angiotensinogen and Disease-Models--Animal

The renin-angiotensin system (RAS) is a highly complex hormonal cascade that spans multiple organs and cell types to regulate solute and fluid balance along with cardiovascular function. Much of our current understanding of the functions of the RAS has emerged from a series of key studies in genetically-modified animals. Here, we review key findings from ground-breaking transgenic models, spanning decades of research into the RAS, with a focus on their use in studying blood pressure. We review the physiological importance of this regulatory system as evident through the examination of mouse models for several major RAS components: angiotensinogen, renin, ACE, ACE2, and the type 1 A angiotensin receptor. Both whole-animal and cell-specific knockout models have permitted critical RAS functions to be defined and demonstrate how redundancy and multiplicity within the RAS allow for compensatory adjustments to maintain homeostasis. Moreover, these models present exciting opportunities for continued discovery surrounding the role of the RAS in disease pathogenesis and treatment for cardiovascular disease and beyond.

Topics: Angiotensin-Converting Enzyme 2; Angiotensinogen; Animals; Blood Pressure; Cardiovascular Diseases; Disease Models, Animal; Gene Expression Regulation; Humans; Kidney; Mice; Mice, Knockout; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin; Renin-Angiotensin System; Signal Transduction; Water-Electrolyte Balance

Angiotensinogen (AGT) is the unique substrate of all angiotensin peptides. We review the recent preclinical research of AGT antisense oligonucleotides (ASOs), a rapidly evolving therapeutic approach. The scope of the research findings not only opens doors for potentially new therapeutics of hypertension and many other diseases, but also provides insights into understanding critical physiological and pathophysiological roles mediated by AGT.

Topics: Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Drug Evaluation, Preclinical; Genetic Therapy; Humans; Hypertension; Kidney; Liver; Molecular Targeted Therapy; Oligonucleotides, Antisense; Rats, Inbred SHR; Renin-Angiotensin System

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.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Humans; Kidney; Kidney Tubules, Proximal; Liver; Mice; Renin; Renin-Angiotensin System

Circulating levels of the renin-angiotensin-aldosterone system (RAAS) components showed circadian oscillations in both spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Cardiac gene expression of the RAAS components also showed circadian variations in both SHR and WKY rats. Of interest, the amplitudes of these circadian fluctuations were different between SHR and WKY rats. Cardiac gene expression levels of the RAAS components were increased in SHR compared to WKY rats at many time points (especially during the active phase). The physiologic relevance of the differential circadian rhythms of circulating and cardiac gene expression levels of the RAAS components remains to be elucidated.

Topics: Angiotensinogen; Animals; Blood Pressure; Circadian Rhythm; Disease Models, Animal; Humans; Hypertension; Renin-Angiotensin System

Diabetes mellitus is one of the most prevalent diseases and is associated with increased incidence of structural and functional derangements in the kidneys, eventually leading to end-stage renal disease in a significant fraction of afflicted individuals. The renoprotective effects of renin-angiotensin system (RAS) blockade have been established; however, the mechanistic pathways have not been fully elucidated. In this review article, the cardinal role of an activated RAS in the pathogenesis of diabetic nephropathy (DN) is discussed with a focus on 4 themes: (1) introduction to RAS cascade, (2) intrarenal RAS in diabetes, (3) clinical outcomes of RAS blockade in DN, and (4) potential of urinary angiotensinogen as an early biomarker of intrarenal RAS status in DN. This review article provides a mechanistic rational supporting the hypothesis that an activated intrarenal RAS contributes to the pathogenesis of DN and that urinary angiotensinogen levels provide an index of intrarenal RAS activity.

Topics: Angiotensinogen; Animals; Biomarkers; Diabetic Nephropathies; Disease Models, Animal; Humans; Kidney Cortex; Mice; Peptidyl-Dipeptidase A; Rats; Renin; Renin-Angiotensin System

Autosomal recessive renal tubular dysgenesis (RTD) is a severe disorder of renal tubular development characterized by early onset and persistent fetal anuria leading to oligohydramnios and the Potter sequence, associated with skull ossification defects. Early death occurs in most cases from anuria, pulmonary hypoplasia, and refractory arterial hypotension. The disease is linked to mutations in the genes encoding several components of the renin-angiotensin system (RAS): AGT (angiotensinogen), REN (renin), ACE (angiotensin-converting enzyme), and AGTR1 (angiotensin II receptor type 1). Here, we review the series of 54 distinct mutations identified in 48 unrelated families. Most of them are novel and ACE mutations are the most frequent, observed in two-thirds of families (64.6%). The severity of the clinical course was similar whatever the mutated gene, which underlines the importance of a functional RAS in the maintenance of blood pressure and renal blood flow during the life of a human fetus. Renal hypoperfusion, whether genetic or secondary to a variety of diseases, precludes the normal development/ differentiation of proximal tubules. The identification of the disease on the basis of precise clinical and histological analyses and the characterization of the genetic defects allow genetic counseling and early prenatal diagnosis.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Genes, Recessive; Genetic Association Studies; Humans; Kidney Tubules, Proximal; Mutation; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Urogenital Abnormalities

In addition to its role as an energy store, adipose tissue also acts as an endocrine organ, synthesizing and secreting hormones and cytokines. This review discusses angiotensin II (Ang-II), the biologically active component of the renin-angiotensin system (RAS). Evidence suggests that a functioning RAS is present in adipose tissue. Animal studies have demonstrated that modifying the amount of Ang-II in the body (eg, using RAS knockout/transgenic animal models or the pharmacological treatment of animal models to prevent the formation or action of Ang-II) directly influences body weight and adiposity. In humans, body fat is correlated with levels of angiotensinogen, a precursor of Ang-II. Thus, the treatment of obesity could be improved through the use of substances that interfere with Ang-II.

Topics: Adipose Tissue; Adiposity; Angiotensin II; Angiotensinogen; Animals; Body Weight; Disease Models, Animal; Humans; Obesity; Receptors, Angiotensin; Renin-Angiotensin System

In recent years, the focus of interest on the role of the renin-angiotensin system (RAS) in the pathophysiology of hypertension and organ injury has changed to a major emphasis on the role of the local RAS in specific tissues. In the kidney, all of the RAS components are present and intrarenal angiotensin II (Ang II) is formed by independent multiple mechanisms. Proximal tubular angiotensinogen, collecting duct renin, and tubular angiotensin II type 1 (AT1) receptors are positively augmented by intrarenal Ang II. In addition to the classic RAS pathways, prorenin receptors and chymase are also involved in local Ang II formation in the kidney. Moreover, circulating Ang II is actively internalized into proximal tubular cells by AT1 receptor-dependent mechanisms. Consequently, Ang II is compartmentalized in the renal interstitial fluid and the proximal tubular compartments with much higher concentrations than those existing in the circulation. Recent evidence has also revealed that inappropriate activation of the intrarenal RAS is an important contributor to the pathogenesis of hypertension and renal injury. Thus, it is necessary to understand the mechanisms responsible for independent regulation of the intrarenal RAS. In this review, we will briefly summarize our current understanding of independent regulation of the intrarenal RAS and discuss how inappropriate activation of this system contributes to the development and maintenance of hypertension and renal injury. We will also discuss the impact of antihypertensive agents in preventing the progressive increases in the intrarenal RAS during the development of hypertension and renal injury.

Topics: Angiotensin II; Angiotensinogen; Animals; Antihypertensive Agents; Chronic Disease; Disease Models, Animal; Humans; Hypertension; Hypertension, Renal; Kidney; Kidney Diseases; Receptors, Angiotensin; Renin; Renin-Angiotensin System

Under classical strategy, scientists have tried first to find a physiological phenomenon specific for essential hypertension, then to identify the protein underlying the physiological abnormality, and finally to clarify the causative gene which encoded the protein. On the other hand, under the reverse genetic approach, the correlation between hypertension and genetic abnormality is identified first, and then the pathogenesis is clarified-in reverse order. Therefore, it is not extraordinary for unexpected results to be obtained in the correlation between a gene and a disease, suggesting that this approach has a possibility to be a breakthrough in the chaos of hypertension research.

Topics: Angiotensinogen; Animals; Asian People; Disease Models, Animal; Gene Expression Regulation; Genetic Linkage; Genetic Predisposition to Disease; Genetic Therapy; Humans; Hypertension; Liposomes; Oligodeoxyribonucleotides, Antisense; Polymorphism, Restriction Fragment Length; Rats; Rats, Inbred SHR; Renin-Angiotensin System; Transfection; White People

The generation of knockout mice using homologous recombination in embryonic stem cells is a powerful tool for physiologic investigations. This experimental approach has provided unique insights into the study of hypertension. Studies using knockout mice have shed new light on blood pressure regulatory mechanisms, molecular mechanisms of end-organ injury, and genetic mechanisms for hypertension. With the development of more accessible approaches for carrying out sophisticated manipulation of the mouse genome, there will be continuing utility of this technique for future studies of hypertension.

Topics: Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Disease Models, Animal; Gene Expression; Humans; Hypertension; Mice; Mice, Knockout; Phenotype; Receptors, Angiotensin; Renin-Angiotensin System; Stem Cells

Essential hypertension is an insidious disease in which the afflicted person risks disability and death from myocardial infarction and stroke. Many factors contribute to the development of essential hypertension, including environment, diet, daily stress, and genetics. Although several single gene disorders causing high blood pressure have been identified, the genetics of essential hypertension are much more complicated. The current hypothesis is that a combination of genetic variations in multiple genes may predispose a person to hypertension. Both overexpression and gene inactivation ("knockout") have proven useful tools to evaluate the genetics of essential hypertension and to identify pathways regulating blood pressure. Molecular and physiologic evaluations of transgenic and knockout mice carried out over the past 5 years have provided a plethora of information about the mechanisms of blood pressure regulation and the development and maintenance of hypertension. This review focuses on the newer mouse models that have been developed to investigate hypertension with an emphasis on vascular and renal mechanisms, contributed by the renin-angiotensin system, and other pathways intersecting with the renin-angiotensin system.

Topics: Angiotensin II; Angiotensinogen; Animals; Disease Models, Animal; Humans; Hypertension; Mice; Mice, Knockout; Mice, Transgenic; Nitric Oxide; Peptidyl-Dipeptidase A; Receptors, Dopamine; Receptors, Neuropeptide; Renin-Angiotensin System

Topics: Angiotensinogen; Calmodulin-Binding Proteins; Disease Models, Animal; Humans; Hypertension; Peptidyl-Dipeptidase A; Renin

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Disease Models, Animal; Endothelins; Humans; Hypertension; Peptidyl-Dipeptidase A; Rats; Renin

In the past few years, a number of key insights have been made concerning the genetic basis of hypertension and blood pressure regulation. The genes responsible for two Mendelian forms of hypertension, glucocorticoid-remediable aldosteronism and Liddle's syndrome, were identified. In addition, research into the role of the renin-angiotensin system in blood pressure regulation has further implicated the angiotensinogen and angiotensin-converting enzyme loci in hypertension and its complications, such as myocardial infarction. Finally, several new candidate genes for hypertension have been identified through the use of genome scanning and contemporary gene expression assays in model organisms.

Topics: Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Gene Expression; Genetic Linkage; Genetic Variation; Genome; Glucocorticoids; Humans; Hyperaldosteronism; Hypertension; Hypokalemia; Mice; Mice, Transgenic; Peptidyl-Dipeptidase A; Rats; Receptors, Angiotensin; Syndrome

Topics: Angiotensinogen; Animals; Disease Models, Animal; Genes; Humans; Hypertension; Neuropeptide Y; Peptidyl-Dipeptidase A; Rats; Rats, Inbred SHR; Receptors, Angiotensin; Renin; Type C Phospholipases

Topics: Angiotensinogen; Animals; Antigens, CD; Chromosome Mapping; Disease Models, Animal; Female; Humans; Hypertension; Leukosialin; Male; Peptidyl-Dipeptidase A; Rats; Rats, Inbred SHR; Repetitive Sequences, Nucleic Acid; Sialoglycoproteins

New technologies in molecular biology and medicine have opened new avenues for the study of disease. As a result of this, the genetic basis of many diseases has been discovered and candidate genes that contribute to the underlying pathology have been identified. An important approach to test the function of these genes is the establishment of transgenic animal models. Candidate genes can be expressed in these animals to study their regulation in vivo. Furthermore, the pathophysiological consequences of the alteration in gene expression can be investigated in detail. Like many other diseases, primary hypertension is influenced by genetic factors. A number of candidate genes have been implicated in its pathogenesis, and current research efforts are directed toward testing these candidates. For this purpose, several transgenic animal models have been established. Most of this transgenic work has been carried out in mice, but recent efforts have focused on the development of transgenic rat models for hypertension, which may provide the better experimental system for the study of cardiovascular regulation.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Disease Models, Animal; Gene Expression Regulation; Humans; Hypertension; Mice; Mice, Transgenic; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renin-Angiotensin System

Hypertension shares several characteristics with diabetes, atherosclerosis and asthma. These common diseases are caused by environmental factors and predisposing genes and they represent a major cost in developed countries. Use of molecular techniques: Much information is expected from the identification of the molecular bases of these diseases, and from the molecular characterization of the predisposing variants and their effects on the clinical manifestations of these pathologies. Hypertension is now a target for genetic studies, and some interesting results have been obtained in humans and in animal models.

Topics: Angiotensinogen; Animals; Cloning, Molecular; Disease Models, Animal; Female; Genetic Markers; Genetic Variation; Humans; Hypertension; Male; Molecular Biology; Rats; Risk Factors

Because of its small size, low cost of maintenance, breeding capabilities in captivity, the marmoset, a New World monkey, appears well suited for clinical and fundamental investigations. The contribution of this laboratory animal in the main areas of biomedical research is succinctly described: viral oncology, infections diseases, immunology, reproduction, toxicology and teratology, odontology, behaviour and neuro-psychopathology. Emphasis is put upon the exceptional interest of the use of marmoset as a biological model in cardiovascular studies.

Topics: Angiotensinogen; Animals; Arteriosclerosis; Callitrichinae; Cardiovascular Diseases; Disease Models, Animal; Hypertension; Research

The review will cover the chemistry and biochemistry of angiotensin-converting enzyme inhibitors with emphasis on data published since the publication of previous reviews. The relative merits of each contribution will be evaluated, as well as their potential for leading to new discoveries. The biology of angiotensin-converting enzyme inhibitors will be brought up-to-date to give the reader an appreciation of the medical implications of this new type of antihypertensive agent.

Topics: Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Disease Models, Animal; Heart Failure; Humans; Hypertension; Kidney; Oligopeptides; Peptidyl-Dipeptidase A; Receptors, Angiotensin; Renin; Structure-Activity Relationship; Substrate Specificity

Aldosterone synthase inhibition provides the potential to attenuate both the mineralocorticoid receptor-dependent and independent actions of aldosterone. In vitro studies with recombinant human enzymes showed LCI699 to be a potent, reversible, competitive inhibitor of aldosterone synthase (K i = 1.4 ± 0.2 nmol/L in humans) with relative selectivity over 11β-hydroxylase.. Hormonal effects of orally administered LCI699 were examined in rat and monkey in vivo models of adrenocorticotropic hormone (ACTH) and angiotensin-II-stimulated aldosterone release, and were compared with the mineralocorticoid receptor antagonist eplerenone in a randomized, placebo-controlled study conducted in 99 healthy human subjects. The effects of LCI699 and eplerenone on cardiac and renal sequelae of aldosterone excess were investigated in a double-transgenic rat (dTG rat) model overexpressing human renin and angiotensinogen.. Rat and monkey in vivo models of stimulated aldosterone release predicted human dose- and exposure-response relationships, but overestimated the selectivity of LCI699 in humans. In the dTG rat model, LCI699 dose-dependently blocked increases in aldosterone, prevented development of cardiac and renal functional abnormalities independent of blood pressure changes, and prolonged survival. Eplerenone prolonged survival to a similar extent, but was less effective in preventing cardiac and renal damage. In healthy human subjects, LCI699 0.5 mg selectively reduced plasma and 24 h urinary aldosterone by 49 ± 3% and 39 ± 6% respectively (Day 1, mean ± SEM; P < 0.001 vs placebo), which was associated with natriuresis and an increase in plasma renin activity. Doses of LCI699 greater than 1 mg inhibited basal and ACTH-stimulated cortisol. Eplerenone 100 mg increased plasma and 24 h urinary aldosterone while stimulating natriuresis and increasing renin activity. In contrast to eplerenone, LCI699 increased the aldosterone precursor 11-deoxycorticosterone and urinary potassium excretion.. These results provide new insights into the cardiac and renal effects of inhibiting aldosterone synthase in experimental models and translation of the hormonal effects to humans. Selective inhibition of aldosterone synthase appears to be a promising approach to treat diseases associated with aldosterone excess.

Topics: Angiotensinogen; Animals; Cytochrome P-450 CYP11B2; Disease Models, Animal; Double-Blind Method; Eplerenone; Haplorhini; Heart; Humans; Imidazoles; Kidney; Male; Placebos; Pyridines; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; Spironolactone; Translational Research, Biomedical

Cross-linking of lysine residues in elastic and collagen fibers is a vital process in aortic development. Inhibition of lysyl oxidase by BAPN (β-aminopropionitrile) leads to thoracic aortopathies in mice. Although the renin-angiotensin system contributes to several types of thoracic aortopathies, it remains unclear whether inhibition of the renin-angiotensin system protects against aortopathy caused by the impairment of elastic fiber/collagen crosslinking.. BAPN (0.5% wt/vol) was started in drinking water to induce aortopathies in male C57BL/6J mice at 4 weeks of age for 4 weeks. Five approaches were used to investigate the impact of the renin-angiotensin system. Bulk RNA sequencing was performed to explore potential molecular mechanisms of BAPN-induced thoracic aortopathies.. Losartan increased plasma renin concentrations significantly, compared with vehicle-infused mice, indicating effective angiotensin II type 1 receptor inhibition. However, losartan did not suppress BAPN-induced aortic rupture and dilatation. Since losartan is a surmountable inhibitor of the renin-angiotensin system, irbesartan, an insurmountable inhibitor, was also tested. Although increased plasma renin concentrations indicated effective inhibition, irbesartan did not ameliorate aortic rupture and dilatation in BAPN-administered mice. Thus, BAPN-induced thoracic aortopathies were refractory to angiotensin II type 1 receptor blockade. Next, we inhibited angiotensin II production by pharmacological or genetic depletion of AGT (angiotensinogen), the unique precursor of angiotensin II. However, neither suppressed BAPN-induced thoracic aortic rupture and dilatation. Aortic RNA sequencing revealed molecular changes during BAPN administration that were distinct from other types of aortopathies in which angiotensin II type 1 receptor inhibition protects against aneurysm formation.. Inhibition of either angiotensin II action or production of the renin-angiotensin system does not attenuate BAPN-induced thoracic aortopathies in mice.

Topics: Aminopropionitrile; Angiotensin II; Angiotensinogen; Animals; Aortic Aneurysm, Thoracic; Aortic Rupture; Dilatation, Pathologic; Disease Models, Animal; Irbesartan; Losartan; Lysine; Male; Mice; Mice, Inbred C57BL; Protein-Lysine 6-Oxidase; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System

[Figure: see text].

Topics: Angiotensin II; Angiotensinogen; Animals; Antihypertensive Agents; Arterial Pressure; Captopril; Disease Models, Animal; Kidney; Liver; Losartan; Rats; Renal Insufficiency, Chronic; Renin-Angiotensin System; RNA, Small Interfering

Idiopathic pulmonary fibrosis (IPF) is a severe disorder leading to progressive and irreversible loss of pulmonary function. In this study we investigated the anti-fibrotic effect of vitamin D using a mouse model of IPF. Lung fibrosis was induced with bleomycin in vitamin D-sufficient and vitamin D-deficient C57BL/6 mice. We found that treatment with active vitamin D analog paricalcitol prevented mouse body weight loss and alleviated lung fibrosis, whereas vitamin D deficiency severely aggravated lung injury. At the molecular level, paricalcitol treatment suppressed the induction of fibrotic inducer TGF-β and extracellular matrix proteins α-SMA, collagen type I and fibronectin in the lung, whereas vitamin D deficiency exacerbated the induction of these proteins. Interestingly, bleomycin treatment activated the local renin-angiotensin system (RAS) in the lung, manifested by the induction of renin, angiotensinogen, angiotensin II and angiotensin receptor type 1 (AT1R). Paricalcitol treatment suppressed the induction of these RAS components, whereas vitamin D deficiency enhanced the activation of the lung RAS. We also showed that treatment of bleomycin-induced vitamin D-deficient mice with AT1R antagonist losartan relieved weight loss, substantially ameliorated lung fibrosis and markedly blocked TGF-β induction in the lung. Moreover, we demonstrated that in lung fibroblast cultures, TGF-β and angiotensin II synergistically induced TGF-β, AT1R, α-SMA, collagen type I and fibronectin, whereas 1,25-dihydroxyvitamin D markedly suppressed the induction of these fibrotic markers. Collectively, these observations strongly suggest that vitamin D mitigates lung fibrosis by blocking the activation of the lung RAS in this mouse model of IPF.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Bleomycin; Disease Models, Animal; Ergocalciferols; Losartan; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Pulmonary Fibrosis; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Transforming Growth Factor beta; Vitamin D

Objective: A cardinal feature of Marfan syndrome is thoracic aortic aneurysm. The contribution of the renin-angiotensin system via AT1aR (Ang II [angiotensin II] receptor type 1a) to thoracic aortic aneurysm progression remains controversial because the beneficial effects of angiotensin receptor blockers have been ascribed to off-target effects. This study used genetic and pharmacological modes of attenuating angiotensin receptor and ligand, respectively, to determine their roles on thoracic aortic aneurysm in mice with fibrillin-1 haploinsufficiency (Fbn1C1041G/+).\ \ Approach and Results: Thoracic aortic aneurysm in Fbn1C1041G/+ mice was found to be strikingly sexual dimorphic. Males displayed aortic dilation over 12 months while aortic dilation in Fbn1C1041G/+ females did not differ significantly from wild-type mice. To determine the role of AT1aR, Fbn1C1041G/+ mice that were either +/+ or -/- for AT1aR were generated. AT1aR deletion reduced expansion of ascending aorta and aortic root diameter from 1 to 12 months of age in males. Medial thickening and elastin fragmentation were attenuated. An antisense oligonucleotide against angiotensinogen was administered to male Fbn1C1041G/+ mice to determine the effects of Ang II depletion. Antisense oligonucleotide against angiotensinogen administration attenuated dilation of the ascending aorta and aortic root and reduced extracellular remodeling. Aortic transcriptome analyses identified potential targets by which inhibition of the renin-angiotensin system reduced aortic dilation in Fbn1C1041G/+ mice.\ \ Conclusions: Deletion of AT1aR or inhibition of Ang II production exerted similar effects in attenuating pathologies in the proximal thoracic aorta of male Fbn1C1041G/+ mice. Inhibition of the renin-angiotensin system attenuated dysregulation of genes within the aorta related to pathology of Fbn1C1041G/+ mice.

Topics: Angiotensinogen; Animals; Aorta, Thoracic; Aortic Aneurysm, Thoracic; Disease Models, Animal; Female; Fibrillin-1; Gene Deletion; Genetic Predisposition to Disease; Haploinsufficiency; Male; Marfan Syndrome; Mice, Inbred C57BL; Mice, Knockout; Oligonucleotides, Antisense; Phenotype; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; Sex Characteristics; Sex Factors; Transcriptome

During type 2 diabetes (T2D) and hypertension there is stimulation of renal proximal tubule angiotensinogen (AGT), but whether urinary excretion of AGT (uAGT) is an indicator of glomerular damage or intrarenal RAS activation is unclear. We tested the hypothesis that elevations in uAGT can be detected in the absence of albuminuria in a mouse model of T2D.. Male C57BL/6 mice (N = 10) were fed a high fat (HFD; 45% Kcal from fat) for 28 weeks, and the metabolic phenotype including body weight, blood pressures, glucose, insulin, ippGTT, HOMA-IR, and cholesterol was examined. In addition, kidney Ang II content and reactive oxygen species (ROS) was measured along with urinary albumin, creatinine, Ang II, and AGT.. All parameters consistent with T2D were present in mice after 12-14 weeks on the HFD. Systolic BP increased after 18 weeks in HFD but not NFD mice. Intrarenal ROS and Ang II concentrations were also increased in HFD mice. Remarkably, these changes paralleled the augmentation uAGT excretion (3.66 ± 0.50 vs. 0.92 ± 0.13 ng/mg by week 29; P < 0.01), which occurred in the absence of overt albuminuria.. In HFD-induced T2D mice, increases in uAGT occur in the absence of overt renal injury, indicating that this biomarker accurately detects early intrarenal RAS activation.

Topics: Albuminuria; Angiotensinogen; Animals; Biomarkers; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet, High-Fat; Disease Models, Animal; Hypertension; Male; Mice; Mice, Inbred C57BL; Obesity; Renin-Angiotensin System

Topics: Angiotensinogen; Animals; Disease Models, Animal; Female; Pre-Eclampsia; Pregnancy; Rats; Rats, Sprague-Dawley; Rats, Transgenic; RNA Interference

Renin cleavage of angiotensinogen has species specificity. As the residues at positions 11 and 12 are different between human angiotensinogen and mouse angiotensinogen, we determined whether these 2 residues in angiotensinogen affect renin cleavage and angiotensin II-mediated blood pressure regulation and atherosclerosis using an adenoassociated viral approach for manipulating angiotensinogen in vivo. Approach and Results: Hepatocyte-specific angiotensinogen deficient (hepAGT. Replacement of L11 and Y12 to V11 and I12, respectively, in mouse angiotensinogen does not affect renin cleavage, blood pressure, and atherosclerosis in LDL receptor-deficient mice.

Topics: Amino Acid Substitution; Angiotensin II; Angiotensinogen; Animals; Atherosclerosis; Blood Pressure; Disease Models, Animal; Female; Hepatocytes; Humans; Hypertension; Male; Mice, Knockout; Plaque, Atherosclerotic; Receptors, LDL; Renin; Species Specificity

BACKGROUND Sepsis is a devastating medical condition. In the USA, about 745 000 people are diagnosed with sepsis annually. Although many anti-inflammatory drugs have been used to manage sepsis, the treatment success rate is very low. This study was undertaken to examine the protective effects of naringenin on sepsis-induced kidney injury in rats. MATERIAL AND METHODS Sepsis was induced in Wistar albino rats by cecal ligation and puncture methods. Histological analysis was performed with hematoxylin and eosin (HE) staining. Reactive oxygen species (ROS) levels were determined by flow cytometery. TUNEL assay was used to demonstrate apoptosis. Sandwich ELISA method was used for the determination of urinary angiotensinogen, and protein expression was determined by Western blot analysis. RESULTS We found that naringenin decreased atrophy in the glomerulus and enabled maintenance of the capsule area and normal tubular cavity of the septic rats. Admistration of naringenin at the dosage of 10 and 20 mg/kg to sepsis rats caused significant reduction in the sepsis-induced apoptosis of kidney cells, accompanied by decrease in Bax and increase in Bcl-2 expression. Moreover, naringenin also decreased the ROS levels in septic rats and downregulated the expression of SOD, CAT, and APX. The effects of naringenin were also examined on the levels of urinary angiotensinogen in sepsis rats. We found that naringenin caused a significant decrease in urinary angiotensinogen levels of septic rats. CONCLUSIONS Naringenin appears to have potential in the treatment of sepsis.

