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Britto-Júnior J, Pereira do Prado GL, Chiavegatto S, Cunha F, Moraes MO, Elisabete A Moraes M, Monica FZ, Antunes E, De Nucci G. The importance of the endothelial nitric oxide synthase on the release of 6-nitrodopamine from mouse isolated atria and ventricles and their role on chronotropism. Nitric Oxide 2023; 138-139:26-33. [PMID: 37269938 DOI: 10.1016/j.niox.2023.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/14/2023] [Accepted: 06/01/2023] [Indexed: 06/05/2023]
Abstract
6-nitrodopamine (6-ND) is released from rat isolated atria, where it acts as a potent positive chronotropic agent. The release of 6-ND from rat isolated atria and ventricles is significantly reduced when pre-incubated with l-NAME, and the release was not affected by tetrodotoxin pre-treatment, indicating that in the heart, the origin of 6-ND is not neurogenic. Since l-NAME inhibits all three isoforms of NO synthase, it was investigated the basal release of 6-ND from isolated atria and ventricles from nNOS-/-, iNOS-/- and eNOS-/- mice of either sex. The release of 6-ND was measured by LC-MS/MS. There were no significant differences in the 6-ND basal release from isolated atria and ventricles from male control mice, as compared to female control mice. The 6-ND release from atria obtained from eNOS-/- mice was significantly reduced when compared to atria obtained from control mice. The 6-ND release in nNOS-/- mice was not significantly different compared to control animals whereas the 6-ND release from atria obtained from iNOS-/- mice was significantly higher when compared to control group. Incubation of the isolated atria with l-NAME caused a significant decrease in the basal atrial rate of control, nNOS-/-, and iNOS-/- mice, but not in eNOS-/- mice. The results clearly indicate that eNOS is the isoform responsible for the synthesis of 6-ND in the mice isolated atria and ventricles and supports the concept that 6-ND is the major mechanism by which endogenous NO modulates heart rate.
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Affiliation(s)
- José Britto-Júnior
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil.
| | - Gustavo L Pereira do Prado
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Silvana Chiavegatto
- Department of Pharmacology, Institute of Biomedical Sciences (ICB), University of Sao Paulo (USP), São Paulo, Brazil; Department of Psychiatry, Institute of Psychiatry (IPq), University of Sao Paulo Medical School (FMUSP), São Paulo, Brazil
| | - Fernando Cunha
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo (USP-RP), Ribeirão Preto, Brazil
| | - Manoel Odorico Moraes
- Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, Brazil
| | - Maria Elisabete A Moraes
- Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, Brazil
| | - Fabiola Z Monica
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Edson Antunes
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil; Department of Pharmacology, Institute of Biomedical Sciences (ICB), University of Sao Paulo (USP), São Paulo, Brazil; Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, Brazil
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Britto-Júnior J, Lima AT, Fuguhara V, Monica FZ, Antunes E, De Nucci G. Investigation on the positive chronotropic action of 6-nitrodopamine in the rat isolated atria. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:1279-1290. [PMID: 36719453 DOI: 10.1007/s00210-023-02394-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 01/10/2023] [Indexed: 02/01/2023]
Abstract
6-Nitrodopamine (6-ND) is released from rat isolated atria being 100 times more potent than noradrenaline and adrenaline, and 10,000 times more potent than dopamine as a positive chronotropic agent. The present study aimed to investigate the interactions of 6-ND with the classical catecholamines, phosphodiesterase (PDE)-3 and PDE4, and the protein kinase A in rat isolated atria. Atrial incubation with 1 pM of dopamine, noradrenaline, or adrenaline had no effect on atrial frequency. Similar results were observed when the atria were incubated with 0.01 pM of 6-ND. However, co-incubation of 6-ND (0.01 pM) with dopamine, noradrenaline, or adrenaline (1 pM each) resulted in significant increases in atrial rate, which persisted over 30 min after washout of the agonists. The increased atrial frequency induced by co-incubation of 6-ND with the catecholamines was significantly reduced by the voltage-gated sodium channel blocker tetrodotoxin (1 µM, 30 min), indicating that the positive chronotropic effect of 6-ND is due in part to activation of nerve terminals. Pre-treatment of the animals with reserpine had no effect on the positive chronotropic effect induced by dopamine, noradrenaline, or adrenaline; however, reserpine markedly reduced the 6-ND (1 pM)-induced positive chronotropic effect. Incubation of the rat isolated atria with the protein kinase A inhibitor H-89 (1 µM, 30 min) abolished the increased atrial frequency induced by dopamine, noradrenaline, and adrenaline, but only attenuated the increases induced by 6-ND. 6-ND induces catecholamine release from adrenergic terminals and increases atrial frequency independently of PKA activation.
