmacokinetic and pharmacodynamic properties. This particular approach in pharmacotherapy is helpful because it can assist in and improve clinical decisions. Application of pharmacogenomics to cardiovascular pharmacotherapy provides for the ability of the medical provider to gain critical knowledge on a patient's response to various treatment options and risk of side effects.

Renin-Angiotensin System in Pathogenesis of Atherosclerosis and Treatment of CVD

Atherosclerosis has complex pathogenesis, which involves at least three serious aspects: inflammation, lipid metabolism alterations, and endothelial injury. There are no effective treatment options, as well as preventive measures for atherosclerosis. However, this disease has various severe complications, the most severe of which is cardiovascular disease (CVD). It is important to note, that CVD is among the leading causes of death worldwide. The renin–angiotensin–aldosterone system (RAAS) is an important part of inflammatory response regulation. This system contributes to the recruitment of inflammatory cells to the injured site and stimulates the production of various cytokines, such as IL-6, TNF-a, and COX-2. There is also an association between RAAS and oxidative stress, which is also an important player in atherogenesis. Angiotensin-II induces plaque formation at early stages, and this is one of the most crucial impacts on atherogenesis from the RAAS. Importantly, while stimulating the production of ROS, Angiotensin-II at the same time decreases the generation of NO. The endothelium is known as a major contributor to vascular function. Oxidative stress is the main trigger of endothelial dysfunction, and, once again, links RAAS to the pathogenesis of atherosclerosis. All these implications of RAAS in atherogenesis lead to an explicable conclusion that elements of RAAS can be promising targets for atherosclerosis treatment. In this review, we also summarize the data on treatment approaches involving cytokine targeting in CVD, which can contribute to a better understanding of atherogenesis and even its prevention.

PRISMA-S: an extension to the PRISMA statement for reporting literature searches in systematic reviews. J Med Libr Assoc 2021;109:174-200. [PMID: 34285662 PMCID: PMC8270366 DOI: 10.5195/jmla.2021.962]

BACKGROUND

Literature searches underlie the foundations of systematic reviews and related review types. Yet, the literature searching component of systematic reviews and related review types is often poorly reported. Guidance for literature search reporting has been diverse and, in many cases, does not offer enough detail to authors who need more specific information about reporting search methods and information sources in a clear, reproducible way. This document presents the PRISMA-S (Preferred Reporting Items for Systematic reviews and Meta-Analyses literature search extension) checklist, and explanation and elaboration.

METHODS

The checklist was developed using a three-stage Delphi survey process, followed by a consensus conference and public review process.

RESULTS

The final checklist includes sixteen reporting items, each of which is detailed with exemplar reporting and rationale.

CONCLUSIONS

The intent of PRISMA-S is to complement the PRISMA Statement and its extensions by providing a checklist that could be used by interdisciplinary authors, editors, and peer reviewers to verify that each component of a search is completely reported and, therefore, reproducible.

Efficacy and safety of aliskiren combination therapy: a protocol for an umbrella review

INTRODUCTION

Efficacy of aliskiren combination therapy with other antihypertensive has been evaluated in the treatment of patients with hypertension in recent systematic reviews. However, most previous reviews only focused on one single health outcome or one setting, none of them made a full summary that assessed the impact of aliskiren combination treatment comprehensively. As such, this umbrella review based on systematic reviews and meta-analyses is aimed to synthesise the evidences on efficacy, safety and tolerability of aliskiren-based therapy for hypertension and related comorbid patients.

METHODS AND ANALYSIS

A comprehensive search of PubMed, EMBASE, Cochrane Library, CNKI published from inception to August 2020 will be conducted. The selected articles are systematic reviews which evaluated efficacy, safety and tolerability of aliskiren combination therapy. Two reviewers will screen eligible articles, extract data and evaluate quality independently. Any disputes will be resolved by discussion or the arbitration of a third person. The quality of reporting evidence will be assessed using the Assessment of Multiple Systematic Reviews V.2 tool tool. We will take a mixed-methods approach to synthesising the review literatures, reporting summary of findings tables and iteratively mapping the results.

ETHICS AND DISSEMINATION

Ethical approval is not required for the study, as we would only collect data from available published materials. This umbrella review will be also submitted to a peer-reviewed journal for publication after completion.