Topics: Acute Kidney Injury; Angiotensinogen; Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Cecum; Disease Models, Animal; Flavanones; Kidney; Kidney Glomerulus; Rats; Rats, Wistar; Reactive Oxygen Species; Sepsis; Urinary Tract

Congestive cardiac failure has become one of the major health challenges of the 21st century and new therapies are needed to address this problem. The concentration of vasoactive intestinal peptide (VIP) in the heart has been shown to decrease as fibrosis (the pathology leading to heart failure) increases and to become undetectable in end stage cardiomyopathy. We sought to determine whether replenishment of myocardial VIP might treat myocardial fibrosis and therefore represent a new therapeutic target. Wistar Kyoto rats on a high (4.4%) salt diet were randomised to zero time control, 4 week infusion of VIP (5 pmol/kg/min) or vehicle control infusion. Myocardial VIP concentration was measured by radioimmunoassay, fibrosis was quantitated by computerised histomorphometry and changes in pro-fibrotic mediators were measured by quantitative rt-PCR. Myocardial VIP increased significantly in VIP treated rats compared with vehicle treated controls (P < 0.01) while fibrosis in the VIP treated rats was significantly lower than in both the zero time control (P < 0.05) and the vehicle infused control (P < 0.0005). Although all six profibrotic mediators which were measured increased over the 4 week experimental period VIP infusion only affected angiotensinogen (Agt) and angiotensin receptor type 1a (AT

Topics: Angiotensinogen; Animals; Biomarkers; Cardiomyopathies; Disease Models, Animal; Fibrosis; Humans; Infusions, Intravenous; Male; Myocardium; Rats; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; Sodium, Dietary; Vasoactive Intestinal Peptide

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; beta Catenin; Blood Pressure; Blood Urea Nitrogen; Bridged Bicyclo Compounds, Heterocyclic; Collagen Type I; Creatinine; Cyclic AMP Response Element-Binding Protein; Disease Models, Animal; Fibronectins; Gene Expression Regulation; Hypertension; Kidney; Male; Nephrectomy; Peptidyl-Dipeptidase A; Plasminogen Activator Inhibitor 1; Pyrimidinones; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Wnt Proteins; Wnt Signaling Pathway

Topics: Angiotensinogen; Animals; Blood Pressure; Cells, Cultured; Collagen Type IV; Disease Models, Animal; Fibrosis; Hepatocytes; Humans; Hypertension; Kidney; Lymphokines; Male; Mice; Mice, Knockout; Platelet-Derived Growth Factor; Primary Cell Culture; Up-Regulation; Ureter

Small interfering RNAs (siRNAs) targeting hepatic angiotensinogen ( Agt) may provide long-lasting antihypertensive effects, but the optimal approach remains unclear. Here, we assessed the efficacy of a novel AGT siRNA in spontaneously hypertensive rats. Rats were treated with vehicle, siRNA (10 mg/kg fortnightly; subcutaneous), valsartan (31 mg/kg per day; oral), captopril (100 mg/kg per day; oral), valsartan+siRNA, or captopril+valsartan for 4 weeks (all groups, n=8). Mean arterial pressure (recorded via radiotelemetry) was lowered the most by valsartan+siRNA (-68±4 mm Hg), followed by captopril+valsartan (-54±4 mm Hg), captopril (-23±2 mm Hg), siRNA (-14±2 mm Hg), and valsartan (-10±2 mm Hg). siRNA and captopril monotherapies improved cardiac hypertrophy equally, but less than the dual therapies, which also lowered NT-proBNP (N-terminal pro-B-type natriuretic peptide). Glomerular filtration rate, urinary NGAL (neutrophil gelatinase-associated lipocalin), and albuminuria were unaffected by treatment. siRNA lowered circulating AGT by 97.9±1.0%, and by 99.8±0.1% in combination with valsartan. Although siRNA greatly reduced renal Ang (angiotensin) I, only valsartan+siRNA suppressed circulating and renal Ang II. This coincided with decreased renal sodium hydrogen exchanger type 3 and phosphorylated sodium chloride cotransporter abundances. Renin and plasma K

Topics: Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Gene Expression Regulation; Hypertension; Injections, Subcutaneous; Liver; Male; Rats; Rats, Inbred SHR; RNA; RNA, Small Interfering

The aim of this study was to investigate the renoprotective effect of bardoxolone methyl (BM), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator with an antioxidant effect, in a salt-sensitive hypertension model induced by aldosterone (Ald) and salt. Tubulointerstitial damage with urinary liver-type fatty acid-binding protein (L-FABP) was evaluated using human L-FABP chromosomal transgenic (L-FABP

Topics: Aldosterone; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Fatty Acid-Binding Proteins; Hypertension, Renal; Kidney; Mice; NF-E2-Related Factor 2; Oleanolic Acid; Oxidative Stress; Protective Agents; Reactive Oxygen Species; Renin-Angiotensin System; Sodium Chloride; Up-Regulation

The intrarenal renin angiotensin system (RAS) is activated in polycystic kidney disease. We have recently shown in the Pkd1 mouse that Gen 2 antisense oligonucleotide (ASO), which suppresses angiotensinogen (Agt) synthesis, is efficacious in slowing kidney cyst formation compared with lisinopril. The aim of this current study was to determine 1) if unilateral nephrectomy accelerates cystogenesis in Pkd1 mice (as previously shown in cilia knockout mice) and 2) whether Agt ASO can slow the progression in this accelerated cystic mouse model. Adult Pkd1 conditional floxed allele mice expressing cre were administered tamoxifen, resulting in global knockout of Pkd1. Three weeks after tamoxifen injection, mice underwent left unilateral nephrectomy. Mice were then treated with Agt ASO (75 mg/kg per week) or aliskiren (20 mg/kg per day)+Agt ASO or control for 8 wk. Unilateral nephrectomy accelerated kidney cyst formation compared with nonnephrectomized mice. Both Agt ASO and Aliskiren+Agt ASO treatments significantly reduced plasma and urinary Agt levels. Blood pressure was lowest in Aliskiren+Agt ASO mice among all treatment groups, and the control group had the highest blood pressure. All mice developed significant kidney cysts at 8 wk after nephrectomy, but Agt ASO and Aliskiren+Agt ASO groups had fewer kidney cysts than controls. Renal pAkt, pS6 levels, and apoptosis were significantly suppressed in those receiving Agt ASO compared with controls. These results indicate that suppressing Agt using an ASO slowed the progression of accelerated cystic kidney disease induced by unilateral nephrectomy in Pkd1 mice by suppressing intrarenal RAS, mammalian target of rapamycin pathway, and cell proliferation.

Topics: Amides; Angiotensinogen; Animals; Apoptosis; Cell Proliferation; Disease Models, Animal; Disease Progression; ErbB Receptors; Female; Fumarates; Genetic Predisposition to Disease; Kidney; Male; Mice, Knockout; Nephrectomy; Oligonucleotides, Antisense; Phenotype; Polycystic Kidney, Autosomal Dominant; Renin; Renin-Angiotensin System; Time Factors; TOR Serine-Threonine Kinases; TRPP Cation Channels

Heart failure with preserved ejection fraction (HFpEF) can arise from cardiac and vascular remodeling processes following long-lasting hypertension. Efficacy of common HF therapeutics is unsatisfactory in HFpEF. Evidence suggests that stimulators of the nitric oxide-sensitive soluble guanylyl cyclase (NOsGC) could be of use here. We aimed to characterize the complex cardiovascular effects of NOsGC stimulation using NO-independent stimulator BAY 41-8543 in a double-transgenic rat (dTGR) model of HFpEF. We show a drastically improved survival rate of treated dTGR. We observed less cardiac fibrosis, macrophage infiltration, and gap junction remodeling in treated dTGR. Microarray analysis revealed that treatment of dTGR corrected the dysregulateion of cardiac genes associated with fibrosis, inflammation, apoptosis, oxidative stress, and ion channel function toward an expression profile similar to healthy controls. Treatment reduced systemic blood pressure levels and improved endothelium-dependent vasorelaxation of resistance vessels. Further comprehensive in vivo phenotyping showed an improved diastolic cardiac function, improved hemodynamics, and less susceptibility to ventricular arrhythmias. Short-term BAY 41-8543 application in isolated untreated transgenic hearts with structural remodeling significantly reduced the occurrence of ventricular arrhythmias, suggesting a direct nongenomic role of NOsGC stimulation on excitation. Thus, NOsGC stimulation was highly effective in improving several HFpEF facets in this animal model, underscoring its potential value for patients.

Topics: Administration, Oral; Angiotensinogen; Animals; Arrhythmias, Cardiac; Blood Pressure; Chronic Disease; Disease Models, Animal; Drug Evaluation, Preclinical; Echocardiography; Heart Failure; Heart Ventricles; Humans; Isolated Heart Preparation; Male; Morpholines; Pyrimidines; Rats; Rats, Transgenic; Renin; Soluble Guanylyl Cyclase; Stroke Volume; Survival Rate; Treatment Outcome

Hypertension may result from high-fat (HF) diet induced-obesity and overexposure to glucocorticoids in utero. Recent studies demonstrated the potent contribution of adipose tissue's renin-angiotensin system (RAS) to systemic RAS, which plays a key role in regulating blood pressure (BP). In this study, we investigated the effects of prenatal dexamethasone (DEX) exposure and postnatal HF diet on RAS of adipose tissue.. RAS and BP of 6-month old rats exposed to prenatal DEX and/or postnatal HF diet were examined.. Prenatal DEX plus postnatal HF exerted a synergistic effect on systolic BP. Prenatal DEX exposure suppressed plasma angiotensin (ANG) I and ANG II, whereas postnatal HF suppressed plasma ANG-(1-7) level. Prenatal DEX increased prorenin receptor and renin levels, but suppressed angiotensinogen (AGT) and angiotensin-converting-enzyme 1 (ACE1) mRNA expressions in adipose tissue. Postnatal HF increased AGT mRNA expression, but suppressed prorenin receptor, renin, ACE2, ANG II type 2 receptor (AT2R), and Mas receptor (MasR) mRNA expression levels.. Prenatal GC exposure altered the ACE1/ANG II/ANG II type 1 receptor (AT1R) axis, whereas postnatal HF negatively impacted the ACE2/ANG-(1-7)/MasR axis. Prenatal DEX exposure and postnatal HF synergistically elevated BP through a distinct programming mechanism of systemic and adipose RAS. Adipose RAS might be a target for precise hypertension treatment.

Topics: Adipose Tissue; Angiotensinogen; Animals; Blood Pressure; Dexamethasone; Diet, High-Fat; Disease Models, Animal; Female; Gene Expression Regulation, Developmental; Hypertension; Peptidyl-Dipeptidase A; Pregnancy; Prenatal Exposure Delayed Effects; Proto-Oncogene Mas; Rats; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Vacuolar Proton-Translocating ATPases

We aimed to examine the effects of a sodium glucose co-transporter 2 (SGLT2) inhibitor on systemic and intrarenal renin-angiotensin system (RAS) in subtotally nephrectomized non-diabetic rats, a model of chronic kidney disease (CKD). Oral administration of the selective SGLT2 inhibitor, TA-1887 (10 mg/kg/day), for 10 weeks induced glycosuria. However, plasma renin activity, plasma angiotensinogen levels, kidney angiotensin II contents and renal injury were not significantly affected by TA-1887. These data indicate that chronic treatment with an SGLT2 inhibitor does not activate the systemic and intrarenal RAS in subjects with non-diabetic CKD.

Topics: Administration, Oral; Angiotensin II; Angiotensinogen; Animals; Disease Models, Animal; Glucosides; Glycosuria; Indoles; Kidney; Male; Nephrectomy; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; Renin; Renin-Angiotensin System; Sodium-Glucose Transporter 2; Sodium-Glucose Transporter 2 Inhibitors

Acupuncture with low-frequency electrical stimulation (Acu/LFES) can prevent muscle atrophy by increasing muscle protein anabolism in mouse models of chronic kidney disease. During the treatment of muscle wasting, we found that Acu/LFES on the gastrocnemius muscle of the leg enhances renal blood flow. We also found that Acu/LFES increases exosome abundance and alters exosome-associated microRNA expression in the circulation. When exosome secretion was blocked using GW4869, the Acu/LFES-induced increase in renal blood flow was limited. This provided evidence that the increased renal blood flow is exosome mediated. To identify how exosomes regulate renal blood flow, we performed microRNA deep sequencing in exosomes isolated from treated and untreated mouse serum and found that the 34 microRNAs are altered by Acu/LFES. In particular, miR-181d-5p is increased in the serum exosome of Acu/LFES-treated mice. In silico searching suggested that miR-181d-5p could target angiotensinogen. Using a luciferase reporter assay, we demonstrated that miR-181 directly inhibits angiotensinogen. When Acu/LFES-treated muscle was excised and incubated in culture medium, we found that the amount of exosomes and miR-181d-5p was increased in the medium providing evidence that Acu/LFES can increase miR-181 secretion. We conclude that Acu/LFES on leg hindlimb increases miR-181 in serum exosome leading to increased renal blood flow. This study provides important new insights about the mechanism(s) by which acupuncture may regulation of muscle-organ cross talk through exosome-derived microRNA.

Topics: Acupuncture Therapy; Angiotensinogen; Animals; Blood Flow Velocity; Disease Models, Animal; Electric Stimulation Therapy; Exosomes; Hindlimb; Kidney; Mice, Inbred C57BL; MicroRNAs; Muscle, Skeletal; Muscular Atrophy; Renal Circulation; Tissue Culture Techniques

We previously showed that complement 3 (C3) is highly expressed in mesenchymal tissues in spontaneously hypertensive rats (SHR). We targeted C3 gene by zinc-finger nuclease (ZFN) gene-editing technology and investigated blood pressure and phenotype in SHR. Blood pressure was measured by tail-cuff and telemetry methods. Histology and expression of liver X receptor α (LXRα), renin, Krüppel-like factor 5 (KLF5), and E-cadherin were evaluated in kidneys. Mesangial cells (MCs) were removed from glomeruli from three strains, and we evaluated the phenotype in vitro. SHR showed the salt-sensitive hypertension that was abolished in C3 knockout (KO) SHR. Proliferation of MCs from SHR was higher than that from Wistar-Kyoto (WKY) rats and showed a synthetic phenotype. Renal injury scores were higher in SHR than in WKY rats and C3 KO SHR. Expression of E-cadherin was lower, and expression of renin was higher in the nephrotubulus from SHR than WKY rats and C3 KO SHR. Expression of C3 α-chain protein and α-smooth muscle actin protein was significantly higher in renal medulla from SHR than from WKY rats. Expression of angiotensinogen, LXRα, renin, and KLF5 mRNA was increased in kidney from SHR compared with C3 KO SHR. Intrarenal angiotensin II levels were significantly higher in kidney from SHR than WKY rats and C3 KO SHR. Urinary epinephrine and norepinephrine excretions were significantly higher in SHR than in WKY rats and C3 KO SHR. These findings showed that increased C3 induces salt-sensitive hypertension with increases in urinary catecholamine excretion and intrarenal activation of the renin-angiotensin system by the dedifferentiation of mesenchymal tissues in kidney from SHR.

Topics: Angiotensinogen; Animals; Blood Pressure; Cadherins; Cell Dedifferentiation; Cell Proliferation; Cells, Cultured; Complement C3; Disease Models, Animal; Genetic Predisposition to Disease; Hypertension; Kidney; Kruppel-Like Transcription Factors; Liver X Receptors; Male; Phenotype; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Transgenic; Renin; Renin-Angiotensin System; Signal Transduction; Sodium Chloride, Dietary

Because of the presence of the blood-brain barrier, brain renin-angiotensin system activity should depend on local (pro)renin synthesis. Indeed, an intracellular form of renin has been described in the brain, but whether it displays angiotensin (Ang) I-generating activity (AGA) is unknown. Here, we quantified brain (pro)renin, before and after buffer perfusion of the brain, in wild-type mice, renin knockout mice, deoxycorticosterone acetate salt-treated mice, and Ang II-infused mice. Brain regions were homogenized and incubated with excess angiotensinogen to detect AGA, before and after prorenin activation, using a renin inhibitor to correct for nonrenin-mediated AGA. Renin-dependent AGA was readily detectable in brain regions, the highest AGA being present in brain stem (>thalamus=cerebellum=striatum=midbrain>hippocampus=cortex). Brain AGA increased marginally after prorenin activation, suggesting that brain prorenin is low. Buffer perfusion reduced AGA in all brain areas by >60%. Plasma renin (per mL) was 40× to 800× higher than brain renin (per gram). Renin was undetectable in plasma and brain of renin knockout mice. Deoxycorticosterone acetate salt and Ang II suppressed plasma renin and brain renin in parallel, without upregulating brain prorenin. Finally, Ang I was undetectable in brains of spontaneously hypertensive rats, while their brain/plasma Ang II concentration ratio decreased by 80% after Ang II type 1 receptor blockade. In conclusion, brain renin levels (per gram) correspond with the amount of renin present in 1 to 20 μL of plasma. Brain renin disappears after buffer perfusion and varies in association with plasma renin. This indicates that brain renin represents trapped plasma renin. Brain Ang II represents Ang II taken up from blood rather than locally synthesized Ang II.

Topics: Amides; Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Blood-Brain Barrier; Brain; Desoxycorticosterone Acetate; Disease Models, Animal; Fumarates; Hypertension; Mice; Mice, Knockout; Random Allocation; Rats; Rats, Inbred SHR; Reference Values; Renin-Angiotensin System

Uncontrolled hypertension is an important contributor to cardiovascular disease. Despite the armamentarium of antihypertensive treatments, there remains a need for novel agents effective in individuals who cannot reach acceptable blood pressure levels. Inhibitors targeting the renin-angiotensin-aldosterone system (RAAS) are widely used but may not optimally inhibit RAAS and demonstrate an acceptable safety profile. Experiments were conducted to characterize a series of AGT (angiotensinogen) antisense oligonucleotides (ASOs) and compare their efficacy and tolerability to traditional RAAS blockade. AGT ASOs which target multiple systemic sites of AGT versus an N-acetylgalactosamine-conjugated AGT ASO that targets the liver were compared with captopril and losartan. Spontaneously hypertensive rats fed an 8% NaCl diet, a model of malignant hypertension resistant to standard RAAS inhibitors, demonstrated robust and durable blood pressure reductions with AGT ASO treatments, which was not observed with standard RAAS blockade. Studies in rat models of acute kidney injury produced by salt deprivation revealed kidney injury with ASO treatment that reduced kidney-expressed AGT, but not in animals treated with the N-acetylgalactosamine AGT ASO despite comparable plasma AGT reductions. Administration of either captopril or losartan also produced acute kidney injury during salt deprivation. Thus, intrarenal RAAS derived from kidney AGT, and inhibited by the standard of care, contributes to the maintenance of renal function during severe RAAS challenge. Such improvements in efficacy and tolerability by a liver-selective AGT inhibitor could be desirable in individuals not at their blood pressure goal with existing RAAS blockade.

Topics: Acute Kidney Injury; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Drug Resistance; Hypertension; Kidney; Oligonucleotides, Antisense; Rats; Rats, Inbred SHR; Renin-Angiotensin System; Treatment Outcome

Using a transgenic cross, we evaluated features of preeclampsia, renal injury and the sFlt1/VEGF changes. Transgenic hAGT and hREN, or wild-type (WT) C57Bl/6 mice were cross-bred: female hAGT × male hREN for preeclampsia (PRE) model and female WT × male WT for pregnant controls (WTP). Samples were collected for plasma VEGF, sFlt1, and urine albumin. Blood pressures (BP) were monitored by telemetry. Vascular reactivity was investigated by wire myography. Kidneys and placenta were immunostained for sFlt1 and VEGF. Eleven PRE and 9 WTP mice were compared. PRE more frequently demonstrated albuminuria, glomerular endotheliosis (80% vs. 11%;

Topics: Albuminuria; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Endothelial Cells; Female; Genetic Predisposition to Disease; Gestational Age; Humans; Kidney Diseases; Kidney Glomerulus; Mice, Inbred C57BL; Mice, Transgenic; Phenotype; Placenta; Pre-Eclampsia; Pregnancy; Renin; Renin-Angiotensin System; Signal Transduction; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Remodeling; Vasoconstriction; Vasodilation

This study intends to explore the role of microRNA-29a (miRNA-29a) in the development of diabetic retinopathy by targeting AGT gene in a rat model.. Fifty-six DR rat models were established and divided into 7 groups (with 8 rats in each group): the model group, the miRNA-29a group, the miRNA-29a knockdown group, the negative control (NC) group, the AGT group, the miRNA-29a+AGT group, and the miRNA-29a knockdown+AGT group respectively, while 8 normal rats were selected as the normal group. The qRT-PCR was used to detect the expression of miRNA-29a and AGT mRNA. The AGT protein expression was measured using Western blotting. The ADPase histochemical staining was applied to detect retinal neo-vascular morphology. The number of retinal vascular endothelial cells was counted by H&E staining.. MiRNA-29a and AGT mRNA expressions were negatively correlated. Compared with rats in the normal group, the miRNA-29a expression in DR rats of each group decreased, but the AGT mRNA and protein expression increased; the vascular distribution was in disorder, and the new retinal vessels, vascular density, and endothelial nuclei all increased. Compared with the model group, miRNA-29a increased, and the AGT mRNA and protein expression decreased in the miRNA-29a group; additionally, the vascular density, tortuosity, and endothelial cell nuclei significantly decreased. The opposite trend was found in the miRNA-29a knockdown group, the miRNA-29a knockdown+AGT group, and the AGT group, particularly in the miRNA-29a knockdown+AGT group.. Overexpression of miRNA-29a could down-regulate AGT expression, thereby preventing the development of DR in a rat model.

Topics: Angiotensinogen; Animals; Blood Glucose; Diabetic Retinopathy; Disease Models, Animal; Endothelial Cells; Gene Knockdown Techniques; HEK293 Cells; Humans; Male; MicroRNAs; Rats; Rats, Sprague-Dawley; Retina; RNA, Messenger; Transfection

Reactive oxygen species (ROS) are produced during the interaction between oxalate/calcium oxalate monohydrate (COM) crystals and renal epithelial cells and are responsible for the various cellular responses through the activation of NADPH oxidase (Nox). Ox and COM also activate the renin-angiotensin-aldosterone system (RAAS). Aldosterone stimulates ROS production through activation of Nox with the involvement of mineralocorticoid receptor (MR), Rac1 and mitogen-activated protein kinases (MAPK). We investigated RAAS pathways in vivo in an animal model of hyperoxaluria and in vitro by exposing renal epithelial cells to COM crystals.. Hyperoxaluria was induced in male SD rats by administering ethylene glycol. One group of rats was additionally given spironolactone. Total RNA was extracted and subjected to genomic microarrays to obtain global transcriptome data. Normal rat kidney cell line (NRK-52E) was incubated with aldosterone(10(-7) M) and COM(67 μg/cm(2)) with or without spironolactone(10(-5) M), a selective inhibitor of SRC family of kinases; protein phosphatase 2(pp2) (10(-5) M) and Nox inhibitor; diphenylene iodonium (DPI) (10(-5) M).. Relative expression of genes encoding for AGT, angiotensin receptors 1b and 2, Renin 1, Cyp11b, HSD11B2, Nr3c2, NOx4 and Rac1 was upregulated in the kidneys of rats with hyperoxaluria. Treatment with spironolactone reversed the effect of hyperoxaluria. Both aldosterone and COM crystals activated Nox and Rac1 expression in NRK52E, while spironolactone inhibited Nox and Rac1 expression. Increased Rac1 expression was significantly attenuated by treatment with PP2 and spironolactone.. Results indicate that hyperoxaluria-induced production of ROS, injury and inflammation are in part associated with the activation of Nox through renin-angiotensin-aldosterone pathway.

Topics: 11-beta-Hydroxysteroid Dehydrogenase Type 2; Angiotensinogen; Animals; Calcium Oxalate; Cell Line; Cytochrome P-450 CYP11B2; Disease Models, Animal; Enzyme Inhibitors; Ethylene Glycol; Gene Expression Profiling; Hyperoxaluria; Male; Mineralocorticoid Receptor Antagonists; NADPH Oxidase 4; NADPH Oxidases; Onium Compounds; Protein Phosphatase 2; rac1 GTP-Binding Protein; Rats; Rats, Sprague-Dawley; Receptors, Angiotensin; Receptors, Mineralocorticoid; Renin; Renin-Angiotensin System; RNA, Messenger; Spironolactone; Steroid 11-beta-Hydroxylase

This study determined whether angiotensinogen (AGT) has angiotensin II-independent effects using multiple genetic and pharmacological manipulations.. All study mice were in low-density lipoprotein receptor -/- background and fed a saturated fat-enriched diet. In mice with floxed alleles and a neomycin cassette in intron 2 of the AGT gene (hypoAGT mice), plasma AGT concentrations were >90% lower compared with their wild-type littermates. HypoAGT mice had lower systolic blood pressure, less atherosclerosis, and diminished body weight gain and liver steatosis. Low plasma AGT concentrations and all phenotypes were recapitulated in mice with hepatocyte-specific deficiency of AGT or pharmacological inhibition of AGT by antisense oligonucleotide administration. In contrast, inhibition of AGT cleavage by a renin inhibitor, aliskiren, failed to alter body weight gain and liver steatosis in low-density lipoprotein receptor -/- mice. In mice with established adiposity, administration of AGT antisense oligonucleotide versus aliskiren led to equivalent reductions of systolic blood pressure and atherosclerosis. AGT antisense oligonucleotide administration ceased body weight gain and further reduced body weight, whereas aliskiren did not affect body weight gain during continuous saturated fat-enriched diet feeding. Structural comparisons of AGT proteins in zebrafish, mouse, rat, and human revealed 4 highly conserved sequences within the des(angiotensin I)AGT domain. des(angiotensin I)AGT, through adeno-associated viral infection in hepatocyte-specific AGT-deficient mice, increased body weight gain and liver steatosis, but did not affect atherosclerosis.. AGT contributes to body weight gain and liver steatosis through functions of the des(angiotensin I)AGT domain, which are independent of angiotensin II production.

Topics: Amides; Amino Acid Sequence; Angiotensin II; Angiotensinogen; Animals; Atherosclerosis; Blood Pressure; Conserved Sequence; Dependovirus; Diet, High-Fat; Disease Models, Animal; Fatty Liver; Fumarates; Genetic Vectors; Genotype; Hepatocytes; Hypertension; Liver; Male; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Oligonucleotides, Antisense; Phenotype; Protein Binding; Protein Interaction Domains and Motifs; Receptors, LDL; Renin; Signal Transduction; Time Factors; Transduction, Genetic; Weight Gain

We report that disturbance to the circadian rhythm of urinary angiotensinogen (AGT) excretion may lead to renal damage, hypertension and diurnal blood pressure (BP) variations. We aim to clarify the circadian rhythm of the intrarenal renin-angiotensin system (RAS) and its contribution to renal damage, hypertension and BP variations, and to evaluate whether the administration of RAS blockers influences the circadian rhythms of intrarenal RAS components. Anti-thymocyte serum (ATS) nephritis rats were used as a chronic progressive glomerulonephritis model (group A) and compared with control rats (group C). Other rats with ATS nephritis received olmesartan medoxomil (an angiotensin II (AngII) type 1 receptor (AT1R) blocker; group AO) or hydralazine (a vasodilator; group AH). The levels of intrarenal RAS components were evaluated every 6 h. The expression levels of intrarenal AGT, AngII and AT1R were increased in group A and peaked at the same time as BP and urinary protein excretion during the rest phase. The amplitude of the circadian fluctuation of these proteins was more increased in group A than in group C. The circadian fluctuation of these proteins was reduced in groups AO and AH. However, renal function, proteinuria and augmentation of intrarenal RAS components were reduced only in group AO. Intrarenal RAS components, such as AGT, AngII and AT1R proteins, were increased and the amplitude of the oscillations of these proteins was augmented in ATS nephritis rats. Interestingly, renal damage may be linked to the activation of the intrarenal RAS independent of the amplitude of its oscillations and BP.

