SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Siman,F.D.M.; Stefanon,I.; Vassallo,D.V.; Padilha,A.S..

We investigated the effects of low ouabain concentrations on systolic (SAP) and diastolic (DAP) arterial pressures and on pressor reactivity in 3-month-old male spontaneously hypertensive rats (SHR). Arterial blood pressure (BP) and pressor reactivity to phenylephrine (PHE) were investigated before and after 0.18 μg/kg ouabain administration (N = 6). The influence of hexamethonium (N = 6), canrenone (N = 6), enalapril (N = 6), and losartan (N = 6) on ouabain actions was evaluated. Ouabain increased BP (SAP: 137 ± 5.1 to 150 ± 4.7; DAP: 93.7 ± 7.7 to 116 ± 3.5 mmHg; P<0.05) but did not change PHE pressor reactivity. Hexamethonium reduced basal BP in control but not in ouabain-treated rats. However, hexamethonium + ouabain increased DAP sensitivity to...

Activation of endogenous angiotensin converting enzyme 2 prevents early injuries induced by hyperglycemia in rat retina

Palavras-chave: Ouabain; Hypertension; Na+ pump; Renin-angiotensin system.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2010000800010

Foureaux,G.; Nogueira,B. S.; Coutinho,D. C. O.; Raizada,M. K.; Nogueira,J. C.; Ferreira,A. J..

Diabetic retinopathy (DR) is a serious complication of diabetes mellitus that may result in blindness. We evaluated the effects of activation of endogenous angiotensin converting enzyme (ACE) 2 on the early stages of DR. Rats were administered an intravenous injection of streptozotocin to induce hyperglycemia. The ACE2 activator 1-[[2-(dimethylamino) ethyl] amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl) sulfonyl] oxy]-9H-xanthone 9 (XNT) was administered by daily gavage. The death of retinal ganglion cells (RGC) was evaluated in histological sections, and retinal ACE2, caspase-3, and vascular endothelial growth factor (VEGF) expressions were analyzed by immunohistochemistry. XNT treatment increased ACE2 expression in retinas of hyperglycemic (HG) rats...

Alternative pathways for angiotensin II generation in the cardiovascular system

Palavras-chave: ACE2 activation; Angiotensin-(1-7); Renin-angiotensin system; Eyes; Diabetic retinopathy.

Ano: 2015

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2015001201109

Becari,C.; Oliveira,E.B.; Salgado,M.C.O..

The classical renin-angiotensin system (RAS) consists of enzymes and peptides that regulate blood pressure and electrolyte and fluid homeostasis. Angiotensin II (Ang II) is one of the most important and extensively studied components of the RAS. The beneficial effects of angiotensin converting enzyme (ACE) inhibitors in the treatment of hypertension and heart failure, among other diseases, are well known. However, it has been reported that patients chronically treated with effective doses of these inhibitors do not show suppression of Ang II formation, suggesting the involvement of pathways alternative to ACE in the generation of Ang II. Moreover, the finding that the concentration of Ang II is preserved in the kidney, heart and lungs of mice with an ACE...

Association of exercise training and angiotensin-converting enzyme 2 activator improves baroreflex sensitivity of spontaneously hypertensive rats

Palavras-chave: Renin-angiotensin system; Angiotensin II; Rat elastase-2; Alternative pathway; Angiotensin-converting enzyme.

Ano: 2011

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000900013

Lopes,P.R.; Moreira,M.C.S.; Marques,S.M.; Pinto,I.S.J.; Macedo,L.M.; Silva,C.C.; Freiria-Oliveira,A.H.; Rebelo,A.C.S.; Reis,A.A.S.; Rosa,D.A.; Ferreira-Neto,M.L.; Castro,C.H.; Pedrino,G.R..

The present study sought to determine cardiovascular effects of aerobic training associated with diminazene aceturate (DIZE), an activator of the angiotensin converting enzyme 2, in spontaneously hypertensive rats (SHRs). Male SHRs (280–350 g) were either subjected to exercise training or not (sedentary group). The trained group was subjected to 8 weeks of aerobic training on a treadmill (five times a week, lasting 60 min at an intensity of 50–60% of maximum aerobic speed). In the last 15 days of the experimental protocol, these groups were redistributed into four groups: i) sedentary SHRs with daily treatment of 1 mg/kg DIZE (S+D1); ii) trained SHRs with daily treatment of 1 mg/kg DIZE (T+D1); iii) sedentary SHRs with daily treatment of vehicle (S+V); and...

