Ionic basis of depressed automaticity and conduction by acetylcholine in rabbit AV node

Nishimura, Masao; Habuchi, Yoshizumi; Hiromasa, Shuichi; Watanabe, Yoshio

doi:10.1152/ajpheart.1988.255.1.h7

Cited by 14 publications

(6 citation statements)

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“…Subsequent investigations showed that ACh could also hyperpolarize membrane potential or stop spontaneous activity [Hiromasa et al, 1983;Nishimura et al, 1988]. Using voltage-clamp of small AVN preparations, Nishimura et al [1988] showed that ACh activated an inwardly rectifying potassium current (I KAch ) that altered passive as well as active membrane properties in a way that could account for the effects of ACh on the AVN. These authors also observed an effect of ACh on the slow inward current (I Ca,L ), which may augment the effect of activation of I KACh .…”

Section: Acetycholine-activated Potassium Current I Kachmentioning

confidence: 99%

Progress and Gaps in Understanding the Electrophysiological Properties of Morphologically Normal Cells From the Cardiac Atrioventricular Node

Hancox¹,

Yuill

Mitcheson

et al. 2003

Int. J. Bifurcation Chaos

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The atrioventricular node (AVN) is a small but critically important component of the cardiac electrical conduction system and is located at the junction between right atrium and right ventricle of the heart. It plays important roles in normal and abnormal impulse propagation. Mathematical models of the conduction properties of the AVN have been made, but detailed in silico reconstruction of AVN electrophysiology lags behind that of other cardiac regions. One important facet of detailed reconstruction of AVN electrical activity is the development of comprehensive, ionic conductance-based models of single cell electrophysiology. With a view to facilitating the construction of such models, this article reviews progress made regarding single AVN cell electrophysiological data during the last decade, predominantly focusing on that derived from morphologically normal AVN cells. Properties and potential roles of a range of currents are discussed: including L-type and T-type calcium currents (I Ca,L and I Ca,T respectively), background current, hyperpolarization-activated current (I f ), delayed and transient outward potassium currents (I Kr and I to , respectively), sodium-calcium exchanger current (I NaCa ), the sustained inward current (I st ) and acetylcholine-activated potassium current (I KACh ).

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Section: Acetycholine-activated Potassium Current I Kachmentioning

confidence: 99%

Progress and Gaps in Understanding the Electrophysiological Properties of Morphologically Normal Cells From the Cardiac Atrioventricular Node

Hancox¹,

Yuill

Mitcheson

et al. 2003

Int. J. Bifurcation Chaos

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show abstract

“…7 The mechanisms of action of acetylcholine on the AVN have been described elsewhere. 8,9 Limitations Although a short-acting muscarinic agonist was clearly a suitable drug for proof of concept for many reasons, this particular drug would be unsuitable for a long-term (pumpbased) clinical application. Acetylcholine is not very stable in solution, and the observed dose-response curves in the present study may be too steep (eg, the therapeutic window is too small).…”

Section: Sigg Et Al Focal Pharmacological Avn Modulation 2387mentioning

confidence: 99%

Focal Pharmacological Modulation of Atrioventricular Nodal Conduction via Implantable Catheter

et al. 2006

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Background-Pharmacological ventricular rate control is an acceptable atrial fibrillation (AF) therapy limited by systemic toxicity. We postulate that focal catheter-based drug delivery into the atrioventricular nodal (AVN) region may effectively control ventricular rate during AF without systemic toxicity. This study evaluated the effects of focally administered acetylcholine on AVN conduction and refractoriness during sinus rhythm and AF. Methods and Results-Canines (nϭ7) were anesthetized and instrumented to assess cardiac electrophysiology and blood pressure. A custom drug delivery catheter was implanted in the AVN region. Incremental doses of acetylcholine starting at 10 g/min were infused until complete AV block was achieved. Acetylcholine induced dose-dependent AV block. AF induction and electrophysiology measurements were performed during baseline and acetylcholine-induced first-degree and third-degree AV block. During AF, infusion of acetylcholine decreased ventricular rates from 182Ϯ32 to 77Ϯ28 and 28Ϯ8 bpm (first-degree and third-degree AV block, respectively; PϽ0.05). At the first-degree AV block dose, AVN effective refractory period increased from 186Ϯ37 to 282Ϯ33 ms, and Wenckebach cycle length increased from 271Ϯ29 to 378Ϯ58 ms (PϽ0.05). The first-degree AV block dose prolonged AV and AH intervals by 26% and 23% (PϽ0.05), whereas AA intervals and blood pressure remained unchanged, demonstrating a local effect. All effects were reversed 20 minutes after infusion was stopped. Conclusions-Focal acetylcholine delivery into the AVN increased AVN refractoriness and significantly decreased ventricular rate response during induced AF in a dose-related, reversible manner without systemic side effects. This may represent a novel therapy for AF whereby ventricular rate is controlled with the use of an implantable drug delivery system. (Circulation. 2006;113:2383-2390.)Key Words: acetylcholine Ⅲ catheters Ⅲ conduction Ⅲ pharmacology Ⅲ tachyarrhythmias C urrent clinical treatment options for arrhythmias include pharmacotherapy, ablation, and medical devices. Although these therapeutic approaches may have some role in the treatment of atrial fibrillation (AF), the successful management of this disease remains an unmet clinical need. Ideally, AF should be treated by a strategy of prevention and, if needed, conversion of the arrhythmia to a regular sinus rhythm. However, pharmacological therapies typically fail to prevent AF, particularly in patients with structural heart disease. Data from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial and from other clinical trials suggest that AF management with the rhythm-control strategy offers no survival advantage over rate control and furthermore that rate control may be more advantageous (lower risk of adverse drug effects, lower number of hospitalizations, and lower healthcare burden). 1,2 For supraventricular tachyarrhythmias with fast ventricular response with origin of the focus in the atria, the most Editorial p 2374 Clinical Pers...

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“…As características eletrofisiológicas de excitabilidade, condutividade e automatismo diferem entre o nódulo atrioventricular e o nódulo sinusal e entre os três tipos de células nodais 18,[21][22][23][24] . A acetilcolina, além de reduzir a velocidade de despolarização diastólica da corrente If, ativa diretamente uma corrente de saída composta pelo íon potássio denominada Ik.…”

Section: As Bases Iônicas Da Ativação Elétrica Do Coração Do Atletaunclassified

Repolarização precoce no eletrocardiograma do atleta: bases iônicas e modelo vetorial

Barbosa¹,

Benchimol-Barbosa²,

Bomfim³

et al. 2004

Arq. Bras. Cardiol.

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Ionic basis of depressed automaticity and conduction by acetylcholine in rabbit AV node

Cited by 14 publications

References 0 publications

Progress and Gaps in Understanding the Electrophysiological Properties of Morphologically Normal Cells From the Cardiac Atrioventricular Node

Progress and Gaps in Understanding the Electrophysiological Properties of Morphologically Normal Cells From the Cardiac Atrioventricular Node

Focal Pharmacological Modulation of Atrioventricular Nodal Conduction via Implantable Catheter

Repolarização precoce no eletrocardiograma do atleta: bases iônicas e modelo vetorial

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