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Affiliation(s)
- José Britto-Júnior
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil.
| | - Antonio Tiago Lima
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Vivian Fuguhara
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Fabiola Z Monica
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Edson Antunes
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Gilberto De Nucci
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
- Department of Pharmacology, Faculty of Medicine, São Leopoldo Mandic, Campinas, SP, Brazil
- Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
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Britto-Júnior J, de Oliveira MG, Dos Reis Gati C, Campos R, Moraes MO, Moraes MEA, Mónica FZ, Antunes E, De Nucci G. 6-NitroDopamine is an endogenous modulator of rat heart chronotropism. Life Sci 2022; 307:120879. [PMID: 35963299 DOI: 10.1016/j.lfs.2022.120879] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/27/2022] [Accepted: 08/08/2022] [Indexed: 01/27/2023]
Abstract
6-Nitrodopamine (6-ND) is released by rat vas deferens and exerts a potent contractile response that is antagonized by tricyclic antidepressants and α1-, β1- and β1/β2-adrenoceptor antagonists. The release of 6-ND, noradrenaline, adrenaline and dopamine from rat isolated right atria was assessed by tandem mass spectrometry. The effects of the catecholamines were evaluated in both rat isolated right atria and in anaesthetized rats. 6-ND was the major catecholamine released from the isolated atria and the release was significantly reduced in nitric oxide synthase inhibitor L-NAME pre-treated atria or in atria obtained from L-NAME chronically treated animals, but unaffected by tetrodotoxin. 6-ND (1 pM) significantly increased the atrial frequency, being 100 times more potent than noradrenaline and adrenaline. Selective β1-blockers reduced the atrial frequency only at concentrations that prevented the increases in atrial frequency induced by 6-ND 1pM. Conversely, β1-blockade did not affect dopamine (10 nM), noradrenaline (100 pM) or adrenaline (100 pM) effect. The reductions in atrial frequency induced by the β1-adrenoceptor antagonists were absent in L-NAME pre-treated atria and in atria obtained from chronic L-NAME-treated animals. Tetrodotoxin did not prevent the reduction in atrial frequency induced by L-NAME or by β1-blockers treated preparations. In anaesthetized rats, at 1 pmol/kg, only 6-ND caused a significant increase in heart rate. Inhibition of 6-ND synthesis by chronic L-NAME treatment reduced both atrial frequency and heart rate. The results indicate that 6-ND is a major modulator of rat heart chronotropism and the reduction in heart rate caused by β1-blockers are due to selective blockade of 6-ND receptor.
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Affiliation(s)
- José Britto-Júnior
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | | | - Carolina Dos Reis Gati
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Rafael Campos
- Superior Institute of Biomedical Sciences, Ceará State University (UECE), Fortaleza, Brazil; Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, CE, Brazil
| | - Manoel Odorico Moraes
- Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, CE, Brazil
| | - Maria Elisabete A Moraes
- Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, CE, Brazil
| | - Fabíola Z Mónica
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Edson Antunes
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil; Clinical Pharmacology Unit, Drug Research and Development Center, Federal University of Ceará (UFC), Fortaleza, CE, Brazil; Department of Pharmacology, Institute of Biomedical Sciences, USP - University of São Paulo, Brazil; Metropolitan University of Santos (UNIMES), Santos, Brazil.