Topics: Angiotensin II; Angiotensinogen; Animals; Antilymphocyte Serum; Circadian Rhythm; Disease Models, Animal; Hydralazine; Kidney; Lymphocytes; Male; Nephritis; Olmesartan Medoxomil; Rats; Rats, Wistar; Receptor, Angiotensin, Type 1; Renin-Angiotensin System

Hypercholesterolemia and hypertension are associated with aortic valve stenosis (AVS) in humans. We have examined aortic valve function, structure, and gene expression in hypercholesterolemic/hypertensive mice.. Control, hypertensive, hypercholesterolemic (Apoe(-/-)), and hypercholesterolemic/hypertensive mice were studied. Severe aortic stenosis (echocardiography) occurred only in hypercholesterolemic/hypertensive mice. There was minimal calcification of the aortic valve. Several structural changes were identified at the base of the valve. The intercusp raphe (or seam between leaflets) was longer in hypercholesterolemic/hypertensive mice than in other mice, and collagen fibers at the base of the leaflets were reoriented to form a mesh. In hypercholesterolemic/hypertensive mice, the cusps were asymmetrical, which may contribute to changes that produce AVS. RNA sequencing was used to identify molecular targets during the developmental phase of stenosis. Genes related to the structure of the valve were identified, which differentially expressed before fibrotic AVS developed. Both RNA and protein of a profibrotic molecule, plasminogen activator inhibitor 1, were increased greatly in hypercholesterolemic/hypertensive mice.. Hypercholesterolemic/hypertensive mice are the first model of fibrotic AVS. Hypercholesterolemic/hypertensive mice develop severe AVS in the absence of significant calcification, a feature that resembles AVS in children and some adults. Structural changes at the base of the valve leaflets include lengthening of the raphe, remodeling of collagen, and asymmetry of the leaflets. Genes were identified that may contribute to the development of fibrotic AVS.

Topics: Angiotensinogen; Animals; Aortic Valve; Aortic Valve Stenosis; Apolipoproteins E; Disease Models, Animal; Female; Fibrosis; Gene Expression Regulation; Hypercholesterolemia; Hypertension; Male; Mice, Inbred C57BL; Mice, Knockout; Plasminogen Activator Inhibitor 1; Renin; Severity of Illness Index

Angiotensin-(1-12) [ANG-(1-12)] is processed into ANG II by chymase in rodent and human heart tissue. Differences in the amino acid sequence of rat and human ANG-(1-12) render the human angiotensinogen (hAGT) protein refractory to cleavage by renin. We used transgenic rats harboring the hAGT gene [TGR(hAGT)L1623] to assess the non-renin-dependent effects of increased hAGT expression on heart function and arterial pressure. Compared with Sprague-Dawley (SD) control rats (n= 11), male homozygous TGR(hAGT)L1623 (n= 9) demonstrated sustained daytime and nighttime hypertension associated with no changes in heart rate but increased heart rate lability. Increased heart weight/tibial length ratio and echocardiographic indexes of cardiac hypertrophy were associated with modest reduction of systolic function in hAGT rats. Robust human ANG-(1-12) immunofluorescence within myocytes of TGR(hAGT)L1623 rats was associated with a fourfold increase in cardiac ANG II content. Chymase enzymatic activity, using the rat or human ANG-(1-12) as a substrate, was not different in the cardiac tissue of SD and hAGT rats. Since both cardiac angiotensin-converting enzyme (ACE) and ACE2 activities were not different among the two strains, the changes in cardiac structure and function, blood pressure, and left ventricular ANG II content might be a product of an increased cardiac expression of ANG II generated through a non-renin-dependent mechanism. The data also underscore the existence in the rat of alternate enzymes capable of acting on hAGT protein. Homozygous transgenic rats expressing the hAGT gene represent a novel tool to investigate the contribution of human relevant renin-independent cardiac ANG II formation and function.

Topics: Angiotensinogen; Animals; Arterial Pressure; Cardiomegaly; Disease Models, Animal; Genotype; Heart Rate; Homozygote; Humans; Hydrolysis; Hypertension; Male; Myocardium; Peptide Fragments; Phenotype; Rats, Sprague-Dawley; Rats, Transgenic; Renin-Angiotensin System; Time Factors; Ultrasonography; Ventricular Function, Left

Urinary angiotensinogen excretion parallels albumin excretion, which is not the case for renin, while renin's precursor, prorenin, is undetectable in urine. We hypothesized that renin and prorenin, given their smaller size, are filtered through the glomerulus in larger amounts than albumin and angiotensinogen, and that differences in excretion rate are because of a difference in reabsorption in the proximal tubule. To address this, we determined the glomerular sieving coefficient of renin and prorenin and measured urinary renin/prorenin 1) after inducing prorenin in Cyp1a1-Ren2 rats and 2) in patients with Dent disease or Lowe syndrome, disorders characterized by defective proximal tubular reabsorption. Glomerular sieving coefficients followed molecular size (renin>prorenin>albumin). The induction of prorenin in rats resulted in a >300-fold increase in plasma prorenin and doubling of blood pressure but did not lead to the appearance of prorenin in urine. It did cause parallel rises in urinary renin and albumin, which losartan but not hydralazine prevented. Defective proximal tubular reabsorption increased urinary renin and albumin 20- to 40-fold, and allowed prorenin detection in urine, at ≈50% of its levels in plasma. Taken together, these data indicate that circulating renin and prorenin are filtered into urine in larger amounts than albumin. All 3 proteins are subsequently reabsorbed in the proximal tubule. For prorenin, such reabsorption is ≈100%. Minimal variation in tubular reabsorption (in the order of a few %) is sufficient to explain why urinary renin and albumin excretion do not correlate. Urinary renin does not reflect prorenin that is converted to renin in tubular fluid.

Topics: Albumins; Angiotensinogen; Animals; Dent Disease; Disease Models, Animal; Glomerular Filtration Rate; Humans; Kidney Glomerulus; Male; Mice; Mice, Inbred C57BL; Middle Aged; Oculocerebrorenal Syndrome; Rats; Renin; Renin-Angiotensin System; Sampling Studies; Translational Research, Biomedical; Urinalysis; Young Adult

Severe hypertension destroys eyesight. The RAS (renin-angiotensin system) may contribute to this. This study relied on an established angiotensin, AngII (angiotensin II)-elevated dTGR (double-transgenic rat) model and same-background SD (Sprague-Dawley) rat controls. In dTGRs, plasma levels of AngII were increased. We determined the general retinal phenotype and observed degeneration of ganglion cells that we defined as vascular degeneration. We also inspected relevant gene expression and lastly observed alterations in the outer blood-retinal barrier. We found that both scotopic a-wave and b-wave as well as oscillatory potential amplitude were significantly decreased in dTGRs, compared with SD rat controls. However, the b/a-wave ratio remained unchanged. Fluorescence angiography of the peripheral retina indicated that exudates, or fluorescein leakage, from peripheral vessels were increased in dTGRs compared with controls. Immunohistological analysis of blood vessels in retina whole-mount preparations showed structural alterations in the retina of dTGRs. We then determined the general retinal phenotype. We observed the degeneration of ganglion cells, defined vascular degenerations and finally found differential expression of RAS-related genes and angiogenic genes. We found the expression of both human angiotensinogen and human renin in the hypertensive retina. Although the renin gene expression was not altered, the AngII levels in the retina were increased 4-fold in the dTGR retina compared with that in SD rats, a finding with mechanistic implications. We suggest that alterations in the outer blood-retinal barrier could foster an area of visual-related research based on our findings. Finally, we introduce the dTGR model of retinal disease.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Hypertensive Retinopathy; Male; Rats, Transgenic; Renin; Renin-Angiotensin System

Maternal vitamin D deficiency is proposed as a risk factor for preeclampsia in humans. We tested the hypothesis that vitamin D depletion aggravates and high supplementation ameliorates the preeclampsia phenotype in an established transgenic rat model of human renin-angiotensin system-mediated preeclampsia. Adult rat dams, transgenic for human angiotensinogen (hAGT) and mated with male rats transgenic for human renin (hREN), were fed either vitamin D-depleted chow (VDd) or enriched chow (VDh) 2 weeks before mating and during pregnancy. Mean blood pressure was recorded by tail-cuff, and 24-hour urine samples were collected in metabolic cages at days 6 and 18 of gestation. Rats were sacrificed at day 21 of gestation. Depleted dams (VDd) had negligible serum 25-hydroxyvitamin D2+3 levels (mean ± SEM; 2.95 ± 0.45 nmol/l vs. VDh 26.20 ± 2.88 nmol/l, P = .01), but in both groups, levels of 1,25(OH)2D3 remained below detection level of 25 pmol/l. Dietary vitamin D depletion did not aggravate hypertension (mean ± SEM BP, day 20 of gestation: 151.38 ± 5.65 mmHg VDd vs. 152.00 ± 4.10 mmHg VDh) or proteinuria. Fetal anthropometrics were similar between the groups, whereas VDd displayed lower placental:fetal weight ratios (0.15 vs. 0.16 g/g, P = .01) and increased sFlt-1/PlGF ratio. Expression of hREN was lower in placenta of VDd dams (0.82 ± 0.44 AU vs. 1.52 ± 0.15 AU, P = .04). Expression of key vitamin D metabolizing enzymes was unchanged. Dietary vitamin D intervention did not alter key aspects of the preeclampsia phenotype using the transgenic rodent model of human renin-angiotensin system-mediated pre-eclampsia, plausibly due to altered vitamin D metabolism or excretion in the transgenic rats.

Topics: Adult; Angiotensinogen; Animals; Blood Pressure Determination; Diet; Disease Models, Animal; Female; Humans; Male; Phenotype; Placenta; Pre-Eclampsia; Pregnancy; Proteinuria; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renal Elimination; Renin; Renin-Angiotensin System; Risk Factors; Vitamin D; Vitamin D Deficiency

Radiofrequency ablation of the renal arteries (RF-ABL) has been shown to decrease blood pressure (BP) in drug-resistant hypertensive patients who receive antihypertensive drug therapy. However, there remain questions regarding how RF-ABL influences BP independent of drug therapy and whether complete renal denervation is necessary to maximally lower BP. To study these questions, we examined the cardiovascular, sympathetic, and renal effects produced by RF-ABL of the proximal renal arteries in spontaneously hypertensive rats (SHR) with established hypertension.. SHR were instrumented (telemetry) for measurement of systolic/diastolic BP (SBP/DBP). Rats then underwent Sham-ABL or RF-ABL adjacent to the renal ostium and BP was recorded for 8 weeks. Changes in sympathetic activity, 24-hour water/sodium excretion, and levels of urinary angiotensinogen (AGT), plasma renin activity, and kidney renin content (KRC) were measured in SHR.. Compared with Sham-ABL, RF-ABL produced a sustained decrease in BP. At 8 weeks, SBP/DBP was 171±6/115±3 and 183±4/129±3mm Hg for RF-ABL and Sham-ABL SHR, respectively. Correlating with the reduction in BP, RF-ABL significantly decreased the low frequency/total and low frequency/high frequency of BP variability and attenuated the hypotensive response to chlorisondamine. Kidney norepinephrine levels were markedly decreased at 8 weeks in RF-ABL vs. Sham-ABL SHR. There were no group differences in 24-hour sodium/water excretion or urinary AGT excretion rate (6 weeks) or plasma renin activity or KRC (8 weeks). In other studies, concurrent RF-ABL plus surgical denervation initially decreased BP to a greater level than RF-ABL alone, but thereafter the reduction in BP between groups was not different.. In hypertensive SHR, bilateral RF-ABL of the proximal renal arteries produced a sustained decease in sympathetic activity and BP without changes in sodium/water excretion or activity of the systemic/renal renin-angiotensin system.

Topics: Angiotensinogen; Animals; Blood Pressure; Catheter Ablation; Disease Models, Animal; Hypertension; Kidney; Male; Natriuresis; Neural Inhibition; Norepinephrine; Rats, Inbred SHR; Rats, Inbred WKY; Renal Artery; Renin; Renin-Angiotensin System; Sympathectomy; Sympathetic Nervous System; Time Factors; Urination

Renin-angiotensin system (RAS) inhibitors reduce glomerular injury and proteinuria, indicating that angiotensin II (Ang II) is involved in glomerular diseases. Although the local RAS is reported to play an essential role in maintaining local tissue functions, the role of the local RAS in regulating glomerular function is not well evaluated. In this study, we analyzed the glomerular expression of RAS components in nephrotic models and the effect of Ang II receptor blockers (ARB) on the expression of angiotensinogen (AGT).. The levels of glomerular expression of RAS components were analyzed in two nephrotic models: anti-nephrin antibody-induced nephropathy and PAN nephropathy, a mimic of human minimal change nephrotic syndrome. The effect of the ARB irbesartan on the expression of AGT in the nephrotic model was analyzed.. Glomerular expression of AGT and the receptors for Ang II was clearly increased in the nephrotic models, while the expression levels of renin, ACE and ACE2 were decreased. ARB treatment suppressed the increase of glomerular expression of AGT in the nephrotic model.. It is conceivable that the promoted local RAS action participated in the glomerular dysfunction, and that ARB treatment ameliorated slit diaphragm injury by inhibiting the positive feedback loop of the activated local Ang II action.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Cells, Cultured; Disease Models, Animal; Female; Kidney Glomerulus; Membrane Proteins; Nephrotic Syndrome; Podocytes; Rats, Wistar; Renin-Angiotensin System; RNA, Messenger

To demonstrate the renoprotective function of human liver-type fatty acid-binding protein (hL-FABP) expressed in proximal tubules in aldosterone (Aldo)-induced renal injury, hL-FABP chromosomal transgenic (Tg) and wild-type (WT) mice received systemic Aldo infusions (Tg-Aldo and WT-Aldo, respectively) were given 1% NaCl water for 28 days. In this model, elevation of systolic blood pressure, monocyte chemoattractant protein-1 expression, macrophage infiltration in the interstitium, tubulointerstitial damage, and depositions of type I and III collagens were observed. Elevation of systolic blood pressure did not differ in WT-Aldo vs. Tg-Aldo animals, however, renal injury was suppressed in Tg-Aldo compared with WT-Aldo mice. Dihydroethidium fluorescence was used to evaluate reactive oxidative stress, which was suppressed in Tg-Aldo compared with WT-Aldo mice. Gene expression of angiotensinogen in the kidney was upregulated, and excretion of urinary angiotensinogen was increased in WT-Aldo mice. This exacerbation was suppressed in Tg-Aldo mice. Expression of hL-FABP was upregulated in proximal tubules of Tg-Aldo mice. Urinary excretion of hL-FABP was significantly greater in Tg-Aldo than in Tg-control mice. In conclusion, hL-FABP ameliorated the tubulointerstitial damage in Aldo-induced renal injury via reducing oxidative stress and suppressing activation of the intrarenal renin-angiotensin system.

Topics: Aldosterone; Angiotensinogen; Animals; Blood Pressure; Chemokine CCL2; Collagen Type I; Collagen Type III; Disease Models, Animal; Fatty Acid-Binding Proteins; Kidney; Macrophages; Male; Mice; Mice, Transgenic; Oxidative Stress; Renal Insufficiency; Renin-Angiotensin System

Renal cyst enlargement is associated with the activation of both the circulating and intrarenal renin-angiotensin systems. Angiotensinogen (AGT) is the substrate for renin. The aim of the present study was to determine the effect of AGT inhibition on renal cyst enlargement. An AGT antisense oligonucleotide (ASO) that selectively inhibits AGT mRNA was injected once weekly in PKD2WS25 mice [an orthologous model of human autosmal dominant polycystic kidney disease (PKD) involving mutation of the Pkd2 gene] from 4 to 16 wk of age. The AGT ASO resulted in a 40% decrease in AGT RNA in the kidney, a 60% decrease in AGT RNA in the liver, and a significant decrease in AGT protein in the kidney and serum. The AGT ASO resulted in a significant decrease in kidney size, cyst volume density, and blood urea nitrogen. The AGT ASO resulted in a significant decrease in transforming growth factor-β and interstitial fibrosis in the kidney. Mice treated with the AGT ASO had a significant decrease in proinflammatory cytokines [chemokine (C-X-C motif) ligand (CXCL)1 and IL-12] in the kidney. Cluster of differentiation (CD)36 is a scavenger receptor found on tubular cells that can activate the renin-angiotensin system. Administration of a CD36 ASO had no effect on PKD and kidney function, suggesting that the effect of the AGT ASO is independent of CD36. In summary, AGT inhibition resulted in significant decreases in kidney size and cyst volume and an improvement in kidney function in PKD mice. The AGT ASO resulted in a decrease in transforming growth factor-β, interstitial fibrosis, and the proinflammatory cytokines CXCL1 and IL-12 in the kidney.

Topics: Angiotensinogen; Animals; Blood Urea Nitrogen; CD36 Antigens; Cells, Cultured; Chemokine CXCL1; Disease Models, Animal; Down-Regulation; Female; Fibrosis; Genetic Therapy; Interleukin-12; Kidney; Male; Mice, Inbred C57BL; Mice, Mutant Strains; Mutation; Oligonucleotides, Antisense; Polycystic Kidney, Autosomal Dominant; Recovery of Function; RNA, Messenger; Transforming Growth Factor beta; TRPP Cation Channels

The renal tissue renin-angiotensin system is activated in chronic kidney diseases. We previously demonstrated that intrarenal ANG II is synthesized primarily from liver-derived angiotensinogen filtered through the glomerulus and that podocyte injury increases the passage of angiotensinogen into the tubular lumen and generation of ANG II. In the present study, we tested the effect of cessation of glomerular filtration by ureteral obstruction on renal ANG II generation in kidneys with podocyte injury under two experimental conditions. Ureteral obstruction is known to activate the renin-angiotensin system in nonproteinuric kidneys. Transgenic mice expressing hCD25 in podocyte (NEP25) were injected with 1.25 or 10 ng/g body wt of LMB2, a hCD25-targeted immunotoxin, subjected to unilateral ureteral ligation on the following day, and euthanized 7 and 4 days later, respectively. In both experiments, compared with the kidney in untreated wild-type mice, renal angiotensinogen protein, as assessed by immunostaining and Western blot analysis, was increased in the contralateral unobstructed kidney. However, it was markedly decreased in the obstructed kidney. Whereas intrarenal ANG II content was increased in the contralateral kidney compared with the untreated kidney (248 ± 83 vs. 106 ± 21 and 298 ± 185 vs. 64.8 ± 20 fmol/g kidney, respectively), this increase was suppressed in the obstructed kidney (161 ± 75 and 113 ± 34 fmol/g kidney, respectively), a pattern opposite to what we expected in obstructed kidneys without podocyte injury. Thus, our study indicates that the major source of increased renal ANG II in podocyte injury is filtered angiotensinogen.

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; Antibodies, Monoclonal; Disease Models, Animal; Down-Regulation; Exotoxins; Female; Glomerular Filtration Rate; Humans; Interleukin-2 Receptor alpha Subunit; Kidney Diseases; Mice, Inbred C57BL; Mice, Transgenic; Podocytes; Renin-Angiotensin System; RNA, Messenger; Signal Transduction; Time Factors; Ureteral Obstruction

To test the hypothesis that in a high-salt induced hypertension in normal rats, whether the changes of intrarenal renin-agiotensin system (RAS) play a critical role in renal damage and could be reflected by urinary angiotensinogen (AGT).. In the study, 27 normotensive male Wistar-Kyoto rats were divided into control group [0.3% (mass faction) NaCl in chow, n=9, NS], high-salt diet group [8% (mass faction) NaCl in chow, n=9, HS] and high-salt diet with Losartan group [8% (mass faction) NaCl in chow and 20 mg/(kg×d) Losartan in gavages, n=9, HS+L)], and were fed for six weeks. The blood pressure was monitored and urine samples were collected every 2 weeks. AGTs in plasma, kidney and urine were measured by ELISA kits. The renal cortex expression of mRNA and protein of AGT were measured by Real-time PCR and immunohistochemistry (IHC). The renin activity and ANG II were measured by radioimmunoassay (RIA) kits.. Compared with NS, the systolic blood pressure (SBP) [(156 ± 2) mmHg vs. (133 ± 3) mmHg, P<0.05] increased significantly at the end of the 2nd week, and the urinary protein [(14.07 ± 2.84) mg/24 h vs. (7.62 ± 3.02) mg/24 h, P<0.05] increased significantly at the end of the 6th week in HS. Compared with HS, there was no significant difference in SBP (P>0.05) but the proteinuria [(9.69 ± 2.73) mg/24 h vs. (14.07 ± 2.84) mg/24 h, P<0.01] decreased significantly in HS+L. Compared with NS, there was no significant difference in the plasma renin activity, angiotensinogen and ANG II level in HS (P>0.05), but the renal cortex renin content [(8.72 ± 1.98) ng/(mL × h) vs. (4.37 ± 1.26) ng/(mL × h), P<0.05], AGT formation [(4.02 ± 0.60) ng/mg vs. (2.59 ± 0.42) ng/mg, P<0.01], ANG II level [(313.8 ± 48.76) pmol/L vs. (188.9 ± 46.95) pmol/L, P<0.05] were increased significantly in HS, and the urinary AGT and ANG II excretion rates increased significantly (P<0.05). Compared with HS, the plasma renin activity, angiotensinogen and ANG II level were significantly increased (P<0.05), but the renal cortex renin content, AGT formation, ANG II level significantly decreased (P<0.05), and the urinary AGT and ANG II excretion rates decreased significantly in HS+L (P<0.05). The urinary AGT excretion rates were positively correlated with the AGT level in the renal cortex (P<0.05).. Up-regulation of intarenal RAS may contribute to renal damage in high-salt induced hypertension rats. Urinary AGT may reflect the status of intrarenal RAS.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Hypertension; Kidney; Male; Proteinuria; Rats; Rats, Inbred WKY; Real-Time Polymerase Chain Reaction; Renin; Renin-Angiotensin System; Sodium Chloride, Dietary; Up-Regulation

Renin cleavage of angiotensinogen (AGT) releases angiotensin I (AngI) in the initial step of producing all angiotensin peptides. It has been suggested recently that redox regulation of a disulfide bond in AGT involving Cys18-Cys137 may be important to its renin cleavage efficiency in vivo. The purpose of this study was to test this prediction in a mouse model by comparing AngII production and AngII-dependent functions in mice expressing wild-type AGT versus a mutated form of AGT lacking the disulfide bond. Wild-type (hepAGT+/+) and hepatocyte-specific AGT-deficient (hepAGT-/-) littermates were developed in an low-density lipoprotein receptor -/- background. hepAGT+/+ mice were injected intraperitoneally with adeno-associated viral (AAV) vector containing a null insert. hepAGT-/- mice were injected with AAV containing a null insert, wild-type AGT or Cys18Ser and Cys137Ser mutated AGT. Two weeks after AAV injection, mice were fed a Western diet for 12 weeks. Administration of AAV containing either form of AGT led to similar plasma AGT concentrations in hepAGT-/- mice. High plasma renin concentrations in hepAGT-/- mice were suppressed equally by both forms of AGT, which were accompanied by comparable increases of plasma AngII concentrations similar to hepAGT+/+ mice. AAV-driven expression of both forms of AGT led to equivalent increases of systolic blood pressure and augmentation of atherosclerotic lesion size in hepAGT-/- mice. These measurements were comparable to systolic blood pressure and atherosclerotic lesions in hepAGT+/+ mice. These data indicate that the Cys18-Cys137 disulfide bond in AGT is dispensable for AngII production and AngII-dependent functions in mice.

Topics: Angiotensin II; Angiotensinogen; Animals; Atherosclerosis; Blood Pressure; Disease Models, Animal; DNA; DNA Mutational Analysis; Mice; Mutation; Renin; Renin-Angiotensin System

The majority of CKD-related complications stem from cardiovascular pathologies such as hypertension. To help reduce cardiovascular complications, aerobic exercise is often prescribed. Emerging evidence suggests high intensity interval training (HIIT) may be more beneficial than traditional aerobic exercise. However, appraisals of varying forms of aerobic exercise, along with descriptions of mechanisms responsible for health-related improvements, are lacking. This study examined the effects of 8 weeks of HIIT (85% VO2max), versus low intensity aerobic exercise (LIT; 45-50% VO2max) and sedentary behaviour (SED), in an animal model of early-stage CKD. Tissue-specific mRNA expression of RAAS-related genes and CKD-related clinical markers were examined. Compared to SED, HIIT resulted in increased plasma albumin (p = 0.001), reduced remnant kidney weight (p = 0.028), and reduced kidney weight-body weight ratios (p = 0.045). Compared to LIT, HIIT resulted in reduced Agt mRNA expression (p = 0.035), reduced plasma LDL (p = 0.001), triglycerides (p = 0.029), and total cholesterol (p = 0.002), increased plasma albumin (p = 0.047), reduced remnant kidney weight (p = 0.005), and reduced kidney weight-body weight ratios (p = 0.048). These results suggest HIIT is a more potent regulator of several markers that describe and influence health in CKD.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Exercise Therapy; Humans; Hypertension; Male; Rats; Renal Insufficiency, Chronic; RNA, Messenger; Serum Albumin; Triglycerides

Few studies have addressed the growing concerns of chronic kidney diseases in children with intrauterine growth restriction (IUGR). Therefore, the purpose of this study was to evaluate long-term kidney dysfunction and determine if urinary angiotensinogen (AGT) was suitable as a novel early biomarker for kidney dysfunction in IUGR offspring.. Pregnant rats underwent bilateral uterine artery ligation, and as a control group, sham surgeries were performed.. The birth weight was reduced, the urinary AGT to creatinine ratio was significantly higher at week 20, and urinary protein levels were significantly higher at week 32 in IUGR rats than in control rats. On the other hand, the histological findings at week 32 revealed long-term kidney dysfunction, more severe glomerulosclerosis, and greater glomerular diameters in IUGR rats. Moreover, AGT mRNA expression and immunohistological staining were significantly increased in IUGR rats; this suggests that the intrarenal renin-angiotensin system (RAS) contributes to renal dysfunction of IUGR offspring.. Urinary AGT elevation prior to urinary protein levels suggests that AGT is an early biomarker. At week 32, kidney dysfunction was severe in IUGR rats and intrarenal RAS appeared to be one of the causes.

Topics: Age Factors; Angiotensinogen; Animals; Biomarkers; Birth Weight; Creatinine; Disease Models, Animal; Early Diagnosis; Female; Fetal Growth Retardation; Kidney; Kidney Diseases; Ligation; Organ Size; Predictive Value of Tests; Pregnancy; Prenatal Exposure Delayed Effects; Proteinuria; Rats, Sprague-Dawley; Renin-Angiotensin System; Up-Regulation; Uterine Artery

We recently demonstrated that adipocyte deficiency of angiotensinogen (AGT) ablated high-fat diet-induced elevations in plasma angiotensin II (Ang II) concentrations and obesity-hypertension in male mice. Hepatocytes are the predominant source of systemic AGT. Therefore, in this study, we defined the contribution of hepatocyte-derived AGT to obesity-induced elevations in plasma AGT concentrations and hypertension. Male Agt(fl/fl) mice expressing albumin-driven Cre recombinase were bred to female Agt(fl/fl) mice to generate Agt(fl/fl) or hepatocyte AGT-deficient male mice (Agt(Alb)). Mice were fed a low-fat or high-fat diet for 16 weeks. Hepatocyte AGT deficiency had no significant effect on body weight. Plasma AGT concentrations were increased in obese Agt(fl/fl) mice. Hepatocyte AGT deficiency markedly reduced plasma AGT and Ang II concentrations in lean and obese mice. Moreover, hepatocyte AGT deficiency reduced the content and release of AGT from adipose explants. Systolic blood pressure was markedly decreased in lean (by 18 mm Hg) and obese Agt(Alb) mice (by 54 mm Hg) compared with Agt(fl/fl) controls. To define mechanisms, we quantified effects of Ang II on mRNA abundance of megalin, an AGT uptake transporter, in 3T3-L1 adipocytes. Ang II stimulated adipocyte megalin mRNA abundance and decreased media AGT concentrations. These results demonstrate that hepatocytes are the predominant source of systemic AGT in both lean and obese mice. Moreover, reductions in plasma angiotensin concentrations in obese hepatocyte AGT-deficient mice may have limited megalin-dependent uptake of AGT into adipocytes for the production of Ang II in the development of obesity-hypertension.