Beneficial Effects of Angiotensin II AT1 Blocker on Cardiovascular Adverse Remodeling Due to Nitric Oxide Synthesis Blockade

Palavras-chave: Intrinsic heart rate; Diminazene aceturate; Aerobic training; Double autonomic blockade; Renin-angiotensin system.

Ano: 2016

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2016000900603

International Journal of Morphology

Fernandes-Santos,Caroline; Mendonça,Leonardo de Souza; Mandarim-de-Lacerda,Carlos Alberto.

We studied with morphological tools the effects of different doses of Losartan upon the cardiovascular remodeling in nitric oxide deficient rats. At 15 weeks of age, thirty Wistar rats were separated in six groups: control (C), L-NAME (LN), and four groups were LN was given plus Losartan at different doses (1, 5, 20 and 40 mg/kg/day). The L-NAME was given for 9 weeks, the Losartan administration starting on the 2nd week of experiment. We studied the heart, thoracic aorta and superior mesenteric artery with light microscopy and stereology. The blood pressure (BP) increased since the first week of L-NAME administration, the Losartan treatment at doses of 20 and 40 mg/kg/day was efficient to reduce BP after the 7th week of treatment. The cardiac adverse...

Tipo: Journal article

Palavras-chave: Losartan; Angiotensin II; L-NAME; Hypertension; Renin-angiotensin system; Stereology; L-NAME.

Ano: 2006

URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022006000400003

Cardiovascular actions of angiotensin-(1-7)

Ferreira,A.J.; Santos,R.A.S..

Angiotensin-(1-7) (Ang-(1-7)) is now considered to be a biologically active member of the renin-angiotensin system. The functions of Ang-(1-7) are often opposite to those attributed to the main effector component of the renin-angiotensin system, Ang II. Chronic administration of angiotensin-converting enzyme inhibitors (ACEI) increases 10- to 25-fold the plasma levels of this peptide, suggesting that part of the beneficial effects of ACEI could be mediated by Ang-(1-7). Ang-(1-7) can be formed from Ang II or directly from Ang I. Other enzymatic pathways for Ang-(1-7) generation have been recently described involving the novel ACE homologue ACE2. This enzyme can form Ang-(1-7) from Ang II or less efficiently by the hydrolysis of Ang I to Ang-(1-9) with...

Characterization of angiotensin-converting enzymes 1 and 2 in the soleus and plantaris muscles of rats

Palavras-chave: Angiotensin-(1-7) receptor Mas; Renin-angiotensin system; Cardiac function; Blood vessels; Angiotensin-converting enzyme 2; Transgenic models.

Ano: 2005

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000400003

Fernandes,T.; Hashimoto,N.Y.; Oliveira,E.M..

Angiotensin-converting enzymes 1 (ACE1) and 2 (ACE2) are key enzymes of the renin-angiotensin system, which act antagonistically to regulate the levels of angiotensin II (Ang II) and Ang-(1-7). Considerable data show that ACE1 acts on normal skeletal muscle functions and architecture. However, little is known about ACE1 levels in muscles with different fiber compositions. Furthermore, ACE2 levels in skeletal muscle are not known. Therefore, the purpose of this study was to characterize protein expression and ACE1 and ACE2 activities in the soleus and plantaris muscles. Eight-week-old female Wistar rats (N = 8) were killed by decapitation and the muscle tissues harvested for biochemical and molecular analyses. ACE1 and ACE2 activities were investigated by a...

Eccentric and concentric cardiac hypertrophy induced by exercise training: microRNAs and molecular determinants

Palavras-chave: Renin-angiotensin system; ACE1; ACE2; Rat skeletal muscle.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2010000900005

Fernandes,T.; Soci,U.P.R.; Oliveira,E.M..

Among the molecular, biochemical and cellular processes that orchestrate the development of the different phenotypes of cardiac hypertrophy in response to physiological stimuli or pathological insults, the specific contribution of exercise training has recently become appreciated. Physiological cardiac hypertrophy involves complex cardiac remodeling that occurs as an adaptive response to static or dynamic chronic exercise, but the stimuli and molecular mechanisms underlying transduction of the hemodynamic overload into myocardial growth are poorly understood. This review summarizes the physiological stimuli that induce concentric and eccentric physiological hypertrophy, and discusses the molecular mechanisms, sarcomeric organization, and signaling pathway...

