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A low concentration of ouabain (0.18 µg/kg) enhances hypertension in spontaneously hypertensive rats by inhibiting the Na+ pump and activating the renin-angiotensin system BJMBR
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...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Ouabain; Hypertension; Na+ pump; Renin-angiotensin system.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2010000800010
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Eucalyptol, an essential oil, reduces contractile activity in rat cardiac muscle BJMBR
Soares,M.C.M.S.; Damiani,C.E.N.; Moreira,C.M.; Stefanon,I.; Vassallo,D.V..
Eucalyptol is an essential oil that relaxes bronchial and vascular smooth muscle although its direct actions on isolated myocardium have not been reported. We investigated a putative negative inotropic effect of the oil on left ventricular papillary muscles from male Wistar rats weighing 250 to 300 g, as well as its effects on isometric force, rate of force development, time parameters, post-rest potentiation, positive inotropic interventions produced by Ca2+ and isoproterenol, and on tetanic tension. The effects of 0.3 mM eucalyptol on myosin ATPase activity were also investigated. Eucalyptol (0.003 to 0.3 mM) reduced isometric tension, the rate of force development and time parameters. The oil reduced the force developed by steady-state contractions (50%...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Eucalyptol; Myocardial contractility; Calcium; Isoproterenol; Tetanic tension.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000300017
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Remodeling in the ischemic heart: the stepwise progression for heart BJMBR
Stefanon,I.; dos Santos,L.; Baldo,M.P..
Abstract Coronary artery disease is the leading cause of death in the developed world and in developing countries. Acute mortality from acute myocardial infarction (MI) has decreased in the last decades. However, the incidence of heart failure (HF) in patients with healed infarcted areas is increasing. Therefore, HF prevention is a major challenge to the health system in order to reduce healthcare costs and to provide a better quality of life. Animal models of ischemia and infarction have been essential in providing precise information regarding cardiac remodeling. Several of these changes are maladaptive, and they progressively lead to ventricular dilatation and predispose to the development of arrhythmias, HF and death. These events depend on cell death...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Coronary occlusion; Inflammation; Collagen remodeling; Mechanical dysfunction; Heart failure; Rats.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000900010
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Gadolinium increases the vascular reactivity of rat aortic rings BJMBR
Angeli,J.K.; Ramos,D.B.; Casali,E.A.; Souza,D.O.G.; Sarkis,J.J.F.; Stefanon,I.; Vassallo,D.V.; Fürstenau,C.R..
Gadolinium (Gd) blocks intra- and extracellular ATP hydrolysis. We determined whether Gd affects vascular reactivity to contractile responses to phenylephrine (PHE) by blocking aortic ectonucleoside triphosphate diphosphohydrolase (E-NTPDase). Wistar rats of both sexes (260-300 g, 23 females, 7 males) were used. Experiments were performed before and after incubation of aortic rings with 3 µM Gd. Concentration-response curves to PHE (0.1 nM to 0.1 mM) were obtained in the presence and absence of endothelium, after incubation with 100 µM L-NAME, 10 µM losartan, or 10 µM enalaprilat. Gd significantly increased the maximum response (control: 72.3 ± 3.5; Gd: 101.3 ± 6.4%) and sensitivity (control: 6.6 ± 0.1; Gd: 10.5 ± 2.8%) to PHE. To investigate the blockade...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Gadolinium; E-NTPDase; Adenosine; Angiotensin II; AT1receptor.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2011000500010
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Acute lead-induced vasoconstriction in the vascular beds of isolated perfused rat tails is endothelium-dependent BJMBR
Silveira,E.A.; Lizardo,J.H.F.; Souza,L.P.; Stefanon,I.; Vassallo,D.V..
Chronic lead exposure induces hypertension in humans and animals, affecting endothelial function. However, studies concerning acute cardiovascular effects are lacking. We investigated the effects of acute administration of a high concentration of lead acetate (100 µΜ) on the pressor response to phenylephrine (PHE) in the tail vascular bed of male Wistar rats. Animals were anesthetized with sodium pentobarbital and heparinized. The tail artery was dissected and cannulated for drug infusion and mean perfusion pressure measurements. Endothelium and vascular smooth muscle relaxation were tested with acetylcholine (5 µg/100 µL) and sodium nitroprusside (0.1 µg/100 µL), respectively, in arteries precontracted with 0.1 µM PHE. Concentration-response curves to PHE...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Lead acetate; Vascular reactivity; Endothelium; Hypertension.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2010000500011
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A single resistance exercise session improves myocardial contractility in spontaneously hypertensive rats BJMBR
Fernandes,A.A.; Faria,T. de O.; Ribeiro Júnior,R.F.; Costa,G.P.; Marchezini,B.; Silveira,E.A.; Angeli,J.K.; Stefanon,I.; Vassallo,D.V.; Lizardo,J.H..
Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Cardiac; Contractility; Myocardium; Proteins; Resistance exercise.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2015000900813
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Differences in functional and structural properties of segments of the rat tail artery BJMBR
Souza,F.M.; Padilha,A.S.; Stefanon,I.; Vassallo,D.V..
