Project description:BackgroundActivity of the circulating renin-angiotensin-aldosterone system (RAAS) has not been comprehensively characterized in cats with systemic hypertension (SH) or cardiomyopathy (CM), and the effects of furosemide or amlodipine treatment on the RAAS have not been fully evaluated in cats.Hypothesis/objectivesTo document RAAS activity in cats with SH or CM compared to healthy cats and determine how RAAS profiles change with furosemide or amlodipine treatment.AnimalsSixty-six client-owned cats: 15 with SH (7 amlodipine-treated, 8 untreated), 17 with advanced CM (7 furosemide-treated, 10 not furosemide-treated), and 34 healthy cats.MethodsEquilibrium concentrations of RAAS peptides and aldosterone were quantified in serum samples by liquid chromatography-mass spectrometry. Variables were compared between groups using Kruskal-Wallis analysis with post hoc Holms-corrected Dunn's testing.ResultsCompared with healthy cats, cats with CM had higher concentrations of angiotensin I, aldosterone, and plasma renin activity (all P < .01), and these differences remained significant (P < .03) after considering subgroups of untreated or furosemide-treated cats. Compared with healthy cats, untreated cats with SH showed no differences in RAAS biomarkers, whereas amlodipine-treated cats had higher concentrations of angiotensins I, II, III, IV, and 1-7, aldosterone, and plasma renin activity (all P < .03). Multivariable analysis determined that furosemide and amlodipine treatments were independent predictors of increased RAAS biomarker concentrations.Conclusions and clinical importanceCats with CM had increased RAAS activity, whereas cats with untreated SH did not. Furosemide and amlodipine both led to nonspecific activation of both classical and alternative RAAS pathways in cats.
Project description:Hyperkalemia is common in clinical practice and can be caused by medications used to treat cardiovascular diseases, particularly renin-angiotensin-aldosterone system inhibitors (RAASis). This narrative review discusses the epidemiology, etiology, and consequences of hyperkalemia, and recommends strategies for the prevention and management of hyperkalemia, mainly focusing on guideline recommendations, while recognizing the gaps or differences between the guidelines. Available evidence emphasizes the importance of healthcare professionals (HCPs) taking a proactive approach to hyperkalemia management by prioritizing patient identification and acknowledging that hyperkalemia is often a long-term condition requiring ongoing treatment. Given the risk of hyperkalemia during RAASi treatment, it is advisable to monitor serum potassium levels prior to initiating these treatments, and then regularly throughout treatment. If RAASi therapy is indicated in patients with cardiorenal disease, HCPs should first treat chronic hyperkalemia before reducing the dose or discontinuing RAASis, as reduction or interruption of RAASi treatment can increase the risk of adverse cardiovascular and renal outcomes or death. Moreover, management of hyperkalemia should involve the use of newer potassium binders, such as sodium zirconium cyclosilicate or patiromer, as these agents can effectively enable optimal RAASi treatment. Finally, patients should receive education regarding hyperkalemia, the risks of discontinuing their current treatments, and need to avoid excessive dietary potassium intake.
Project description:Hypertension during pregnancy increases the risk of adverse maternal and fetal outcomes, but the mechanisms of pregnancy hypertension are not precisely understood. Elevated plasma renin activity and aldosterone concentrations play an important role in the normal physiologic adaptation to pregnancy. These effectors are reduced in patients with pregnancy hypertension, creating an opportunity to define the features of the renin-angiotensin-aldosterone system (RAAS) that are characteristic of this disorder. In the current study, we used a novel LC-MS/MS-based methodology to develop comprehensive profiles of RAAS peptides and effectors over gestation in a cohort of 74 pregnant women followed prospectively for the development of gestational hypertension and pre-eclampsia (HYP, 27 patients) versus those remaining normotensive (NT, 47 patients). In NT pregnancy, the plasma renin activity surrogate, (PRA-S, calculated from the sum of Angiotensin I + Angiotensin II) and aldosterone concentrations significantly increased from the first to the third trimester, accompanied by a modest increase in the concentrations of angiotensin peptide metabolites. In contrast, in HYP pregnancies, PRA-S and angiotensin peptides were largely unchanged over gestation, and third-trimester aldosterone concentrations were significantly lower compared with those in NT pregnancies. The results indicated that the predominant features of pregnancies that develop HYP are stalled or waning activation of the RAAS in the second half of pregnancy (accompanied by unchanging levels of angiotensin peptides) and the attenuated secretion of aldosterone.