Effect of angiotensin-(1-7) on reperfusion arrhythmias in isolated rat hearts

Palavras-chave: Exercise training; Cardiac hypertrophy; Renin-angiotensin system; AT1 receptor; Akt; MicroRNAs.

Ano: 2011

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000900003

There is increasing evidence that angiotensin-(1-7) (Ang-(1-7)) is an endogenous biologically active component of the renin-angiotensin system (RAS). In the present study, we investigated the effects of Ang-(1-7) on reperfusion arrhythmias in isolated rat hearts. Isolated rat hearts were perfused with two different media, i.e., Krebs-Ringer (2.52 mM CaCl2) and low-Ca2+ Krebs-Ringer (1.12 mM CaCl2). In hearts perfused with Krebs-Ringer, Ang-(1-7) produced a concentration-dependent (27-210 nM) reduction in coronary flow (25% reduction at highest concentration), while only slight and variable changes in contraction force and heart rate were observed. Under the same conditions, angiotensin II (Ang II; 27 and 70 nM) produced a significant reduction in coronary...

Effect of selective angiotensin antagonists on the antidiuresis produced by angiotensin-(1-7) in water-loaded rats

Palavras-chave: Renin-angiotensin system; Reperfusion arrhythmias; Angiotensin-(1-7); Coronary flow; Isolated heart.

Ano: 1997

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997000600016

Baracho,N.C.V.; Simões-e-Silva,A.C.; Khosla,M.C.; Santos,R.A.S..

In the present study we evaluated the nature of angiotensin receptors involved in the antidiuretic effect of angiotensin-(1-7) (Ang-(1-7)) in water-loaded rats. Water diuresis was induced in male Wistar rats weighing 280 to 320 g by water load (5 ml/100 g body weight by gavage). Immediately after water load the rats were treated subcutaneously with (doses are per 100 g body weight): 1) vehicle (0.05 ml 0.9% NaCl); 2) graded doses of 20, 40 or 80 pmol Ang-(1-7); 3) 200 nmol Losartan; 4) 200 nmol Losartan combined with 40 pmol Ang-(1-7); 5) 1.1 or 4.4 nmol A-779; 6) 1.1 nmol A-779 combined with graded doses of 20, 40 or 80 pmol Ang-(1-7); 7) 4.4 nmol A-779 combined with graded doses of 20, 40 or 80 pmol Ang-(1-7); 8) 95 nmol CGP 42112A, or 9) 95 nmol CGP...

Enhanced expression of Ang-(1-7) during pregnancy

Palavras-chave: Renin-angiotensin system; Angiotensin receptors; Antidiuresis; Losartan; A-779; Ang-(1-7).

Ano: 1998

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000900016

Brosnihan,K.B.; Neves,L.A.A.; Anton,L.; Joyner,J.; Valdes,G.; Merrill,D.C..

Pregnancy is a physiological condition characterized by a progressive increase of the different components of the renin-angiotensin system (RAS). The physiological consequences of the stimulated RAS in normal pregnancy are incompletely understood, and even less understood is the question of how this system may be altered and contribute to the hypertensive disorders of pregnancy. Findings from our group have provided novel insights into how the RAS may contribute to the physiological condition of pregnancy by showing that pregnancy increases the expression of both the vasodilator heptapeptide of the RAS, angiotensin-(1-7) [Ang-(1-7)], and of a newly cloned angiotensin converting enzyme (ACE) homolog, ACE2, that shows high catalytic efficiency for Ang II...

Hypertensive effects of the iv administration of picomoles of ouabain

Palavras-chave: Pregnancy; Renin-angiotensin system; Preeclampsia; Angiotensin-(1-7).

Ano: 2004

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004000800017

Padilha,A.S.; Salaices,M.; Vassallo,D.V.; Batista,P.R.; Siman,F.D.M..

