Renin-angiotensin system blocking drugs

Orphan GPCR GPRC5C Facilitates Angiotensin II-Induced Smooth Muscle Contraction

BACKGROUND

GPCRs (G-protein-coupled receptors) play a central role in the regulation of smooth muscle cell (SMC) contractility, but the function of SMC-expressed orphan GPCR class C group 5 member C (GPRC5C) is unclear. The aim of this project is to define the role of GPRC5C in SMC in vitro and in vivo.

METHODS

We studied the role of GPRC5C in the regulation of SMC contractility and differentiation in human and murine SMC in vitro, as well as in tamoxifen-inducible, SMC-specific GPRC5C knockout mice under basal conditions and in vascular disease in vivo.

RESULTS

Mesenteric arteries from tamoxifen-inducible, SMC-specific GPRC5C knockout mice showed ex vivo significantly reduced angiotensin II (Ang II)-dependent calcium mobilization and contraction, whereas responses to other relaxant or contractile factors were normal. In vitro, the knockdown of GPRC5C in human aortic SMC resulted in diminished Ang II-dependent inositol phosphate production and lower myosin light chain phosphorylation. In line with this, tamoxifen-inducible, SMC-specific GPRC5C knockout mice showed reduced Ang II-induced arterial hypertension, and acute inactivation of GPRC5C was able to ameliorate established arterial hypertension. Mechanistically, we show that GPRC5C and the Ang II receptor AT1 dimerize, and knockdown of GPRC5C resulted in reduced binding of Ang II to AT1 receptors in HEK293 cells, human and murine SMC, and arteries from tamoxifen-inducible, SMC-specific GPRC5C knockout mice.

CONCLUSIONS

Our data show that GPRC5C regulates Ang II-dependent vascular contraction by facilitating AT1 receptor-ligand binding and signaling.

Nanotechnology-Based Strategies for Extended-Release Delivery of Angiotensin Receptor Blockers (ARBs): A Comprehensive Review

There has been a significant shift in the perception of hypertension as an important contributor to the global disease burden. Approximately 6 % and 8 % of pregnancies are affected by hypertension, which can adversely affect the mother and the fetus. Furthermore, a hypertensive individual is at increased risk of developing kidney disease, arterial hardening, eye damage, and strokes. Using angiotensin receptor blockers (ARBs) is widespread in treating hypertension, heart failure, coronary artery disease, and diabetic nephropathy. Despite this, some ARBs have limited use due to their poor oral bioavailability and water solubility. To tackle this, a variety of nanoparticle (NP)-based systems, such as polymeric NPs (i. e., dendrimers), polymeric micelles, polymer-drug conjugates, lipid NPs, nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid NPs (SLNs), nanostructured lipid carriers (NLCs), carbon-based nanocarriers, inorganic NPs, and nanocrystals, have been recently developed for efficient delivery of losartan, Valsartan (Val), Olmesartan (OLM), Telmisartan (TEL), Candesartan, Eprosartan, Irbesartan, and Azilsartan to target cells. This review article provides a literature-based comparison of the various classes of ARBs, their mechanisms of action, and an overview of the nanoformulations developed for ARB delivery and successfully applied to managing hypertension, diabetic complications, and other conditions.

Effect of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers on need for operative intervention for idiopathic adhesive capsulitis

Background

The exact pathogenesis of idiopathic adhesive capsulitis (IAC) is not fully understood, but an inflammatory profibrotic cascade, largely mediated by transforming growth factor-beta 1 (TGF- β1) has been implicated. Angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACE-Is) both decrease the activity of TGF-β1. The aim of this study was to determine the impact of ACE-Is or ARBs use on the need for operative intervention in IAC.

Methods

This was a retrospective cohort study of patients from a single institutional database with IAC, divided into two cohorts, with and without ACE-I and/or ARB use as the primary exposure and a minimum 2-year follow-up. The primary outcome measured was the incidence of operative intervention including manipulation under anesthesia (MUA) and arthroscopic capsular release (ACR). Additional multivariable logistic regression analysis was performed to evaluate associations between ACE-I/ARB use and likelihood of undergoing an operative procedure.

Results

A total of 17,645 patients met inclusion criteria, with 5424 patients in the ACE-I/ARB cohort and 12,221 in the non-ACE-I/ARB cohort. Overall, 422 (2.4%) patients underwent surgical treatment, 378 (2.1%) ACR, and 74 (0.4%) MUA. There was no significant difference between cohorts in the frequency of surgical procedures or time to procedure since diagnosis. There were no significant differences between individual ACE-Is or ARBs, although Losartan was found to have a trend of decreased rate of intervention (31.7% vs. 36.8%, P = .209) when compared to patients not on losartan that did not reach statistical significance. Patient factors predictive of undergoing MUA/ACR were diabetes (P = .013), obesity (P < .001), and male sex (P < .001). Increasing patient age reduces the likelihood of undergoing operative intervention, with patients aged 50-70 years (P = .022) and age >70 years (P < .001) demonstrating reduced odds as compared to patients aged <30 years.

Conclusion

Patients with IAC have an overall low (2.4%) rate of requiring surgical intervention. While the antifibrotic mechanism of ACE inhibitors and ARBs did not significantly affect the rate of requiring surgical intervention, male gender, obesity, younger age, and diabetes, all increased the risk for operative intervention. Losartan, specifically, may have a disease modifying effect on IAC that should be investigated with larger controlled trials.

Angiotensin Receptor Blockers and Angiotensin-Converting Enzyme Inhibitors Have No Significant Relationship With Postoperative Arthrofibrosis After Shoulder Arthroscopy

Purpose

To determine the effect of perioperative angiotensin II receptor blocker (ARB) or angiotensin-converting enzyme inhibitors (ACEi) on postoperative arthrofibrosis, as defined by requiring manipulation under anesthesia (MUA) or new diagnosis of adhesive capsulitis (AC) following arthroscopic shoulder procedures.

Methods

Patients were retrospectively identified using Current Procedural Terminology surgical billing codes to identify patients who underwent any shoulder arthroscopic procedure at a single urban academic institution from 2012 to 2020 with a minimum 2-year follow-up. Patients were excluded if <30 years old at time of surgery, as these patients rarely use ARB and ACEi medications, or if they had pre-existing AC. Demographics, active medication prescriptions at the time of surgery, and medical comorbidities were recorded. Multivariable logistic regression was performed to determine the effect of ARB/ACEi on subsequent MUA or AC by 90 days, 1 year, and 2 years.

