Angiotensin II

About: Angiotensin II is a research topic. Over the lifetime, 51382 publications have been published within this topic receiving 1941691 citations.

Pirfenidone controls the feedback loop of the AT1R/p38 MAPK/renin-angiotensin system axis by regulating liver X receptor-α in myocardial infarction-induced cardiac fibrosis

Abstract: Pirfenidone (PFD), an anti-fibrotic small molecule drug, is used to treat fibrotic diseases, but its effects on myocardial infarction (MI)-induced cardiac fibrosis are unknown. The aim of this study was to determine the effects of PFD on MI-induced cardiac fibrosis and the possible underlying mechanisms in rats. After establishment of the model, animals were administered PFD by gavage for 4 weeks. During the development of MI-induced cardiac fibrosis, we found activation of a positive feedback loop between the angiotensin II type 1 receptor (AT1R)/phospho-p38 mitogen-activated protein kinase (p38 MAPK) pathway and renin-angiotensin system (RAS), which was accompanied by down-regulation of liver X receptor-α (LXR-α) expression. PFD attenuated body weight, heart weight, left ventricular weight, left ventricular systolic pressure, and ±dp/dtmax changes induced by MI, which were associated with a reduction in cardiac fibrosis, infarct size, and hydroxyproline concentration. Moreover, PFD inhibited the AT1R/p38 MAPK pathway, corrected the RAS imbalance [decreased angiotensin-converting enzyme (ACE), angiotensin II, and angiotensin II type 1 receptor expression, but increased ACE2 and angiotensin (1-7) activity and Mas expression] and strongly enhanced heart LXR-α expression. These results indicate that the cardioprotective effects of PFD may be due, in large part, to controlling the feedback loop of the AT1R/p38 MAPK/RAS axis by activation of LXR-α.

Angiotensin II–Dependent Hypertension Requires Cyclooxygenase 1–Derived Prostaglandin E2 and EP1 Receptor Signaling in the Subfornical Organ of the Brain

Abstract: Cyclooxygenase (COX)-derived prostanoids have long been implicated in blood pressure (BP) regulation. Recently prostaglandin E(2) (PGE(2)) and its receptor EP(1) (EP(1)R) have emerged as key players in angiotensin II (Ang II)-dependent hypertension (HTN) and related end-organ damage. However, the enzymatic source of PGE(2,) that is, COX-1 or COX-2, and its site(s) of action are not known. The subfornical organ (SFO) is a key forebrain region that mediates systemic Ang II-dependent HTN via reactive oxygen species (ROS). We tested the hypothesis that cross-talk between PGE(2)/EP(1)R and ROS signaling in the SFO is required for Ang II HTN. Radiotelemetric assessment of blood pressure revealed that HTN induced by infusion of systemic "slow-pressor" doses of Ang II was abolished in mice with null mutations in EP(1)R or COX-1 but not COX-2. Slow-pressor Ang II-evoked HTN and ROS formation in the SFO were prevented when the EP(1)R antagonist SC-51089 was infused directly into brains of wild-type mice, and Ang-II-induced ROS production was blunted in cells dissociated from SFO of EP(1)R(-/-) and COX-1(-/-) but not COX-2(-/-) mice. In addition, slow-pressor Ang II infusion caused a ≈3-fold increase in PGE(2) levels in the SFO but not in other brain regions. Finally, genetic reconstitution of EP(1)R selectively in the SFO of EP(1)R-null mice was sufficient to rescue slow-pressor Ang II-elicited HTN and ROS formation in the SFO of this model. Thus, COX 1-derived PGE(2) signaling through EP(1)R in the SFO is required for the ROS-mediated HTN induced by systemic infusion of Ang II and suggests that EP(1)R in the SFO may provide a novel target for antihypertensive therapy.

Agents with vasodilator properties in acute heart failure

Abstract: Millions of patients worldwide are admitted for acute heart failure (AHF) each year and physicians caring for these patients are confronted with the short-term challenges of reducing symptoms while preventing end organ dysfunction without causing additional harm, and the intermediate-term challenges of improving clinical outcomes such as hospital readmission and survival. There are limited data demonstrating the efficacy of any currently available therapies for AHF to meet these goals. After diuretics, vasodilators are the most common intravenous therapy for AHF, but neither nitrates, nitroprusside, nor nesiritide have robust evidence supporting their ability to provide meaningful effects on clinical outcomes, except perhaps early symptom improvement. Recently, a number of novel agents with vasodilating properties have been developed for the treatment of AHF. These agents include serelaxin, natriuretic peptides (ularitide, cenderitide), β-arrestin-biased angiotensin II type 1 receptor ligands (TRV120027), nitroxyl donors (CXL-1020, CXL-1427), soluble guanylate cyclase modulators (cinaciguat, vericiguat), short-acting calcium channel blockers (clevidipine), and potassium channel activators (nicorandil). These development programmes range from the stage of early dose-finding studies (e.g. TRV120027, CXL-1427) to large, multicentre mortality trials (e.g. serelaxin, ularitide). There is an urgent need for agents with vasodilating properties that will improve both in-hospital and post-discharge clinical outcomes, and these novel approaches may provide opportunities to address this need.

Recent Insights in the Paracrine Modulation of Cardiomyocyte Contractility by Cardiac Endothelial Cells

Abstract: The cardiac endothelium is formed by a continuous monolayer of cells that line the cavity of the heart (endocardial endothelial cells (EECs)) and the luminal surface of the myocardial blood vessels (intramyocardial capillary endothelial cells (IMCEs)). EECs and IMCEs can exercise substantial control over the contractility of cardiomyocytes by releasing various factors such as nitric oxide (NO) via a constitutive endothelial NO-synthase (eNOS), endothelin-1, prostaglandins, angiotensin II, peptide growth factors, and neuregulin-1. The purpose of the present paper is actually to shortly review recent new information concerning cardiomyocytes as effectors of endothelium paracrine signaling, focusing particularly on contractile function. The modes of action and the regulatory paracrine role of the main mediators delivered by cardiac endothelial cells upon cardiac contractility identified in cardiomyocytes are complex and not fully described. Thus, careful evaluation of new therapeutic approaches is required targeting important physiological signaling pathways, some of which have been until recently considered as deleterious, like reactive oxygen species. Future works in the field of cardiac endothelial cells and cardiac function will help to better understand the implication of these mediators in cardiac physiopathology.

Perfusion imaging of the rat kidney with MR.

Abstract: PURPOSE: To develop a technique for measurement of regional renal perfusion with magnetic resonance (MR) imaging. MATERIALS AND METHODS: Quantitative renal perfusion images in rats were obtained by measurement of the reduction in kidney MR image signal intensity after steady state magnetic labeling of arterial blood in the suprarenal aorta. Labeling was achieved with adiabatic fast passage inversion of arterial water. RESULTS: Cortical renal blood flow was 4.9 mL/g/min +/- 0.15 (12 rats), which correlated well with previous measurements obtained with other techniques. Serial perfusion images obtained every 5 minutes during intravenous infusion of either acetylcholine or angiotensin II showed that one increased and the other decreased renal blood flow, respectively, also correlating with previous measurements. CONCLUSION: Quantitative measurement of cortical renal blood flow can be obtained with proton MR imaging techniques, with use of endogenous arterial water as a tracer. This technique should be readil...