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Type: Artigo de periódico
Title: Cholinergic-adrenergic Antagonism In The Induction Of Tachyarrhythmia By Electrical Stimulation In Isolated Rat Atria.
Author: Zafalon, Nivaldo
Bassani, José W M
Bassani, Rosana A
Abstract: Atrial tachyarrhythmias (AT) are the most common cardiac rhythm disturbance. In the present study, we analyzed the cholinergic-adrenergic interaction in the in vitro induction of cholinergic-dependent tachyarrhythmia by high-frequency electric stimulation. Tachyarrhythmia was evoked in isolated rat right atria by trains of electric stimuli. Atrial response was expressed as the tachyarrhythmia induction index (ATI, i.e. the fraction of applied trains that resulted in arrhythmia induction). ATI was reversibly increased by 0.6 microM carbachol (CCh), which also decreased atrial spontaneous rate (ASR). In contrast, 10 nM isoproterenol (ISO), 100 microM tyramine and the phosphodiesterase inhibitor isobutyl-methylxanthine (IBMX, 100 microM) increased ASR and decreased ATI. Amiodarone (AMI, 10 microM) reduced ATI in the presence and absence of CCh. Further CCh addition restored ATI in atria treated with either IBMX or AMI, but not when both compounds were present. Increase in ATI by CCh in atria pretreated with IBMX plus ISO was significantly attenuated by 3 mM NaF. The antagonism between cholinergic muscarinic and beta-adrenergic receptor stimulation (the former facilitating and the latter inhibiting tachyarrhythmia installation) possibly involves regulation of the phosphorylation status of adenosine cyclic 3'-5'-monophosphate (cAMP)-dependent protein kinase substrates. Additionally, cAMP-independent, AMI-sensitive mechanism stimulated by CCh (possibly muscarinic-dependent K(+) current activation) seems to contribute to AT facilitation.
Subject: 1-methyl-3-isobutylxanthine
Anti-arrhythmia Agents
Cholinergic Agonists
Cyclic Amp
Disease Models, Animal
Dose-response Relationship, Drug
Electric Stimulation
Heart Atria
Phosphodiesterase Inhibitors
Phosphoric Monoester Hydrolases
Rats, Wistar
Receptors, Adrenergic
Receptors, Cholinergic
Receptors, Muscarinic
Sodium Fluoride
Time Factors
Citation: Journal Of Molecular And Cellular Cardiology. v. 37, n. 1, p. 127-35, 2004-Jul.
Rights: fechado
Identifier DOI: 10.1016/j.yjmcc.2004.04.020
Date Issue: 2004
Appears in Collections:Unicamp - Artigos e Outros Documentos

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