Transmural dispersion of repolarization and cardiac remodeling in ventricles of rabbit with right ventricular hypertrophy

Meedech, Pradtana; Saengklub, Nakkawee; Limprasutr, Vudhiporn; Kalandakanond-Thongsong, Sarinee; Kijtawornrat, Anusak; Hamlin, Robert L.

doi:10.1016/j.vascn.2014.09.012

Cited by 1 publication

(2 citation statements)

References 44 publications

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“…In our ventricular AP experiments, APs showed rapid initial repolarisation, but lacked an inscribed notch. Rabbit ventricular APs lacking a pronounced notch have also been seen in other studies (e.g., Giles and Imaizumi 1988;Kelly et al 2013;Meedech et al 2015). In our experiments, 10 lmol/L NS5806 produced significant AP shortening at APD 20 -APD 90 , an effect distinct from phase 1 repolarization ( Fig.…”

Section: Functional Relevance?supporting

confidence: 89%

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Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806

Cheng

Cannell

Hancox

2017

Physiological Reports

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Transient outward potassium current (Ito) in the heart underlies phase 1 repolarization of cardiac action potentials and thereby affects excitation–contraction coupling. Small molecule activators of Ito may therefore offer novel treatments for cardiac dysfunction, including heart failure and atrial fibrillation. NS5806 has been identified as a prototypic activator of canine Ito. This study investigated, for the first time, actions of NS5806 on rabbit atrial and ventricular Ito. Whole cell patch‐clamp recordings of Ito and action potentials were made at physiological temperature from rabbit ventricular and atrial myocytes. 10 μmol/L NS5806 increased ventricular Ito with a leftward shift in Ito activation and accelerated restitution. At higher concentrations, stimulation of Ito was followed by inhibition. The EC 50 for stimulation was 1.6 μmol/L and inhibition had an IC 50 of 40.7 μmol/L. NS5806 only inhibited atrial Ito (IC 50 of 18 μmol/L) and produced a modest leftward shifts in Ito activation and inactivation, without an effect on restitution. 10 μmol/L NS5806 shortened ventricular action potential duration (APD) at APD 20‐APD 90 but prolonged atrial APD. NS5806 also reduced atrial AP upstroke and amplitude, consistent with an additional atrio‐selective effect on Na+ channels. In contrast to NS5806, flecainide, which discriminates between Kv1.4 and 4.x channels, produced similar levels of inhibition of ventricular and atrial Ito. NS5806 discriminates between rabbit ventricular and atrial Ito, with mixed activator and inhibitor actions on the former and inhibitor actions against the later. NS5806 may be of significant value for pharmacological interrogation of regional differences in native cardiac Ito.

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Section: Functional Relevance?supporting

confidence: 89%

“…; Meedech et al. ). In our experiments, 10 μ mol/L NS5806 produced significant AP shortening at APD 20 ‐APD 90 , an effect distinct from phase 1 repolarization (Fig.…”

Section: Discussionmentioning

confidence: 97%

Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806

Cheng

Cannell

Hancox

2017

Physiological Reports

View full text Add to dashboard Cite

show abstract

Transmural dispersion of repolarization and cardiac remodeling in ventricles of rabbit with right ventricular hypertrophy

Cited by 1 publication

References 44 publications

Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806

Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806

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Transmural dispersion of repolarization and cardiac remodeling in ventricles of rabbit with right ventricular hypertrophy

Cited by 1 publication

References 44 publications

Differential responses of rabbit ventricular and atrial transient outward current (Ito) to the Ito modulator NS5806

Differential responses of rabbit ventricular and atrial transient outward current (Ito) to the Ito modulator NS5806

Contact Info

Product

Resources

About

Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806

Differential responses of rabbit ventricular and atrial transient outward current (I_to) to the I_to modulator NS5806