Results

In total, 5,559 patients were included in the final analysis. A majority of the cohort (53.4%) underwent arthroscopic surgery between the ages of 50 to 69 years. Most patients were male (61.8%) and without obesity (67.3%). In total, 18.9% and 15.0% were taking an ARB or ACEi medication perioperatively, respectively. Within 2 years' postoperatively, 51 patients (0.9%) underwent subsequent ipsilateral MUA, and 174 patients (3.1%) developed AC. Patients taking ARBs had a 17.5% rate of postoperative arthrofibrosis within 2-years compared with 19.1% in those not on ARBs, although this difference was not significant (P = .58). Likewise, no significant difference was found between those taking ACEi versus not (15.0% vs 15.0%, P = .99). Individual generic ARB/ACEi subgroup analysis did not demonstrate any significant associations with rate of postoperative arthrofibrosis (P > .05).

Conclusions

ARBs or ACEi did not significantly affect the rate of postoperative arthrofibrosis following shoulder arthroscopy, however female sex, diabetes mellitus, and Black/African American race were associated with an increased rate of necessitating MUA or developing AC within 2 years postoperatively.

Level of Evidence

Level III, retrospective cohort study.

Angiotensin-Converting Enzyme and Hypertension: A Systemic Analysis of Various ACE Inhibitors, Their Side Effects, and Bioactive Peptides as a Putative Therapy for Hypertension

Hypertension is a major risk factor for heart attack, produce atherosclerosis (hardening of the arteries), congestive heart failure, stroke, kidney infection, blindness, end-stage renal infection, and cardiovascular diseases. Many mechanisms are involved in causing hypertension, i.e., via calcium channels, alpha and beta receptors, and the renin-angiotensin system (RAS). RAS has an important role in blood pressure control and is also involved in the metabolism of glucose, homeostasis, and balance of electrolytes in the body. The components of RAS that are involved in the regulation of blood pressure are angiotensinogen, Ang I (angiotensin I), Ang II (angiotensin II), ACE (angiotensin-converting enzyme), and ACE 2 (angiotensin-converting enzyme 2). These components provide for relevant therapeutic targets for the treatment of hypertension, and various drugs are commercially available that target individual components of RAS. Angiotensin receptor blockers (ARBs) and ACE inhibitors are the most popular among these drugs. ACE is chosen in this review as it makes an important target for blood pressure control because it converts Ang I into Ang II and also acts on the vasodilator, bradykinin, to degrade it into inactive peptides. This review highlights various aspects of blood pressure regulation in the body with a focus on ACE, drugs targeting the components involved in regulation, their associated side effects, and a need to shift to alternative therapy for putative hypertension treatment in the form of bioactive peptides from food.

Independent Prognostic and Predictive Role of Interstitial Macrophages in Kidney Biopsies of IgA Nephropathy Patients

A relevant percentage of IgAN patients experience a progressive decline in kidney function. According to the KDIGO guidelines, proteinuria and eGFR are the only validated prognostic markers. The role of interstitial macrophages in kidney biopsies of IgAN patients and the outcome of patients treated with renin-angiotensin system inhibitors (RASBs) alone or combined with glucocorticoids were evaluated. Clinical and laboratory records (age, gender, hypertension, hematuria, proteinuria, eGFR, serum creatinine, and therapy), MEST-C parameters of the Oxford classification, C4d deposition, peritubular capillaries, and glomerular and interstitial macrophages in 47 IgAN patients undergoing kidney biopsy consecutively between 2003 and 2016 were examined. A high number of interstitial macrophages significantly correlated with peritubular capillary rarefaction and impairment of kidney function. Cox's multivariable regression analysis revealed that a value > 19.5 macrophages/HPF behaved as an independent marker of an unfavorable outcome. Patients exhibiting > 19.5 macrophages/HPF treated at the time of diagnosis with RASBs combined with methylprednisolone had an estimated probability of a favorable outcome higher than patients treated with RASBs alone. Thus, a value > 19.5 macrophages/HPF in IgAN biopsies can predict an unfavorable outcome and endorse a well-timed administration of glucocorticoids. Studies evaluating urine biomarkers associated with peritubular capillary rarefaction in patients with marked macrophage infiltration may help personalized treatment decisions.

Renin-angiotensin system: The underlying mechanisms and promising therapeutical target for depression and anxiety

Emotional disorders, including depression and anxiety, contribute considerably to morbidity across the world. Depression is a serious condition and is projected to be the top contributor to the global burden of disease by 2030. The role of the renin-angiotensin system (RAS) in hypertension and emotional disorders is well established. Evidence points to an association between elevated RAS activity and depression and anxiety, partly through the induction of neuroinflammation, stress, and oxidative stress. Therefore, blocking the RAS provides a theoretical basis for future treatment of anxiety and depression. The evidence for the positive effects of RAS blockers on depression and anxiety is reviewed, aiming to provide a promising target for novel anxiolytic and antidepressant medications and/or for improving the efficacy of currently available medications used for the treatment of anxiety and depression, which independent of blood pressure management.

Antihypertensive Use and the Risk of Alzheimer's Disease and Related Dementias among Older Adults in the USA

BACKGROUND

Epidemiological evidence on different classes of antihypertensives and risks of Alzheimer's disease and related dementias (ADRD) is inconclusive and limited. This study examined the association between antihypertensive use (including therapy type and antihypertensive class) and ADRD diagnoses among older adults with hypertension.

METHODS

A retrospective, cross-sectional study was conducted, involving 539 individuals aged ≥ 65 years who used antihypertensives and had ADRD diagnosis selected from 2013 to 2018 Medical Expenditure Panel Survey (MEPS) data. The predictors were therapy type (monotherapy or polytherapy) and class of antihypertensives defined using Multum Lexicon therapeutic classification (with calcium channel blockers [CCBs] as the reference group). Weighted logistic regression was used to assess the relationships of therapy type and class of antihypertensives use with ADRD diagnosis, adjusting for sociodemographic characteristics and health status.

RESULTS

We found no significant difference between monotherapy and polytherapy on the odds of ADRD diagnosis. As to monotherapy, those who used angiotensin-converting enzyme inhibitors (ACEIs) had significantly lower odds of developing AD compared to those who used CCBs (OR 0.36, 95 % CI 0.13-0.99).

CONCLUSIONS

Findings of the study suggest the need for evidence-based drug therapy to manage hypertension in later adulthood and warrant further investigation into the mechanism underlying the protective effect of antihypertensives, particularly ACEIs, against the development of AD among older adults with hypertension.

