Sulfur Dioxide Derivative Prevents the Prolongation of Action Potential During the Isoproterenol-Induced Hypertrophy of Rat Cardiomyocytes

Two electrophysiological manifestations of myocardial infarction (MI)-induced myocyte hypertrophy are prolongation of action potential duration (APD) and reduction of transient outward current ( I to) density. Because high-intensity sprint training (HIST) ameliorated myocyte hypertrophy and improved myocyte Ca2+ homeostasis and contractility after MI, the present study evaluated whether 6–8 wk of HIST would shorten the prolonged APD and improve the depressed I to in post-MI myocytes. There were no differences in resting membrane potential and action potential amplitude (APA) measured in myocytes isolated from sham-sedentary (Sed), MI-Sed, and MI-HIST groups. Times required for repolarization to 50 and 90% APA were significantly ( P < 0.001) prolonged in MI-Sed myocytes. HIST reduced times required for repolarization to 50 and 90% APA to values observed in Sham-Sed myocytes. The fast and slow components of I towere significantly ( P < 0.0001) reduced in MI-Sed myocytes. HIST significantly ( P < 0.001) enhanced the fast and slow components of I to in MI myocytes, although not to levels observed in Sham-Sed myocytes. There were no significant differences in steady-state I toinactivation and activation parameters among Sham-Sed, MI-Sed, and MI-HIST myocytes. Likewise, recovery from time-dependent inactivation was also similar among the three groups. We suggest that normalization of APD after MI by HIST may be mediated by restoration of I to toward normal levels.

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Class III Antiarrhythmic Effects of Dofetilide in Rabbit Atrial Myocardium

Journal of Cardiovascular Pharmacology and Therapeutics ◽

10.1177/107424849600100306 ◽

1996 ◽

Vol 1 (3) ◽

pp. 229-234 ◽

Cited By ~ 1

Author(s):

Regan T. Pallandi ◽

Nigel H. Lovell ◽

Terence J. Campbell

Keyword(s):

Action Potential ◽

Action Potential Duration ◽

Interstimulus Interval ◽

Class Iii ◽

Atrial Myocardium ◽

New Class ◽

Class Iii Antiarrhythmic Agent ◽

Prolongation Of Action Potential ◽

Dose Dependent ◽

Microelectrode Techniques

Background Dofetilide is a new class III antiarrhythmic agent with demonstrated efficacy in ventricular and atrial tachyarrhythmias. We investigated its class HI actions and their modulation by stimulation rate in rabbit atrial myocardium. Methods and Results Standard microelectrode techniques were used to record action potentials from rabbit atrial tissue at varying stimulation rates. Dofetilide produced a dose-dependent prolongation of action potential duration at concentrations from 1 nM to 1 μM at an interstimulus interval of 1000 ms. Action potential duration at 90% repolarization (action potential duration) was prolonged from 116 ± 11.7 ms in control solutions to 148 ± 13.9 ms at 1nM dofetilide and 186 ± 49.3 ms at 1 μM dofetilide ( P < .05 for 1 nM vs control; P < .01 for 1 μM vs control). Reduction of interstimulus interval to 500 ms had no significant effect on action potential duration prolongation by dofetilide. At faster rates than this, and particularly at an interstimulus interval less than 330 ms, a marked “reverse rate dependence” of the class III effect was observed. Specifically, the high therapeutic concentration of 10 nM showed no effect on action potential duration at interstimulus interval of 250 ms or 200 ms, and even at a concentration of 30 nM, the small class III effect was no longer statistically significant at these rates. Conclusion Dofetilide prolongs action potential duration in rabbit atrial myocardium, but this effect is significantly attenuated at stimulation rates above 2 Hz.

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Different Densities of Na-Ca Exchange Current in T-Tubular and Surface Membranes and Their Impact on Cellular Activity in a Model of Rat Ventricular Cardiomyocyte

BioMed Research International ◽

10.1155/2017/6343821 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

M. Pásek ◽

J. Šimurda ◽

G. Christé

Keyword(s):

Action Potential ◽

Transport Systems ◽

Duration Of Action ◽

Rat Cardiomyocytes ◽

Adult Rat ◽

Before And After ◽

Action Potential Waveform ◽

Intracellular Ca ◽

Tubular Membranes ◽

Potential Waveform

The ratio of densities of Na-Ca exchanger current (INaCa) in the t-tubular and surface membranes (INaCa-ratio) computed from the values ofINaCaand membrane capacitances (Cm) measured in adult rat ventricular cardiomyocytes before and after detubulation ranges between 1.7 and 25 (potentially even 40). Variations of action potential waveform and of calcium turnover within this span of theINaCa-ratio were simulated employing previously developed model of rat ventricular cell incorporating separate description of ion transport systems in the t-tubular and surface membranes. The increase ofINaCa-ratio from 1.7 to 25 caused a prolongation of APD (duration of action potential at 90% repolarisation) by 12, 9, and 6% and an increase of peak intracellular Ca2+transient by 45, 19, and 6% at 0.1, 1, and 5 Hz, respectively. The prolonged APD resulted from the increase ofINaCadue to the exposure of a larger fraction of Na-Ca exchangers to higher Ca2+transients under the t-tubular membrane. The accompanying rise of Ca2+transient was a consequence of a higher Ca2+load in sarcoplasmic reticulum induced by the increased Ca2+cycling between the surface and t-tubular membranes. However, the reason for large differences in theINaCa-ratio assessed from measurements in adult rat cardiomyocytes remains to be explained.