PROSPERO REGISTRATION NUMBER

CRD42020192131.

Angiotensin (1-12) in Humans With Normal Blood Pressure and Primary Hypertension

The importance of canonical versus noncanonical mechanisms for the generation of angiotensins remains a major challenge that, in part, is heavily swayed by the relative efficacy of therapies designed to inhibit renin, ACE (angiotensin-converting enzyme), or the Ang II (Angiotensin II) receptor. Ang (1-12) (angiotensin [1-12]) is an Ang II forming substrate serving as a source for Ang II-mediated tissue actions. This study identifies for the first time the presence of Ang (1-12) in the blood of 52 normal (22 women) and 19 (13 women) patients with hypertension not receiving antihypertensive medication at the time of the study. Normal subjects of comparable ages and body habitus had similar circulating plasma Ang (1-12) concentrations (women: 2.02±0.62 [SD] ng/mL; men 2.05±0.55 [SD] ng/mL, P>0.05). The higher values of plasma Ang (1-12) concentrations in hypertensive men (2.51±0.49 ng/mL, n=6) and women (2.33±0.63 [SD] ng/mL, n=13) were statistically significant (P<0.02) and correlated with elevated plasma renin activity, systolic and pulse pressure, and plasma concentrations of NT-proBNP (N-terminal prohormone BNP). The increased plasma Ang (1-12) in patients with hypertension was not mirrored by similar changes in plasma angiotensinogen and Ang II concentrations. The first identification of an age-independent presence of Ang (1-12) in the blood of normotensive subjects and patients with hypertension, irrespective of sex, implicates this non-renin dependent substrate as a source for Ang II production in the blood and its potential contribution to the hypertensive process.

PRISMA-S: an extension to the PRISMA Statement for Reporting Literature Searches in Systematic Reviews

BACKGROUND

Literature searches underlie the foundations of systematic reviews and related review types. Yet, the literature searching component of systematic reviews and related review types is often poorly reported. Guidance for literature search reporting has been diverse, and, in many cases, does not offer enough detail to authors who need more specific information about reporting search methods and information sources in a clear, reproducible way. This document presents the PRISMA-S (Preferred Reporting Items for Systematic reviews and Meta-Analyses literature search extension) checklist, and explanation and elaboration.

METHODS

The checklist was developed using a 3-stage Delphi survey process, followed by a consensus conference and public review process.

RESULTS

The final checklist includes 16 reporting items, each of which is detailed with exemplar reporting and rationale.

CONCLUSIONS

The intent of PRISMA-S is to complement the PRISMA Statement and its extensions by providing a checklist that could be used by interdisciplinary authors, editors, and peer reviewers to verify that each component of a search is completely reported and therefore reproducible.

Deep neural network modeling based virtual screening and prediction of potential inhibitors for renin protein

Renin enzyme plays an essential role in the Renin-Angiotensin System (RAS), and it is involved in the pathogenesis of hypertension and several other cardiovascular diseases (CVDs). Inhibition of renin is an effective way to intervene with the pathogenesis of these diseases. Docking-based virtual screening, 3D-Quantitative Structure-Activity Relationship (3D-QSAR), and structure-based drug design are the most frequently used strategies towards discovering novel inhibitors targeting renin. In this study, we have developed a 2D fingerprint-based Deep Neural Network (DNN) classifier for virtual screening and a DNN-QSAR model for biological activity prediction. The resulting hits from the DNN-QSAR model were then subjected to the molecular docking to identify further top hits. Molecular Dynamics (MD) simulation was conducted to get a better insight into the binding mode of identified hits. We have discovered six compounds from the Maybridge chemical database with the predicted IC₅₀ values ranging from 24.2 nM to 83.6 nM. To the best of our knowledge, this is the first study that used a cascaded DNN model to identify potential lead compounds for the inhibition of renin target. Through the results presented in this study, we provide evidence of the DNN method being a useful approach to identify new chemical entities/novel lead compounds that may overcome the limitation of existing conventional strategies used in drug discovery research.Communicated by Ramaswamy H. Sarma.