Losartan Mitigates Oxidative Stress in the Brains of Aged and Inflamed IL-10-/- Mice

Chronic inflammation, oxidative stress, and dysregulation of the renin-angiotensin system are closely linked, and their crosstalk commonly contributes to age-related physical and cognitive decline. The primary dementia-protective benefits of Angiotensin II type 1 receptor (AT1R) blockers are believed to arise from systemic effects on blood pressure. However, there is an independently regulated brain-specific renin-angiotensin system. Here, we examined the impact of 4 weeks of oral Losartan treatment on the brains of aged (100 weeks old) IL-10-/- mice, an animal model of chronic inflammation and frailty. Our data show that aged IL-10-/- mice have higher AT1R and Nitrotyrosine (oxidative stress marker) levels in their frontal cortex tissue but not in cerebellar or hippocampal tissue compared to age- and sex-matched wild type mice. Losartan treatment for 4 weeks is associated with lower AT1R protein level, Nitrotyrosine, and Tau protein in the frontal cortex of aged IL-10-/- mice. Our results highlight the impact of Losartan, an AT1R blocker commonly prescribed for treating high blood pressure, on the brain-specific angiotensin system and AT1R-linked downstream effects such as brain oxidative stress damage and Tau burden in a frailty mouse model.

The renin-angiotensin system and cardiovascular autonomic control in aging

Aging is the greatest independent risk factor for developing hypertension and cardiovascular-related diseases including systolic hypertension, vascular disease, ischemic events, arrhythmias, and heart failure. Age-related cardiovascular risk is associated with dysfunction of peripheral organ systems, such as the heart and vasculature, as well as an imbalance in the autonomic nervous system characterized by increased sympathetic and decreased parasympathetic neurotransmission. Given the increasing prevalence of aged individuals worldwide, it is critical to better understand mechanisms contributing to impaired cardiovascular autonomic control in this population. In this regard, the renin-angiotensin system has emerged as an important hormonal modulator of cardiovascular function in aging, in part through modulation of autonomic pathways controlling sympathetic and parasympathetic outflow to cardiovascular end organs. This review will summarize the role of the RAS in cardiovascular autonomic control during aging, with a focus on current knowledge of angiotensin II versus angiotensin-(1-7) pathways in both rodent models and humans, pharmacological treatment strategies targeting the renin-angiotensin system, and unanswered questions for future research.

Decreased Tissue Kallikrein Levels and the Risk of Ischemic Stroke: A Community-Based Cross-Sectional Study in China

Aim

Tissue kallikrein (TK) exerts protective effects on cardiac cerebrovascular diseases (CCVDs). Changes in TK level in plasma are associated with ischemic stroke and coronary artery disease (CAD); however, a causal correlation could not be established. Therefore, we investigated the association between TK levels and CCVDs in a community-based cross-sectional study in China.

Methods

A total of 6043 subjects (4242 men and 1801 women) were enrolled in this community-based cross-sectional study. Then, TK levels were measured using an enzyme-linked immunosorbent assay kit. Multivariate linear regression model and logistic regression were used to assess the correlations between TK levels and CCVDs. Subsequently, the receiver operating characteristic (ROC) curve was drawn to assess the value of TK level in evaluating the risk of ischemic stroke. Finally, the influence of various medications was evaluated on TK levels.

Results

The TK level was significantly lower in subjects with ischemic stroke (P < 0.001) and hypertension (P < 0.001) and negatively associated with ischemic stroke (P < 0.001) but not associated with hypertension, coronary heart disease, and diabetes compared to the traditional risk factors. The diagnostic accuracy for ischemic stroke, as quantified by the area under the curve, was 0.892 (95% CI, 0.884–0.900) for TK level, deeming it as a promising assessment tool. Moreover, no appreciable influence of various drugs therapy was found in TK levels (P = 0.222) except for those taking antilipemic agents.

Conclusion

TK is a strong and independent endogenous protective factor against ischemic stroke in the Chinese population and could be a promising biomarker for the risk of ischemic stroke.

Antiretroviral Treatment and Antihypertensive Therapy

The presence of hypertension among the population with human immunodeficiency virus (HIV) has become a new threat to the health and well-being of people living with this disease, in particular, among those who received antiretroviral therapy. The estimated prevalence of high blood pressure in HIV-infected patients is significantly higher than the rate observed in HIV-uninfected subjects. The approach to the HIV-positive patient requires the assessment of individual cardiovascular risk and its consideration when designing the individualized target. On the other hand, the numerous pharmacological interactions of antiretroviral (ARV) drugs are essential elements to take into account. Serum levels of any kind of antihypertensive drugs may be influenced by the coadministration of protease inhibitors, non-nucleoside reverse transcriptase inhibitor, or other antiretroviral. Similarly, plasma concentrations of antiretroviral drugs can be increased by the concomitant use of calcium channel blockers or diuretics. In this regard, the treatment of high blood pressure in HIV patients should be preferentially based on ACE inhibitors or thiazide/thiazide-like diuretics or their combination.

The Therapeutic Potential of Targeting the Angiotensin Pathway as a Novel Therapeutic Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Post-surgical adhesion is a common complication after abdominal or pelvic surgeries. Despite improvements in surgical techniques or the application of physical barriers, little improvements have been achieved. It causes bowel obstruction, pelvic pain, and infertility in women and has an adverse effect on the quality of life. Renin-Angiotensin System (RAS) is traditionally considered as a blood pressure regulator. However, recent studies also indicate that the RAS plays a vital role in other processes, including oxidative stress, fibrosis, proliferation, inflammation, and the wound healing process. Angiotensin II (Ang II) is the main upstream effector of the RAS that can bind to the AT1 receptor (ATIR). A growing body of evidence has revealed that targeting Angiotensin-Converting Enzyme Inhibitors (ACEIs), Angiotensin II type 1 Receptor Blockers (ARBs), and Direct Renin Inhibitors (DRIs) can prevent post-surgical adhesions. Here we provide an overview of the therapeutic effect of RAS antagonists for adhesion.

METHODS

PubMed, EMBASE, and the Cochrane library were reviewed to identify potential agents targeting the RAS system as a potential approach for post-surgical adhesion.

RESULTS

Available evidence suggests the involvement of the RAS signaling pathway in inflammation, proliferation, and fibrosis pathways as well as in post-surgical adhesions. Several FDA-approved drugs are being used for targeting the RAS system. Some of them are being tested in different models to reduce fibrosis and improve adhesion after surgery, including Telmisartan, valsartan, and enalapril.

CONCLUSION

Identification of the pathological causes of post-surgical adhesion and the potential role of targeting Renin-Angiotensin System may help prevent this problem. Based on the pathological function of RAS signaling after surgeries, the administration of ARBs may be considered as a novel and efficient approach to prevent postsurgical adhesions. Pre-clinical and clinical studies should be carried out to have better information on the clinical significance of this therapy against post-surgical adhesion formation.