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Odnoshivkina YG, Sytchev VI, Petrov AM. Cholesterol regulates contractility and inotropic response to β2-adrenoceptor agonist in the mouse atria: Involvement of G i-protein-Akt-NO-pathway. J Mol Cell Cardiol 2016; 107:27-40. [PMID: 27170493 DOI: 10.1016/j.yjmcc.2016.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 10/21/2022]
Abstract
Majority of cardiac β2-adrenoceptors is located in cholesterol-rich microdomains. Here, we have investigated the underlying mechanisms by which a slight to moderate cholesterol depletion with methyl-β-cyclodextrin (MβCD, 1 and 5mM) interferes with contractility and inotropic effect of β2-adrenergic agonist (fenoterol, 50μM) in the mouse atria. Treatment with MβCD itself increased amplitude of Ca2+ transient but did not change the contraction amplitude due to a clamping action of elevated NO. Cholesterol depletion significantly attenuated the positive inotropic response to fenoterol which is accompanied by increase in NO generation and decrease in Ca2+ transient. Influence of 1mM MβCD on the fenoterol-driven changes in both contractility and NO level was strongly attenuated by inhibition of Gi-protein (pertussis toxin), Akt (Akt 1/2 kinase inhibitor) or NO-synthase (L-NAME). After exposure to 5mM MβCD, pertussis toxin or Akt inhibitor could recover the β2-agonist effects on contractility, NO production and Ca2+ transient, while L-NAME only reduced NO level. An adenylyl cyclase activator (forskolin, 50nM) had no influence on the MβCD-induced changes in the β2-agonist effects. Obtained results suggest that slight cholesterol depletion upregulates Gi-protein/Akt/NO-synthase signaling that attenuates the positive inotropic response to β2-adrenergic stimulation without altering the Ca2+ transient. Whilst moderate cholesterol depletion additionally could suppress the enhancement of the Ca2+ transient amplitude caused by the β2-adrenergic agonist administration in Gi-protein/Akt-dependent but NO-independent manner.
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Affiliation(s)
- Yulia G Odnoshivkina
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Vaycheslav I Sytchev
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia.
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Odnoshivkina UG, Sytchev VI, Nurullin LF, Giniatullin AR, Zefirov AL, Petrov AM. β2-adrenoceptor agonist-evoked reactive oxygen species generation in mouse atria: implication in delayed inotropic effect. Eur J Pharmacol 2015; 765:140-53. [PMID: 26297975 DOI: 10.1016/j.ejphar.2015.08.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/05/2015] [Accepted: 08/17/2015] [Indexed: 12/20/2022]
Abstract
Fenoterol, a β2-adrenoceptor agonist, has anti-apoptotic action in cardiomyocytes and induces a specific pattern of downstream signaling. We have previously reported that exposure to fenoterol (5 μM) results in a delayed positive inotropic effect which is related to changes in both Ca2+ transient and NO. Here, the changes in reactive oxygen species (ROS) production in response to the fenoterol administration and the involvement of ROS in effect of this agonist on contractility were investigated in mouse isolated atria. Stimulation of β2-adrenoceptor increases a level of extracellular ROS, while intracellular ROS level rises only after removal of fenoterol from the bath. NADPH-oxidase inhibitor (apocynin) prevents the increase in ROS production and the Nox2 isoform is immunofluorescently colocalized with β2-adrenoceptor at the atrial myocytes. Treatments with antioxidants (N-acetyl-L-cysteine, NADPH inhibitors, exogenous catalases) significantly inhibit the fenoterol induced increase in the contraction amplitude, probably by attenuating Ca2+ transient and up-regulating NO production. ROS generated in a β2-adrenoceptor-dependent manner can potentiate the activity of some Ca2+ channels. Indeed, inhibition of ryanodine receptors, TRPV-or L-type Ca2+- channels shows a similar efficacy in reduction of positive inotropic effect of both fenoterol and H2O2. In addition, detection of mitochondrial ROS indicates that fenoterol triggers a slow increase in ROS which is prevented by rotenone, but rotenone has no impact on the inotropic effect of fenoterol. We suggest that stimulation of β2-adrenoceptor with fenoterol causes the activation of NADPH-oxidase and after the agonist removal extracellularly generated ROS penetrates into the cell, increasing the atrial contractions probably via Ca2+ channels.
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Affiliation(s)
- Ulia G Odnoshivkina
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Vaycheslav I Sytchev
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Leniz F Nurullin
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of Russian Academy of Sciences, Laboratory of Biophysics of Synaptic Processes, Lobatchevsky str. 2/31, P.O. 30, Kazan 420111, Russia
| | - Arthur R Giniatullin
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Andrei L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia.