Renin inhibitors versus angiotensin converting enzyme (ACE) inhibitors for primary hypertension

BACKGROUND

Renin inhibitors (RIs) reduce blood pressure more than placebo, with the magnitude of this effect thought to be similar to that for angiotensin converting enzyme (ACE) inhibitors. However, a drug's efficacy in lowering blood pressure cannot be considered as a definitive indicator of its effectiveness in reducing mortality and morbidity. The effectiveness and safety of RIs compared to ACE inhibitors in treating hypertension is unknown.

OBJECTIVES

To evaluate the benefits and harms of renin inhibitors compared to ACE inhibitors in people with primary hypertension.

SEARCH METHODS

The Cochrane Hypertension Group Information Specialist searched the following databases for randomized controlled trials up to August 2020: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers about further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We included randomized, active-controlled, double-blinded studies (RCTs) with at least four weeks follow-up in people with primary hypertension, which compared renin inhibitors with ACE inhibitors and reported morbidity, mortality, adverse events or blood pressure outcomes. We excluded people with proven secondary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials, evaluated the risks of bias and entered the data for analysis.

MAIN RESULTS

We include 11 RCTs involving 13,627 participants, with a mean baseline age from 51.5 to 74.2 years. Follow-up duration ranged from four weeks to 36.6 months. There was no difference between RIs and ACE inhibitors for the outcomes: all-cause mortality: risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.18; 5 RCTs, 5962 participants; low-certainty evidence; total myocardial infarction: RR 0.86, 95% CI 0.22 to 3.39; 2 RCTs, 957 participants; very low-certainty evidence; adverse events: RR 0.98, 95% CI 0.93 to 1.03; 10 RTCs, 6007 participants;  moderate-certainty evidence; serious adverse events: RR 1.21, 95% CI 0.89 to 1.64; 10 RTCs, 6007 participants; low-certainty evidence; and withdrawal due to adverse effects: RR 0.85, 95% CI 0.68 to 1.06; 10 RTCs, 6008 participants; low-certainty evidence. No data were available for total cardiovascular events, heart failure, stroke, end-stage renal disease or change in heart rate. Low-certainty evidence suggested that RIs reduced systolic blood pressure: mean difference (MD) -1.72, 95% CI -2.47 to -0.97; 9 RCTs, 5001 participants;  and diastolic blood pressure: MD -1.18, 95% CI -1.65 to -0.72; 9 RCTs, 5001 participants,  to a greater extent than ACE inhibitors, but we judged this to be more likely due to bias than a true effect.  AUTHORS' CONCLUSIONS: For the treatment of hypertension, we have low certainty that renin inhibitors (RI) and angiotensin converting enzyme (ACE) inhibitors do not differ for all-cause mortality and myocardial infarction. We have low to moderate certainty that they do not differ for adverse events. Small reductions in blood pressure with renin inhibitors compared to ACE inhibitors are of low certainty.  More independent, large, long-term trials are needed to compare RIs with ACE inhibitors, particularly assessing morbidity and mortality outcomes, but also on blood pressure-lowering effect.

Vaccines against components of the renin-angiotensin system

Even though effective drugs for treating hypertension are available, a great percentage of patients have inadequate control of their blood pressure. Unwanted side effects and inappropriate oral drug adherence are important factors that contribute to the global problem of uncontrolled hypertension. Vaccination could provide a revolutionary therapy with long-lasting effects, increasing patient compliance and therefore better control of high blood pressure. Nowadays, current immunization approaches against hypertension target renin, angiotensin I, angiotensin II, and angiotensin II type 1 receptor, key elements of the renin–angiotensin system. This article reviews the different vaccination attempts with proteins and peptides against the different molecules of the renin–angiotensin system in the last two decades, safety issues, and other novel prospects biomarkers in hypertension, and summarizes the potential of this immunomodulatory approach in clinical practice.

Clinical efficacy, safety and tolerability of Aliskiren Monotherapy (AM): an umbrella review of systematic reviews

Background

Aliskiren is a newly developed drug. Its role in lowering BP has been recognized. However, the role of aliskiren in treating heart and renal diseases are still controversial.

Objective

To evaluate the existing evidence about clinical efficacy, safety and tolerability of aliskiren monotherapy (AM).

Methods

An umbrella review of systematic reviews of interventional studies. We searched Pubmed, Embase and Cochrane Library up to June 2019. Two reviewers applied inclusion criteria to the select potential articles independently. The extract and analyze of accessible data were did by two reviewers independently too. Discrepancies were resolved with discussion or the arbitration of the third author.