The investigation of resistance vessels is generally costly and difficult to execute. The present study investigated the diameters and the vascular reactivity of different segments of the rat tail artery (base, middle, and tail end) of 30 male Wister rats (EPM strain) to characterize a conductance or resistance vessel, using a low-cost simple technique. The diameters (mean ± SEM) of the base and middle segments were 471 ± 4.97 and 540 ± 8.39 µm, respectively, the tail end was 253 ± 2.58 µm. To test reactivity, the whole tail arteries or segments were perfused under constant flow and the reactivity to phenylephrine (PHE; 0.01-300 µg) was evaluated before and after removal of the endothelium or drug administration. The maximal response (Emax) and sensitivity...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Rat tail artery; Phenylephrine; Resistance artery; Endothelium; Conductance artery.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008000500011
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The left ventricular contractility of the rat heart is modulated by changes in flow and a1-adrenoceptor stimulation BJMBR
Vassallo,P.F.; Stefanon,I.; Rossoni,L.V.; Tucci,P.J.F.; Vassallo,D.V..
Myocardial contractility depends on several mechanisms such as coronary perfusion pressure (CPP) and flow as well as on <FONT FACE="Symbol">a</font>1-adrenoceptor stimulation. Both effects occur during the sympathetic stimulation mediated by norepinephrine. Norepinephrine increases force development in the heart and produces vasoconstriction increasing arterial pressure and, in turn, CPP. The contribution of each of these factors to the increase in myocardial performance needs to be clarified. Thus, in the present study we used two protocols: in the first we measured mean arterial pressure, left ventricular pressure and rate of rise of left ventricular pressure development in anesthetized rats (N = 10) submitted to phenylephrine (PE)...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Myocardial performance; Coronary perfusion pressure; Coronary flow; Phenylephrine.
Ano: 1998 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998001000019
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Correction Braz J Med Biol Res 1994; 27(11): 2667-2679 - Analysis of right and left ventricular performance of the rat heart with chronic myocardial infarction BJMBR
Stefanon,I.; Auxiliadora-Martins,M.; Vassallo,D.V.; Mill,J.G..
Tipo: Info:eu-repo/semantics/article
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009000900015
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Acute exposure to lead increases myocardial contractility independent of hypertension development BJMBR
Fioresi,M.; Furieri,L.B.; Simões,M.R.; Ribeiro Junior,R.F.; Meira,E.F.; Fernandes,A.A.; Stefanon,I.; Vassallo,D.V..
We studied the effects of the acute administration of small doses of lead over time on hemodynamic parameters in anesthetized rats to determine if myocardial contractility changes are dependent or not on the development of hypertension. Male Wistar rats received 320 µg/kg lead acetateiv once, and their hemodynamic parameters were measured for 2 h. Cardiac contractility was evaluated in vitro using left ventricular papillary muscles as were Na+,K+-ATPase and myosin Ca2+-ATPase activities. Lead increased left- (control: 112 ± 3.7 vs lead: 129 ± 3.2 mmHg) and right-ventricular systolic pressures (control: 28 ± 1.2vs lead: 34 ± 1.2 mmHg) significantly without modifying heart rate. Papillary muscles were exposed to 8 µM lead acetate and evaluated 60 min later....
Tipo: Info:eu-repo/semantics/article Palavras-chave: Lead; Myocardial contractility; Ventricular pressure.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013000200178
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Lead reduces tension development and the myosin ATPase activity of the rat right ventricular myocardium BJMBR
Vassallo,D.V.; Lebarch,E.C.; Moreira,C.M.; Wiggers,G.A.; Stefanon,I..
Lead (Pb2+) poisoning causes hypertension, but little is known regarding its acute effects on cardiac contractility. To evaluate these effects, force was measured in right ventricular strips that were contracting isometrically in 45 male Wistar rats (250-300 g) before and after the addition of increasing concentrations of lead acetate (3, 7, 10, 30, 70, 100, and 300 µM) to the bath. Changes in rate of stimulation (0.1-1.5 Hz), relative potentiation after pauses of 15, 30, and 60 s, effect of Ca2+ concentration (0.62, 1.25, and 2.5 mM), and the effect of isoproterenol (20 ng/mL) were determined before and after the addition of 100 µM Pb2+. Effects on contractile proteins were evaluated after caffeine treatment using tetanic stimulation (10 Hz) and measuring...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Lead; Right ventricular strips; Contraction; Heart; Myosin ATPase activity.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008000900008
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Ventricular performance and Na+-K+ ATPase activity are reduced early and late after myocardial infarction in rats BJMBR
Stefanon,I.; Cade,J.R.; Fernandes,A.A.; Ribeiro Junior,R.F.; Targueta,G.P.; Mill,J.G.; Vassallo,D.V..
Myocardial infarction leads to compensatory ventricular remodeling. Disturbances in myocardial contractility depend on the active transport of Ca2+ and Na+, which are regulated by Na+-K+ ATPase. Inappropriate regulation of Na+-K+ ATPase activity leads to excessive loss of K+ and gain of Na+ by the cell. We determined the participation of Na+-K+ ATPase in ventricular performance early and late after myocardial infarction. Wistar rats (8-10 per group) underwent left coronary artery ligation (infarcted, Inf) or sham-operation (Sham). Ventricular performance was measured at 3 and 30 days after surgery using the Langendorff technique. Left ventricular systolic pressure was obtained under different ventricular diastolic pressures and increased extracellular Ca2+...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Heart failure; Ouabain; Na+-K+ ATPase; Myocardial infarction; Calcium handling.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009001000005
Registros recuperados: 12
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