Clitoria ternatea L. extract prevents kidney damage by suppressing the Ang II/Nox4/oxidative stress cascade in l-NAME-induced hypertension model of rats

Clitoria ternatia L. (CT) has been reported to have anti-inflammatory and antioxidant effects. This study investigated the effect of CT aqueous flower extract on blood pressure and renal alterations in N^ω-nitro-l-arginine methyl ester hydrochloride (l-NAME)-induced hypertensive rats. Male Sprague Dawley rats received l-NAME in drinking water and were treated with CT flower extract or lisinopril. CT aqueous flower extract and lisinopril alleviated l-NAME-induced hypertension (p < 0.05). Glomerular extracellular matrix accumulation, renal fibrosis, and increased serum creatinine levels were observed in l-NAME-induced hypertensive rats and attenuated by CT flower extract or lisinopril co-treatment (p < 0.05). High levels of plasma angiotensin II (Ang II) and upregulated nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) protein expression in the kidneys induced by l-NAME were alleviated by CT flower extract or lisinopril co-treatment (p < 0.05). Furthermore, CT flower extract and lisinopril treatment reduced lipid peroxidation and elevated plasma and kidney malondialdehyde levels in l-NAME-induced hypertensive rats (p < 0.05). In conclusion, CT flower extract prevented l-NAME-induced renal injury and dysfunction in rats. The possible mechanism may be related to the suppression of Ang II-mediated Nox4 expression and the oxidative stress cascade in rats.

Renal haemodynamic and protective effects of renoactive drugs in type 2 diabetes: Interaction with SGLT2 inhibitors

Diabetic kidney disease remains the leading cause of end‐stage kidney disease and a major risk factor for cardiovascular disease. Large cardiovascular outcome trials and dedicated kidney trials have shown that sodium‐glucose cotransporter (SGLT)2 inhibitors reduce cardiovascular morbidity and mortality and attenuate hard renal outcomes in patients with type 2 diabetes (T2D). Underlying mechanisms explaining these renal benefits may be mediated by decreased glomerular hypertension, possibly by vasodilation of the post‐glomerular arteriole. People with T2D often receive several different drugs, some of which could also impact the renal vasculature, and could therefore modify both renal efficacy and safety of SGLT2 inhibition. The most commonly prescribed drugs that could interact with SGLT2 inhibitors on renal haemodynamic function include renin‐angiotensin system inhibitors, calcium channel blockers and diuretics. Herein, we review the effects of these drugs on renal haemodynamic function in people with T2D and focus on studies that measured glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) with gold‐standard techniques. In addition, we posit, based on these observations, potential interactions with SGLT2 inhibitors with an emphasis on efficacy and safety.

This invited review describes the renal haemodynamic and protective effects of commonly prescribed drugs in people with type 2 diabetes and their interaction with SGLT2 inhibitors.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers as therapeutic options in the treatment of renal cancer: A meta-analysis

AIMS

Angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) which have been used in the treatment of cardiovascular diseases, have also been shown to have anti-tumor effects against various cancers that include renal cancer. The aim of current paper was to explore the potential clinical impact of ACEI/ARB inhibitors in renal cancer.

MAIN METHODS

We used several databases: EMBASE, PubMed and the Cochrane library, to identify clinical studies that assessed the relationship between ACEIs/ARBs treatment and risk of renal cancer incidence or survival of renal cancer patients. The hazard ratio (HR) with 95% confidence intervals were obtained for assessing the relationship between ACEIs/ARBs and renal cancer mortality.

KEY FINDING

The HR for the relationship between ASIs use and survival of renal cancer indicated that patients with renal cancer being treated with ACEIs/ARBs had a significantly lower mortality than non-user (HR 0.723, 95% CI 0.568-0.921, p = 0.009). The HR for the relationship between ACEIs use and survival of renal cancer indicated that patients with renal cancer that used ACEIs had a higher mortality than non-users (HR 1.352, 95% CI 0.917-1.991, p = 0.128). The HR for the relationship between ARBs use and survival of renal cancer indicated that patients with renal cancer that used ARBs had a decreased of mortality than non-users (HR 0.818, 95% CI 0.691-0.969, p = 0.02).

SIGNIFICANCE

This meta-analysis demonstrated that treatment with ACEIs/ARBs may improve renal cancer survival and reduce the mortality of patients with renal cancer.

Aliskiren improves renal morphophysiology and inflammation in Wistar rats with 2K1C renovascular hypertension

Hypertension is characterized by persistent elevated blood pressure levels, one of the leading causes of death in the world. Renovascular hypertension represents the most common cause of secondary hypertension, and its progress is associated with overactivation of the renin angiotensin aldosterone system (RAAS), causing systemic and local changes. Aliskiren is a renin-inhibiting drug that optimizes RAAS suppression. In this sense, the objective of the present study was to analyze the morphophysiology of the left kidney in Wistar rats with renovascular hypertension after treatment with Aliskiren. Parameters such as systolic blood pressure, urinary creatinine and protein excretion, renal cortex structure and ultrastructure, fibrosis and tissue inflammation were analyzed. Our results showed that the hypertensive animals treated with Aliskiren presented a reestablishment of blood pressure, expression of renin, and renal function, as well as a remodeling of morphological alterations through the reduction of fibrosis. The treatment regulated the laminin expression and decreased pro-inflammatory cytokines, restoring the integrity of the glomerular filtration barrier. Therefore, our findings suggest that Aliskiren has a renoprotective effect acting on the improvement of the morphology, physiology and pathology of the renal cortex of animals with renovascular hypertension.

The skeletal renin-angiotensin system: A potential therapeutic target for the treatment of osteoarticular diseases

The classical renin-angiotensin system (RAS) is known to be a key regulator of blood pressure as well as fluid and electrolyte homeostasis. Additionally, it is now evident that components of the RAS are produced and act locally in many tissues, including liver, kidney, heart, lung, eye, bone, reproductive organ, adipose, and adrenal tissue, and these components are collectively known as tissue RAS. Recently, several studies have shown that local bone RAS is directly involved in bone metabolism, and activation of skeletal RAS plays an important role in bone diseases, such as osteoporosis, arthritis, and deterioration as well as in fracture healing. Based on the identification of RAS components in bone, we examined a new therapeutic approach to attenuate bone diseases through RAS inhibitors: renin inhibitor, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. In this paper, we provide a systematic review of the skeletal RAS in the pathophysiology of bone diseases and the beneficial effect of RAS inhibitors on bone tissue.