Results

Eventually, our review identified 14 eligible studies. Results showed that for essential hypertension patients, aliskiren showed a great superiority over placebo in BP reduction, BP response rate and BP control rate. Aliskiren and placebo, ARBs or ACEIs showed no difference in the number or extent of adverse events. For heart failure patients, AM did not reduce BNP levels (SMD -0.08, − 0.31 to 0.15) or mortality rate (RR 0.76, 0.32 to 1.80), but it decreased NT-proBNP (SMD -0.12, − 0.21 to − 0.03) and PRA levels (SMD 0.52, 0.30 to 0.75), increased PRC levels (SMD -0.66, − 0.8 to − 0.44). For patients who are suffered from hypertension and diabetes and/or nephropathy or albuminuria at the same time, aliskiren produced no significant effects (RR 0.97, 0.81 to 1.16).

Conclusion

We found solid evidence to support the benefits of aliskiren in the treatment of essential hypertension, aliskiren can produce significant effects in lowering BP and reliable safety. However, the effects of aliskiren in cardiovascular and renal outcomes were insignificant.

Trial registration

Study has been registered in PROSPERO (CRD42019142141).

Clinical efficacy, safety and tolerability of aliskiren monotherapy: a protocol for an umbrella review

INTRODUCTION

Aliskiren is a newly developed medicine. As one of the effective renin-angiotensin-aldosterone system inhibitors, its role in lowering blood pressure has been recognised. However, its safety and tolerability still remain controversial. The aim of the paper is to systematically summarise the published studies about the clinical efficacy and side effects of aliskiren monotherapy.

METHODS AND ANALYSIS

A comprehensive review of PubMed, Embase and Cochrane Library databases published from inception until June 2019 will be conducted. The selected articles are meta-analyses that integrated the randomised controlled studies, which evaluated efficacy, safety and tolerability of aliskiren monotherapy. Two people will select eligible articles and extract data independently. Any disputes will be resolved by discussion or the arbitration of a third person. The quality of reporting evidence will be assessed using the AMSTAR 2 tool. Study selection process will be presented using a flowchart. We will re-analyse each outcome with the random effect methods if necessary. If possible, we will also calculate 95% prediction intervals for each random effect estimate, by using Egger's test to evaluate if the reporting bias existed.

ETHICS AND DISSEMINATION

Ethical approval is not required for the study, as we only collected data from available published materials. This umbrella review will be also submitted to a peer-reviewed journal for publication after completion.

PROSPERO REGISTRATION NUMBER

CRD42019142141.

Proteomic Analysis of Longitudinal Changes in Blood Pressure

Hypertension is the leading risk factor for premature death worldwide. The identification of modifiable causes of hypertension remains an imperative task. We aimed to investigate associations between 79 proteins implicated in cardiovascular disease and longitudinal blood pressure (BP) changes in three Swedish prospective cohorts. In a discovery phase, we investigated associations between baseline circulating protein levels assessed with a proximity extension assay and BP stage progression at follow-up 5 years later among persons without BP-lowering drugs at baseline in two independent community-based cohorts from the Prospective Investigation of the Vasculature in Uppsala Seniors study (PIVUS) and the Uppsala Longitudinal Study of Adult Men (ULSAM). We used an independent cohort, the Malmö Diet and Cancer Study (MDC), for replication. The primary outcome of BP stage progression was defined as per the 2017 AHA/ACC (American Heart Association/ American College of Cardiology) Guideline BP categories. We also investigated associations of protein levels with changes in BP on a continuous scale, and meta-analyzed all three cohorts. Levels of renin were associated with BP stage progression with a 5% false discovery rate (FDR) in the ULSAM (n = 238) and PIVUS (n = 566) cohorts, but we could not replicate this association in the MDC cohort (n = 2659). The association in the discovery cohorts was modest, with an odds ratio for BP stage progression over 5 years of 1.33 (95% confidence interval 1.14 to 1.56) per standard deviation of baseline renin. In conclusion, we could not find any novel robust associations with longitudinal BP increase in a proximity extension assay-based proteomics investigation in three cohorts.