Ouabain, an endogenous digitalis compound, has been detected in nanomolar concentrations in the plasma of several mammals and is associated with the development of hypertension. In addition, plasma ouabain is increased in several hypertension models, and the acute or chronic administration of ouabain increases blood pressure in rodents. These results suggest a possible association between ouabain and the genesis or development and maintenance of arterial hypertension. One explanation for this association is that ouabain binds to the α-subunit of the Na+ pump, inhibiting its activity. Inhibition of this pump increases intracellular Na+, which reduces the activity of the sarcolemmal Na+/Ca2+ exchanger and thereby reduces Ca2+ extrusion. Consequently,...

Increased angiotensin-converting enzyme activity in the left ventricle after infarction

Palavras-chave: Ouabain; Hypertension; Vascular reactivity; Renin-angiotensin system.

Ano: 2011

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000900015

An increase in angiotensin-converting enzyme (ACE) activity has been observed in the heart after myocardial infarction (MI). Since most studies have been conducted in chronically infarcted individuals exhibiting variable degrees of heart failure, the present study was designed to determine ACE activity in an earlier phase of MI, before heart failure development. MI was produced in 3-month old male Wistar rats by ligation of the anterior branches of the left coronary artery, control rats underwent sham surgery and the animals were studied 7 or 15 days later. Hemodynamic data obtained for the anesthetized animals showed normal values of arterial blood pressure and of end-diastolic pressure in the right and left ventricular cavities of MI rats. Right and left...

Influence of antihypertensive drugs on aortic and coronary effects of Ang-(1-7) in pressure-overloaded rats

Palavras-chave: Angiotensin-converting enzyme; Myocardial infarction; Angiotensin II; Renin-angiotensin system.

Ano: 1997

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997000500018

Nunes,A.D.C.; Souza,A.P.S.; Macedo,L.M.; Alves,P.H.; Pedrino,G.R.; Colugnati,D.B.; Mendes,E.P.; Santos,R.A.S.; Castro,C.H..

This study investigated the influence of antihypertensive drugs, such as angiotensin-converting enzyme inhibitors (ACEIs), AT1 receptor blockers (ARBs), voltage-gated L-type calcium channel blockers, and mineralocorticoid receptor antagonists (MRAs), on the effects of angiotensin-(1-7) [Ang-(1-7)] on aorta and coronary arteries from pressure-overloaded rats. Pressure overload was induced by abdominal aortic banding (AB). To evaluate the role of antihypertensive drugs on the effect of Ang-(1-7), AB male Wistar rats weighing 250–300 g were treated with vehicle or low doses (5 mg·kg-1·day-1, gavage) of losartan, captopril, amlodipine, or spironolactone. Isolated aortic rings and isolated perfused hearts under constant flow were used to evaluate the effect of...

Ligand-induced endocytosis and nuclear localization of angiotensin II receptors expressed in CHO cells

Palavras-chave: Angiotensin-(1-7); Renin-angiotensin system; Coronary artery; Antihypertensive drugs; Cardiac hypertrophy.

Ano: 2017

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2017000400604

Merjan,A.J.; Kanashiro,C.A.; Krieger,J.E.; Han,S.W.; Paiva,A.C.M..

A construct (AT1R-NF) containing a "Flag" sequence added to the N-terminus of the rat AT1 receptor was stably expressed in Chinese hamster ovary cells and quantified in the cell membrane by confocal microscopy after reaction with a fluorescein-labeled anti-Flag monoclonal antibody. Angiotensin II bound to AT1R-NF and induced endocytosis with a half-time of 2 min. After 60-90 min, fluorescence accumulated around the cell nucleus, suggesting migration of the ligand-receptor complex to the nuclear membrane. Angiotensin antagonists also induced endocytosis, suggesting that a common step in the transduction signal mechanism occurring after ligand binding may be responsible for the ligand-receptor complex internalization.

Mechanisms of endothelial dysfunction in obesity-associated hypertension

Palavras-chave: Angiotensin II; Agonist-induced receptor internalization; Endocytosis; Fluorescence-tagged receptor; Nuclear angiotensin receptors; Renin-angiotensin system.

Ano: 2001

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2001000900011

Lobato,N.S.; Filgueira,F.P.; Akamine,E.H.; Tostes,R.C.; Carvalho,M.H.C.; Fortes,Z.B..