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Kinin-Induced Prolongation of Action-Potential Duration in Right Ventricular Muscle from Rat: Involvement of B1 and B2 Receptors

Journal of Cardiovascular Pharmacology ◽

10.1097/00005344-199608000-00023 ◽

1996 ◽

Vol 28 (2) ◽

pp. 337-343 ◽

Cited By ~ 4

Author(s):

L. Gouin ◽

R. Cardinal ◽

A. Adam ◽

G. Drapeau ◽

R. Nadeau

Keyword(s):

Action Potential ◽

Right Ventricular ◽

Action Potential Duration ◽

Ventricular Muscle ◽

Prolongation Of Action Potential ◽

B2 Receptors

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Different effects of β-adrenergic stimulation on the prolongation of action potential by Dofetilide and Ambasilide

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(96)82421-1 ◽

1996 ◽

Vol 27 (2) ◽

pp. 374-375

Author(s):

Jügen Schreieck ◽

Viktor Gjini ◽

Michael Korth ◽

Albert Schömig ◽

Claus Schmitt

Keyword(s):

Action Potential ◽

Adrenergic Stimulation ◽

Prolongation Of Action Potential

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Ionic mechanisms of thiopental on prolongation of action potential duration in rat ventricular myocytes

International Congress Series ◽

10.1016/j.ics.2005.07.039 ◽

2005 ◽

Vol 1283 ◽

pp. 279-280

Author(s):

W.K. Park ◽

M.H. Kim ◽

J.E. Chae ◽

C.H. Chang

Keyword(s):

Action Potential ◽

Action Potential Duration ◽

Ventricular Myocytes ◽

Rat Ventricular Myocytes ◽

Ionic Mechanisms ◽

Prolongation Of Action Potential

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Over-expression of Kv1.5 in rat cardiomyocytes extremely shortens the duration of the action potential and causes rapid excitation

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2006.05.030 ◽

2006 ◽

Vol 345 (3) ◽

pp. 1116-1121 ◽

Cited By ~ 14

Author(s):

Yasutaka Tanabe ◽

Katsuharu Hatada ◽

Naoki Naito ◽

Yoshiyasu Aizawa ◽

Masaomi Chinushi ◽

...

Keyword(s):

Action Potential ◽

Rat Cardiomyocytes ◽

Over Expression

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Exaggerated block of hERG (KCNH2) and prolongation of action potential duration by erythromycin at temperatures between 37°C and 42°C

Heart Rhythm ◽

10.1016/j.hrthm.2005.04.029 ◽

2005 ◽

Vol 2 (8) ◽

pp. 860-866 ◽

Cited By ~ 33

Author(s):

Jiqing Guo ◽

Shu Zhan ◽

James P. Lees-Miller ◽

GuoQi Teng ◽

Henry J. Duff

Keyword(s):

Action Potential ◽

Action Potential Duration ◽

Prolongation Of Action Potential

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Potentiation of twitch contraction in guinea pig ureter by sodium vanadate

AJP Cell Physiology ◽

10.1152/ajpcell.1992.263.5.c953 ◽

1992 ◽

Vol 263 (5) ◽

pp. C953-C958 ◽

Cited By ~ 11

Author(s):

S. Sunano ◽

K. Moriyama ◽

K. Shimamura

Keyword(s):

Guinea Pig ◽

Action Potential ◽

Membrane System ◽

Muscle Membrane ◽

Sodium Vanadate ◽

Duration Of Action ◽

Twitch Contraction ◽

Smooth Muscle Membrane ◽

Prolongation Of Action Potential ◽

Ca Agonist

The effect of sodium vanadate on action potential and twitch contraction of guinea pig ureter was studied and compared with that of ouabain, elevated K+, low temperature, and a Ca agonist (BAY K 8644), which can be expected to exert certain comparative effects. Sodium vanadate markedly potentiated twitch contraction. Potentiation by vanadate was associated with marked prolongation of relaxation time. Sodium vanadate caused only slight depolarization of the membrane but marked changes in action potential. The duration of action potential was prolonged and the number of oscillatory spike potentials increased. These effects were different from those of other treatments. It is concluded that prolongation of action potential and the increase in the number of spikes are the main cause of potentiation of twitch contraction by sodium vanadate. In addition, inhibition of Ca pump activity of the smooth muscle membrane system by vanadate might also be involved in potentiation of twitch contraction.

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