Protective Effects of Nanoparticle-Loaded Aliskiren on Cardiovascular System in Spontaneously Hypertensive Rats

Aliskiren, a renin inhibitor, has been shown to have cardioprotective and blood pressure (BP) lowering effects. We aimed to determine the effects of nanoparticle-loaded aliskiren on BP, nitric oxide synthase activity (NOS) and structural alterations of the heart and aorta developed due to spontaneous hypertension in rats. Twelve week-old male spontaneously hypertensive rats (SHR) were divided into the untreated group, group treated with powdered or nanoparticle-loaded aliskiren (25 mg/kg/day) and group treated with nanoparticles only for 3 weeks by gavage. BP was measured by tail-cuff plethysmography. NOS activity, eNOS and nNOS protein expressions, and collagen content were determined in both the heart and aorta. Vasoactivity of the mesenteric artery and wall thickness, inner diameter, and cross-sectional area (CSA) of the aorta were analyzed. After 3 weeks, BP was lower in both powdered and nanoparticle-loaded aliskiren groups with a more pronounced effect in the latter case. Only nanoparticle-loaded aliskiren increased the expression of nNOS along with increased NOS activity in the heart (by 30%). Moreover, nanoparticle-loaded aliskiren decreased vasoconstriction of the mesenteric artery and collagen content (by 11%), and CSA (by 25%) in the aorta compared to the powdered aliskiren group. In conclusion, nanoparticle-loaded aliskiren represents a promising drug with antihypertensive and cardioprotective effects.

Treatment of Hypertension in Complex Older Adults: How Many Medications Are Needed?

Background: Many older adults with hypertension receive multiple antihypertensives. It is unclear whether treatment with several antihypertensive classes results in greater cardiovascular benefits than fewer antihypertensive classes. Objectives: We investigated (a) the longitudinal associations between treatment with ≥ 3 versus 1-2 classes and death and major adverse cardiovascular events (MACE) and (b) whether these associations varied by the presence of mobility disability. Methods: We included 6,011 treated hypertensive adults ≥65 from the Medical Expenditure Panel Survey (MEPS), a nationally representative community sample. Times to MACE and death were compared between those receiving ≥3 versus 1-2 classes using multivariable proportional hazards regression. We used inverse probability of treatment weighting to account for indication and contraindication bias. Results: There were no significant differences in the risk of mortality (hazard ratio [HR] = 0.96, p = .769) or MACE (HR = 1.10, p = .574) between the exposure groups, and there were no significant exposure × mobility disability interactions. Discussion: We found no benefit of ≥3 versus 1-2 antihypertensive classes in reducing mortality and cardiovascular events in a representative cohort of older adults, raising concern about the added benefit of additional antihypertensives in the real world.

Intratubular and intracellular renin-angiotensin system in the kidney: a unifying perspective in blood pressure control

The renin-angiotensin system (RAS) is widely recognized as one of the most important vasoactive hormonal systems in the physiological regulation of blood pressure and the development of hypertension. This recognition is derived from, and supported by, extensive molecular, cellular, genetic, and pharmacological studies on the circulating (tissue-to-tissue), paracrine (cell-to-cell), and intracrine (intracellular, mitochondrial, nuclear) RAS during last several decades. Now, it is widely accepted that circulating and local RAS may act independently or interactively, to regulate sympathetic activity, systemic and renal hemodynamics, body salt and fluid balance, and blood pressure homeostasis. However, there remains continuous debate with respect to the specific sources of intratubular and intracellular RAS in the kidney and other tissues, the relative contributions of the circulating RAS to intratubular and intracellular RAS, and the roles of intratubular compared with intracellular RAS to the normal control of blood pressure or the development of angiotensin II (ANG II)-dependent hypertension. Based on a lecture given at the recent XI International Symposium on Vasoactive Peptides held in Horizonte, Brazil, this article reviews recent studies using mouse models with global, kidney- or proximal tubule-specific overexpression (knockin) or deletion (knockout) of components of the RAS or its receptors. Although much knowledge has been gained from cell- and tissue-specific transgenic or knockout models, a unifying and integrative approach is now required to better understand how the circulating and local intratubular/intracellular RAS act independently, or with other vasoactive systems, to regulate blood pressure, cardiovascular and kidney function.