Obesity is strongly associated with high blood pressure, dyslipidemia, and type 2 diabetes. These conditions synergistically increase the risk of cardiovascular events. A number of central and peripheral abnormalities can explain the development or maintenance of high blood pressure in obesity. Of great interest is endothelial dysfunction, considered to be a primary risk factor in the development of hypertension. Additional mechanisms also related to endothelial dysfunction have been proposed to mediate the development of hypertension in obese individuals. These include: increase in both peripheral vasoconstriction and renal tubular sodium reabsorption, increased sympathetic activity and overactivation of both the renin-angiotensin system and the...

Perinatal development and adult blood pressure

Palavras-chave: Hypertension; Obesity; Endothelial dysfunction; Oxidative stress; Renin-angiotensin system; Nitric oxide.

Ano: 2012

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2012000500003

Ashton,N..

A growing body of evidence supports the concept of fetal programming in cardiovascular disease in man, which asserts that an insult experienced in utero exerts a long-term influence on cardiovascular function, leading to disease in adulthood. However, this hypothesis is not universally accepted, hence animal models may be of value in determining potential physiological mechanisms which could explain how fetal undernutrition results in cardiovascular disease in later life. This review describes two major animal models of cardiovascular programming, the in utero protein-restricted rat and the cross-fostered spontaneously hypertensive rat. In the former model, moderate maternal protein restriction during pregnancy induces an increase in offspring blood...

Potential Radioprotective Effect of AT1 Receptor Antagonists Against Morphological and Ultrastructural Changes in the Testes Induced by Ionizing Radiation

Palavras-chave: Hypertension; Pregnancy; Low-protein diet; Glucocorticoid; Renin-angiotensin system; Spontaneously hypertensive rat.

Ano: 2000

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000700002

International Journal of Morphology

Schwarz,Franciele Cristina; Mansano,Naira da Silva; Chies,Agnaldo Bruno; Viani,Gustavo Arruda; Spadella,Maria Angélica.

Radiotherapy is a source of human exposure to ionizing radiation. This pure energy causes deleterious effects on tissues, which result from oxidative stress, a phenomenon in which there is the participation of the Renin-Angiotensin System (RAS). The male genital organs are extremely radiosensitive and the action of radiation in the testes can significantly affect spermatogenesis. In search of potential radioprotective for male genital system, this study investigated whether the AT1 receptor antagonists minimize radiation-induced damage to reproductive tissues, by decreasing oxidative stress. Male Wistar rats were divided into six groups: 0 Gray (Gy) (control), 5 Gy (single dose in the scrotal area), telmisartan, losartan, 5Gy+telmisartan and 5Gy+losartan....

Tipo: Journal article

Palavras-chave: Ionizing radiation; Testicular ultrastructure; Spermatogenesis; Renin-angiotensin system; Oxidative stress; Angiotensin II type 1 receptor blockers.

Ano: 2017

URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022017000300005

Reduced plasma levels of angiotensin-(1-7) and renin activity in preeclamptic patients are associated with the angiotensin I- converting enzyme deletion/deletion genotype

Velloso,E.P.; Vieira,R.; Cabral,A.C.; Kalapothakis,E; Santos,R.A.S..

The relationship between preeclampsia and the renin-angiotensin system (RAS) is poorly understood. Angiotensin I-converting enzyme (ACE) is a key RAS component and plays an important role in blood pressure homeostasis by generating angiotensin II (Ang II) and inactivating the vasodilator angiotensin-(1-7) (Ang-(1-7)). ACE (I/D) polymorphism is characterized by the insertion (I) or deletion (D) of a 287-bp fragment, leading to changes in ACE activity. In the present study, ACE (I/D) polymorphism was correlated with plasma Ang-(1-7) levels and several RAS components in both preeclamptic (N = 20) and normotensive pregnant women (N = 20). The percentage of the ACE DD genotype (60%) in the preeclamptic group was higher than that for the control group (35%);...

Renal actions of angiotensin-(1-7)

Palavras-chave: Renin-angiotensin system; Angiotensin-converting enzyme; Renin; Angiotensin-(1-7); ACE polymorphism (I/D); Preeclampsia.

Ano: 2007

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007000400018

The heptapeptide angiotensin-(1-7) is considered to be a biologically active endproduct of the renin-angiotensin system. This angiotensin, which is devoid of the most known actions of angiotensin II such as induction of drinking behavior and vasoconstriction, has several selective effects in the brain and periphery. In the present article we briefly review recent evidence for a physiological role of angiotensin-(1-7) in the control of hydroelectrolyte balance