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Fellet AL, E. Boveris A, T. Arranz C, Balaszczuk AM. Cardiac mitochondrial nitric oxide: a regulator of heart rate? Am J Hypertens 2008; 21:377-81. [PMID: 18292759 DOI: 10.1038/ajh.2007.90] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Alterations in autonomic control and myocardial nitric-oxide (NO) production are likely linked to the development and progression of heart dysfunction. By focusing on heart rate, the complexity of the actions of NO at distinct levels throughout the autonomic nervous system and its relationship with other regulators can be demonstrated. Given the multiple and opposing actions of NO on cardiac control, it is difficult to interpret a response after a global intervention in the NO system. The diversity of intracellular pathways activated by NO, and their differing sensitivities to different levels of NO, might account for some aspects of reported specific but opposite effects. We discuss factors that might contribute to this diversity of actions. A proper elucidation of the effects of NO on metabolic pathways and on energy generation could lead to novel therapeutic strategies aimed at the early treatment of heart dysfunction.
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Mónica FZT, Bricola AAO, Báu FR, Freitas LLL, Teixeira SA, Muscará MN, Abdalla FMF, Porto CS, De Nucci G, Zanesco A, Antunes E. Long-term nitric oxide deficiency causes muscarinic supersensitivity and reduces beta(3)-adrenoceptor-mediated relaxation, causing rat detrusor overactivity. Br J Pharmacol 2008; 153:1659-68. [PMID: 18297104 DOI: 10.1038/bjp.2008.39] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Overactive bladder is a complex and widely prevalent condition, but little is known about its physiopathology. We have carried out morphological, biochemical and functional assays to investigate the effects of long-term nitric oxide (NO) deficiency on muscarinic receptor and beta-adrenoceptor modulation leading to overactivity of rat detrusor muscle. EXPERIMENTAL APPROACH Male Wistar rats received N(omega)-nitro-L-arginine methyl ester (L-NAME) in drinking water for 7-30 days. Functional responses to muscarinic and beta-adrenoceptor agonists were measured in detrusor smooth muscle (DSM) strips in Krebs-Henseleit solution. Measurements of [(3)H]inositol phosphate, NO synthase (NOS) activity, [(3)H]quinuclidinyl benzilate ([(3)H]QNB) binding and bladder morphology were also performed. KEY RESULTS Long-term L-NAME treatment significantly increased carbachol-induced DSM contractile responses after 15 and 30 days; relaxing responses to the beta(3)-adrenoceptor agonist BRL 37-344 were significantly reduced at 30 days. Constitutive NOS activity in bladder was reduced by 86% after 7 days and maintained up to 30 days of L-NAME treatment. Carbachol increased sixfold the [(3)H]inositol phosphate in bladder tissue from rats treated with L-NAME. [(3)H]QNB was bound with an apparent K(D) twofold higher in bladder membranes after L-NAME treatment compared with that in control. No morphological alterations in DSM were found. CONCLUSIONS AND IMPLICATIONS Long-term NO deficiency increased rat DSM contractile responses to a muscarinic agonist, accompanied by significantly enhanced K(D) values for muscarinic receptors and [(3)H]inositol phosphate accumulation in bladder. This supersensitivity for muscarinic agonists along with reductions of beta(3)-adrenoceptor-mediated relaxations indicated that overactive DSM resulted from chronic NO deficiency.
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Affiliation(s)
- F Z T Mónica
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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Montes-Gil AC, Zanfolin M, Okuyama CE, Lilla S, Alves DP, Santagada V, Perissutti E, Lavecchia A, Fiorino F, Severino B, Caliendo G, Priviero FBM, Mendes GD, Donato JL, de Nucci G. Pharmacokinetic profile of atenolol aspirinate. Arch Pharm (Weinheim) 2007; 340:445-55. [PMID: 17763375 DOI: 10.1002/ardp.200700070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We report microwave-assisted synthetic routes, the pharmacokinetic profile along with results from ulcerogenicity and mutagenicity studies of atenolol aspirinate, and an already described derivative, in which acetyl salicylic acid (aspirin) was connected to atenolol by an ester linkage. Atenolol aspirinate was stable towards aqueous hydrolysis but rapidly hydrolyzed in plasma (t(1/2) = 7.6 min). The results showed that the rapid and complete hydrolysis generates atenolol salicylate, which assumes a conformation stabilized by two intramolecular H-bonds, avoiding its further hydrolysis to salicylic acid and atenolol.