Topics: Angiotensinogen; Animals; Blood Pressure; Body Weight; Cells, Cultured; Disease Models, Animal; Female; Gene Expression Regulation; Hepatocytes; Hypertension; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Obesity; RNA, Messenger; Thinness

The pregnant female human angiotensinogen (hAGN) transgenic rat mated with the male human renin (hREN) transgenic rat is a model of preeclampsia (TgA) with increased blood pressure, proteinuria, and placenta alterations of edema and necrosis at late gestation. We studied vascular responses and the role of COX-derived prostanoids in the uterine artery (UA) at early gestation in this model. TgA UA showed lower stretch response, similar smooth muscle α-actin content, and lower collagen content compared with Sprague-Dawley (SD) UA. Vasodilation to acetylcholine was similar in SD and TgA UA (64 ± 8 vs. 75 ± 6% of relaxation, P > 0.05), with an acetylcholine-induced contraction in TgA UA that was abolished by preincubation with indomethacin (78 ± 6 vs. 83 ± 11%, P > 0.05). No differences in the contraction to phenylephrine were observed (159 ± 11 vs. 134 ± 12 %KMAX, P > 0.05), although in TgA UA this response was greatly affected by preincubation with indomethacin (179 ± 16 vs. 134 ± 9 %KMAX, P < 0.05, pD2 5.92 ± 0.08 vs. 5.85 ± 0.03, P < 0.05). Endothelium-independent vasodilation was lower in TgA UA (92 ± 2 vs. 74 ± 5% preconstricted tone, P < 0.05), and preincubation with indomethacin restored the response to normal values (90 ± 3 vs. 84 ± 3%). Immunostaining showed similar signals for α-actin, COX-2, and eNOS between groups (P > 0.05). Plasma thromboxane levels were similar between groups. In summary, TgA UA displays functional alterations at early gestation before the preeclamptic phenotype is established. Inhibition of COX enzymes normalizes some of the functional defects in the TgA UA. An increased role for COX-derived prostanoids in this model of preeclampsia may contribute to the development of a hypertensive pregnancy.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Female; Humans; Male; Phenotype; Pre-Eclampsia; Pregnancy; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; Uterine Artery

The aim of the present study was to determine whether long-term high salt intake in the drinking water induces hypertension in wild-type (WT) mice and whether a chymase inhibitor or other antihypertensive drugs could reverse the increase of blood pressure. Eight-week-old male WT mice were supplied with drinking water containing 2% salt for 12 wk (high-salt group) or high-salt drinking water plus an oral chymase inhibitor (TPC-806) at four different doses (25, 50, 75, or 100 mg/kg), captopril (75 mg/kg), losartan (100 mg/kg), hydrochlorothiazide (3 mg/kg), eplerenone (200 mg/kg), or amlodipine (6 mg/kg). Control groups were given normal water with or without the chymase inhibitor. Blood pressure and heart rate gradually showed a significant increase in the high-salt group, whereas a dose-dependent depressor effect of the chymase inhibitor was observed. There was also partial improvement of hypertension in the losartan- and eplerenone-treated groups but not in the captopril-, hydrochlorothiazide-, and amlodipine-treated groups. A high salt load significantly increased chymase-dependent ANG II-forming activity in the alimentary tract. In addition, the relative contribution of chymase to ANG II formation, but not actual average activity, showed a significant increase in skin and skeletal muscle, whereas angiotensin-converting enzyme-dependent ANG II-forming activity and its relative contribution were reduced by high salt intake. Plasma and urinary renin-angiotensin system components were significantly increased in the high-salt group but were significantly suppressed in the chymase inhibitor-treated group. In conclusion, 2% salt water drinking for 12 wk caused moderate hypertension and activated the renin-angiotensin system in WT mice. A chymase inhibitor suppressed both the elevation of blood pressure and heart rate, indicating a definite involvement of chymase in salt-sensitive hypertension.

Topics: Albuminuria; Aldosterone; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Calcium Channel Blockers; Chymases; Disease Models, Animal; Diuretics; Heart Rate; Hypertension; Male; Mice, Inbred C57BL; Mineralocorticoid Receptor Antagonists; Renin-Angiotensin System; Serine Proteinase Inhibitors; Sodium Chloride, Dietary; Time Factors

The renin-angiotensin-aldosterone system (RAAS) plays pivotal roles in the pathogenesis of chronic kidney disease (CKD) progression. Aliskiren, a direct renin inhibitor, inhibits the rate-limiting step of the RAAS without any alternative pathway. It is proven to reduce albuminuria in CKD patients treated with angiotensin blockade. However, there are few reports which evaluate the advantage of aliskiren as the first-line drug against CKD progression in RAAS-activated hypertensive patients.. Tsukuba hypertensive mice (THM), double transgenic mice carrying both the human renin and human angiotensinogen genes, were fed a high-salt diet and treated with hydraladine, ramipril and aliskiren for 10 weeks. Blood pressure and urinary albumin excretion were measured every 2 weeks during the experimental period. We evaluated renal histological changes and gene expression. Plasma angiotensin concentration was measured to evaluate the RAAS inhibitory effect.. High-salt-loaded THM showed severe hypertension and renal injury. All antihypertensive drugs suppressed blood pressure and prevented renal disease progression. RAAS blockade showed a higher renoprotective effect than hydraladine despite an equivalent blood pressure lowering effect. Aliskiren exhibited even stronger renoprotection than ramipril. Plasma angiotensin concentration was increased in THM fed both normal salt and high salt. Hydraladine did not alter the plasma angiotensin concentration. Ramipril significantly decreased angiotensin II concentration. Aliskiren treatment almost completely suppressed angiotensin I and resulted in lower angiotensin II concentration than ramipril treatment.. Aliskiren prevents renal disease progression by suppressing both angiotensin I and II in RAAS-activated pathology. Our data suggest the application of a renin inhibitor for preventing kidney disease progression in CKD patients.

Topics: Albuminuria; Amides; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Cytoprotection; Disease Models, Animal; Disease Progression; Down-Regulation; Fumarates; Humans; Hydralazine; Hypertension; Kidney; Kidney Diseases; Mice; Mice, Transgenic; Ramipril; Renin; Renin-Angiotensin System; Sodium Chloride, Dietary; Time Factors

Intrarenal angiotensin II is increased in kidney diseases independently of plasma angiotensin II and is thought to promote progressive deterioration of renal architecture. Here we investigated the mechanism of enhanced renal angiotensin II generation in kidney glomerular diseases. For this, kidney- or liver-specific angiotensinogen gene (Agt) knockout was superimposed on the mouse model of inducible podocyte injury (NEP25). Seven days after induction of podocyte injury, renal angiotensin II was increased ninefold in NEP25 mice with intact Agt, accompanied by increases in urinary albumin and angiotensinogen excretion, renal angiotensinogen protein, and its mRNA. Kidney Agt knockout attenuated renal Agt mRNA but not renal angiotensin II, renal, or urinary angiotensinogen protein. In contrast, liver Agt knockout markedly reduced renal angiotensin II to 18.7% of that of control NEP25 mice, renal and urinary angiotensinogen protein, but not renal Agt mRNA. Renal angiotensin II had no relationship with renal Agt mRNA, or with renal renin mRNA, which was elevated in liver Agt knockouts. Kidney and liver dual Agt knockout mice showed phenotypes comparable to those of liver Agt knockout mice. Thus, increased renal angiotensin II generation upon severe podocyte injury is attributed to increased filtered angiotensinogen of liver origin resulting from loss of macromolecular barrier function of the glomerular capillary wall that occurs upon severe podocyte injury.

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; Antibodies, Monoclonal; Disease Models, Animal; Exotoxins; Genotype; Kidney Diseases; Kidney Tubules, Proximal; Liver; Membrane Proteins; Mice, Knockout; Phenotype; Podocytes; RNA, Messenger; Sodium; Time Factors; Up-Regulation

Angiotensinogen (AGT) is the precursor of active vasoconstrictive octapeptide angiotensin II (Ang II) in the renin-angiotensin-aldosterone system. Blocking the AGT-converting enzymes in the pathway and the Ang II receptor through pharmacological agents has been proven to be effective in lowering blood pressure (BP) in hypertensive patients. In this study, we developed chemically modified small interfering RNAs (siRNA) to target hepatic AGT mRNA in rats. Lipid nanoparticle encapsulated siRNAs were efficiently delivered to rat liver and resulted in significant reduction in hepatic Agt mRNA levels and plasma AGT concentration without impairing liver function. Single intravenous injection of Agt siRNA led to significant and sustained BP lowering in spontaneous hypertensive rats and in Sprague-Dawley rats, and the effect was maintained by weekly siRNA dosing. Data presented here provide proof-of-feasibility for the use of siRNA technology for inhibition of peripheral AGT levels via hepatic mRNA silencing with beneficial effects on BP in preclinical rat models. Similar approach could be used for validation of novel hypertension hepatic and extrahepatic targets.

Topics: Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Hepatocytes; Hypertension; Liver; Male; Nanoparticles; Rats; Rats, Inbred SHR; Rats, Sprague-Dawley; Renin-Angiotensin System; RNA, Small Interfering

The purpose of this study was to investigate the effect of the renin inhibitor, aliskiren, on retinal ischemia-reperfusion injury. Retinal ischemia was induced by increasing intraocular pressure to 130 mmHg. At 7 days after ischemia, retinal damage was evaluated by measuring the retinal thickness and the number of retinal ganglion cells. Western blot was used to measure changes in the (pro)renin receptor expression. Retinal mRNA expressions of prorenin, angiotensinogen and angiotensin II type 1 receptor (AT1-R) were measured by real-time polymerase chain reaction. Rats were treated with the renin inhibitor, aliskiren. Although the number of retinal ganglion cells and the inner retinal thickness were significantly decreased at 7 days after ischemia, treatment with aliskiren significantly inhibited retinal ischemic injury. Administration of aliskiren increased mRNA expression of prorenin in the retina at 3 h after the reperfusion. The expression of the (pro)renin receptor was not changed after ischemia-reperfusion injury with or without aliskiren. Although there was an increase in the retinal expression of AT1-R at 3 h after the reperfusion, aliskiren administration suppressed this expression. A renin inhibitor attenuated subsequent ischemic damage in the rat retina via the inhibition of the prorenin-induced angiotensin generation.

Topics: Amides; Angiotensinogen; Animals; Blotting, Western; Cell Survival; Disease Models, Animal; Electroretinography; Fumarates; Infusion Pumps, Implantable; Intraocular Pressure; Male; Prorenin Receptor; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Receptor, Angiotensin, Type 1; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Reperfusion Injury; Retina; Retinal Diseases; Retinal Ganglion Cells; RNA, Messenger

Genetic polymorphisms of the human angiotensinogen gene are frequent and may induce up to 30% increase of plasma angiotensinogen concentrations with a blood pressure increase of up to 5mmHg. Their role for the pathogenesis of human arterial hypertension remains unclear. High plasma angiotensinogen levels could increase the sensitivity to other blood pressure stressors.. Male transgenic rats with a 9-fold increase of plasma angiotensinogen concentrations and male non-transgenic rats aged 10 weeks were treated or not with NG-Nitro-L-arginine-methyl ester for 3 weeks in their drinking water (n=3/group). Systolic blood pressure and body weight were measured at baseline and at the end of the study when left ventricular weight and ventricular expression of angiotensin I-converting enzyme and procollagen Iα1 were determined (polymerase chain reaction).. At baseline, transgenic rats had +18mmHg higher bood pressure and -8% lower body weight compared to non-transgenic rats (P<0.05) without significant changes for the vehicle groups throughout the study (P>0.05). NG-Nitro-L-arginine-methyl ester increased blood pressure, left ventricular weight and left ventricular weight indexed for body weight by +41%, +17.6% and +18.6% (P<0.05) in transgenic and +25%, +5.3% and +6.7% (P>0.05) in non-transgenic rats compared to untreated animals, respectively. Cardiac gene expression showed no differences between groups (P>0.05).. Increased plasma angiotensinogen levels may sensitize to additional blood pressure stressors. Our preliminary results point towards an independent role of angiotensinogen in the pathogenesis of human hypertension and associated end-organ damage.

Topics: Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Enzyme Inhibitors; Humans; Hypertension; Male; NG-Nitroarginine Methyl Ester; Rats; Rats, Transgenic

A strong causal link exists between psychological stress and insulin resistance as well with hypertension. Meanwhile, stress-related responses play critical roles in glucose metabolism in hypertensive patients. As clinical trials suggest that angiotensin-receptor blocker delays the onset of diabetes in hypertensive patients, we investigated the effects of irbesartan on stress-induced adipose tissue inflammation and insulin resistance. C57BL/6J mice were subjected to 2-week intermittent restraint stress and orally treated with vehicle, 3 and 10 mg/kg/day irbesartan. The plasma concentrations of lipid and proinflammatory cytokines [Monocyte Chemoattractant Protein-1 (MCP-1), tumor necrosis factor-α, and interleukin-6] were assessed with enzyme-linked immunosorbent assay. Monocyte/macrophage accumulation in inguinal white adipose tissue (WAT) was observed with CD11b-positive cell counts and mRNA expressions of CD68 and F4/80 using immunohistochemistry and RT-PCR methods respectively. The mRNA levels of angiotensinogen, proinflammatory cytokines shown above, and adiponectin in WAT were also assessed with RT-PCR method. Glucose metabolism was assessed by glucose tolerance tests (GTTs) and insulin tolerance tests, and mRNA expression of insulin receptor substrate-1 (IRS-1) and glucose transporter 4 (GLUT4) in WAT. Restraint stress increased monocyte accumulation, plasma free fatty acids, expression of angiotensinogen and proinflammatory cytokines including MCP-1, and reduced adiponectin. Irbesartan reduced stress-induced monocyte accumulation in WAT in a dose dependent manner. Irbesartan treatment also suppressed induction of adipose angiotensinogen and proinflammatory cytokines in WAT and blood, and reversed changes in adiponectin expression. Notably, irbesartan suppressed stress-induced reduction in adipose tissue weight and free fatty acid release, and improved insulin tolerance with restoration of IRS-1 and GLUT4 mRNA expressions in WAT. The results indicate that irbesartan improves stress-induced adipose tissue inflammation and insulin resistance. Our results suggests that irbesartan treatment exerts additive benefits for glucose metabolism in hypertensive patients with mental stress.

Topics: Adipokines; Adipose Tissue, White; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Biphenyl Compounds; Chemokine CCL2; Disease Models, Animal; Dose-Response Relationship, Drug; Insulin Resistance; Irbesartan; Lipolysis; Male; Mice, Inbred C57BL; Panniculitis; Stress, Physiological; Tetrazoles

Angiotensin-(1-12) [ANG-(1-12)], a new member of the renin-angiotensin system, is recognized as a renin independent precursor for ANG II. However, the processing of ANG-(1-12) in the circulation in vivo is not fully established. We examined the effect of angiotensin converting enzyme (ACE) and chymase inhibition on angiotensin peptides formation during an intravenous infusion of ANG-(1-12) in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). WKY and SHR were assigned to a short ANG-(1-12) infusion lasting 5, 15, 30, or 60 min (n = 4-10 each group). In another experiment WKY and SHR were assigned to a continuous 15-min ANG-(1-12) infusion with pretreatment of saline, lisinopril (10 mg/kg), or chymostatin (10 mg/kg) (n = 7-13 each group). Saline or lisinopril were infused intravenously 15 min before the administration of ANG-(1-12) (2 nmol·kg(-1)·min(-1)), whereas chymostatin was given by bolus intraperitoneal injection 30 min before ANG-(1-12). Infusion of ANG-(1-12) increased arterial pressure and plasma ANG-(1-12), ANG I, ANG II, and ANG-(1-7) levels in WKY and SHR. Pretreatment with lisinopril caused increase in ANG-(1-12) and ANG I and large decreases in ANG II compared with the other two groups in both strains. Pretreatment of chymostatin had no effect on ANG-(1-12), ANG I, and ANG II levels in both strains, whereas it increased ANG-(1-7) levels in WKY. We conclude that ACE acts as the primary enzyme for the conversion of ANG-(1-12) to smaller angiotensin peptides in the circulation of WKY and SHR and that chymase may be an ANG-(1-7) degrading enzyme.

Topics: Angiotensin I; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Blood Pressure; Chymases; Disease Models, Animal; Hypertension; Infusions, Intravenous; Lisinopril; Male; Oligopeptides; Peptide Fragments; Peptidyl-Dipeptidase A; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Chronic kidney disease (CKD) is an independent risk factor for the development of cardiovascular disease. The perivascular adipose tissue is closely implicated in the development of atherosclerosis; however, the contribution to CKD-associated atherogenesis remains undefined. Eight-week-old apoE-deficient mice were uninephrectomized and fed a high-cholesterol diet starting at 12 wk of age. The atherosclerotic lesion area in the thoracic aorta was comparable in 16-wk-old uninephrectomized (UNX) mice and sham control mice; however, the lesion area was markedly exaggerated in 20-wk-old UNX mice compared with the control (54%, P < 0.05). While the accumulation of monocytes/macrophages and the mRNA expression levels of inflammatory cytokines/chemokines in the thoracic periaortic adipose tissue (PAT) did not differ between the two groups, angiotensinogen (AGT) mRNA expression and the angiotensin II (ANG II) concentration in the PAT were significantly higher in 16-wk-old UNX mice than in the control (1.9- and 1.5-fold increases vs. control, respectively; P < 0.05). ANG II concentrations in both the plasma and epididymal white adipose tissue (WAT) were comparable between the two groups, suggesting that PAT-specific activation of the renin-angiotensin system (RAS) is primarily involved in CKD-associated atherogenesis. The homeostasis model assessment-insulin resistance (HOMA-IR) index and plasma insulin level after glucose loading were significantly elevated in 16-wk-old UNX mice. In vitro stimulation of preadipocytes with insulin exaggerated the AGT mRNA expression along with increased mRNA expression of PPARγ. These findings suggest that PAT-specific RAS activation probably primarily contributes in accelerating atherosclerotic development in UNX mice and could thus represent a therapeutic target for preventing CKD-associated atherogenesis.

Topics: Adipocytes; Adipose Tissue; Angiotensin II; Angiotensinogen; Animals; Aorta, Thoracic; Apolipoproteins E; Atherosclerosis; Cholesterol, Dietary; Disease Models, Animal; Insulin; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nephrectomy; PPAR gamma; Renal Insufficiency, Chronic; Renin-Angiotensin System

Transgenic rats with low brain angiotensinogen, TGR(ASrAOGEN)680, expressing an antisense RNA against angiotensinogen in glial cells, provide an interesting tool to evaluate the role of brain angiotensins in different behavior responses. The present study was conducted to test the hypothesis that angiotensin-(1-7) [Ang-(1-7)] and serotonin can modulate anxiety and depression-related behaviors in the TGR(ASrAOGEN)680 rats. Therefore, the effect of acute intracerebroventricular administration of Ang-(1-7) and intraperitoneal administration of the selective serotonin reuptake inhibitor fluoxetine was evaluated in TGR(ASrAOGEN) rats subjected to the elevated plus maze (EPM) and forced swimming (FST) tests. Transgenic rats spent a lower percentage of time in the open arms of EPM and showed a significant increase in the immobility time in FST, indicating that a low angiotensinogen level in the brain leads to anxiety-like behavior accompanied by a depression-like state. Administration of both, Ang-(1-7) and fluoxetine reversed the anxiety- and depressive-like behavior of transgenic rats with low brain angiotensinogen, suggesting that this may be, at least in part, related to a decreased level of Ang-(1-7) and serotonin in the brain of these animals.

Topics: Angiotensin I; Angiotensinogen; Animals; Anxiety; Brain; Depression; Disease Models, Animal; Drug Administration Routes; Fluoxetine; Male; Maze Learning; Peptide Fragments; Psychotropic Drugs; Rats; Rats, Sprague-Dawley; Rats, Transgenic; RNA, Antisense; Selective Serotonin Reuptake Inhibitors; Swimming

Melusin is an integrin β1-interacting protein proposed to act as a biomechanical sensor in the heart. We characterized mechanisms and signalling pathways regulating cardiac melusin expression.. Infusion of arginine(8) -vasopressin (AVP) in Sprague-Dawley (SD) rats, spontaneously hypertensive rats (SHR) and double transgenic rats (dTGR) harbouring both human angiotensinogen and renin genes as well as infusion of angiotensin II (Ang II) in SD rats were used. The effect of direct left ventricular (LV) wall stretch was analysed by using isolated perfused rat heart preparation. For the cell culture studies, mouse atrial HL-1 cell line and neonatal rat ventricular myocytes (NRVMs) were used.. Left atrial melusin mRNA levels increased already after 30 min of AVP infusion. Ang II caused significant upregulation of left atrial melusin mRNA (2.1-fold at 6 h, P < 0.05) and protein (1.9-fold at 72 h, P < 0.05) levels. In contrast, LV melusin mRNA levels remained unchanged in response to both infusions, as well as to aortic banding-induced pressure overload. Direct LV wall stress or late-stage hypertensive heart disease did not modify LV melusin gene expression either. Interestingly, in atrial HL-1 cells, cyclic stretching increased melusin mRNA levels. Stretching and treatments with hypertrophic agonists increased melusin mRNA and protein levels in NRVMs, endothelin-1 being the most potent. PD98059, an extracellular signal-regulated protein kinase 1/2 inhibitor, markedly attenuated the endothelin-1-induced upregulation of melusin gene expression in NRVMs.. Multiple hypertrophic stimuli regulate melusin expression predominately in the atria, which may represent a necessary initial step in early adaptive remodelling processes.

Topics: Angiotensinogen; Animals; Animals, Newborn; Arginine Vasopressin; Cell Line; Cytoskeletal Proteins; Disease Models, Animal; Gene Expression Regulation; Heart Atria; Heart Ventricles; Humans; Hypertension; Hypertrophy, Left Ventricular; Male; Mice; Muscle Proteins; Myocytes, Cardiac; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Rats, Transgenic; Renin; RNA, Messenger; Signal Transduction; Time Factors

The role of proximal tubule (PT) angiotensinogen (AGT) in modulating blood pressure has previously been examined using mice expressing PT human AGT and human renin, or rat AGT. These animals are hypertensive; however, the question remains whether alterations in mouse PT AGT alone affects arterial pressure.. Mouse AGT cDNA was knocked-in to the endogenous kidney androgen protein (KAP) gene using an internal ribosomal entry site (IRES)-based strategy.. The KAP-mAGT animals showed kidney-specific KAP-AGT mRNA expression; renal in situ hybridization detected KAP-AGT mRNA only in PT. Urinary AGT was markedly increased in KAP-mAGT mice. On a high Na diet, radiotelemetric arterial pressure showed a systolic pressure elevation; no significant difference in arterial pressure was observed on a normal diet. Plasma renin concentration (PRC) was reduced in KAP-mAGT animals given a high Na diet, but was not different between mouse lines during normal Na intake. Plasma AGT concentration was not altered by overexpression of PT mouse AGT.. In summary, PT overexpression of mouse AGT leads to salt-sensitive hypertension without recruitment of the systemic renin-angiotensin system.

Topics: Angiotensinogen; Animals; Blood Pressure; Chimera; Disease Models, Animal; Female; Gene Knock-In Techniques; Hypertension; Kidney Tubules, Proximal; Male; Mice; Mice, Inbred C57BL; Renin; Renin-Angiotensin System; RNA, Messenger; Sodium Chloride, Dietary

The intrarenal renin-angiotensin system contributes to hypertension by regulating sodium and water reabsorption throughout the nephron. Sex differences in the intrarenal components of the renin-angiotensin system have been involved in the greater incidence of high blood pressure and progression to kidney damage in males than females.. This study investigated whether there is a sex difference in the intrarenal gene expression and urinary excretion of angiotensinogen (AGT) during angiotensin II (Ang II)-dependent hypertension and high-salt (HS) diet.. Male and female Sprague-Dawley rats were divided into 5 groups for each sex: Normal-salt control, HS diet (8% NaCl), Ang II-infused (80 ng/min), Ang II-infused plus HS diet, and Ang II-infused plus HS diet and treatment with the Ang II receptor blocker, candesartan (25 mg/L in the drinking water). Rats were evaluated for systolic blood pressure (SBP), kidney AGT mRNA expression, urinary AGT excretion, and proteinuria at different time points during a 14-day protocol.. Both male and female rats exhibited similar increases in urinary AGT, with increases in SBP during chronic Ang II infusion. HS diet greatly exacerbated the urinary AGT excretion in Ang II-infused rats; males had a 9-fold increase over Ang II alone and females had a 2.5-fold increase. Male rats displayed salt-sensitive SBP increases during Ang II infusion and HS diet, and female rats did not. In the kidney cortex, males displayed greater AGT gene expression than females during all treatments. During Ang II infusion, both sexes exhibited increases in AGT gene message compared with same-sex controls. In addition, HS diet combined with Ang II infusion exacerbated the proteinuria in both sexes. Concomitant Ang II receptor blocker treatment during Ang II infusion and HS diet decreased SBP and urinary AGT similarly in both sexes; however, the decrease in proteinuria was greater in the females.. During Ang II-dependent hypertension and HS diet, higher intrarenal renin-angiotensin system activation in males, as reflected by higher AGT gene expression and urinary excretion, indicates a mechanism for greater progression of high blood pressure and might explain the sex disparity in development of salt-sensitive hypertension.

Topics: Angiotensin II; Angiotensinogen; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Hemodynamics; Hypertension; Kidney; Male; Oxidative Stress; Rats; Rats, Sprague-Dawley; Sex Characteristics; Sex Factors; Sodium Chloride, Dietary

ANG II-stimulated production of reactive oxygen species (ROS) through NADPH oxidase is suggested to activate MAPK pathways, which are implicated in neurally mediated pressor effects of ANG II. Emerging evidence suggests that ANG-(1-7) up regulates MAPK phosphatases to reduce MAPK signaling and attenuate actions of ANG II. Whether angiotensin peptides participate in long-term regulation of these systems in the brain is not known. Therefore, we determined tissue and mitochondrial ROS, as well as expression and activity of MAPK phosphatase-1 (MKP-1) in brain dorsal medullary tissue of hypertensive transgenic (mRen2)27 rats exhibiting higher ANG II/ANG-(1-7) tone or hypotensive transgenic rats with targeted decreased glial expression of angiotensinogen, ASrAOGEN (AS) exhibiting lower ANG II/ANG-(1-7) tone compared with normotensive Sprague-Dawley (SD) rats that serve as the control strain. Transgenic (mRen2)27 rats showed higher medullary tissue NADPH oxidase activity and dihydroethidium fluorescence in isolated mitochondria vs. SD or AS rats. Mitochondrial uncoupling protein 2 was lower in AS and unchanged in (mRen2)27 compared with SD rats. MKP-1 mRNA and protein expression were higher in AS and unchanged in (mRen2)27 compared with SD rats. AS rats also had lower phosphorylated ERK1/2 and JNK consistent with higher MKP-1 activity. Thus, an altered brain renin-angiotensin system influences oxidative stress status and regulates MKP-1 expression. However, there is a dissociation between these effects and the hemodynamic profiles. Higher ROS was associated with hypertension in (mRen2)27 and normal MKP-1, whereas the higher MKP-1 was associated with hypotension in AS, where ROS was normal relative to SD rats.