The renin-angiotensin system in cardiovascular autonomic control: recent developments and clinical implications

Complex and bidirectional interactions between the renin-angiotensin system (RAS) and autonomic nervous system have been well established for cardiovascular regulation under both physiological and pathophysiological conditions. Most research to date has focused on deleterious effects of components of the vasoconstrictor arm of the RAS on cardiovascular autonomic control, such as renin, angiotensin II, and aldosterone. The recent discovery of prorenin and the prorenin receptor have further increased our understanding of RAS interactions in autonomic brain regions. Therapies targeting these RAS components, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers, are commonly used for treatment of hypertension and cardiovascular diseases, with blood pressure-lowering effects attributed in part to sympathetic inhibition and parasympathetic facilitation. In addition, a vasodilatory arm of the RAS has emerged that includes angiotensin-(1-7), ACE2, and alamandine, and promotes beneficial effects on blood pressure in part by reducing sympathetic activity and improving arterial baroreceptor reflex function in animal models. The role of the vasodilatory arm of the RAS in cardiovascular autonomic regulation in clinical populations, however, has yet to be determined. This review will summarize recent developments in autonomic mechanisms involved in the effects of the RAS on cardiovascular regulation, with a focus on newly discovered pathways and therapeutic targets for this hormone system.

Inhibition of renin-angiotensin axis reduces the risk of thrombus formation in the left atrial appendage in patients with hypertension complicated by atrial fibrillation

Aims:

We examined whether the use of a renin-angiotensin-aldosterone system (RAS) inhibitor plays a role in protecting against left atrial appendage thrombus (LAAT) in patients with hypertension complicated by atrial fibrillation (AF).

Methods:

Two observational studies were conducted on patients with diagnoses of hypertension and AF, who were categorized into RAS inhibitor user or nonuser groups. Demographic characteristics, clinical characteristics, echocardiographic parameters and hemostatic markers were examined and the occurrence of LAAT during follow-up were recorded.

Results:

In the first study (n = 131), LA peak systolic strain and LAA emptying flow velocity (LAA eV) were significantly increased in patients on RAS inhibitors compared with the nonuser group (p < 0.05). Lower D-dimer and fibrinogen levels were observed in patients on RAS inhibitors (p < 0.05). In the second study (n = 99), 25.9% (n = 11) of patients on RAS inhibitors developed LAAT, compared with 46.7% (n = 21) in the nonuser group (p < 0.05). After controlling for risk factors related to LAAT, use of RAS inhibitors remained associated with a significantly lower risk of developing LAAT (HR, 0.406; 95% CI, 0.191–0.862; p = 0.019).

Conclusions:

RAS inhibitors use was associated with a significant reduction in the risk of LAAT in patients with hypertension and AF.

Effects of Low Muscle Mass on Albuminuria and Chronic Kidney Disease in Patients With Type 2 Diabetes: The Korean Sarcopenic Obesity Study (KSOS)

Background

Previous studies have shown that chronic kidney disease (CKD) is associated with accelerated loss of skeletal muscle in patients on dialysis. However, the relationships of sarcopenia with albuminuria and early-stage CKD in patients with type 2 diabetes have not been examined.

Methods

We analyzed diabetic subgroup data from 409 patients with type 2 diabetes from the Korean Sarcopenic Obesity Study (KSOS). Sarcopenia was defined as a skeletal muscle mass index (SMI; SMI [%] = total skeletal muscle mass [kg]/weight [kg] × 100) less than 2 SD below the sex-specific mean for a younger reference group. The estimated glomerular filtration rates and urinary albumin-to-creatinine ratios were used to assess renal function and albuminuria.

Results

The prevalence of sarcopenia was significantly increased in the albuminuria group compared with the normo-albuminuria group (26.7% vs 12.6%, p = .001), as well as in CKD 3 group compared with the CKD 1-2 group (46.7% vs 15.1%, p = .005). After adjusting for age, SMI was negatively correlated with urinary albumin-to-creatinine ratios and positively correlated with aspartate aminotransferase, alanine aminotransferase, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels. Multiple logistic regression analysis revealed that the odds ratio for albuminuria association was 3.02 (95% CI 1.37-6.67) in the lowest tertile of SMI compared with the highest tertile after adjusting for various confounding factors.

Conclusions

Sarcopenia is more prevalent in individuals with albuminuria than in those without albuminuria. Furthermore, increased albuminuria is independently associated with low muscle mass in patients with type 2 diabetes.

KLF 15 Works as an Early Anti-Fibrotic Transcriptional Regulator in Ang II-Induced Renal Fibrosis via Down-Regulation of CTGF Expression

BACKGROUND/AIMS

Angiotensin II (Ang II) has been regarded as an important profibrogenic cytokine in renal fibrosis. Krüppel-like factor 15 (KLF15) has been identified as an important negative transcription factor in renal fibrosis. However, little is known about the role of KLF15 in Ang II-induced renal fibrosis.

METHODS

In this study, we randomized mice into a control group, Ang II group or Ang II plus losartan group. KLF15 expression was examined with real-time PCR and immunofluorescence in these groups. In vitro, KLF15 expression was examined by Western blot in rat renal fibroblasts (NRK-49F) stimulated with Ang II, and the effect of altered KLF15 expression on the regulation of the profibrotic factor connective tissue growth factor (CTGF) was further explored with co-immunoprecipitation (CoIP) and chromatin immunoprecipitation (ChIP) analyses.

RESULTS

Compared with the control group, the murine model of Ang II-induced renal fibrosis demonstrated a significant decrease in renal KLF15 expression at 4 weeks and presented with progressive renal fibrosis at 6 weeks. Meanwhile, losartan, an angiotensin type 1 (AT1) receptor antagonist, effectively prevented the down-regulation of KLF15 expression induced by Ang II infusion. In vitro, NRK-49F cells stimulated with Ang II exhibited a significant decrease in KLF15 expression, accompanied by a marked increase in the expression of profibrotic factors and in the production of extracellular matrix. The up-regulation of CTGF expression induced by Ang II stimulation was inhibited by KLF15 overexpression in NRK-49F cells, and losartan treatment prevented the down-regulation of KLF15 expression and the up-regulation of CTGF expression induced by Ang II stimulation. Furthermore, CoIP and ChIP assays revealed that the transcription regulator KLF15 directly bound to the co-activator P/CAF and repressed its recruitment to the CTGF promoter.

CONCLUSIONS

Ang II down-regulates KLF15 expression via the AT1 receptor, and KLF15 is likely to inhibit Ang II-induced CTGF expression by repressing the recruitment of the co-activator P/CAF to the CTGF promoter.

Chronic treatment with angiotensin-converting enzyme inhibitor increases cardiac fibrosis in young rats submitted to early ovarian failure

BACKGROUND

We investigated whether the treatment with enalapril maleate, combined with aerobic physical training, promotes positive effects on the autonomic balance, the morphology and the cardiac function in female rats submitted to early ovarian failure.

METHODS

Thirty-five female Wistar rats, ovariectomized at 10weeks of age, were assigned into Ovariectomized rats (OVX) and Ovariectomized rats treated with enalapril maleate (OVX-EM, 10mg^-1·kg^-1·d^-1) Each group was subdivided into sedentary and trained (aerobic swimming training for 10weeks). All animals were submitted to a) double pharmacological autonomic blockade, b) study of morphology and cardiac function by echocardiography, and c) analysis of cardiac fibrosis.

