Topic
Renin–angiotensin system
About: Renin–angiotensin system is a research topic. Over the lifetime, 21508 publications have been published within this topic receiving 736150 citations. The topic is also known as: Renin-angiotensin system & Renin-Angiotensin-Aldosterone System.
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TL;DR: Nitric oxide (NO), the smallest signalling molecule known, is produced by three isoforms of NO synthase (NOS), which can be expressed in many cell types in response to lipopolysaccharide, cytokines, or other agents.
Abstract: Nitric oxide (NO), the smallest signalling molecule known, is produced by three isoforms of NO synthase (NOS; EC 1.14.13.39). They all utilize l-arginine and molecular oxygen as substrates and require the cofactors reduced nicotinamide-adenine-dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), and (6R-)5,6,7,8-tetrahydrobiopterin (BH(4)). All NOS bind calmodulin and contain haem. Neuronal NOS (nNOS, NOS I) is constitutively expressed in central and peripheral neurons and some other cell types. Its functions include synaptic plasticity in the central nervous system (CNS), central regulation of blood pressure, smooth muscle relaxation, and vasodilatation via peripheral nitrergic nerves. Nitrergic nerves are of particular importance in the relaxation of corpus cavernosum and penile erection. Phosphodiesterase 5 inhibitors (sildenafil, vardenafil, and tadalafil) require at least a residual nNOS activity for their action. Inducible NOS (NOS II) can be expressed in many cell types in response to lipopolysaccharide, cytokines, or other agents. Inducible NOS generates large amounts of NO that have cytostatic effects on parasitic target cells. Inducible NOS contributes to the pathophysiology of inflammatory diseases and septic shock. Endothelial NOS (eNOS, NOS III) is mostly expressed in endothelial cells. It keeps blood vessels dilated, controls blood pressure, and has numerous other vasoprotective and anti-atherosclerotic effects. Many cardiovascular risk factors lead to oxidative stress, eNOS uncoupling, and endothelial dysfunction in the vasculature. Pharmacologically, vascular oxidative stress can be reduced and eNOS functionality restored with renin- and angiotensin-converting enzyme-inhibitors, with angiotensin receptor blockers, and with statins.
3,077 citations
TL;DR: The organ- and cell-specific expression of ACE2 and its unique cleavage of key vasoactive peptides suggest an essential role for ACE2 in the local renin-angiotensin system of the heart and kidney.
Abstract: ACE2, the first known human homologue of angiotensin-converting enzyme (ACE), was identified from 5' sequencing of a human heart failure ventricle cDNA library. ACE2 has an apparent signal peptide, a single metalloprotease active site, and a transmembrane domain. The metalloprotease catalytic domains of ACE2 and ACE are 42% identical, and comparison of the genomic structures indicates that the two genes arose through duplication. In contrast to the more ubiquitous ACE, ACE2 transcripts are found only in heart, kidney, and testis of 23 human tissues examined. Immunohistochemistry shows ACE2 protein predominantly in the endothelium of coronary and intrarenal vessels and in renal tubular epithelium. Active ACE2 enzyme is secreted from transfected cells by cleavage N-terminal to the transmembrane domain. Recombinant ACE2 hydrolyzes the carboxy terminal leucine from angiotensin I to generate angiotensin 1-9, which is converted to smaller angiotensin peptides by ACE in vitro and by cardiomyocytes in culture. ACE2 can also cleave des-Arg bradykinin and neurotensin but not bradykinin or 15 other vasoactive and hormonal peptides tested. ACE2 is not inhibited by lisinopril or captopril. The organ- and cell-specific expression of ACE2 and its unique cleavage of key vasoactive peptides suggest an essential role for ACE2 in the local renin-angiotensin system of the heart and kidney. The full text of this article is available at http://www. circresaha.org.
2,711 citations
TL;DR: Renin activity increased with Na restriction, was significantly higher on upright activity during both normal and restricted Na intake, and was most markedly elevated following the diuretic.
Abstract: A radioimmunoassay for angiotensin I and its application to the determination of renin activity is described. The assay employs antibodies raised to copolymers of angiotensin I and succinylated poly-l-lysine. Angiotensin labeled with 125I and purified by high voltage paper electrophoresis is employed as a tracer. Incubation is carried out in plasma in the presence of 3 metal binding reagents which serve to inhibit effectively proteolytic attack on angiotensin I. Immunoassay of generated angiotensin I is carried out directly on plasma diluted 1:20. Fifteen normal volunteers were studied on a metabolic ward at 2 levels of Na intake, during recumbency and upright posture, and following the administration of furosemide. Renin activity increased with Na restriction, was significantly higher on upright activity during both normal and restricted Na intake, and was most markedly elevated following the diuretic. Renin values obtained by immunoassay of angiotensin I correspond closely to those observed by ...
2,348 citations
TL;DR: A hypothetical model of the active site of angiotensin-converting enzyme, based on known chemical and kinetic properties of the enzyme, has enabled a new class of potent and specific inhibitors, carboxyalkanoyl and mercaptoalkanoysl derivatives of proline, to be designed.
Abstract: A hypothetical model of the active site of angiotensin-converting enzyme, based on known chemical and kinetic properties of the enzyme, has enabled us to design a new class of potent and specific inhibitors. These compounds, carboxyalkanoyl and mercaptoalkanoyl derivatives of proline, inhibit the contractile response of guinea pig ileal strip to angiotensin I and augment its response to bradykinin. When administered orally to rats, these agents inhibit the pressor effect of angiotensin I, augment the vasodepressor effect of bradykinin, and lower blood pressure in a model of renovascular hypertension.
1,759 citations
TL;DR: It is shown that renin expression and plasma angiotensin II production were increased severalfold in vitamin D receptor-null (VDR-null) mice, leading to hypertension, cardiac hypertrophy, and increased water intake, and 1,25(OH)(2)D(3) is a novel negative endocrine regulator of the renin-angiotens in system.
Abstract: Inappropriate activation of the renin-angiotensin system, which plays a central role in the regulation of blood pressure, electrolyte, and volume homeostasis, may represent a major risk factor for hypertension, heart attack, and stroke. Mounting evidence from clinical studies has demonstrated an inverse relationship between circulating vitamin D levels and the blood pressure and/or plasma renin activity, but the mechanism is not understood. We show here that renin expression and plasma angiotensin II production were increased severalfold in vitamin D receptor-null (VDR-null) mice, leading to hypertension, cardiac hypertrophy, and increased water intake. However, the salt- and volume-sensing mechanisms that control renin synthesis are still intact in the mutant mice. In wild-type mice, inhibition of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] synthesis also led to an increase in renin expression, whereas 1,25(OH)(2)D(3) injection led to renin suppression. We found that vitamin D regulation of renin expression was independent of calcium metabolism and that 1,25(OH)(2)D(3) markedly suppressed renin transcription by a VDR-mediated mechanism in cell cultures. Hence, 1,25(OH)(2)D(3) is a novel negative endocrine regulator of the renin-angiotensin system. Its apparent critical role in electrolytes, volume, and blood pressure homeostasis suggests that vitamin D analogues could help prevent or ameliorate hypertension.
1,744 citations