Topics: Angiotensin I; Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Dual Specificity Phosphatase 1; Gene Expression Regulation; Hypertension; Ion Channels; JNK Mitogen-Activated Protein Kinases; Male; Medulla Oblongata; Mitochondria; Mitochondrial Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; NADPH Oxidases; Oligonucleotides, Antisense; Oxidative Stress; Peptide Fragments; Phosphorylation; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Reactive Oxygen Species; Renin; Renin-Angiotensin System; Signal Transduction; Uncoupling Protein 2

The present study examined the inhibitory action of temporary treatment with an angiotensin type 1 (AT(1)) receptor blocker (ARB) on vascular remodeling using hypertensive mice with overexpression of the human renin (hRN) and angiotensinogen (hANG) genes.. hRN/hANG transgenic mice (hRN/hANG-Tg) were treated with an ARB, valsartan, from 4 weeks of age. In some mice, valsartan treatment was stopped at 8 weeks of age (temporary treatment). Inflammatory vascular injury was induced by polyethylene-cuff placement around the femoral artery at the age of 10 weeks.. Compared with wild-type (WT) mice, hRN/hANG-Tg showed higher blood pressure (BP) and enhancement of oxidative stress and medial thickening even before cuff placement. Inflammatory vascular remodeling and oxidative stress after cuff placement were further enhanced in hRN/hANG-Tg. Temporary treatment with valsartan continuously lowered BP even after cessation of administration, and inhibited these changes. In contrast, administration of hydralazine lowered BP to a similar level to that with valsartan, but did not inhibit medial thickening and inflammatory vascular remodeling. In contrast to the valsartan treatment, BP immediately increased to the untreated level after cessation of hydralazine.. These results indicate that temporary ARB treatment leads to prolonged effect of BP lowering and prevents vascular remodeling in hypertensive mice induced by activation of the human renin-angiotensin system. The inhibitory action of valsartan is not due to the BP lowering but is at least in part due to a decrease in oxidative stress and inflammation.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Arteries; Blood Vessels; Disease Models, Animal; Hydralazine; Hypertension; Mice; Mice, Inbred C57BL; NADPH Oxidases; Neointima; Oxidative Stress; Renin; Tetrazoles; Valine; Valsartan

The hypertensive double-transgenic (dTG) rat strain, expressing human renin and angiotensinogen, develops severe hypertension and organ damage and 50% of individuals die by 7 weeks of age. Here, we characterise a variation of this model in which animals present stable hypertension.. The effect of renin-angiotensin system blockers on blood pressure was determined with adult dTG rats treated with enalapril from 3 to 12 weeks of age. Tissue expression levels of renin and angiotensinogen were determined in dTG rats and rhesus monkeys by quantitative PCR.. Upon withdrawal from enalapril, mean arterial pressure (MAP) rose to 160-180 mmHg, with 95% of the female dTG rats surviving for 6 to 12 months, In Sprague-Dawley (SD) rats and rhesus monkeys, renin mRNA was absent or weakly expressed in most tissues, except for the kidneys and adrenals. In dTG rats, human renin expression was high in many additional tissues. The expression of human angiotensinogen in dTG rats followed a similar tissue pattern to SD and rhesus monkey angiotensinogen. Oral dosing of aliskiren, enalapril or losartan provided a similar maximal reduction in MAP and duration of efficacy in telemetrised dTG rats.. Enalapril-pretreated dTG rats are suitable for long-term MAP monitoring and sequential evaluation of human renin inhibitors.

Topics: Amides; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Enalapril; Female; Fumarates; Gene Expression Regulation; Heart Rate; Humans; Hypertension; Macaca mulatta; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; RNA, Messenger; Tissue Distribution

Polycystic ovary syndrome (PCOS) is the most common reproductive dysfunction in premenopausal women. PCOS is also associated with increased risk of cardiovascular disease when PCOS first occurs and later in life. Hypertension, a common finding in women with PCOS, is a leading risk factor for cardiovascular disease. The mechanisms responsible for hypertension in women with PCOS have not been elucidated.. This study characterized the cardiovascular-renal consequences of hyperandrogenemia in a female rat model.. Female Sprague-Dawley rats (aged 4-6 weeks) were implanted with dihydrotestosterone or placebo pellets lasting 90 days. After 10 to 12 weeks, blood pressure (by radiotelemetry), renal function (glomerular filtration rate, morphology, protein, and albumin excretion), metabolic parameters (plasma insulin, glucose, leptin, cholesterol, and oral glucose tolerance test), inflammation (plasma tumor necrosis factor-α), oxidative stress (mRNA expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, p22(phox), p47(phox), gp91(phox), and NOX4), nitrate/nitrite excretion and mRNA expression of components of the renin-angiotensin system (angiotensinogen, angiotensin-I-converting enzyme [ACE], and AT1 receptor) were determined.. Plasma dihydrotestosterone increased 3-fold in hyperandrogenemic female (HAF) rats, whereas plasma estradiol levels did not differ compared with control females. HAF rats exhibited estrus cycle dysfunction. They also had increased food intake and body weight, increased visceral fat, glomerular filtration rate, renal injury, insulin resistance and metabolic dysfunction, oxidative stress, and increased expression of angiotensinogen and ACE and reduced AT1 receptor expression.. The HAF rat is a unique model that exhibits many of the characteristics of PCOS in women and is a useful model to study the mechanisms responsible for PCOS-mediated hypertension.

Topics: Angiotensinogen; Animals; Blood Glucose; Blood Pressure; Cardiovascular Diseases; Dihydrotestosterone; Disease Models, Animal; Estradiol; Female; Glomerular Filtration Rate; Glucose Tolerance Test; Kidney Diseases; Leptin; Metabolic Syndrome; Oxidative Stress; Polycystic Ovary Syndrome; Rats; Rats, Sprague-Dawley; Renin-Angiotensin System

The role of the renin-angiotensin system in cognitive impairment is unclear. This work was undertaken to test our hypothesis that renin-angiotensin system may contribute to cognitive decline and brain damage caused by chronic cerebral ischemia. C57BL/6J mice were subjected to bilateral common carotid artery stenosis with microcoil to prepare mice with chronic cerebral hypoperfusion, a model of subcortical vascular dementia. The effects of aliskiren, a direct renin inhibitor, or Tempol, a superoxide scavenger, on brain damage and working memory in these mice were examined. Chronic cerebral hypoperfusion significantly increased brain renin activity and angiotensinogen expression in C57BL/6J mice, which was attributed to the increased renin in activated astrocytes and microvessels and the increased angiotensinogen in activated astrocytes in white matter. Aliskiren pretreatment significantly inhibited brain renin activity and ameliorated brain p67(phox)-related NADPH oxidase activity, oxidative stress, glial activation, white matter lesion, and spatial working memory deficits in C57BL/6J mice with bilateral common carotid artery stenosis. To elucidate the role of oxidative stress in brain protective effects of aliskiren, we also examined the effect of Tempol in the same mice with bilateral common carotid artery stenosis. Tempol pretreatment mimicked the brain protective effects of aliskiren in this mouse model. Posttreatment of mice with aliskiren or Tempol after bilateral common carotid artery stenosis also prevented cognitive decline. In conclusion, chronic cerebral hypoperfusion induced the activation of the brain renin-angiotensin system. Aliskiren ameliorated brain damage and working memory deficits in the model of chronic cerebral ischemia through the attenuation of oxidative stress. Thus, direct renin inhibition seems to be a promising therapeutic strategy for subcortical vascular dementia.

Topics: Amides; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Brain Damage, Chronic; Brain Ischemia; Cognition Disorders; Cyclic N-Oxides; Dementia, Vascular; Disease Models, Animal; Fumarates; Hypertension; Male; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Oxidative Stress; Renin; Renin-Angiotensin System; Risk Factors; Spin Labels

Combination therapy of angiotensin-converting enzyme (ACE) inhibition and AT(1) receptor blockade has been shown to provide greater renoprotection than ACE inhibitor alone in human diabetic nephropathy, suggesting that ACE-independent pathways for ANG II formation are of major significance in disease progression. Studies were performed to determine the magnitude of intrarenal ACE-independent formation of ANG II in type II diabetes. Although renal cortical ACE protein activity [2.1 +/- 0.8 vs. 9.2 +/- 2.1 arbitrary fluorescence units (AFU) x mg(-1) x min(-1)] and intensity of immunohistochemical staining were significantly reduced and ACE2 protein activity (16.7 +/- 3.2 vs. 7.2 +/- 2.4 AFU x mg(-1) x min(-1)) and intensity elevated, kidney ANG I (113 +/- 24 vs. 110 +/- 45 fmol/g) and ANG II (1,017 +/- 165 vs. 788 +/- 99 fmol/g) levels were not different between diabetic and control mice. Afferent arteriole vasoconstriction due to conversion of ANG I to ANG II was similar in magnitude in kidneys of diabetic (-28 +/- 3% at 1 microM) and control (-23 +/- 3% at 1 microM) mice; a response completely inhibited by AT(1) receptor blockade. In control kidneys, afferent arteriole vasoconstriction produced by ANG I was significantly attenuated by ACE inhibition, but not by serine protease inhibition. In contrast, afferent arteriole vasoconstriction produced by intrarenal conversion of ANG I to ANG II was significantly attenuated by serine protease inhibition, but not by ACE inhibition in diabetic kidneys. In conclusion, there is a switch from ACE-dependent to serine protease-dependent ANG II formation in the type II diabetic kidney. Pharmacological targeting of these serine protease-dependent pathways may provide further protection from diabetic renal vascular disease.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Angiotensinogen; Animals; Arterioles; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Disease Models, Animal; Kidney; Male; Mice; Mice, Mutant Strains; Peptidyl-Dipeptidase A; Rats; Rats, Sprague-Dawley; Receptors, Leptin; Serine Proteases; Signal Transduction; Vasoconstriction

Angiotensin-converting enzyme (ACE) inhibition (ACEi) ameliorates the development of hypertension and the intrarenal ANG II augmentation in ANG II-infused mice. To determine if these effects are associated with changes in the mouse intrarenal renin-angiotensin system, the expression of angiotensinogen (AGT), renin, ACE, angiotensin type 1 receptor (AT(1)R) mRNA (by quanitative RT-PCR) and protein [by Western blot (WB) and/or immunohistochemistry (IHC)] were analyzed. C57BL/6J male mice (9-12 wk old) were distributed as controls (n = 10), ANG II infused (ANG II = 8, 400 ng x kg(-1) x min(-1) for 12 days), ACEi only (ACEi = 10, lisinopril, 100 mg/l), and ANG II infused + ACEi (ANG II + ACEi = 11). When compared with controls (1.00), AGT protein (by WB) was increased by ANG II (1.29 +/- 0.13, P < 0.05), and this was not prevented by ACEi (ACEi + ANG II, 1.31 +/- 0.14, P < 0.05). ACE protein (by WB) was increased by ANG II (1.21 +/- 0.08, P < 0.05), and it was reduced by ACEi alone (0.88 +/- 0.07, P < 0.05) or in combination with ANG II (0.80 +/- 0.07, P < 0.05). AT(1)R protein (by WB) was increased by ANG II (1.27 +/- 0.06, P < 0.05) and ACEi (1.17 +/- 0.06, P < 0.05) but not ANG II + ACEi [1.15 +/- 0.06, not significant (NS)]. Tubular renin protein (semiquantified by IHC) was increased by ANG II (1.49 +/- 0.23, P < 0.05) and ACEi (1.57 +/- 0.15, P < 0.05), but not ANG II + ACEi (1.10 +/- 0.15, NS). No significant changes were observed in AGT, ACE, or AT(1)R mRNA. In summary, reduced responses of intrarenal tubular renin, ACE, and the AT(1)R protein to the stimulatory effects of chronic ANG II infusions, in the presence of ACEi, are associated with the effects of this treatment to ameliorate augmentations in blood pressure and intrarenal ANG II content during ANG II-induced hypertension.

Topics: Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Disease Models, Animal; Hypertension; Kidney; Lisinopril; Male; Mice; Mice, Inbred C57BL; Peptidyl-Dipeptidase A; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Vasoconstrictor Agents

Spontaneously hypertensive rats develop left ventricular hypertrophy, increased blood pressure and blood pressure variability, which are important determinants of heart damage, like the activation of renin-angiotensin system.. To investigate the effects of the time-course of hypertension over 1) hemodynamic and autonomic patterns (blood pressure; blood pressure variability; heart rate); 2) left ventricular hypertrophy; and 3) local and systemic Renin-angiotensin system of the spontaneously hypertensive rats.. MALE SPONTANEOUSLY HYPERTENSIVE RATS WERE RANDOMIZED INTO TWO GROUPS: young (n=13) and adult (n=12). Hemodynamic signals (blood pressure, heart rate), blood pressure variability (BPV) and spectral analysis of the autonomic components of blood pressure were analyzed. LEFT ventricular hypertrophy was measured by the ratio of LV mass to body weight (mg/g), by myocyte diameter (mum) and by relative fibrosis area (RFA, %). ACE and ACE2 activities were measured by fluorometry (UF/min), and plasma renin activity (PRA) was assessed by a radioimmunoassay (ng/mL/h). Cardiac gene expressions of Agt, Ace and Ace2 were quantified by RT-PCR (AU).. The time-course of hypertension in spontaneously hypertensive rats increased BPV and reduced the alpha index in adult spontaneously hypertensive rats. Adult rats showed increases in left ventricular hypertrophy and in RFA. Compared to young spontaneously hypertensive rats, adult spontaneously hypertensive rats had lower cardiac ACE and ACE2 activities, and high levels of PRA. No change was observed in gene expression of Renin-angiotensin system components.. The observed autonomic dysfunction and modulation of Renin-angiotensin system activity are contributing factors to end-organ damage in hypertension and could be interacting. Our findings suggest that the management of hypertensive disease must start before blood pressure reaches the highest stable levels and the consequent established end-organ damage is reached.

Topics: Age Factors; Angiotensin-Converting Enzyme 2; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Hemodynamics; Hypertension; Hypertrophy, Left Ventricular; Male; Peptidyl-Dipeptidase A; Random Allocation; Rats; Rats, Inbred SHR; Renin-Angiotensin System

The mRen(2).Lewis (mRen2) strain is an ANG II-dependent model of hypertension expressing marked sex differences in blood pressure and tissue injury that also exhibits estrogen and salt sensitivity. Because estrogen and salt influence angiotensinogen (AGT), circulating and renal expression of the protein were assessed in the mRen2 using a sensitive and specific ELISA. Hemizygous female and male mRen2 were placed on normal (1% NaCl, NS)- or high (8% NaCl, HS)-salt diets from 5 to 15 wk of age while a separate NS cohort was ovariectomized (OVX). The OVX mRen2 exhibited higher blood pressure (184 +/- 6 vs. 149 +/- 5 mmHg, n = 6), a 16-fold increase in urinary AGT (uAGT) (0.2 +/- 0.02 vs. 0.01 +/- 0.01 microg x kg(-1) x day(-1), P < 0.01), but no change in proteinuria (PROT). Excretion of AGT was correlated with blood pressure and PROT in the female groups. The HS diet led to higher blood pressure (224 +/- 8 mmHg), a 180-fold increase in uAGT (1.8 +/- 0.2 microg x kg(-1) x day(-1)), and increased PROT (98 +/- 9 vs. 7 +/- 1 mg x kg(-1) x day(-1)). Compared with females, NS males expressed higher excretion of uAGT (3.0 +/- 0.4 microg x kg(-1) x day(-1)) and PROT (32 +/- 5 mg x kg(-1) x day(-1)); both were increased eightfold with HS (uAGT: 23 +/- 3 microg x kg(-1) x day(-1); PROT: 285 +/- 28 mg x kg(-1) x day(-1)) without a change in blood pressure. Although uAGT was markedly higher in the OVX and HS groups, neither renal cortical AGT mRNA or protein expression was increased. Moreover, AGT release in cortical slices was similar for the NS and HS females. We conclude that the increase in uAGT with estrogen depletion or HS likely may be a biomarker for glomerular damage reflecting filtration of the circulating protein in the mRen2.

Topics: Angiotensinogen; Animals; Biomarkers; Blood Pressure; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Estrogens; Female; Hypertension; Kidney; Male; Mice; Ovariectomy; Proteinuria; Rats; Rats, Inbred Lew; Rats, Transgenic; Renin; RNA, Messenger; Sex Factors; Sodium Chloride, Dietary; Time Factors; Up-Regulation

The Spontaneously Diabetic Torii-Lepr(fa) (SDT-fa/fa) rat, a new model of obese type 2 diabetes, shows obesity, hyperglycemia, and hyperlipidemia from 6 weeks of age. Diabetic complications such as nephropathy and cataract are observed with aging; however, blood pressure change with age has not previously been examined. In this study, blood pressure was periodically measured and the change was investigated. Blood pressure in male SDT-fa/fa rats was elevated at 8, 16, and 24 weeks of age, whereas the heart rate was not changed. In addition to hyperglycemia, hyperlipidemia, and proteinuria, hyperleptinemia and increased urine angiotensinogen were observed in SDT-fa/fa rats. Blood pressure and heart rate in the male original SDT (SDT-+/+) rat did not significantly change. In conclusion, the SDT-fa/fa rat is a promising model, showing significant hypertension with diabetes mellitus.

Topics: Angiotensinogen; Animals; Blood Pressure; Diabetes Mellitus, Type 2; Disease Models, Animal; Heart Rate; Hyperglycemia; Hyperlipidemias; Hypertension; Leptin; Male; Obesity; Proteinuria; Rats; Rats, Sprague-Dawley

Hypertension is a well-recognized complication of autosomal recessive polycystic kidney disease (ARPKD). The renin-angiotensin system (RAS) is a key regulator of blood pressure; however, data on the RAS in ARPKD are limited and conflicting, showing both up- and down-regulation. In the current study, we characterized intrarenal and systemic RAS activation in relationship to hypertension and progressive cystic kidney disease in the ARPKD orthologous polycystic kidney (PCK) rat. Clinical and histological measures of kidney disease, kidney RAS gene expression by quantitative real-time PCR, angiotensin II (Ang II) immunohistochemistry, and systemic Ang I and II levels were assessed in 2-, 4-, and 6-month-old cystic PCK and age-matched normal rats. PCK rats developed hypertension and progressive cystic kidney disease without significant worsening of renal function or relative kidney size. Intrarenal renin, ACE and Ang II expression was increased significantly in cystic kidneys; angiotensinogen and Ang II Type I receptor were unchanged. Systemic Ang I and II levels did not differ. This study demonstrates that intrarenal, but not systemic, RAS activation is a prominent feature of ARPKD. These findings help reconcile previous conflicting reports and suggest that intrarenal renin and ACE gene upregulation may represent a novel mechanism for hypertension development or exacerbation in ARPKD.

Topics: Aging; Angiotensin I; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Disease Progression; Gene Expression Regulation; Hypertension; Kidney; Male; Mutation; Peptidyl-Dipeptidase A; Polycystic Kidney, Autosomal Recessive; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Time Factors

Calcium-sensitizing agents improve cardiac function in acute heart failure; however, their long-term effects on cardiovascular mortality are unknown. We tested the hypothesis that levosimendan, an inodilator that acts through calcium sensitization, opening of ATP-dependent potassium channels and phosphodiesterase III inhibition, improves cardiac function and survival in double transgenic rats harboring human renin and angiotensinogen genes (dTGRs), a model of angiotensin II (Ang II)-induced hypertensive heart failure. Levosimendan (1 mg kg(-1)) was administered orally to 4-week-old dTGRs and normotensive Sprague-Dawley rats for 4 weeks. Untreated dTGRs developed severe hypertension, cardiac hypertrophy, heart failure with impaired diastolic relaxation, and exhibited a high mortality rate at the age of 8 weeks. Levosimendan did not decrease blood pressure and did not prevent cardiac hypertrophy. However, levosimendan improved systolic function, decreased cardiac atrial natriuretic peptide mRNA expression, ameliorated Ang II-induced cardiac damage and decreased mortality. Levosimendan did not correct Ang II-induced diastolic dysfunction and did not influence heart rate. In a separate survival study, levosimendan increased dTGR survival by 58% and median survival time by 27% (P=0.004). Our findings suggest that levosimendan ameliorates Ang II-induced hypertensive heart failure and reduces mortality. The results also support the notion that the effects of levosimendan in dTGRs are mediated by blood pressure-independent mechanisms and include improved systolic function and amelioration of Ang II-induced coronary and cardiomyocyte damage.

Topics: Angiotensin II; Angiotensinogen; Animals; bcl-2-Associated X Protein; Blood Pressure; Cardiotonic Agents; Disease Models, Animal; Heart; Heart Failure; Heart Rate; Humans; Hydrazones; Hypertension; Major Histocompatibility Complex; Male; Pyridazines; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; Renin-Angiotensin System; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Simendan

Clinically and experimentally, a case for omega-3 polyunsaturated fatty acid (PUFA) cardioprotection in females has not been clearly established. The goal of this study was to investigate whether dietary omega-3 PUFA supplementation could provide ischemic protection in female mice with an underlying genetic predisposition to cardiac hypertrophy. Mature female transgenic mice (TG) with cardiac-specific overexpression of angiotensinogen that develop normotensive cardiac hypertrophy and littermate wild-type (WT) mice were fed a fish oil-derived diet (FO) or PUFA-matched control diet (CTR) for 4 wk. Myocardial membrane lipids, ex vivo cardiac performance (intraventricular balloon) after global no-flow ischemia and reperfusion (15/30 min), and reperfusion arrhythmia incidence were assessed. FO diet suppressed cardiac growth by 5% and 10% in WT and TG, respectively (P < 0.001). The extent of mechanical recovery [rate-pressure product (RPP) = beats/min x mmHg] of FO-fed WT and TG hearts was similar (50 +/- 7% vs. 45 +/- 12%, 30 min reperfusion), and this was not significantly different from CTR-fed WT or TG. To evaluate whether systemic estrogen was masking a protective effect of the FO diet, the responses of ovariectomized (OVX) WT and TG mice to FO dietary intervention were assessed. The extent of mechanical recovery of FO-fed OVX WT and TG (RPP, 50 +/- 4% vs. 64 +/- 8%) was not enhanced compared with CTR-fed mice (RPP, 60 +/- 11% vs. 80 +/- 8%, P = 0.335). Dietary FO did not suppress the incidence of reperfusion arrhythmias in WT or TG hearts (ovary-intact mice or OVX). Our findings indicate a lack of cardioprotective effect of dietary FO in females, determined by assessment of mechanical and arrhythmic activity postischemia in a murine ex vivo heart model.

Topics: Angiotensin II; Angiotensinogen; Animals; Arrhythmias, Cardiac; Dietary Fats, Unsaturated; Disease Models, Animal; Estrogens; Female; Fish Oils; Genetic Predisposition to Disease; Hypertrophy; Mice; Mice, Transgenic; Myocardial Ischemia; Myocardium; Ovariectomy; Reperfusion Injury

Blood pressure (BP) is more salt sensitive in men than in premenopausal women. In Dahl salt-sensitive rats (DS), high-salt (HS) diet increases BP more in males than females. In contrast to the systemic renin-angiotensin system, which is suppressed in response to HS in male DS, intrarenal angiotensinogen expression is increased, and intrarenal levels of ANG II are not suppressed. In this study, the hypothesis was tested that there is a sexual dimorphism in HS-induced upregulation of intrarenal angiotensinogen mediated by testosterone that also causes increases in BP and renal injury. On a low-salt (LS) diet, male DS had higher levels of intrarenal angiotensinogen mRNA than females. HS diet for 4 wk increased renal cortical angiotensinogen mRNA and protein only in male DS, which was prevented by castration. Ovariectomy of female DS had no effect on intrarenal angiotensinogen expression on either diet. Radiotelemetric BP was similar between males and castrated rats on LS diet. HS diet for 4 wk caused a progressive increase in BP, protein and albumin excretion, and glomerular sclerosis in male DS rats, which were attenuated by castration. Testosterone replacement in castrated DS rats increased BP, renal injury, and upregulation of renal angiotensinogen associated with HS diet. Testosterone contributes to the development of hypertension and renal injury in male DS rats on HS diet possibly through upregulation of the intrarenal renin-angiotensin system.

Topics: Albuminuria; Angiotensinogen; Animals; Blood Pressure; Body Weight; Disease Models, Animal; Drug Implants; Estradiol; Female; Hypertension; Kidney; Male; Orchiectomy; Ovariectomy; Rats; Rats, Inbred Dahl; Receptor, Angiotensin, Type 1; Renin-Angiotensin System; RNA, Messenger; Sex Factors; Sodium Chloride, Dietary; Telemetry; Testosterone; Time Factors; Up-Regulation

Angiotensin-(1-12) [ANG-(1-12)] is a newly identified peptide detected in a variety of rat tissues, including the brain. To determine whether brain ANG-(1-12) participates in blood pressure regulation, we treated male adult (mRen2)27 hypertensive rats (24-28 wk of age) with Anti-ANG-(1-12) IgG or Preimmune IgG via an intracerebroventricular cannula for 14 days. Immunoneutralization of brain ANG-(1-12) lowered systolic blood pressure (-43 +/- 8 mmHg on day 3 and -26 +/- 7 mmHg on day 10 from baseline, P < 0.05). Water intake was lower on intracereroventricular day 6 in the Anti-ANG-(1-12) IgG group, accompanied by higher plasma osmolality on day 13, but there were no differences in urine volume, food intake, or body weight during the 2-wk treatment. In Preimmune IgG-treated animals, there were no significant changes in these variables over the 2-wk period. The antihypertensive effects produced by endogenous neutralization of brain ANG-(1-12) suggest that ANG-(1-12) is functionally active in brain pathways regulating blood pressure.

Topics: Angiotensinogen; Angiotensins; Animals; Blood Pressure; Body Weight; Brain; Disease Models, Animal; Drinking; Eating; Hypertension; Immunoglobulin G; Infusion Pumps, Implantable; Male; Osmolar Concentration; Peptide Fragments; Rats; Rats, Transgenic; Renin; Time Factors; Urodynamics

Hypertensive patients with large blood pressure variability (BPV) have aggravated end-organ damage. However, the pathogenesis remains unknown. We investigated whether exaggerated BPV aggravates hypertensive cardiac remodeling and function by activating inflammation and angiotensin II-mediated mechanisms. A model of exaggerated BPV superimposed on chronic hypertension was created by performing bilateral sinoaortic denervation (SAD) in spontaneously hypertensive rats (SHRs). SAD increased BPV to a similar extent in Wistar Kyoto rats and SHRs without significant changes in mean blood pressure. SAD aggravated left ventricular and myocyte hypertrophy and myocardial fibrosis to a greater extent and impaired left ventricular systolic function in SHRs. SAD induced monocyte chemoattractant protein-1, transforming growth factor-beta, and angiotensinogen mRNA upregulations and macrophage infiltration of the heart in SHRs. The effects of SAD on cardiac remodeling and inflammation were much smaller in Wistar Kyoto rats compared with SHRs. Circulating levels of norepinephrine, the active form of renin, and inflammatory cytokines were not affected by SAD in Wistar Kyoto rats and SHRs. A subdepressor dose of candesartan abolished the SAD-induced left ventricular/myocyte hypertrophy, myocardial fibrosis, macrophage infiltration, and inductions of monocyte chemoattractant protein-1, transforming growth factor-beta, and angiotensinogen and subsequently prevented systolic dysfunction in SHRs with SAD. These findings suggest that exaggerated BPV induces chronic myocardial inflammation and thereby aggravates cardiac remodeling and systolic function in hypertensive hearts. The cardiac angiotensin II system may play a role in the pathogenesis of cardiac remodeling and dysfunction induced by a combination of hypertension and exaggerated BPV.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Benzimidazoles; Biphenyl Compounds; Blood Pressure; Chemokine CCL2; Chronic Disease; Disease Models, Animal; Heart Diseases; Heart Ventricles; Hypertension; Hypertrophy; Inflammation; Macrophages; Male; Myocytes, Cardiac; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Tetrazoles; Transforming Growth Factor beta; Ventricular Remodeling

To investigate the role of brain angiotensin II (ANG II) in the pathogenesis of injury following ischemic stroke, mice overexpressing renin and angiotensinogen (R+A+) and their wild-type control animals (R-A-) were used for experimental ischemia studies. Focal brain ischemia was induced by middle cerebral artery occlusion (MCAO). The severity of ischemic injury was determined by measuring neurological deficits and histological damage at 24 and 48 h after MCAO, respectively. To exclude the influence of blood pressure and local collateral blood flow, brain slices were used for oxygen and glucose deprivation (OGD) studies. The severity of OGD-induced damage was determined by measuring indicators of tissue swelling and cell death, the intensity of the intrinsic optical signal (IOS), and the number of propidium iodide (PI) staining cells, respectively. Results showed 1) R+A+ mice showed higher neurological deficit score (3.8 +/- 0.5 and 2.5 +/- 0.3 for R+A+ and R-A-, respectively, P < 0.01) and larger infarct volume (22.2 +/- 1.6% and 14.1 +/- 1.2% for R+A+ and R-A-, respectively, P < 0.01); 2) The R+A+ brain slices showed more severe tissue swelling and cell death in the cortex (IOS: 140 +/- 6% and 114 +/- 10%; PI: 139 +/- 20 cells/field and 39 +/- 9 cells/field for R+A+ and R-A-, respectively, P < 0.01); 3) treatment with losartan (20 micromol/l) abolished OGD-induced exaggeration of cell injury seen in R+A+ mice. The data indicate that activation of ANG II/AT(1) signaling is harmful to brain exposed to ischemia.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Blood Pressure; Brain; Brain Ischemia; Cell Death; Disease Models, Animal; Humans; Infarction, Middle Cerebral Artery; Losartan; Male; Mice; Mice, Transgenic; Receptor, Angiotensin, Type 1; Regional Blood Flow; Renin; Severity of Illness Index; Signal Transduction

Preeclampsia is the major cause of maternal and fetal mortality/morbidity. Because hypertension is an important risk factor for preeclampsia, we investigated whether hypertensive mice that overexpress human renin and angiotensinogen develop superimposed preeclampsia. Given that the mechanisms underlying this disease are still poorly understood, animal models are of great use for elucidation. Blood pressure and proteinuria were measured by telemetry and ELISA, respectively. Heart function was evaluated by echocardiography, whereas pathological cardiac hypertrophy-related genes were assessed by real-time PCR. Soluble fms-like tyrosine kinase 1 plasma concentrations were quantitated by ELISA and placental expression by real-time PCR. Transgenic mice develop de novo proteinuria during gestation and marked blood pressure elevation, which are hallmarks of superimposed preeclampsia on chronic hypertension. Abnormal placentation present in these mothers produced a significant decrease in pup and placental weight and was associated with an increased placental expression of soluble fms-like tyrosine kinase 1. We also found heightened circulating levels of this receptor, when adjusted for placental mass, as has been observed in women who suffer from preeclampsia. Cardiac hypertrophy could be observed in the transgenic mice and was exacerbated by gestation. As a result, heart function was significantly decreased, and markers of pathological hypertrophy were increased. Our data, thus, confirm the characterization of a new model of superimposed preeclampsia on chronic hypertension. Because chronically hypertensive women are at risk of developing the pathology, our model reflects a clinical reality and is, thus, an excellent tool to elucidate the molecular mechanisms triggering this disease.