Project description:As in other fields, chronotherapy applied to arterial hypertension (AHT) may have implications on oxidative stress. We compared the levels of some redox markers between hypertensive patients with morning and bedtime use of renin-angiotensin-aldosterone system (RAAS) blockers. This was an observational study that included patients older than 18 years with a diagnosis of essential AHT. Blood pressure (BP) figures were measured using twenty-four-hour ambulatory BP monitoring (24-h ABPM). Lipid peroxidation and protein oxidation were assessed using the thiobarbituric acid reactive substances (TBARS) and reduced thiols assays. We recruited 70 patients with a median age of 54 years, of whom 38 (54%) were women. In hypertensive patients with bedtime use of RAAS blockers, reduced thiol levels showed a positive correlation with nocturnal diastolic BP decrease. TBARS levels were associated with bedtime use of RAAS blockers in dipper and non-dipper hypertensive patients. In non-dipper patients, bedtime use of RAAS blockers was also associated with a decrease in nocturnal diastolic BP. Chronotherapy applied to bedtime use of some BP-lowering drugs in hypertensive patients may be linked to a better redox profile.
Project description:Purpose of reviewThis review summarises the literature data and provides an overview of the role and impact of the use of renin-angiotensin-aldosterone system (RAAS) inhibitors in patients with coronavirus disease 2019 (COVID-19) infection.Recent findingsThe angiotensin-converting enzyme 2 (ACE2) has a key role in the regulation of the RAAS pathway, downregulating angiotensin II and attenuating inflammation, vasoconstriction and oxidative stress. Additionally, it plays an instrumental part in COVID-19 infection as it facilitates the cell entry of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enables its replication. The use and role of RAAS inhibitors therefore during the COVID-19 pandemic have been intensively investigated. Although it was initially assumed that RAAS inhibitors may relate to worse clinical outcomes and severe disease, data from large studies and meta-analyses demonstrated that they do not have an adverse impact on clinical outcomes or prognosis. On the contrary, some experimental and retrospective observational cohort studies showed a potential protective mechanism, although this effect remains to be seen in large clinical trials.
Project description:Chronic activation of the renin-angiotensin-aldosterone system (RAAS) promotes and perpetuates the syndromes of congestive heart failure, systemic hypertension, and chronic kidney disease. Excessive circulating and tissue angiotensin II (AngII) and aldosterone levels lead to a pro-fibrotic, -inflammatory, and -hypertrophic milieu that causes remodeling and dysfunction in cardiovascular and renal tissues. Understanding of the role of the RAAS in this abnormal pathologic remodeling has grown over the past few decades and numerous medical therapies aimed at suppressing the RAAS have been developed. Despite this, morbidity from these diseases remains high. Continued investigation into the complexities of the RAAS should help clinicians modulate (suppress or enhance) components of this system and improve quality of life and survival. This review focuses on updates in our understanding of the RAAS and the pathophysiology of AngII and aldosterone excess, reviewing what is known about its suppression in cardiovascular and renal diseases, especially in the cat and dog.
Project description:With the multiplication of COVID-19 severe acute respiratory syndrome cases due to SARS-COV2, some concerns about angiotensin-converting enzyme 1 (ACE1) inhibitors (ACEi) and angiotensin II type 1 receptor blockers (ARB) have emerged. Since the ACE2 (angiotensin-converting enzyme 2) enzyme is the receptor that allows SARS COV2 entry into cells, the fear was that pre-existing treatment with ACEi or ARB might increase the risk of developing severe or fatal severe acute respiratory syndrome in case of COVID-19 infection. The present article discusses these concerns. ACE2 is a membrane-bound enzyme (carboxypeptidase) that contributes to the inactivation of angiotensin II and therefore physiologically counters angiotensin II effects. ACEis do not inhibit ACE2. Although ARBs have been shown to up-regulate ACE2 tissue expression in experimental animals, evidence was not always consistent in human studies. Moreover, to date there is no evidence that ACEi or ARB administration facilitates SARS-COV2 cell entry by increasing ACE2 tissue expression in either animal or human studies. Finally, some studies support the hypothesis that elevated ACE2 membrane expression and tissue activity by administration of ARB and/or infusion of soluble ACE2 could confer protective properties against inflammatory tissue damage in COVID-19 infection. In summary, based on the currently available evidence and as advocated by many medical societies, ACEi or ARB should not be discontinued because of concerns with COVID-19 infection, except when the hemodynamic situation is precarious and case-by-case adjustment is required.