RESULTS

The OVX-EM sedentary group showed a significant increase in cardiac fibrosis, relative heart weight, interventricular septum thickness and increased sympathetic participation and reduced participation of the vagal tone in the determination of the basal heart rate when compared to the OVX sedentary group. Physical training reduced cardiac fibrosis in both groups, however, with less intensity in the OVX-EM group. It also increased the absolute and relative heart weight and the end-systolic volume. Finally, the OVX-EM trained group showed higher values for left ventricular end-systolic volume and lower values for ejection fraction and shortening fraction than the sedentary OVX-EM group.

CONCLUSION

Enalapril maleate exacerbated cardiac fibrosis and increased sympathetic participation in the basal heart rate determination, without significantly affecting the cardiac function. Aerobic physical training did not change the cardiac autonomic control, but reduced cardiac fibrosis and had little effect on the cardiac function.

Sex chromosome complement involvement in angiotensin receptor sexual dimorphism

This study aimed to define whether sex chromosome complement (SCC) may differentially modulate sex differences in relative gene expression of basal Agtr1a, Agtr2, and Mas1 receptors at fore/hindbrain nuclei and at medulla/cortical kidney. Samples were collected from gonadectomized male (XX and XY) and female (XX and XY) mice of the "four core genotypes" model. At brain level, a SCC effect at the area postrema was demonstrated. An increase in mRNA level of Agtr1a and Agtr1a/Agtr2 ratio in XY-SCC mice was associated with a decrease in Mas1 compared to XX-SCC mice. In the renal cortex, a SCC effect for Agtr2 and Mas1 was observed. Regardless of sex (male or female), XX-SCC mice expressed higher levels of mRNA Agtr2 and Mas1 than XY-SCC mice {F(1,12) = 6,126,p < 0.05; F(1,21) = 5,143,p < 0.05}. Furthermore, XX-female mice showed a significant increase in Mas1 expression compared to XY-female mice. These results reveal a SCC modulatory effect at central and kidney level on angiotensin receptor expression, with an enhancement of the vasodilatory arm in XX-mice and an increase in the vasoconstriction arm in XY-mice, which may underlie sex differences in the regulation of arterial pressure.

Physical training promotes similar effects to the blockade of angiotensin-converting enzyme on the cardiac morphology and function in old female rats subjected to premature ovarian failure

We investigated the effects of angiotensin-converting enzyme (ACE) inhibition and aerobic physical training on the heart of old female rats (82-wk-old) submitted to premature ovarian failure (10-wk.-old). We used different approaches: morphology and function by echocardiography, reactivity of the coronary bed and left ventricular contractibility (Langendorff Technique). Female Wistar ovariectomized (OVX) rats (n=42) were assigned to one of four groups: OVX, vehicle treated only; OVX-EM, Enalapril Maleate only (EM, 10mg·kg^-1·d^-1); OVX-T, aerobic trained only; and OVX-EMT, treated with Enalapril Maleate and aerobic trained. Both Enalapril Maleate treatment and aerobic training were done in the last 20weeks of the experimental protocol. When compared to the OVX group, the OVX-EM group showed lower values of wall thickness and left ventricular (LV) mass, lower values of coronary bed reactivity and reduced maximum response of LV contractility to dobutamine, while the OVX-T group showed lower values of LV wall thickness, increase in end-systolic volume, reduced maximum response of LV contractility to dobutamine, and left intraventricular pressure due to increased flow. The combination of treatments (EM and aerobic physical training) did not promote additional important effects on the parameters evaluated. Our results suggest similar beneficial effects of physical training and EM treatment on the morphology and cardiac function in old female rats submitted to premature ovarian failure. Although the causes of these benefits are still unknown, both treatments have promoted a decrease in cardiac contractility, and the reduced β1-adrenergic sensitivity suggests that both treatments may attenuate the sympathetic effect on the heart.

Membrane-anchored proteases in endothelial cell biology

PURPOSE OF REVIEW

The endothelial cell plasma membrane is a metabolically active, dynamic, and fluid microenvironment where pericellular proteolysis plays a critical role. Membrane-anchored proteases may be expressed by endothelial cells as well as mural cells and leukocytes with distribution both inside and outside of the vascular system. Here, we will review the recent advances in our understanding of the direct and indirect roles of membrane-anchored proteases in vascular biology and the possible conservation of their extravascular functions in endothelial cell biology.

RECENT FINDINGS

Membrane-anchored proteases belonging to the serine or metalloprotease families contain amino-terminal or carboxy-terminal domains, which serve to tether their extracellular protease domains directly at the plasma membrane. This architecture enables protease function and substrate repertoire to be regulated through dynamic localization in distinct areas of the cell membrane. These proteases are proving to be key components of the cell machinery for regulating vascular permeability, generation of vasoactive peptides, receptor tyrosine kinase transactivation, extracellular matrix proteolysis, and angiogenesis.

SUMMARY

A complex picture of the interdependence between membrane-anchored protease localization and function is emerging that may provide a mechanism for precise coordination of extracellular signals and intracellular responses through communication with the cytoskeleton and with cellular signaling molecules.

Cardioprotective Angiotensin-(1-7) Peptide Acts as a Natural-Biased Ligand at the Angiotensin II Type 1 Receptor

Hyperactivity of the renin-angiotensin-aldosterone system through the angiotensin II (Ang II)/Ang II type 1 receptor (AT1-R) axis constitutes a hallmark of hypertension. Recent findings indicate that only a subset of AT1-R signaling pathways is cardiodeleterious, and their selective inhibition by biased ligands promotes therapeutic benefit. To date, only synthetic biased ligands have been described, and whether natural renin-angiotensin-aldosterone system peptides exhibit functional selectivity at AT1-R remains unknown. In this study, we systematically determined efficacy and potency of Ang II, Ang III, Ang IV, and Ang-(1-7) in AT1-R-expressing HEK293T cells on the activation of cardiodeleterious G-proteins and cardioprotective β-arrestin2. Ang III and Ang IV fully activate similar G-proteins than Ang II, the prototypical AT1-R agonist, despite weaker potency of Ang IV. Interestingly, Ang-(1-7) that binds AT1-R fails to promote G-protein activation but behaves as a competitive antagonist for Ang II/Gi and Ang II/Gq pathways. Conversely, all renin-angiotensin-aldosterone system peptides act as agonists on the AT1-R/β-arrestin2 axis but display biased activities relative to Ang II as indicated by their differences in potency and AT1-R/β-arrestin2 intracellular routing. Importantly, we reveal Ang-(1-7) a known Mas receptor-specific ligand, as an AT1-R-biased agonist, selectively promoting β-arrestin activation while blocking the detrimental Ang II/AT1-R/Gq axis. This original pharmacological profile of Ang-(1-7) at AT1-R, similar to that of synthetic AT1-R-biased agonists, could, in part, contribute to its cardiovascular benefits. Accordingly, in vivo, Ang-(1-7) counteracts the phenylephrine-induced aorta contraction, which was blunted in AT1-R knockout mice. Collectively, these data suggest that Ang-(1-7) natural-biased agonism at AT1-R could fine-tune the physiology of the renin-angiotensin-aldosterone system.