Topics: Angiotensinogen; Animals; Animals, Newborn; Blood Pressure; Cardiomegaly; Chronic Disease; Disease Models, Animal; Female; Humans; Hypertension; Mice; Mice, Inbred C57BL; Mice, Transgenic; Placenta; Pre-Eclampsia; Pregnancy; Proteinuria; Renin; Renin-Angiotensin System

Alcoholic cardiomyopathy (ACM) develops in response to chronic alcohol intake and it is hypothesized that activation of the renin-angiotensin system (RAS) and disorders in energy metabolism may play important roles in its onset. Given that the expression of peroxisome proliferator-activated receptors (PPARalpha and PPARgamma) changes with alterations in cardiac metabolism and myocardial remodeling, this study was designed to test the hypothesis that protein expression of PPARalpha and PPARgamma is correlated with RAS activation in ACM.. For the first experiment, rats were divided into 3 groups: 30 received alcohol (intragastric administration with ad libitum drinking), 30 received alcohol and irbesartan (5 mg/kg/d, p.o.), and 30 served as controls. RAS activity and protein expression of PPARalpha and PPARgamma were evaluated in rats following 6 months of alcohol feeding using radioimmunoassay, reverse transcriptase PCR, and Western blot methods. For the second experiment, rats were divided into 4 groups: 10 rats received alcohol/irbesartan (5 mg/kg/d, p.o.)/PD98059 (methyl ethyl ketone [MEK]-1 inhibitor) (0.3 mg/kg/d, p.o.), 10 rats received alcohol/PD98059, 10 rats received alcohol/irbesartan, and 10 rats received alcohol alone. Myocardial PPARalpha and PPARgamma protein expression was detected following 6 months of alcohol feeding using Western blot method.. Compared with controls, myocardial angiotensin (Ang) I, Ang II, and renin levels were progressively increased at 2, 4, and 6 months of alcohol intake. mRNA expression of renin, angiotensinogen, angiotensin-converting enzyme (ACE), and AT1 was increased at 6 months. Moreover, activated RAS downregulated PPARalpha and upregulated PPARgamma protein expression as ACM progressed. Finally, extracellular signal regulated kinase 1 and 2 (ERK1/2) was shown to play a key role in the regulation of protein expression of PPARalpha and PPARgamma.. These results suggest that RAS is activated during the development of ACM. Moreover, ERK1/2 plays a key role in the regulation of protein expression of PPARalpha and PPARgamma by RAS in ACM.

Topics: Angiotensin I; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Biphenyl Compounds; Cardiomyopathy, Alcoholic; Disease Models, Animal; Flavonoids; Irbesartan; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Myocardium; Peptidyl-Dipeptidase A; PPAR alpha; PPAR gamma; Rats; Rats, Wistar; Renin; Renin-Angiotensin System; Tetrazoles; Ventricular Remodeling

Accumulating evidence shows that angiotensin II (ANG II) can be generated locally in the lung tissue and may have autocrine and/or paracrine actions on the cellular level. In addition, ANG II precursor, angiotensinogen, as well as ANG II type 1 receptor (AT(1)), are also expressed in the lung tissue. Recent studies revealed that ANG II promoted acute lung injury induced by acid aspiration or sepsis, and that ANG II receptor blockade had a protective effect against acute lung injury. Therefore, the authors hypothesized that ventilator-induced lung injury might also be exacerbated by local ANG II action, and that ANG II receptor blockade would protect the lung from ventilator-induced lung injury.. Forty Sprague Dawley rats weighing 300-350 g were randomly divided into the following experimental groups (10 rats in each group): (1) control group: rats were unventilated; (2) LVT (low volume ventilation) group: rats were ventilated with 8 mL/kg tidal volume room air for 2 h; (3) HVT (high volume ventilation) group: rats were ventilated with 40 mL/kg tidal volume room air for 2 h; (4) HVT + Losartan group: rats were pretreated with Losartan (30 mg/kg, i.p.) prior to high volume ventilation. The samples of pulmonary tissue and lung lavage fluid were collected after experiments. The expression of angiotensinogen and AT(1) receptor mRNA in lung tissue was measured by reverse transcriptase-polymerase chain reaction. Apoptosis of the lung cells was assayed with terminal deoxynucleodityl transferase-mediated nick-end labeling method. Lung pathological changes were examined with optical microscopy. Total protein, wet/dry ratios (W/D), myeloperoxidase (MPO) activity, and neutrophil counts of the lung tissue or lavage fluid were measured with corresponding methods.. Compared with control or LVT, HVT caused significant ventilator-induced lung injury and increased the expression of angiotensinogen and AT(1) receptor mRNA in the lung. Total protein, the number of apoptotic cells, W/D ratio, MPO activity, and neutrophil counts were significantly higher in the HVT group than in the LVT or control group. Pretreatment with Losartan attenuated ventilator-induced lung injury and prevented the increase in total protein, the number of apoptotic cells, W/D ratio, MPO, and neutrophil counts caused by high volume ventilation.. Our study indicates that HVT causes remarkable lung injury and up-regulates angiotensinogen and AT(1) receptor expression of in the lung, and that Losartan, a selective inhibitor of subtype AT(1) receptors for angiotensin II, can relieve acute lung injury caused by high volume ventilation.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Apoptosis; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Losartan; Lung; Male; Neutrophil Infiltration; Peroxidase; Pulmonary Edema; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Respiration, Artificial; Respiratory Distress Syndrome; RNA, Messenger

There are two major pathophysiologic processes involved in the development of hypertension: (1) expanded extracellular fluid volume and (2) vasoconstriction. We have developed a model of preeclampsia in the rat, in which excessive volume expansion (VE) plays a role. These animals excrete increased amounts of the bufodienolide, marinobufagenin (MBG), even before their hypertension and proteinuria become established. Furthermore, their hypertension is corrected by administration of resibufogenin (RBG), a compound structurally similar to MBG.. We studied two models of experimental hypertension in the nonpregnant animal, produced either by deoxycorticosterone acetate (DOCA)-salt administration or by angiotensin infusion.. RBG administered to the DOCA-salt rats lowered blood pressure and reduced proteinuria in the VE animals, but had no affect on the rats infused with angiotensin. Furthermore, although the production of superoxide anion in the aortas of both groups of hypertensive rats was increased over control, RBG reduced these levels to normal in the VE (DOCA-salt) animals only. RBG had no effect in the angiotensin-infused rats. The urinary excretion of angiotensinogen did not rise in VE-mediated hypertension, but did increase in the angiotensin-infused rats.. MBG plays an important role in the causation of hypertension in the VE rats, but not in the vasoconstrictive model. RBG is effective only in VE-mediated hypertension.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Bufanolides; Creatinine; Desoxycorticosterone; Disease Models, Animal; Hypertension, Renal; Male; Mineralocorticoids; Proteinuria; Rats; Rats, Inbred Strains; Sodium Chloride; Superoxides; Vasoconstrictor Agents

The balance between norepinephrine (NE) synthesis, release, and reuptake is disrupted after acute myocardial infarction, resulting in elevated extracellular NE. Stimulation of sympathetic neurons in vitro increases NE synthesis and the synthetic enzyme tyrosine hydroxylase (TH) to a greater extent than it increases NE reuptake and the NE transporter (NET), which removes NE from the extracellular space. We used TGR(ASrAOGEN) transgenic rats, which lack postinfarct sympathetic hyperactivity, to test the hypothesis that increased cardiac sympathetic nerve activity accounts for the imbalance in TH and NET expression in these neurons after myocardial infarction. TH and NET mRNA levels were identical in the stellate ganglia of unoperated TGR(ASrAOGEN) rats compared with Sprague Dawley (SD) controls, but the threefold increase in TH and twofold increase in NET mRNA seen in the stellate ganglia of SD rats 1 wk after ischemia-reperfusion was absent in TGR(ASrAOGEN) rats. Similarly, the increase in TH and NET protein observed in the base of the SD ventricle was absent in the base of the TGR (ASrAOGEN) ventricle. Neuronal TH content was depleted in the left ventricle of both genotypes, whereas NET was unchanged. Basal heart rate and cardiac function were similar in both genotypes, but TGR(ASrAOGEN) hearts were more sensitive to the beta-agonist dobutamine. Tyramine-induced release of endogenous NE generated similar changes in ventricular pressure and contractility in both genotypes, but postinfarct relaxation was enhanced in TGR(ASrAOGEN) hearts. These data support the hypothesis that postinfarct sympathetic hyperactivity is the major stimulus increasing TH and NET expression in cardiac neurons.

Topics: Adrenergic beta-Agonists; Angiotensinogen; Animals; Animals, Genetically Modified; Coronary Vessels; Disease Models, Animal; Dobutamine; Female; Heart; Heart Rate; Ligation; Male; Myocardial Contraction; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Norepinephrine Plasma Membrane Transport Proteins; Rats; Rats, Sprague-Dawley; RNA, Messenger; Stellate Ganglion; Sympathetic Nervous System; Sympathomimetics; Tyramine; Tyrosine 3-Monooxygenase; Up-Regulation; Ventricular Function, Left

Sympathetic hyperactivity (SH) and renin angiotensin system (RAS) activation are commonly associated with heart failure (HF), even though the relative contribution of these factors to the cardiac derangement is less understood. The role of SH on RAS components and its consequences for the HF were investigated in mice lacking alpha(2A) and alpha(2C) adrenoceptor knockout (alpha(2A)/alpha(2C)ARKO) that present SH with evidence of HF by 7 mo of age. Cardiac and systemic RAS components and plasma norepinephrine (PN) levels were evaluated in male adult mice at 3 and 7 mo of age. In addition, cardiac morphometric analysis, collagen content, exercise tolerance, and hemodynamic assessments were made. At 3 mo, alpha(2A)/alpha(2C)ARKO mice showed no signs of HF, while displaying elevated PN, activation of local and systemic RAS components, and increased cardiomyocyte width (16%) compared with wild-type mice (WT). In contrast, at 7 mo, alpha(2A)/alpha(2C)ARKO mice presented clear signs of HF accompanied only by cardiac activation of angiotensinogen and ANG II levels and increased collagen content (twofold). Consistent with this local activation of RAS, 8 wk of ANG II AT(1) receptor blocker treatment restored cardiac structure and function comparable to the WT. Collectively, these data provide direct evidence that cardiac RAS activation plays a major role underlying the structural and functional abnormalities associated with a genetic SH-induced HF in mice.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Heart Failure; Heart Rate; Losartan; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Genetic; Myocytes, Cardiac; Norepinephrine; Physical Conditioning, Animal; Receptors, Adrenergic, alpha-2; Renin-Angiotensin System; Sympathetic Nervous System

We compared the effect n-3 polyunsaturated fatty acids (PUFAs) with direct renin inhibition on electrophysiological remodeling in angiotensin II-induced cardiac injury. We treated double-transgenic rats expressing the human renin and angiotensinogen genes (dTGRs) from week 4 to 7 with n-3 PUFA ethyl-esters (Omacor; 25-g/kg diet) or a direct renin inhibitor (aliskiren; 3 mg/kg per day). Sprague-Dawley rats were controls. We performed electrocardiographic, magnetocardiographic, and programmed electrical stimulation. Dietary n-3 PUFAs increased the cardiac content of eicosapentaenoic and docosahexaenoic acid. At week 7, mortality in dTGRs was 31%, whereas none of the n-3 PUFA- or aliskiren-treated dTGRs died. Systolic blood pressure was modestly reduced in n-3 PUFA-treated (180+/-3 mm Hg) compared with dTGRs (208+/-5 mm Hg). Aliskiren-treated dTGRs and Sprague-Dawley rats were normotensive (110+/-3 and 119+/-6 mm Hg, respectively). Both n-3 PUFA-treated and untreated dTGRs showed cardiac hypertrophy and increased atrial natriuretic peptide levels. Prolonged QRS and QT(c) intervals and increased T-wave dispersion in dTGRs were reduced by n-3 PUFAs or aliskiren. Both treatments reduced arrhythmia induction from 75% in dTGRs to 17% versus 0% in Sprague-Dawley rats. Macrophage infiltration and fibrosis were reduced by n-3 PUFAs and aliskiren. Connexin 43, a mediator of intermyocyte conduction, was redistributed to the lateral cell membranes in dTGRs. n-3 PUFAs and aliskiren restored normal localization to the intercalated disks. Thus, n-3 PUFAs and aliskiren improved electrical remodeling, arrhythmia induction, and connexin 43 expression, despite a 70-mm Hg difference in blood pressure and the development of cardiac hypertrophy.

Topics: Amides; Angiotensinogen; Animals; Animals, Genetically Modified; Antihypertensive Agents; Arrhythmias, Cardiac; Blood Pressure; Cardiac Pacing, Artificial; Cardiomegaly; Connexin 43; Dietary Fats; Disease Models, Animal; Electrocardiography; Electrophysiology; Fatty Acids, Omega-3; Fumarates; Humans; Hypertension; Magnetocardiography; Male; Rats; Rats, Sprague-Dawley; Renin; Up-Regulation

Identification of angiotensin-(1-12) as an intermediate precursor derived directly from angiotensinogen led us to explore whether the heart has the capacity to process angiotensin-(1-12) into biologically active angiotensin peptides. The generation of angiotensin I, angiotensin II, and angiotensin-(1-7) from exogenous angiotensin-(1-12) was evaluated in the effluent of isolated perfused hearts mounted on a Langendorff apparatus in three normotensive and two hypertensive strains: Sprague-Dawley, Lewis, congenic mRen2.Lewis, Wistar-Kyoto, and spontaneously hypertensive rats. Hearts were perfused with Krebs solution for 60 min before and after the addition of angiotensin-(1-12) (10 nmol/l). Angiotensin-(1-12) caused the rapid appearance of both angiotensin I and angiotensin II in the perfusate that peaked between 30 and 60 min of recirculation. Production of angiotensin-(1-7) from exogenous angiotensin-(1-12) rose steadily over the course of the 60-min experiment. These data directly demonstrate that angiotensin-(1-12) is a substrate for the formation of angiotensin peptides in cardiac tissue. This finding further suggests that this angiotensinogen-derived product is a previously unrecognized important precursor peptide to the renin-angiotensin system cascade.

Topics: Angiotensin I; Angiotensin II; Angiotensinogen; Angiotensins; Animals; Animals, Genetically Modified; Disease Models, Animal; Hypertension; Male; Myocardium; Peptide Fragments; Perfusion; Rats; Rats, Inbred Lew; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Renin; Renin-Angiotensin System; Time Factors

A low expression of angiotensinogen in the heart has been construed as indicating a circulating uptake mechanism to explain the local effects of angiotensin II on tissues. The recent identification of angiotensin-(1-12) in an array of rat organs suggests this propeptide may be an alternate substrate for local angiotensin production. To test this hypothesis, tissues from 11-wk-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats (n = 14) were stained with purified antibodies directed to the COOH terminus of angiotensin-(1-12). Robust angiotensin-(1-12) staining was predominantly found in ventricular myocytes with less staining found in the medial layer of intracoronary arteries and vascular endothelium. In addition, angiotensin-(1-12) immunoreactivity was present in the proximal, distal, and collecting renal tubules within the deep cortical and outer medullary zones in both strains. Preadsorption of the antibody with angiotensin-(1-12) abolished staining in both tissues. Corresponding tissue measurements by radioimmunoassay showed 47% higher levels of angiotensin-(1-12) in the heart of SHR compared with WKY rats (P < 0.05). In contrast, renal angiotensin-(1-12) levels were 16.5% lower in SHR compared with the WKY rats (P < 0.05). This study shows for first time the localization of angiotensin-(1-12) in both cardiac myocytes and renal tubular components of WKY and SHR. In addition, we show that increased cardiac angiotensin-(1-12) concentrations in SHR is associated with a small, but statistically significant, reduction in renal angiotensin-(1-12) levels.

Topics: Angiotensinogen; Animals; Antibody Specificity; Disease Models, Animal; Hypertension; Immunohistochemistry; Kidney Tubules; Male; Myocardium; Myocytes, Cardiac; Peptide Fragments; Radioimmunoassay; Rats; Rats, Inbred SHR; Rats, Inbred WKY

Sex differences in blood pressure are evident in experimental models and human subjects, yet the mechanisms underlying this disparity remain equivocal. The current study sought to define the extent of male-female differences in the circulating and tissue renin-angiotensin aldosterone systems (RAASs) of congenic mRen(2). Lewis and control Lewis rats. Male congenics exhibited higher systolic blood pressure than females [200 +/- 4 vs. 146 +/- 7 mmHg, P < 0.01] or Lewis males and females [113 +/- 2 vs. 112 +/- 2 mmHg, P > 0.05]. Plasma ANG II levels were twofold higher in male congenics [47 +/- 3 vs. 19 +/- 3 pM, P < 0.01] and fivefold higher than in male or female Lewis rats [6 +/- 1 vs. 6 +/- 1 pM]. ANG I levels were also highest in the males; however, plasma ANG-(1-7) was higher in female congenics. Male congenics exhibited greater circulating renin and angiotensin-converting enzyme (ACE) activities, as well as angiotensinogen, than female littermates. Renal cortical and medullary ANG II levels were also higher in the male congenics versus all the other groups; ANG I was lower in the males. Cortical ACE2 activity was higher in male congenics, yet neprilysin activity and protein were greater in the females, which may contribute to reduced renal levels of ANG II. These data reveal that sex differences in both the circulating and renal RAAS are apparent primarily in the hypertensive group. The enhanced activity of the RAAS in male congenics may contribute to the higher pressure and tissue injury evident in the strain.

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Angiotensinogen; Angiotensins; Animals; Animals, Genetically Modified; Blood Pressure; Disease Models, Animal; Female; Hypertension; Kidney; Male; Mice; Myocardium; Neprilysin; Peptide Fragments; Peptidyl-Dipeptidase A; Rats; Rats, Inbred Lew; Renin; Renin-Angiotensin System; Sex Factors

The aim of the present study was to evaluate the depth of endovascular trophoblast invasion and associated remodelling of spiral arteries in a transgenic model of pre-eclampsia in the rat, a species showing a comparable deep invasion during normal pregnancy as the human. Pre-eclamptic (PE) transgenic rats (TGR) (hAngiotensinogen female x hRenin male) and non-PE reversely mated (RM) TGR rats were compared to normal Sprague-Dawley rats (C). Day 18 implantation sites were collected and the presence of endovascular trophoblast, fibrinoid, endothelial and smooth muscle cells were evaluated in spiral arteries in three parallel layers in the mesometrial triangle using an image analysis system (KS-400). In a separate group of animals peak-systolic and end-diastolic velocities were measured by Doppler in uterine and arcuate arteries, and the resistance indices (RI) were calculated. In PE and RM rats, the entire mesometrial triangle contained significantly more endovascular trophoblast and vascular fibrinoid deposits than the C group. No difference was found between the groups in the overall amount of smooth muscle surrounding the lumen, but in the PE and RM groups significantly more muscle was present in parts of the contours covered by trophoblast. There was significantly less CD31-positive endothelium in the total lumen contours of the PE and RM groups than in the C group, but in parts of the contours covered by trophoblast more residual endothelium was present in both TGR groups. Comparison of the three layers indicated deeper invasion in both the PE and RM groups than in the C group. By Doppler analysis of the proximal uterine artery the RI was found to be significantly lower in the PE and the RM group than in the C group. In the arcuate artery, the RI was significantly lower in the PE group as compared to the RM and C groups. We conclude that in this transgenic PE rat model there is deeper endovascular invasion of spiral arteries and decreased RI of uterine arteries at day 18 of pregnancy.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Arteries; Cell Adhesion; Disease Models, Animal; Endothelium, Vascular; Female; Hemodynamics; Male; Placental Circulation; Pre-Eclampsia; Pregnancy; Rats; Rats, Sprague-Dawley; Renin; Trophoblasts; Uterus

We investigated whether or not p38 mitogen-activated protein kinase inhibition ameliorates angiotensin II-induced target organ damage. We used double transgenic rats harboring both human renin and angiotensinogen genes (dTGRs). dTGR, with or without p38 inhibitor (BIRB796; 30 mg/kg per day in the diet), and nontransgenic Sprague-Dawley rats were studied in 2 protocols. In protocol 1 (week 7), systolic blood pressure of untreated dTGRs was 204+/-4 mm Hg, but partially reduced after BIRB796 treatment (166+/-7 mm Hg), whereas Sprague-Dawley rats were normotensive. The cardiac hypertrophy index was unchanged in untreated and BIRB796-treated dTGRs. The beta-myosin heavy chain expression of BIRB796-treated hearts was significantly lower in BIRB796 compared with dTGRs, indicating a delayed switch to the fetal isoform. BIRB796 treatment significantly reduced cardiac fibrosis, connective tissue growth factor, tumor necrosis factor-alpha, interleukin-6, and macrophage infiltration. Albuminuria was not reduced in BIRB796-treated dTGRs. Tubular and glomerular damage with tumor necrosis factor-alpha expression was unaltered, although serum creatinine and cystatin C were normalized. Renal macrophage infiltration, fibrosis, and vessel damage were reduced. In protocol 2 (week 8), we focused on mortality and arrhythmogenic electrical remodeling. Mortality of untreated dTGRs was 100% but was reduced to 10% in the BIRB796 group. Cardiac magnetic field mapping showed prolongation of depolarization and repolarization in untreated dTGRs compared with Sprague-Dawley rats with a partial reduction by BIRB796. Programmed electrical stimulation elicited ventricular tachycardias in 81% of untreated dTGRs but only in 48% of BIRB796-treated dTGRs. In conclusion, BIRB796 improved survival, target organ damage, and arrhythmogenic potential in angiotensin II-induced target organ damage.

Topics: Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Cardiovascular Diseases; Disease Models, Animal; Kidney Diseases; Male; Naphthalenes; p38 Mitogen-Activated Protein Kinases; Protein Kinase Inhibitors; Pyrazoles; Rats; Rats, Sprague-Dawley; Renin

Although progress in the genetics of essential hypertension may seem disappointing, it has considerable potential in defining research directions that will ultimately translate into clinical practice. The hypothesis that genetic variation at the angiotensinogen locus impacts on individual susceptibility to develop essential hypertension has motivated a substantial body of research by us and many others. We examine how analyses of the mechanisms by which variation in angiotensinogen expression may contribute to disease susceptibility and may have arisen in human populations have progressed in recent years. Although the objective of personalized medicine is still in the future, a genetic hypothesis based on human variation can uniquely empower functional genomics approaches to reach such an ultimate goal.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Gene Expression; Genetic Predisposition to Disease; Humans; Hypertension; Mice; Nephrons; Rats; Renin-Angiotensin System

Polymorphisms of the angiotensinogen (Agt) gene may affect blood pressure. We used a mouse model to test for the role of the Agt genotype in low-renin or high-renin forms of hypertension. Mice bearing one, two, three, or four copies of the Agt gene underwent renal artery clipping to induce high-renin two-kidney, one-clip renovascular hypertension (2K1C), or uninephrectomy, salt loading, and application of deoxycorticosterone-acetate (DOCA) pellets to induce low-renin mineralocorticoid hypertension. Appropriate control animals were also studied. Blood pressure was measured by tail cuff as well as by direct intra-arterial recordings. There was a small effect of the Agt genotype on baseline blood pressure before induction of hypertension. The extent of 2K1C hypertension was not affected by the genotype. In contrast, there was a marked gene-dose effect on DOCA-hypertension (21.2 mmHg over all genotypes). Treatment of DOCA mice with the angiotensin II type 1 receptor antagonist abolished the genotype effect on blood pressure and left ventricular hypertrophy. There was a trend towards less suppression of endogenous aldosterone by DOCA treatment with increasing number of Agt gene copies. We conclude that the Agt genotype exerts a marked effect on blood pressure in a low-renin form of hypertension but no effect in the face of stimulated renin, at least in mice.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Genotype; Hypertension; Kidney; Mice; Mice, Inbred C57BL; Renin-Angiotensin System

Rats harboring the human renin and angiotensinogen genes (dTGR) feature angiotensin (ANG) II/hypertension-induced cardiac damage and die suddenly between wk 7 and 8. We observed by electrocardiogram (ECG) telemetry that ventricular tachycardia (VT) is a common terminal event in these animals. Our aim was to investigate electrical remodeling. We used ECG telemetry, noninvasive cardiac magnetic field mapping (CMFM) at wk 5 and 7, and performed in vivo programmed electrical stimulation at wk 7. We also investigated whether or not losartan (Los; 30 mg x kg(-1) x day(-1)) would prevent electrical remodeling. Cardiac hypertrophy and systolic blood pressure progressively increased in dTGR compared with Sprague-Dawley (SD) controls. Already by wk 5, untreated dTGR showed increased perivascular and interstitial fibrosis, connective tissue growth factor expression, and monocyte infiltration compared with SD rats, differences that progressed through time. Left-ventricular mRNA expression of potassium channel subunit Kv4.3 and gap-junction protein connexin 43 were significantly reduced in dTGR compared with Los-treated dTGR and SD. CMFM showed that depolarization and repolarization were prolonged and inhomogeneous. Los ameliorated all disturbances. VT could be induced in 88% of dTGR but only in 33% of Los-treated dTGR and could not be induced in SD. Untreated dTGR show electrical remodeling and probably die from VT. Los treatment reduces myocardial remodeling and predisposition to arrhythmias. ANG II target organ damage induces VT.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Animals, Genetically Modified; Blood Pressure; Cardiac Pacing, Artificial; Cardiomegaly; Connexin 43; Death, Sudden, Cardiac; Disease Models, Animal; Electrocardiography; Heart Conduction System; Hypertension; Losartan; Male; Myocardium; Rats; Rats, Sprague-Dawley; Renin; RNA, Messenger; Shal Potassium Channels; Tachycardia, Ventricular; Telemetry; Time Factors; Ventricular Remodeling

Hypertensive mice that express the human renin and angiotensinogen genes are used as a model for human hypertension because they develop hypertension secondary to increased renin-angiotensin system activity. Our study investigated the cellular localization and distribution of COX-1, COX-2, mPGES-1, and mPGES-2 in organ tissues from a mouse model of human hypertension. Male (n = 15) and female (n = 15) double transgenic mice (h-Ang 204/1 h-Ren 9) were used in the study. Lung, kidney, and heart tissues were obtained from mice at necropsy and fixed in 10% neutral buffered formalin followed by embedding in paraffin wax. Cut sections were stained immunohistochemically with antibodies to COX-1, COX-2, mPGES-1, and mPGES-2 and analyzed by light microscopy. Renal expression of COX-1 was the highest in the distal convoluted tubules, cortical collecting ducts, and medullary collecting ducts; while proximal convoluted tubules lacked COX-1 expression. Bronchial and bronchiolar epithelial cells, alveolar macrophages, and cardiac vascular endothelial cells also had strong COX-1 expression, with other renal, pulmonary, or cardiac microanatomic locations having mild-to-moderate expression. mPGES-2 expression was strong in the bronchial and bronchiolar epithelial cells, mild to moderate in various renal microanatomic locations, and absent in cardiac tissues. COX-2 expression was strong in the proximal and distal convoluted tubules, alveolar macrophages, and bronchial and bronchiolar epithelial cells. Marked mPGES-1 was present only in bronchial and bronchiolar epithelial cells; while mild-to-moderate expression was present in other pulmonary, renal, or cardiac microanatomic locations. Expression of these molecules was similar between males and females. Our work suggests that in hypertensive mice, there are (a) significant microanatomic variations in the pulmonary, renal, and cardiac distribution and cellular localization of COX-1, COX-2, mPGES-1, and mPGES-2, and (b) no differences in expression between genders.