Project description:The renin-angiotensin-aldosterone system (RAAS) is not the sole, but perhaps the most important volume regulator in vertebrates. To gain insights into the function and evolution of its components, we conducted a phylogenetic analysis of its main related genes. We found that important parts of the system began to appear with primitive chordates and tunicates and that all major components were present at the divergence of bony fish, with the exception of the Mas receptor. The Mas receptor first appears after the bony-fish/tetrapod divergence. This phase of evolutionary innovation happened about 400 million years ago. We found solid evidence that angiotensinogen made its appearance in cartilage fish. The presence of several RAAS genes in organisms that lack all the components shows that these genes have had other ancestral functions outside of their current role. Our analysis underscores the utility of sequence comparisons in the study of evolution. Such analyses may provide new hypotheses as to how and why in today's population an increased activity of the RAAS frequently leads to faulty salt and volume regulation, hypertension, and cardiovascular diseases, opening up new and clinically important research areas for evolutionary medicine.
Project description:The role of the renin-angiotensin-aldosterone system (RAAS) in many cardiovascular disorders, including hypertension, cardiac hypertrophy, and atherosclerosis, is well established, whereas its relationship with cardiac arrhythmias is a new area of investigation. Atrial fibrillation and malignant ventricular tachyarrhythmias, especially in the setting of cardiac hypertrophy or failure, seem to be examples of RAAS-related arrhythmias because treatment with RAAS modulators, including angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor blockers, reduces the incidence of these arrhythmias. RAAS has a multitude of electrophysiological effects and can potentially cause arrhythmia through a variety of mechanisms. We review new experimental results that suggest that RAAS has proarrhythmic effects on membrane and sarcoplasmic reticulum ion channels and that increased oxidative stress is likely contributing to the increased arrhythmic incidence. A summary of ongoing clinical trials that will address the clinical usefulness of RAAS modulators for prevention or treatment of arrhythmias is presented.
Project description:Because adult podocytes cannot proliferate and are therefore unable to self-renew, replacement of these cells depends on stem/progenitor cells. Although podocyte number is higher after renin-angiotensin-aldosterone system (RAAS) inhibition in glomerular diseases, the events explaining this increase are unclear. Cells of renin lineage (CoRL) have marked plasticity, including the ability to acquire a podocyte phenotype. To test the hypothesis that RAAS inhibition partially replenishes adult podocytes by increasing CoRL number, migration, and/or transdifferentiation, we administered tamoxifen to Ren1cCreERxRs-tdTomato-R CoRL reporter mice to induce permanent labeling of CoRL with red fluorescent protein variant tdTomato. We then induced experimental FSGS, typified by abrupt podocyte depletion, with a cytopathic antipodocyte antibody. RAAS inhibition by enalapril (angiotensin-converting enzyme inhibitor) or losartan (angiotensin-receptor blocker) in FSGS mice stimulated the proliferation of CoRL, increasing the reservoir of these cells in the juxtaglomerular compartment (JGC). Compared with water or hydralazine, RAAS inhibition significantly increased the migration of CoRL from the JGC to the intraglomerular compartment (IGC), with more glomeruli containing RFP+CoRL and, within these glomeruli, more RFP+CoRL. Moreover, RAAS inhibition in FSGS mice increased RFP+CoRL transdifferentiation in the IGC to phenotypes, consistent with those of podocytes (coexpression of synaptopodin and Wilms tumor protein), parietal epithelial cells (PAX 8), and mesangial cells (α8 integrin). These results show that in the context of podocyte depletion in FSGS, RAAS inhibition augments CoRL proliferation and plasticity toward three different glomerular cell lineages.