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Affiliation(s)
- Ana C Montes-Gil
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, São Paulo, Brazil
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Ferreira AJ, Jacoby BA, Araújo CAA, Macedo FAFF, Silva GAB, Almeida AP, Caliari MV, Santos RAS. The nonpeptide angiotensin-(1-7) receptor Mas agonist AVE-0991 attenuates heart failure induced by myocardial infarction. Am J Physiol Heart Circ Physiol 2006; 292:H1113-9. [PMID: 17056670 DOI: 10.1152/ajpheart.00828.2006] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nonpeptide AVE-0991, which has been reported as a selective ligand for the angiotensin-(1-7) [ANG-(1-7)] receptor Mas, has actions similar to those attributed to the cardioprotective product of the renin-angiotensin system, ANG-(1-7). In this study, we evaluated the cardiac effects of AVE-0991 in normal and infarcted male Wistar rats. Myocardial infarction was induced by left coronary artery ligation. At the end of the treatment, the Langendorff technique was used to analyze cardiac function. Left ventricle serial sections were dyed with Gomori trichrome stain to quantify the infarcted area. In normal hearts, AVE-0991 produced a significant decrease in perfusion pressure and an increase in systolic tension, rate of tension rise and fall (+/-dT/dt), and heart rate. These effects were completely blocked by the perfusion of the hearts with a solution containing the selective ANG-(1-7) antagonist A-779. N(G)-nitro-l-arginine methyl ester treatment abolished the AVE-0991-induced vasodilation in isolated hearts. AVE-0991 significantly attenuated the decrease in systolic tension (sham operated, 13.00 +/- 1.02 g; infarction, 7.18 +/- 0.66 g; AVE treated, 9.23 +/- 1.05 g, n = 5), +dT/dt, -dT/dt, and heart rate induced by myocardial infarction. Infarction-induced vasoconstriction was completely prevented by AVE-0991 treatment. Furthermore, AVE-0991 significantly decreased the infarcted area (6.98 +/- 1.01 vs. 3.94 +/- 1.04 mm(2) in AVE-treated rats). These data indicate that the compound AVE-0991 produces beneficial effects in isolated perfused rat hearts involving the ANG-(1-7) receptor Mas and the release of nitric oxide. In addition, our results indicate that AVE-0991 attenuates postischemic heart failure.
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Affiliation(s)
- Anderson J Ferreira
- Department of Morphology, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil
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Fellet AL, Di Verniero C, Arza P, Tomat A, Varela A, Arranz C, Balaszczuk AM. Effect of acute nitric oxide synthase inhibition in the modulation of heart rate in rats. Braz J Med Biol Res 2003; 36:669-76. [PMID: 12715087 DOI: 10.1590/s0100-879x2003000500015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute nitric oxide synthase inhibition with N G-nitro-L-arginine methyl ester (L-NAME) on chronotropic and pressor responses was studied in anesthetized intact rats and rats submitted to partial and complete autonomic blockade. Blood pressure and heart rate were monitored intra-arterially. Intravenous L-NAME injection (7.5 mg/kg) elicited the same hypertensive response in intact rats and in rats with partial (ganglionic and parasympathetic blockade) and complete autonomic blockade (38 +/- 3, 55 +/- 6, 54 +/- 5, 45 +/- 5 mmHg, respectively; N = 9, P = NS). L-NAME-induced bradycardia at the time when blood pressure reached the peak plateau was similar in intact rats and in rats with partial autonomic blockade (43 +/- 8, 38 +/- 5, 46 +/- 6 bpm, respectively; N = 9, P = NS). Rats with combined autonomic blockade showed a tachycardic response to L-NAME (10 3 bpm, P<0.05 vs intact animals, N = 9). Increasing doses of L-NAME (5.0, 7.5 and 10 mg/kg, N = 9) caused a similar increase in blood pressure (45 +/- 5, 38 +/- 3, 44 +/- 9 mmHg, respectively; P = NS) and heart rate (31 +/- 4, 34 +/- 3, 35 +/- 4 bpm, respectively; P = NS). Addition of L-NAME (500 micro M) to isolated atria from rats killed by cervical dislocation and rats previously subjected to complete autonomic blockade did not affect spontaneous beating or contractile strength (N = 9). In vivo results showed that L-NAME promoted a tachycardic response in rats with complete autonomic blockade, whereas the in vitro experiments showed no effect on intrinsic heart rate, suggesting that humoral mechanisms may be involved in the L-NAME-induced cardiac response.
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Affiliation(s)
- A L Fellet
- C tedra de Fisiolog a, Facultad de Farmacia y Bioqu mica, Universidad de Buenos Aires, Buenos Aires, Argentina.
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