Topics: Angiotensinogen; Animals; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Female; Humans; Hypertension; Immunohistochemistry; Intramolecular Oxidoreductases; Kidney; Lung; Male; Mice; Mice, Transgenic; Microsomes; Myocardium; Prostaglandin-E Synthases; Renin

Pharmacological and genetic interference with the renin-angiotensin system (RAS) seems to alter voluntary ethanol consumption. However, understanding the influence of the RAS on ethanol dependence and its treatment requires modeling the neuroadaptations that occur with prolonged exposure to ethanol. Increased ethanol consumption was induced in rats through repeated cycles of intoxication and withdrawal. Expression of angiotensinogen, angiotensin-converting enzyme, and the angiotensin II receptor, AT1a, was examined by quantitative reverse transcription polymerase chain reaction. Increased ethanol consumption after a history of dependence was associated with increased angiotensinogen expression in medial prefrontal cortex but not in nucleus accumbens or amygdala. Increased angiotensinogen expression also demonstrates that the astroglia is an integral part of the plasticity underlying the development of dependence. The effects of low central RAS activity on increased ethanol consumption were investigated using either spirapril, a blood-brain barrier-penetrating inhibitor of angiotensin-converting enzyme, or transgenic rats (TGR(ASrAOGEN)680) with reduced central angiotensinogen expression. Spirapril reduced ethanol intake in dependent rats compared to controls. After induction of dependence, TGR(ASrAOGEN)680 rats had increased ethanol consumption but to a lesser degree than Wistar rats with the same history of dependence. These data suggest that the central RAS is sensitized in its modulatory control of ethanol consumption in the dependent state, but pharmacological or genetic blockade of the system appears to be insufficient to halt the progression of dependence.

Topics: Adaptation, Physiological; Alcoholism; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Animals, Genetically Modified; Central Nervous System; Disease Models, Animal; Enalapril; Ethanol; Humans; Neuronal Plasticity; Rats; Rats, Wistar; Receptors, Angiotensin; Renin-Angiotensin System; RNA, Antisense

Catecholaminergic and angiotensinergic systems are involved in the neural control of blood pressure. The present study analysed the expression of tyrosine hydroxylase (TH), a key enzyme for catecholamine synthesis and of angiotensinogen (AGT), the precursor of angiotensin II (Ang II), in areas of the central nervous system (CNS) involved with cardiovascular regulation such as nucleus tractus solitarius (NTS), ventrolateral medulla (VLM), locus coeruleus (LC) and hypothalamic paraventricular nucleus (PVN) 2 h, 3 and 7 days after aortic coarctated hypertensive rats. In situ hybridization, was employed for the analysis of messenger RNA (mRNA) expression with anatomical resolution. No changes were seen in TH and AGT mRNA expression in the analysed areas 2 h and 3 days after aortic coarctation when compared to the respective sham group. TH mRNA expression was increased in the NTS and LC of rats 7 days after coarctation hypertension when compared to sham rats. Time course analysis, showed an increase in TH mRNA expression in the NTS 7 days after aortic coarctation when compared to 2 h and 3 days groups, as well as an increase in LC 3 days and 7 days following coarctation hypertension in comparison with the 2 h group. Analysis of AGT mRNA in the NTS expression revealed a decrease at 3 days, followed by an increase in mRNA expression 7 days following coarctation hypertension when compared to the sham group. Time course analysis, showed an increase in AGT mRNA expression in the NTS 7 days after coarctation when compared to 2 h and 3 days groups. The results show that TH and AGT mRNA expression changes during the different phases of experimental hypertension, suggesting that the noradrenaline (NOR) and angiotensin II (Ang II) might participate in the modulation/maintenance of coarctation hypertension.

Topics: Angiotensin II; Angiotensinogen; Animals; Aortic Coarctation; Blood Pressure; Brain; Brain Stem; Catecholamines; Disease Models, Animal; Gene Expression; Hypertension; Male; Paraventricular Hypothalamic Nucleus; Rats; Rats, Inbred WKY; RNA, Messenger; Time Factors; Tyrosine 3-Monooxygenase; Up-Regulation

Meconium aspiration syndrome (MAS) is common among newborn children but its mechanism is unclear. The syndrome is known to produce a strong inflammatory reaction in the lungs resulting in massive cell death. In this work we studied lung cell death by apoptosis after meconium aspiration in forty two-week-old rabbit pups. Analyzing lung samples by ISEL-DNA end labeling demonstrated the specific spread of apoptotic bodies throughout the lungs. These bodies were shrunken and smaller in size compared to normal cells and many of them were lacking cell membranes. About 70% of all apoptotic bodies were found among the airway epithelium cell eight hours after meconium instillation. In comparison, among lung alveolar cells, only about 20% cells were apoptotic in the same animals. In meconium-treated lungs and A549 cells, a significant increase of angiotensinogen mRNA and Caspase-3 expression were observed. The pretreatment of cells with Caspase-3 inhibitor ZVAD-fmk significantly inhibited meconium-induced lung cell death by apoptosis. These findings demonstrate the apoptotic process in meconium-instilled lungs or A549 cells in culture. Our results show lung airway epithelial and A549 cell apoptosis after meconium instillation. We suggest that studies of lung airway epithelial cell death are essential to understanding the pathophysiology of MAS and may present a key point in future therapeutic applications.

Topics: Amino Acid Chloromethyl Ketones; Angiotensinogen; Animals; Apoptosis; Bronchoalveolar Lavage Fluid; Caspase 3; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Disease Models, Animal; Epithelial Cells; Humans; Infant, Newborn; Lung; Meconium Aspiration Syndrome; Rabbits; Reverse Transcriptase Polymerase Chain Reaction

Hypertension is the most common risk factor for hemorrhagic stroke. An experimental model of stroke, the stroke-prone spontaneously hypertensive rat (SHRSP), which has been enormously useful in studies of cerebral circulation, has been used in >1000 papers. However, SHRSP usually have an ischemic or less commonly hemorrhagic stroke in the cortex, not in the brain stem, cerebellum, or basal ganglia, as in patients with hypertension. The goal of this study was to develop a model of hemorrhagic stroke in hypertensive mice.. A genetic model of hypertensive mice, double transgenic mice (R+/A+) that overexpress both human renin (R+) and human angiotensinogen (A+), and nonhypertensive control mice were divided into 3 groups: (1) high-salt diet; (2) Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthases, in drinking water; and (3) high-salt diet and L-NAME.. All R+/A+ mice on high-salt diet and L-NAME died within 10 weeks, with hemorrhage in the brain stem, and several of the mice had hemorrhages in brain stem, cerebellum, and basal ganglia. No control mice on high-salt diet and L-NAME had hemorrhagic stroke. Arterial pressure in R+/A+ mice increased progressively during high-salt diet and L-NAME. In R+/A+ and control mice, high-salt diet or L-NAME alone did not increase arterial pressure.. We now describe the first model of spontaneous hemorrhagic strokes in hypertensive mice. The type and locations of stroke are reasonably similar to those observed in patients with hypertension.

Topics: Angiotensinogen; Animal Feed; Animals; Blood Pressure; Brain; Circadian Rhythm; Disease Models, Animal; Female; Humans; Hypertension; Intracranial Hemorrhages; Mice; Mice, Transgenic; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Renin; Salts; Stroke

Blood pressure-independent (BP) effects of angiotensin (Ang) II and endothelin (ET) on coronaries (remodeling) in high renin hypertension are incompletely understood.. We studied the effects of subdepressor doses of Ang II receptor (AT1) blockade with losartan (10 mg/kg/day gavage) and endothelin A receptor (ETA) blockade with LU135252 (30 mg/kg/day) on the coronaries of rats harboring human renin and angiotensinogen genes (dTGR). Nontransgenic Sprague-Dawley rats were controls. The rats were treated between the ages of 6 and 10 weeks. Coronary cross-sectional area [CSA; 0.79 x (external diameter2 - internal diameter2)], cell proliferation, and infiltration of monocytes/macrophages were determined.. Monotherapy did not lower BP while combination treatment did (p < 0.05). All treatments reduced mortality (p < 0.01). CSA was decreased by all treatments compared to vehicle, independent of blood pressure (p < 0.05). Extensive proliferation by PCNA staining and infiltration of ED-1-positive cells was diminished by both treatment and the combination.. The data show that Ang II promotes coronary inflammation and remodeling, in part independent of blood pressure but dependent upon ET signaling. Combination treatment directed at both pathways may improve outcome, independent of blood pressure reduction.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensinogen; Animals; Animals, Genetically Modified; Aorta; Blood Pressure; Cell Movement; Cell Proliferation; Coronary Vessels; Disease Models, Animal; Endothelin A Receptor Antagonists; Humans; Hypertension; Macrophages; Male; Rats; Rats, Sprague-Dawley; Renin

The purpose of this study was to evaluate the physiological significance of a tissue renin-angiotensin system in the proximal tubule of the kidney. To accomplish this, we produced mice that express human renin (hREN) under the control of the kidney androgen-regulated promoter (KAP), which is androgen responsive. One of the lines expressed the hREN transgene primarily in the kidney. Renal expression of the transgene was undetectable in females but could be induced by testosterone treatment. Because the renin-angiotensin system is species specific, we bred KAP2-hREN mice with the mice expressing human angiotensinogen under the same promoter (KAP-hAGT) to produce offspring that expressed both transgenes. We measured mean arterial blood pressure (MAP) in the carotid artery of double-transgenic and control mice using radiotelemetry. Double-transgenic female mice had a normal baseline MAP (116 +/- 4 mmHg, n = 8), which increased by 15 mmHg after 2 wk of testosterone treatment, and returned to baseline after elimination of the testosterone pellet. The change in arterial pressure paralleled the change in plasma testosterone. There was no MAP change in testosterone-treated control littermates. We conclude that dual production of renin and angiotensinogen in the renal proximal tubule can result in a systemic increase in arterial pressure. These data support a role for a tissue-specific renin-angiotensin system in the renal proximal tubule that contributes to the regulation of systemic blood pressure.

Topics: Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Female; Humans; Hypertension, Renal; Kidney Tubules, Proximal; Male; Mice; Mice, Transgenic; Promoter Regions, Genetic; Renin; Renin-Angiotensin System; Transgenes

To explore the role of angiotensin II, we assessed hemodynamics and cardiac function in angiotensinogen-deficient mice in comparison to wild-type animals. Left ventricular end-diastolic diameter and wall thickness were evaluated by echocardiography and systolic and diastolic left ventricular function by pressure-volume relations using a micro-conductance catheter. Compared to wild-type animals, the angiotensinogen-deficient mice were hypotensive and showed impaired systolic function. The hearts were dilated, demonstrated by echocardiography and by a right-ward shift of the pressure-volume loops, but end-diastolic pressure, isovolumic relaxation (tau) and diastolic stiffness were unchanged. Afterload, however, was reduced leading to maintained cardiac output. Although a blockade of the renin-angiotensin system via angiotensin converting enzyme inhibitors or angiotensin AT1 receptor antagonist is beneficial after cardiac failure, the absence of angiotensin peptides during the ontogenesis leads to dilated cardiomyopathy.

Topics: Angiotensin II; Angiotensinogen; Animals; Cardiomyopathy, Dilated; Disease Models, Animal; Echocardiography; Hemodynamics; Hypotension; Male; Mice; Mice, Knockout; Netherlands; Receptors, Angiotensin; Stroke Volume; Ventricular Function, Left

To determine whether carotid artery stiffness was increased in patients with untreated essential hypertension who are homozygous for the T allele of the M235T polymorphism of the angiotensinogen (AGT) gene and in mutant mice carrying three copies of the angiotensinogen (Agt) gene.. Using echotracking systems, we studied carotid mechanical properties in 98 never-treated hypertensive patients according to their AGT genotype, and in Agt mutant mice.. Patients homozygous for the T allele had a reduced carotid distensibility and an increased stiffness of the carotid wall material (Young's elastic modulus), independent of blood pressure, compared with patients homozygous for the M allele. In Agt1/2 mice, carotid distensibility was not significantly different from that of Agt1/1 (wild-type). Moreover, the stiffness of the arterial wall material was lower in Agt1/2 mice than in wild-type mice. In Agt1/2 mice, the greater blood pressure was not associated with arterial hypertrophy, resulting in a greater circumferential wall stress. The in-vivo and in-vitro pressor responses to angiotensin II were reduced in Agt1/2 mice, whereas the contractile response to phenylephrine was not significantly different between Agt1/1 and Agt1/2 mice, indicating the integrity of the contractile apparatus and suggesting a dysfunction of the angiotensin II type 1 receptor signalling pathways in Agt1/2 mice.. These data suggest that the angiotensinogen TT genotype at position 235 could be a genetic marker for arterial stiffness in patients with never-treated hypertension, whereas in Agt1/2 mice the dysfunction of the angiotensin II type 1 receptor signalling pathways could explain the lack of arterial wall hypertrophy and stiffness.

Topics: Adult; Aged; Aged, 80 and over; Angiotensinogen; Animals; Carotid Arteries; Disease Models, Animal; Female; Genotype; Homozygote; Humans; Hypertension; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Middle Aged; Polymorphism, Genetic; Receptor, Angiotensin, Type 1; Signal Transduction

Enhanced efficiency of the reaction between transgenic Ren-2 mouse renin and endogenous rat angiotensinogen has been suggested as 1 mechanism that contributes to the accelerated hypertension and increased tissue angiotensin of the (mRen-2)27 transgenic rat. This was tested in a study conducted at pH 7.4 in vitro that compared the kinetic constants of purified mouse Ren-2 and rat renin (each at 100, 75, 50, and 25 pmol/L) reacting with physiologic concentrations of rat angiotensinogen (0 to 4 micromol/L). Under these conditions, the kinetic constants for Ren-2 (Km, 1.8 micromol/L; Kcat, 0.07/s; and Kcat/Km, 0.04 L x micromol(-1) x s(-1)) were not different from rat renin. However, Ren-2 renin acting on its homologous mouse angiotensinogen was confirmed as being much slower. We conclude that hypertension in the Ren-2 rat is not related to renin kinetics. Other mechanisms are considered, with reference to human essential hypertension.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Disease Models, Animal; Hypertension; Kinetics; Male; Mice; Mice, Inbred BALB C; Rats; Rats, Sprague-Dawley; Renin; Species Specificity

The role of angiotensin II in pressure overload is still debated because notwithstanding its effects on myocyte contractility angiotensin II is not an obligatory factor for the development of hypertrophy. To define the role of angiotensin II in acute pressure overload we studied the effects of AT1 blockade (valsartan 80mg per day) on myocardial contractility, cardiac growth factor gene expression, and myocardial hypertrophy in aortic banded (60mmHg) pigs. Acute pressure overload caused an abrupt reduction of myocardial contractility, measured by the end-systolic stiffness constant, and a sharp increase in end-systolic stress which rapidly normalized (within 12h) in the placebo group. In AT1-blocked animals end-systolic stiffness constant remained significantly depressed up to 24h and end-systolic stress was still elevated up to 48h (both P<0.05 vs placebo). In both groups confocal microscopy revealed that granular staining of angiotensin II in cardiomyocyte cytoplasm disappeared after 30min of pressure overload. AT1 blockade abolished following cardiac overexpression of angiotensinogen and endothelin-1 genes as shown in RT-PCR studies and the consequent angiotensin II and endothelin-1 release in the coronary circulation. Conversely, insulin-like growth factor-I and ACE mRNA overexpression, as well as the onset of left ventricular mass increase, were not significantly affected by AT1 blockade.. (1) mechanical stress releases preformed angiotensin II from myocyte in vivo; (2) the AT1 blockade abolishes cardiac angiotensin II and endothelin-1 production with delayed recovery of myocardial contractility; whereas (3) the overexpression of insulin-like growth factor-I gene and the development of myocardial hypertrophy are not angiotensin II-mediated effects.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Angiotensinogen; Animals; Aortic Valve Stenosis; Cardiac Catheterization; Cytoplasm; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Heart; Insulin-Like Growth Factor I; Microscopy, Confocal; Myocardium; Receptor, Angiotensin, Type 1; Receptors, Angiotensin; Renin-Angiotensin System; RNA, Messenger; Stress, Mechanical; Swine; Systole; Tetrazoles; Valine; Valsartan

Rats exposed chronically to a cold environment (5 degrees C/4 degrees F) develop hypertension. This cold-induced hypertension (CIH) is a non-genetic, non-pharmacological, non-surgical model of environmentally induced hypertension in rats. The renin-angiotensin system (RAS) appears to play a role in both initiating and/or maintaining the high blood pressure in CIH. The goal of the present study was to evaluate the role of central and peripheral circulating RAS components, angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and angiotensin (Ang) II, in CIH. Seventy-two Sprague-Dawley adult male rats were used. Thirty-six rats were kept in cold room at 5 degrees C while the other 36 were at 24 degrees C as controls for 5 weeks. Systolic blood pressure (SBP) was recorded by tail cuff. The SBP was increased in rats exposed to cold within 1 week, and this increase was significant for the next 2-5 weeks of the cold exposure (p<0.01). Three subgroups of the cold-treated and control rats (n=12) were sacrificed at 1, 3 and 5 weeks. The brain and liver were removed and plasma was saved. The AGT mRNA significantly increased in the hypothalamus and liver in cold-treated rats from the first week of exposure to cold, and was maintained throughout the time of exposure to cold (n=4, p<0.01). The AGT protein levels in the brain, liver and plasma did not differ significantly between cold-treated and control rats (p>0.05, n=4). The hypothalamic Ang II levels were significantly increased, whereas plasma Ang II levels significantly decreased, in the rats of 5 weeks of cold exposure (n=8, p<0.05). Plasma ACE significantly increased in the rats of 1 week of cold exposure (p<0.05, n=12). The results show differential regulation of RAS components, AGT, ACE and Ang II, between brain and periphery in cold-exposed rats. We conclude that the exposure to low temperature initially increases plasma RAS but with continuous exposure to cold, the brain RAS maintains the hypertension, probably by sustained sympathetic activation, which would provide increased metabolism but also vasoconstriction leading to hypertension.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Brain; Cold Temperature; Disease Models, Animal; Hypertension; Hypothalamus; Liver; Male; Peptidyl-Dipeptidase A; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Renin-Angiotensin System; RNA, Messenger; Time Factors

We tested the hypothesis that endothelin-converting enzyme (ECE) inhibition ameliorates end-organ damage in rats harboring both human renin and human angiotensinogen genes (dTGR). Hypertension develops in the animals, and they die by age 7 weeks of heart and kidney failure. Three groups were studied: dTGR (n=12) receiving vehicle, dTGR receiving ECE inhibitor (RO0687629; 30 mg/kg by gavage; n=10), and Sprague-Dawley control rats (SD; n=10) receiving vehicle, all after week 4, with euthanasia at week 7. Systolic blood pressure was not reduced by ECE inhibitor compared with dTGR (205+/-6 versus 206+/-6 mm Hg at week 7, respectively). In contrast, ECE inhibitor treatment significantly reduced mortality rate to 20% (2 of 10), whereas untreated dTGR had a 52% mortality rate (7 of 12). ECE inhibitor treatment ameliorated cardiac damage and reduced left ventricular ECE activity below SD levels. Echocardiography at week 7 showed reduced cardiac hypertrophy (4.8+/-0.2 versus 5.7+/-0.2 mg/g, P<0.01) and increased left ventricular cavity diameter (5.5+/-0.3 versus 3.1+/-0.1 mm, P<0.001) and filling volume (0.42+/-0.04 versus 0.16+/-0.06 mL, P<0.05) after ECE inhibitor compared with untreated dTGR. ECE inhibitor treatment also reduced cardiac fibrosis, tissue factor expression, left ventricular basic fibroblast growth factor mRNA levels, and immunostaining in the vessel wall, independent of high blood pressure. In contrast, the ECE inhibitor treatment showed no renoprotective effect. These data are the first to show that ECE inhibition reduces angiotensin II-induced cardiac damage.

Topics: Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Aorta; Aspartic Acid Endopeptidases; Disease Models, Animal; Echocardiography; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Extracellular Matrix; Fibroblast Growth Factor 2; Fibronectins; Heart Diseases; Heart Ventricles; Humans; Immunohistochemistry; Kidney; Male; Metalloendopeptidases; Prodrugs; Rats; Rats, Sprague-Dawley; Renin; RNA, Messenger

Recent experimental evidence suggests a role for tissue renin-angiotensin systems in the development of hypertension. To test the importance of tissue renin-angiotensin systems in the development and maintenance of angiotensin II-dependent hypertension, we generated a transgenic model in which exon 2 of the human angiotensinogen gene is flanked by loxP sites (hAGT(flox)) so that this region of the gene can be deleted by the cre-recombinase. Double transgenic human renin and hAGT(flox) (R(+)/A(+flox)) mice of two independent lines exhibited elevated blood pressure. Acute administration of an adenovirus containing cre-recombinase (Adcre) lowered blood pressure by 30 mm Hg over a 4-day period as measured with fluid filled catheters. The chronic effect of Adcre administration on blood pressure was determined by radiotelemetry in a separate group of R(+)/A(+flox) mice. Blood pressure decreased by 25 mm Hg from baseline by day 8 post-Adcre, but increased on each day thereafter until it was 90% of baseline by day 21 post-Adcre. Expression analysis indicated the absence of detectable hAGT mRNA in the liver at day 5 post-Adcre, but reappeared at normal levels at days 14 to 21 post-Adcre. These studies suggest that Adcre is effective for acute, but not chronic, elimination of hepatic hAGT. Chronic elimination of hepatic hAGT will likely require the use of transgenic mice endogenously expressing cre-recombinase in the liver.

Topics: Adenoviridae; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Genetic Therapy; Genetic Vectors; Hypertension; Integrases; Mice; Mice, Transgenic; Viral Proteins

Hypertension-induced damage of kidney and heart is of major clinical relevance, but its pathophysiology is only partially understood. As there is considerable evidence for involvement of angiotensin II, we generated a new mouse model by breeding angiotensinogen (AOGEN) deficient mice with transgenic animals expressing the rat AOGEN gene only in brain and liver. This genetic manipulation overcame the hypotension of AOGEN-deficient mice and even caused hypertension indistinguishable in its extent from the parent transgenic mice with an intact endogenous AOGEN gene. In contrast to normal mice, however, crossbred animals lacked detectable expression of AOGEN in kidney and heart. As a consequence they showed markedly reduced cardiac hypertrophy and fibrosis. Furthermore, hypertension-induced alterations in kidney histology and function were less pronounced in crossbred mice than in equally hypertensive animals expressing AOGEN locally. The dysmorphogenesis observed in kidneys from AOGEN-deficient mice was absent in mice expressing this gene only in liver and brain. Our results support an important role of local AOGEN expression in hypertension-induced end-organ damage but not in the development of the kidney.

Topics: Angiotensinogen; Animals; Brain; Cardiomegaly; Disease Models, Animal; Fibrosis; Heart Diseases; Hypertension; Kidney Diseases; Liver; Mice; Mice, Transgenic; Myocardium; Organ Size; Organ Specificity; Renin-Angiotensin System

The regulation of blood pressure during pregnancy involves several biological pathways. Candidate genes implicated in hypertensive diseases during pregnancy include those of the renin-angiotensin system and nitric oxide synthase (NOS). We evaluated blood pressure and metabolic characteristics during pregnancy in mutant mice. These included mice with a null mutation in the endothelial NOS (eNOS) gene (Nos3(-/-)), four copies of the angiotensinogen gene (Agt(2/2)), and mutations in both genes [four copies of Agt and heterozygous deficient for eNOS (Agt(2/2)Nos3(+/-)), four copies of Agt and homozygous deficient for eNOS (Agt(2/2)Nos3(-/-))]. Blood pressure measurements of nulliparous females from mutant strains were compared with two common laboratory strains C57Bl6/J and SV129 throughout their first pregnancy. Serum and urine analysis for the evaluation of renal and liver physiology were measured in the prepregnant state and during the third trimester of pregnancy. Throughout pregnancy blood pressures in all mutant strains were higher compared with controls. Agt(2/2)Nos3(-/-) showed the highest blood pressures and C57Bl6/J the lowest. Control mice, but not mutant mice, showed a second trimester decline in blood pressure. No immediate differences were noted regarding behavioral characteristics, renal or liver function parameters. Mice deficient for eNOS, mice with overexpression of Agt, and mice with mutations in both genes demonstrated higher blood pressure throughout pregnancy. There was no evidence of renal dysfunction, liver dysfunction, or hemolysis among any of the strains studied. We conclude that Nos3 and Agt are important genes in the regulation of blood pressure during pregnancy.

Topics: Angiotensinogen; Animals; Area Under Curve; Behavior, Animal; Blood Pressure; Breeding; Disease Models, Animal; Energy Metabolism; Female; Gene Expression Regulation, Enzymologic; Genotype; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Pre-Eclampsia; Pregnancy; Proteinuria

We examined whether xanthine oxidoreductase (XOR), a hypoxia-inducible enzyme capable of generating reactive oxygen species, is involved in the onset of angiotensin (Ang) II-induced vascular dysfunction in double-transgenic rats (dTGR) harboring human renin and human angiotensinogen genes. In 7-week-old hypertensive dTGR, the endothelium-mediated relaxation of noradrenaline (NA)-precontracted renal arterial rings to acetylcholine (ACh) in vitro was markedly impaired compared with Sprague Dawley rats. Preincubation with superoxide dismutase (SOD) improved the endothelium-dependent vascular relaxation, indicating that in dTGR, endothelial dysfunction is associated with increased superoxide formation. Preincubation with the XOR inhibitor oxypurinol also improved endothelium-dependent vascular relaxation. The endothelium-independent relaxation to sodium nitroprusside was similar in both strains. In dTGR, serum 8-isoprostaglandin F(2alpha), a vasoconstrictor and antinatriuretic arachidonic acid metabolite produced by oxidative stress, was increased by 100%, and the activity of XOR in the kidney was increased by 40%. Urinary nitrate plus nitrite (NO(x)) excretion, a marker of total body NO generation, was decreased by 85%. Contractile responses of renal arteries to Ang II, endothelin-1 (ET-1), and NA were decreased in dTGR, suggesting hypertension-associated generalized changes in the vascular function rather than a receptor-specific desensitization. Valsartan (30 mg/kg PO for 3 weeks) normalized blood pressure, endothelial dysfunction, and the contractile responses to ET-1 and NA. Valsartan also normalized serum 8-isoprostaglandin F(2alpha) levels, renal XOR activity, and, to a degree, NO(x) excretion. Thus, overproduction of Ang II in dTGR induces pronounced endothelial dysfunction, whereas the sensitivity of vascular smooth muscle cells to nitric oxide is unaltered. Ang II-induced endothelial dysfunction is associated with increased oxidative stress and vascular xanthine oxidase activity.