Aliskiren and l-arginine treatments restore depressed baroreflex sensitivity and decrease oxidative stress in renovascular hypertension rats

Renovascular hypertension is characterized by increased angiotensin II and oxidative stress, and by endothelial dysfunction. The purpose of this study was to test whether the administration of aliskiren (ALSK) and l-arginine (l-ARG) would restore impaired baroreflex sensitivity and reduce oxidative stress in a rat renovascular hypertension model. Hypertension was induced by clipping the left renal artery, and the following five groups were created: SHAM; two-kidney, 1-clip (2K1C); 2K1C plus ALSK (ALSK); 2K1C plus l-ARG (l-ARG); and 2K1C plus ALSK+l-ARG (ALSK+l-ARG). After 21 days of treatment, only the ALSK+l-ARG group was effective in normalizing the arterial pressure (108.8±2.8 mm Hg). The l-ARG and ALSK+l-ARG groups did not show hypertrophy of the left ventricle. All the treatments restored the depressed baroreflex sensitivity to values found in the SHAM group. Acute administration of TEMPOL restored the depressed baroreflex sensitivity in the 2K1C group to values that resembled those presented by the other groups. All treatments were effective for an increase in the antioxidant pathway and reduction in the oxidative pathway. In conclusion, the treatment with ALSK or l-ARG reduced oxidative stress and restored reduced baroreflex sensitivity in renovascular hypertension. In addition, the treatments were able to normalize blood pressure and reverse left ventricular hypertrophy when used in combination.

Angiotensin-(1-7) Attenuates Kidney Injury Due to Obstructive Nephropathy in Rats

Background

Angiotensin-(1–7) [Ang-(1–7)] counteracts many actions of the renin-angiotensin-aldosterone system. Despite its renoprotective effects, extensive controversy exists regarding the role of Ang-(1–7) in obstructive nephropathy, which is characterized by renal tubulointerstitial fibrosis and apoptosis.

Methods

To examine the effects of Ang-(1–7) in unilateral ureteral obstruction (UUO), male Sprague-Dawley rats were divided into three groups: control, UUO, and Ang-(1–7)-treated UUO rats. Ang-(1–7) was continuously infused (24 μg/[kg·h]) using osmotic pumps. We also treated NRK-52E cells in vitro with Ang II (1 μM) in the presence or absence of Ang-(1–7) (1 μM), Mas receptor antagonist A779 (1 μM), and Mas receptor siRNA (50 nM) to examine the effects of Ang-(1–7) treatment on Ang II-stimulated renal injury via Mas receptor.

Results

Angiotensin II (Ang II) and angiotensin type 1 receptor (AT₁R) protein expression was higher in UUO kidneys than in controls. Ang-(1–7) treatment also decreased proapoptotic protein expression in UUO kidneys. Ang-(1–7) also significantly ameliorated TUNEL positive cells in UUO kidneys. Additionally, Ang-(1–7) reduced profibrotic protein expression and decreased the increased tumor growth factor (TGF)-β1/Smad signaling present in UUO kidneys. In NRK-52E cells, Ang II induced the expression of TGF-β1/Smad signaling effectors and proapoptotic and fibrotic proteins, as well as cell cycle arrest, which were attenuated by Ang-(1–7) pretreatment. However, treatment with A779 and Mas receptor siRNA enhanced Ang II-induced apoptosis and fibrosis. Moreover, Ang II increased tumor necrosis factor-α converting enzyme (TACE) and decreased angiotensin-converting enzyme 2 (ACE2) expression in NRK-52E cells, while pretreatment with Ang-(1–7) or A779 significantly inhibited or enhanced these effects, respectively.

Conclusion

Ang-(1–7) prevents obstructive nephropathy by suppressing renal apoptosis and fibrosis, possibly by regulating TGF-β1/Smad signaling and cell cycle arrest via suppression of AT₁R expression. In addition, Ang-(1–7) increased and decreased ACE2 and TACE expression, respectively, which could potentially mediate a positive feedback mechanism via the Mas receptor.

A critical role of cardiac fibroblast-derived exosomes in activating renin angiotensin system in cardiomyocytes

Chronic activation of the myocardial renin angiotensin system (RAS) elevates the local level of angiotensin II (Ang II) thereby inducing pathological cardiac hypertrophy, which contributes to heart failure. However, the precise underlying mechanisms have not been fully delineated. Herein we report a novel paracrine mechanism between cardiac fibroblasts (CF)s and cardiomyocytes whereby Ang II induces pathological cardiac hypertrophy. In cultured CFs, Ang II treatment enhanced exosome release via the activation of Ang II receptor types 1 (AT1R) and 2 (AT2R), whereas lipopolysaccharide, insulin, endothelin (ET)-1, transforming growth factor beta (TGFβ)1 or hydrogen peroxide did not. The CF-derived exosomes upregulated the expression of renin, angiotensinogen, AT1R, and AT2R, downregulated angiotensin-converting enzyme 2, and enhanced Ang II production in cultured cardiomyocytes. In addition, the CF exosome-induced cardiomyocyte hypertrophy was blocked by both AT1R and AT2R antagonists. Exosome inhibitors, GW4869 and dimethyl amiloride (DMA), inhibited CF-induced cardiomyocyte hypertrophy with little effect on Ang II-induced cardiomyocyte hypertrophy. Mechanistically, CF exosomes upregulated RAS in cardiomyocytes via the activation of mitogen-activated protein kinases (MAPKs) and Akt. Finally, Ang II-induced exosome release from cardiac fibroblasts and pathological cardiac hypertrophy were dramatically inhibited by GW4869 and DMA in mice. These findings demonstrate that Ang II stimulates CFs to release exosomes, which in turn increase Ang II production and its receptor expression in cardiomyocytes, thereby intensifying Ang II-induced pathological cardiac hypertrophy. Accordingly, specific targeting of Ang II-induced exosome release from CFs may serve as a novel therapeutic approach to treat cardiac pathological hypertrophy and heart failure.