Topics: Acetylcholine; Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Antihypertensive Agents; Dinoprost; Disease Models, Animal; Endothelium, Vascular; F2-Isoprostanes; Humans; Hypertension; Ketone Oxidoreductases; Male; Nitrates; Nitrites; Nitroprusside; Norepinephrine; Rats; Rats, Sprague-Dawley; Renal Artery; Renin; Superoxide Dismutase; Tetrazoles; Valine; Valsartan; Vasoconstrictor Agents; Vasodilation

The SHHF/Mcc-fa(cp) (spontaneous hypertension and heart failure) rat is advanced as a novel and suitable non-primate model of pregnancy-associated hypertension and fetal growth restriction because it simultaneously has spontaneous pregnancy-associated hypertension, small for gestational age (SGA) offsprings, and altered placental gene expression. Pregnancy-associated hypertension is a major contributor to maternal and fetal morbidity and mortality with the potential to result in maternal death and the need for iatrogenic preterm delivery. It has been reported to develop spontaneously in humans, but not in animals; consequently, progress in identifying the cause and pathogenesis of this disorder has been hampered. Spontaneous hypertension and heart failure rats develop hypertension spontaneously as they age, therefore we sought to determine whether these rats developed hypertension and SGA offsprings during pregnancy. Our results show that systolic blood pressure (BP) increased >40 mm Hg by the end of the first trimester and remained at this elevated level for the remainder of pregnancy, but decreased after parturition. Placenta weights of SHHF rats (0.60 +/- 0.02 g, n = 36) were significantly higher than Wistar-Kyoto (WKY) rats (0.42 +/- 0.01 g, n = 22, P < .05), but pup weights were significantly lower (2.68 +/- 0.06 g for SHHF rats compared to 3.24 +/- 0.06 g for WKY controls, P < .05). Histologic examination revealed pathologic lesions in neither heart, liver, placenta, nor kidney. L-Arginine administered in drinking water prevented the elevation of BP, particularly during the third trimester. Placentas from SHHF rats displayed altered expression of several genes whose protein products have been implicated in preeclampsia, including serotonin receptor, sodium channel, carbonic anhydrase, estrogen receptor regulator, major histocompatibility complex proteins, superoxide dismutase, and angiotensiogen. In addition, gene expression profiling showed alteration of a number of subcellular putative myristoylproteins not previously associated with preeclampsia, particularly those engaged in post-translational modifications in the placenta. Thus, SHHF rats may be a valuable tool, because it simultaneously has spontaneous pregnancy-associated hypertension, SGA offsprings, and altered placental gene expression.

Topics: Angiotensinogen; Animals; Birth Weight; Disease Models, Animal; Female; Fetal Growth Retardation; Fetal Weight; Gene Expression Profiling; Hypertension; Placenta; Pre-Eclampsia; Pregnancy; Pregnancy Complications, Cardiovascular; Protein Processing, Post-Translational; Rats; Rats, Inbred WKY; Rats, Mutant Strains

Topics: Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Disease Models, Animal; Fibrosis; Kidney Diseases; Mice; Plasminogen Activator Inhibitor 1; Renin-Angiotensin System; Transforming Growth Factor beta; Ureteral Obstruction

Statins are effective in prevention of end-organ damage; however, the benefits cannot be fully explained on the basis of cholesterol reduction. We used an angiotensin II (Ang II)-dependent model to test the hypothesis that cerivastatin prevents leukocyte adhesion and infiltration, induction of inducible nitric oxide synthase (iNOS), and ameliorates end-organ damage.. We analyzed intracellular targets, such as mitogen-activated protein kinase and transcription factor (nuclear factor-kappaB and activator protein-1) activation. We used immunohistochemistry, immunocytochemistry, electrophoretic mobility shift assays, and enzyme-linked immunosorbent assay techniques. We treated rats transgenic for human renin and angiotensinogen (dTGR) chronically from week 4 to 7 with cerivastatin (0.5 mg/kg by gavage).. Untreated dTGR developed hypertension, cardiac hypertrophy, and renal damage, with a 100-fold increased albuminuria and focal cortical necrosis. dTGR mortality at the age of seven weeks was 45%. Immunohistochemistry showed increased iNOS expression in the endothelium and media of small vessels, infiltrating cells, afferent arterioles, and glomeruli of dTGR, which was greater in cortex than medulla. Phosphorylated extracellular signal regulated kinase (p-ERK) was increased in dTGR; nuclear factor-kappaB and activator protein-1 were both activated. Cerivastatin decreased systolic blood pressure compared with untreated dTGR (147 +/- 14 vs. 201 +/- 6 mm Hg, P < 0.001). Albuminuria was reduced by 60% (P = 0.001), and creatinine was lowered (0.45 +/- 0.01 vs. 0.68 +/- 0.05 mg/dL, P = 0. 003); however, cholesterol was not reduced. Intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression was diminished, while neutrophil and monocyte infiltration in the kidney was markedly reduced. ERK phosphorylation and transcription factor activation were reduced. In addition, in vitro incubation of vascular smooth muscle cells with cerivastatin (0.5 micromol/L) almost completely prevented the Ang II-induced ERK phosphorylation.. Cerivastatin reduced inflammation, cell proliferation, and iNOS induction, which led to a reduction in cellular damage. Our findings suggest that 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase inhibition ameliorates Ang II-induced end-organ damage. We suggest that these effects were independent of cholesterol.

Topics: Albuminuria; Angiotensin II; Angiotensinogen; Animals; Animals, Genetically Modified; Blood Pressure; Cell Division; Cholesterol; Creatinine; Disease Models, Animal; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Intercellular Adhesion Molecule-1; Kidney; Kidney Failure, Chronic; Leukocytes; Male; Mitogen-Activated Protein Kinases; NF-kappa B; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Organ Size; Phosphorylation; Plasminogen Activators; Pyridines; Rats; Rats, Sprague-Dawley; Renin; Thromboplastin; Transcription Factor AP-1; Urea; Vascular Cell Adhesion Molecule-1; Vasoconstrictor Agents

Hypertension and kidney damage in the double transgenic rat (dTGR) harboring both human renin and human angiotensinogen genes are dependent on the human components of the renin angiotensin system. We tested the hypothesis that monocyte infiltration and increased adhesion molecule expression are involved in the pathogenesis of kidney damage in dTGR. We also evaluated the effects of long-term angiotensin-converting enzyme (ACE) inhibition, AT1 blockade, and human renin inhibition on monocyte recruitment and inflammatory response in dTGR. Systolic blood pressure and 24-hour albuminuria were markedly increased in 7-week-old dTGR as compared with age-matched normotensive Sprague Dawley rats. We found a significant monocyte/macrophage infiltration in the renal perivascular space and increased expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the interstitium, intima, and adventitia of the small renal vessels. alphaLbeta2 integrin and alpha4beta1 integrin, the corresponding ligands for ICAM-1 and VCAM-1, were also found on infiltrating monocytes/macrophages. The expression of plasminogen activator inhibitor-1 and fibronectin in the kidneys of dTGR were increased and distributed similarly to ICAM-1. In 4-week-old dTGR, long-term treatment with ACE inhibition (cilazapril), AT1 receptor blockade (valsartan), and human renin inhibition (RO 65-7219) (each drug 10 mg/kg by gavage once a day for 3 weeks) completely prevented the development of albuminuria. However, only cilazapril and valsartan were able to decrease blood pressure to normotensive levels. Interestingly, the drugs were all equally effective in preventing monocyte/macrophage infiltration and the overexpression of adhesion molecules, plasminogen activator inhibitor-1, and fibronectin in the kidney. Our findings indicate that angiotensin II causes monocyte recruitment and vascular inflammatory response in the kidney by blood pressure-dependent and blood pressure-independent mechanisms. ACE inhibition, AT1 receptor blockade, and human renin inhibition all prevent monocyte/macrophage infiltration and increased adhesion molecule expression in the kidneys of dTGR.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Chemokine CCL2; Disease Models, Animal; Fibronectins; Gene Expression Regulation; Humans; Hypertension; Integrin alpha4beta1; Integrins; Intercellular Adhesion Molecule-1; Kidney; Lymphocyte Function-Associated Antigen-1; Macrophages; Male; Monocytes; Plasminogen Activator Inhibitor 1; Rats; Rats, Sprague-Dawley; Receptors, Lymphocyte Homing; Renal Circulation; Renin; Vascular Cell Adhesion Molecule-1

Inhibition of angiotensin action, pharmacologically or genetically, during the neonatal period leads to renal anomalies involving hypoplastic papilla and dilated calyx. Recently, we documented that angiotensinogen (Agt -/-) or angiotensin type 1 receptor nullizygotes (Agtr1 -/-) do not develop renal pelvis nor ureteral peristaltic movement, both of which are essential for isolating the kidney from the high downstream ureteral pressure. We therefore examined whether these renal anomalies could be characterized as "obstructive" nephropathy.. Agtr1 -/- neonatal mice were compared with wild-type neonates, the latter subjected to surgical complete unilateral ureteral ligation (UUO), by analyzing morphometrical, immunohistochemical, and molecular indices. Agtr1 -/- mice were also subjected to a complete UUO and were compared with wild-type UUO mice by quantitative analysis. To assess the function of the urinary tract, baseline pelvic and ureteral pressures were measured.. The structural anomalies were qualitatively indistinguishable between the Agtr1 -/- without surgical obstruction versus the wild type with complete UUO. Thus, in both kidneys, the calyx was enlarged, whereas the papilla was atrophic; tubulointerstitial cells underwent proliferation and also apoptosis. Both were also characterized by interstitial macrophage infiltration and fibrosis, and within the local lesion, transforming growth factor-beta 1, platelet-derived growth factor-A and insulin-like growth factor-1 were up-regulated, whereas epidermal growth factor was down-regulated. Moreover, quantitative differences that exist between mutant kidneys without surgical obstruction and wild-type kidneys with surgical UUO were abolished when both underwent the same complete surgical UUO. The hydraulic baseline pressure was always lower in the pelvis than that in the ureter in the wild type, whereas this pressure gradient was reversed in the mutant.. The abnormal kidney structure that develops in neonates during angiotensin inhibition is attributed largely to "functional obstruction" of the urinary tract caused by the defective development of peristaltic machinery.

Topics: Actins; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Animals, Newborn; Apoptosis; Cell Division; Disease Models, Animal; Epidermal Growth Factor; Gene Expression Regulation, Developmental; In Situ Hybridization; In Situ Nick-End Labeling; Insulin-Like Growth Factor I; Kidney Diseases; Kidney Medulla; Kidney Pelvis; Macrophages; Mice; Mice, Knockout; Muscle, Smooth; Peptidyl-Dipeptidase A; Platelet-Derived Growth Factor; Pressure; RNA, Messenger; Transforming Growth Factor beta; Ureter; Ureteral Obstruction

We studied the role of angiotensin II in pressure overload-induced B-type natriuretic peptide (BNP) gene expression by using a double transgenic rat (dTGR) model, in which transgenic rats for the human angiotensinogen and renin genes are crossed. Pressure overload produced by [Arg8]-vasopressin (AVP) infusion (i.v., 0.05 microg/kg/min for 2 h) in conscious, chronically instrumented rats, resulted in a significantly greater increase in BNP mRNA levels in the left atrium of the dTGR rats than in Sprague-Dawley (SD) control rats (3.6- vs 1.6-fold, p < 0.05), while in the left ventricle there was no significant difference between the strains. In dTGR rats, the early activation of the BNP gene expression was associated with a decrease in immunoreactive BNP levels in the atrium (27.5%, p < 0.05), but not in the ventricle. In SD rats, ir-BNP levels did not change significantly in either atria or ventricles in response to AVP infusion. These results show that the pressure overload-induced activation of BNP gene expression differs between atrial and ventricular myocytes in the dTGR model of experimental hypertension.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Atrial Natriuretic Factor; Blood Pressure; Disease Models, Animal; Gene Expression; Heart Atria; Humans; Hypertension; Male; Natriuretic Peptide, Brain; Rats; Rats, Sprague-Dawley; Renin; RNA, Messenger

We tested the hypothesis that the tissue-specific intrarenal renin-angiotensin system (RAS) can participate in the regulation of blood pressure independently of its endocrine counterpart, by generating two transgenic models that differ in their tissue-specific expression of human angiotensinogen (AGT). Human AGT expression was driven by its endogenous promoter in the systemic model and by the kidney androgen-regulated protein promoter in the kidney-specific model. Using molecular, biochemical, and physiological measurements, we demonstrate that human AGT mRNA and protein are restricted to the kidney in the kidney-specific model. Plasma ANG II was elevated in the systemic model but not in the kidney-specific model. Nevertheless, blood pressure was markedly elevated in both the systemic and kidney-specific transgenic mice. Acute administration of the selective ANG II AT-1 receptor antagonist losartan lowered blood pressure in the systemic model but not in the kidney-specific model. These results provide evidence for the potential importance of the intrarenal RAS in blood pressure regulation by showing that expression of AGT specifically in the kidney leads to chronic hypertension independently of the endocrine RAS.

Topics: Angiotensin Receptor Antagonists; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Gene Targeting; Humans; Hypertension; Kidney; Losartan; Mice; Mice, Transgenic; Organ Specificity; Promoter Regions, Genetic; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Renin-Angiotensin System; RNA, Messenger

Transgenic animals are new and important models for the study of candidate genes in hypertension research as well as in other fields of medicine. For detailed genetic characterization of the transgenic animals, and to account for the symptoms arising from the insertion of transgenes in the genome, it is essential to identify these insertion sites. In this study, the insertion sites of the transgenes of candidate genes for hypertension were identified by fluorescence in situ hybridization (FISH) after G-banding of the chromosomes in transgenic rats and mice. This technique combines high resolution G-banding and fluorescence in situ hybridization for the mapping of four different candidate genes in six different transgenic rats as well as three different mouse transgenic lines. The presented results will help to draw conclusions about the influence of the respective integration site on transgene expression.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Chromosome Banding; Chromosome Mapping; Disease Models, Animal; Endothelin-2; Humans; Hypertension; In Situ Hybridization, Fluorescence; Mice; Mice, Transgenic; Rats; Rats, Sprague-Dawley; Renin

We developed a model of spontaneously high human renin hypertension in the rat by producing two transgenic strains, one for human angiotensinogen with the endogenous promoter and one for human renin with the endogenous promoter. Neither transgenic strain was hypertensive. These strains were then crossed, producing a double transgenic strain. The double transgenic rats, both males and females, developed severe hypertension (mean systolic pressure, 200 mm Hg) and died after a mean of 55 days if untreated. The rats had a human plasma renin concentration of 269 +/- 381 (+/-SD) ng angiotensin I (Ang I)/mL per hour, plasma renin activity of 177 +/- 176 ng Ang I/mL per hour, rat angiotensinogen concentration of 1.49 +/- 1 microgram Ang I/mL, and human angiotensinogen concentration of 78 +/- 39 micrograms Ang I/mL (n = 49). Control rats had plasma renin activity of 3.7 +/- 3.9 ng Ang I/mL per hour and rat angiotensinogen of 1.32 +/- 0.16 micrograms Ang I/mL. Angiotensinogen transgene expression by RNase protection assay was ubiquitously present but most prominent in liver. Renin transgene expression was high in kidney but absent in liver. The rats featured severe cardiac hypertrophy, with increased cross section of cardiomyocytes but little myocardial fibrosis. The kidneys showed atrophic tubules, thickened vessel walls, and increased interstitium. Both the angiotensin-converting enzyme inhibitor lisinopril and the specific human renin inhibitor remikiren lowered blood pressure to normal values. Double transgenic mice have been developed that exhibit features quite similar to those described here; their gene expressions are similar. The specificity of rodent and human renin is similarly documented. Although many elegant physiological studies can now be done in mice, rats nevertheless offer flexibility, particularly in terms of detailed cardiac and renal physiology and pharmacology. We conclude that this double transgenic strain will facilitate simultaneous investigation of genetic and pathophysiological aspects of renin-induced hypertension. The fact that human renin can be studied in the rat is a unique feature of this model.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Blood Pressure; Cardiomegaly; Crosses, Genetic; Disease Models, Animal; Female; Humans; Hypertension, Malignant; Kidney; Male; Myocardium; Rats; Rats, Sprague-Dawley; Renin

The present study was designed to investigate the development of atherosclerotic lesions in hypertensive transgenic mice carrying both the human renin and angiotensinogen genes (Tsukuba hypertensive mice; THM). THM and C57BL/6J control mice 2 to 3 months of age were fed with either an atherogenic or a normal diet for 14 weeks. Although the systolic blood pressure of either strain remained the same regardless of diet, it was significantly higher in THM than in C57BL/6J on both diets. Total plasma cholesterol concentrations in mice on the atherogenic diet were significantly higher than those in mice fed the normal diet. Lipoprotein profiles of cholesterol in THM were fundamentally similar to those in C57BL/6J on either the atherogenic or normal diet. Compared with controls, however, microscopic analyses revealed accelerated damage of cellular structure in the aortic root in THM fed with the atherogenic diet. Remarkably, the surface area of atherosclerotic lesion in THM was shown by quantitative image analysis to be 4 times larger than that in C57BL/6J on the same atherogenic diet. These findings suggested that hypertension induced by the activated renin-angiotensin system is involved in the development of atherosclerotic lesions. Therefore, THM should be a useful animal model for the study on the pathogenesis of atherosclerosis.

Topics: Angiotensinogen; Animals; Aorta; Arteriosclerosis; Blood Glucose; Blood Pressure; Cholesterol; Diet, Atherogenic; Disease Models, Animal; Female; Humans; Hypertension; Mice; Mice, Inbred C57BL; Mice, Transgenic; Renin; Renin-Angiotensin System

Maternal hypertension is a common complication of pregnancy and its pathophysiology is poorly understood. This phenomenon was studied in an animal model by mating transgenic mice expressing components of the human renin-angiotensin system. When transgenic females expressing angiotensinogen were mated with transgenic males expressing renin, the pregnant females displayed a transient elevation of blood pressure in late pregnancy, due to secretion of placental human renin into the maternal circulation. Blood pressure returned to normal levels after delivery of the pups. Histopathologic examination revealed uniform enlargement of glomeruli associated with an increase in urinary protein excretion, myocardial hypertrophy, and necrosis and edema in the placenta. These mice may provide molecular insights into pregnancy-associated hypertension in humans.

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Cardiomegaly; Crosses, Genetic; Disease Models, Animal; Female; Humans; Hypertension; Kidney Glomerulus; Male; Mice; Mice, Transgenic; Placenta; Pregnancy; Pregnancy Complications, Cardiovascular; Renin

The effective development of human renin inhibitors meets its major obstacle in the absence of a suitable experimental rodent model and the species-specificity of human renin, exclusively cleaving its natural substrate human angiotensinogen. We have reconstructed the human renin-angiotensin system in transgenic rats over expressing the human angiotensinogen gene TGR (hAOGEN) 1623 by chronically injecting i.v. human recombinant renin. We have first established new in vitro enzyme kinetic techniques to measure the various components of the chimeric renin-angiotensin system and distinguished the two human and rat-specific pathways of generating angiotensin I by the human specific renin inhibitor Ro 42-5892 (Hoffmann-La Roche). Male heterozygous TGR had plasma levels of rat angiotensinogen of 1.2 +/- 0.2 mg Ang l/ml while the plasma levels of the transgene were 141 +/- 98 mg Ang l/ml (n = 41; not normally distributed). Transgene expression was found in the liver kidney, aorta, heart and adrenals. Four rats were infused i.v. with human recombinant renin at 50 ng/h over 9 days which chronically increased their blood pressure to > 200 mmHg while total plasma renin activity increased by a factor of 300. Rat renin disappeared form the plasma. This new model of experimental human renin-induced hypertension in rats will facilitate the screening and characterization of human renin inhibitors.

Topics: Angiotensinogen; Animals; Animals, Genetically Modified; Disease Models, Animal; Gene Transfer Techniques; Humans; Hypertension, Renovascular; In Vitro Techniques; Male; Rats; Renin; Renin-Angiotensin System

Topics: Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Crosses, Genetic; Disease Models, Animal; Female; Humans; Hypertension; Male; Mice; Mice, Transgenic; Placenta; Pregnancy; Pregnancy Complications, Cardiovascular; Renin

To investigate the effects of renal transplantation on the plasma and local kidney renin-angiotensin systems of the recipients the left kidneys of 13 adult male Wistar-Kyoto rats (WKY) and 13 stroke-prone spontaneously hypertensive rats (SHRSP) were transplanted to bilaterally nephrectomized (WKYxSHRSP)-F1 hybrids. Nine unilaterally nephrectomized WKY and nine SHRSP served as controls. Four weeks after surgery recipients of an SHRSP kidney but not recipients of a WKY kidney had significant post-transplantation hypertension. Plasma renin activity (PRA) was higher in SHRSP than in WKY. Transplanted rats had lower PRAs than nontransplanted controls. Plasma ACE activity was lowest in SHRSP, intermediate in transplanted F1 hybrids and highest in WKY. Plasma Ang I and Ang II concentrations closely paralleled each other. They were not significantly different between WKY and SHRSP and lower in transplanted than in nontransplanted rats. ACE and renin mRNA were lower in transplanted than in nontransplanted kidneys. Glomerular angiotensin II receptor density was higher in transplanted than in nontransplanted kidneys with no significant differences between strains. We conclude that renal transplantation has profound long-term effects on the recipients' plasma and local kidney renin-angiotensin systems. These do not appear to be involved in the pathogenesis of post-transplantation hypertension in recipients of an SHRSP kidney, but may reflect a role for the intrarenal renin-angiotensin system in long-term renal adaptation and repair processes after transplantation.

Topics: Acetylcholinesterase; Angiotensin I; Angiotensin II; Angiotensinogen; Animals; Disease Models, Animal; Hybridization, Genetic; Hypertension; Kidney; Kidney Transplantation; Male; Nephrectomy; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renin; Renin-Angiotensin System; RNA, Messenger

Activation of antinatriuretic systems such as the renin-angiotensin system, is of major importance in the pathogenesis of sodium retention in cirrhosis. In this study, we studied the intrarenal renin-angiotensin system by measuring renin and angiotensinogen mRNA expression in the kidney of rats subjected to long-term bile duct ligation in a phase before the development of ascites, when sodium retention is already present. Experiments were performed in sham-operated and bile duct-ligated rats 3 wk after surgery. Balance studies showed lower sodium excretion and greater sodium retention in the bile duct-ligated rats compared with the control animals. Plasma renin activity (4.41 +/- 1.01 ng Angiotensin I/ml/hr in the bile duct-ligated group vs. 4.20 +/- 0.74 in the controls) and plasma renin concentration were not different between the two groups. However, plasma renin substrate was significantly decreased in bile duct-ligated animals. Total kidney renin mRNA was significantly higher in the bile duct-ligated animals (0.83 +/- 0.14 densitometric units vs. 0.44 +/- 0.04 in the controls), as determined on Northern-blot analysis and densitometric quantitation. Angiotensinogen mRNA expression in the kidneys of bile duct-ligated rats was significantly decreased (0.09 +/- 0.01 densitometric units) compared with that of the controls (0.21 +/- 0.03). These results indicate that sodium-retaining, nonascitic bile duct-ligated rats show abnormalities of the intrarenal renin angiotensin system that precede changes in plasma renin activity. Our data suggest that the intrarenal renin angiotensin system may participate in the initiation of the renal pathophysiological abnormalities present in bile duct-ligated rats.

Topics: Angiotensinogen; Animals; Bile Ducts; Disease Models, Animal; Gene Expression; Hypertension, Portal; Kidney; Ligation; Liver Cirrhosis, Experimental; Male; Rats; Rats, Sprague-Dawley; Renin; RNA, Messenger

Topics: Angiotensinogen; Animals; Aorta, Thoracic; Aortic Coarctation; Blood Pressure; Disease Models, Animal; Gene Expression; Hypertension, Renal; Kidney; Male; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptors, Angiotensin; Renin; Renin-Angiotensin System; RNA, Messenger; Tissue Distribution

Activation of the intrarenal renin-angiotensin system may contribute to the pathophysiology of heart failure by accelerating the generation of angiotensin II at local sites within the kidneys. Activation of the local intrarenal renin-angiotensin system occurs in rats and with mild heart failure. The aim of the present study was to examine components of the circulating as well as the intrarenal renin-angiotensin system in rats with severe heart failure.. Six weeks after experimental myocardial infarction (heart failure, HF; n = 8) or sham operation (control, C; n = 6), haemodynamics and the circulating and intrarenal components of the renin-angiotensin system were studied.. HF rats were characterised by large infarctions (scar tissue > 40% of the left ventricular circumference). In comparison to sham operated controls, large myocardial infarctions resulted in severe heart failure with decreased systolic [108(SEM 3) mm Hg v 132(3) in C; p < 0.001] and diastolic arterial blood pressure [83(3) mm Hg v 95(2) in C; p < 0.05], decreased left ventricular systolic pressure [109(3) mm Hg v 132(3) in C; p < 0.005] and increased left ventricular end diastolic pressure [27(2) mm Hg v 5(1) in C; p < 0.0001]. In rats with severe heart failure, the circulating renin-angiotensin system was activated, with an increase in plasma renin activity (3.5-fold, p < 0.05) and plasma angiotensin II concentration (threefold, p < 0.01). In parallel, the intrarenal renin-angiotensin system was activated in severe heart failure. Increases occurred in renal renin mRNA level (1.7-fold, p < 0.01), renal angiotensinogen mRNA level (1.8-fold, p < 0.05), and renal angiotensin II concentration (twofold, p < 0.05) compared to C. Intrarenal angiotensin II concentrations exceeded plasma levels by a factor of 50 and were positively correlated with renal angiotensinogen mRNA levels (r = 0.874, p < 0.001), suggesting that local synthesis is the major source of angiotensin II found in the kidney.. The intrarenal renin-angiotensin system may be selectively activated in mild heart failure, while both circulating and intrarenal renin-angiotensin systems are induced as the extent of left ventricular function worsens.

Topics: Angiotensin II; Angiotensinogen; Animals; Blotting, Northern; Disease Models, Animal; Heart Failure; Kidney; Male; Myocardial Infarction; Rats; Rats, Sprague-Dawley; Renin; Renin-Angiotensin System

Puromycin aminonucleoside (PA)-nephrotic rats have a high plasma renin activity (PRA) and low angiotensinogen levels. We measured proteinuria, urine renin, and urine angiotensinogen daily, for 11 days after PA injection. Proteinuria and urine angiotensinogen were evident on day 5, and urine renin on day 6. Peak levels of urine renin and angiotensinogen were attained on day 8. These data suggest that angiotensinogen urine excretion may contribute to its low plasma levels, and urine renin loss may limit a further increase in PRA.

Topics: Angiotensinogen; Animals; Disease Models, Animal; Male; Nephrosis; Puromycin Aminonucleoside; Rats; Rats, Inbred Strains; Renin