Drug therapy of apparent treatment-resistant hypertension: focus on mineralocorticoid receptor antagonists

Apparent treatment-resistant hypertension (aTRH) is defined as blood pressure (BP) >140/90 mmHg despite three different antihypertensive drugs including a diuretic. aTRH is associated with an increased risk of cardiovascular events, including stroke, chronic renal failure, myocardial infarction, congestive heart failure, aortic aneurysm, atrial fibrillation, and sudden death. Preliminary studies of renal nerve ablation as a therapy to control aTRH were encouraging. However, these results were not confirmed by the Symplicity 3 trial. Therefore, attention has refocused on drug therapy. Secondary forms of hypertension and associated conditions such as obesity, sleep apnea, and primary aldosteronism are common in patients with aTRH. The pivotal role of aldosterone in the pathogenesis of aTRH in many cases is well recognized. For patients with aTRH, the Joint National Committee-8, the European Society of Hypertension, and a recent consensus conference recommend that a diuretic, ACE inhibitor, or angiotensin receptor blocker and calcium channel blocker combination be used to maximally tolerated doses before starting a 'fourth-line' drug such as a mineralocorticoid receptor (MR) antagonist. Although the best fourth-line drug for aTRH has not been extensively investigated, a number of studies summarized here show that an MR antagonist is effective in reducing BP when added to the standard multi-drug regimen.

Comparison of benazepril and losartan on endothelial function and vascular stiffness in patients with Type 2 diabetes mellitus and hypertension: A randomized controlled trial

INTRODUCTION

The purpose of this study was to compare the effects of benazepril and losartan on endothelial function and vascular stiffness, in patients with diabetes mellitus and hypertension.

MATERIALS AND METHODS

We included hypertensive diabetic patients with an office systolic blood pressure (BP) ⩾ 130 mmHg and/or diastolic BP ⩾ 80 mmHg. Patients were rolled over to amlodipine for 6 weeks, then we performed C-reactive protein assays, BP measurement and vascular tests; next, patients were randomized to benazepril or losartan. The tests were repeated after 12 weeks.

RESULTS

We randomized 14 patients to benazepril and 16 to losartan. There were no differences in systolic (139 versus 134 mmHg, p = 0.618) and diastolic (82 versus 80 mmHg, p = 0.950) BP at the end of the study. C-reactive protein values were lower in the benazepril group (0.38 versus 0.42 mg/dl, p = 0.020). There was a slightly higher flow-mediated vasodilation (FMD) response in the benazepril group (45% increase, p = 0.057) than in the losartan group (19% increase, p = 0.132). Both central systolic BP (129 versus 123 mmHg, p = 0.934) and carotid-femoral pulse wave velocity (cfPWV) (8.5 versus 8.5 m/s, p = 0.280) were the same between groups.

CONCLUSIONS

Hypertensive diabetic patients using benazepril had a greater reduction in C-reactive protein, and a slight improvement in FMD, than those taking losartan.

The cost-effectiveness of irbesartan for hypertension

High blood pressure is a very common problem in the adult and elderly population, both in developed and developing countries. A relatively large number of drug classes are available to treat this condition and prevent its complications, which are not only more frequent in the aforementioned patients but also those affected by metabolic syndrome and/or Type 2 diabetes. Irbesartan is an angiotensin-receptor blocker class drug with good antihypertensive efficacy and specific pharmacological characteristics, whose efficacy has been more deeply evaluated in metabolically complex hypertensive patients. In this review, the authors will analyze its effectiveness in preventing or delaying organ damage in hypertensive patients, with a closer look at the economic implications of treating hypertension with irbesartan in the context of available antihypertensive drugs.

Effects of Tulbaghia violacea Harv. (Alliaceae) rhizome methanolic extract on kidney function and morphology in Dahl salt-sensitive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tulbaghia violacea has been used traditionally for the treatment of several ailments, including hypertension. The herb has been shown to have antihypertensive properties which have been attributed to its angiotensin-converting enzymeinhibitory (ACEI) activity. It could, therefore, prove beneficial in ameliorating renal pathology associated with hypertension. To evaluate the effects of long-term administration of Tulbaghia violacea on renal function and morphology in the Dahl salt-sensitive (DSS) rat model.

MATERIALS AND METHODS

Male DSS rats were treated intra-peritoneally (i.p.) as follows: methanolic extract of Tulbaghia violacea: (TVL) (50 mg/kg/b.w.), captopril: (CAP) (25 mg/kg/b.w.), or distilled water, control: (CON) (3 ml/kg/b.w.). Blood pressure (BP) was measured bi-weekly, whilst 24-h urine volumes and electrolyte concentrations were assessed weekly. Animals were sacrificed on day 49 by halothane overdose. Blood was removed for determination of plasma and serum electrolytes. Left kidney tissues were harvested for the determination of nuclear factor-kappaβ (NF-kβ) and transforming growth factor-β (TGF-β) gene expressions.

RESULTS

TVL significantly reduced mean arterial pressure (MAP) and diastolic blood pressure (DBP). TVL showed reduced blood urea nitrogen, serum creatinine, total protein in urine as well as increased serum total protein. TVL decreased thiobarbituric acid reactive substances (TBARS) and increased glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity and nitric oxide significantly. NF-kβ and TGF-β) gene expressions were significantly reduced in TVL and CAP treated rats. Moreover, renal morphology improved significantly in TVL and CAP treated animals.

CONCLUSION

TVL and CAP demonstrated marked improvement in renal function and morphology.

Anti-hypertensive drugs in children and adolescents

Worldwide the prevalence of essential hypertension in children and adolescents continues to increase. Traditionally providers have used “off-label” drugs to treat pediatric hypertension, meaning that rigorous clinical trials of these drugs have not been specifically performed in pediatric patient populations. Consequently providers have extrapolated dosing, safety and efficacy from trials in adults. This practice is sub-optimal as children demonstrate unique differences in drug metabolism and response. Use of unstudied or understudied drugs increases risk of adverse events and/or can lead to sub-optimal efficacy. Recognizing these concerns, regulatory agencies have created financial incentives for industry to conduct pediatric clinical trials. These incentives, coupled with the emerging pediatric hypertension epidemic, have spurred over 30 clinical trials of anti-hypertensive drugs over the past 15 years and have resulted in labeling of 10 new drugs by the United States Food and Drug Administration for treatment of hypertension in children and adolescents. Unfortunately the financial incentive structures focus on newer drugs and drug classes. Consequently there is now a relative dearth of trial data for older but sometimes commonly prescribed pediatric antihypertensive drugs. This article reviews recent pediatric antihypertensive drug trials with a focus on trial design and endpoints, drug dosing, safety, efficacy and specific drug indications. We also review the available data and experience for some of the more commonly prescribed, but less well studied “older” pediatric antihypertensive drugs.