Transient outward current, I(to1), is altered in cardiac memory

Hangang Yu, David McKinnon, Jane E. Dixon, Junyuan Gao, Randy Wymore, Ira S. Cohen, Peter Danilo, Alexei Shvilkin, Evgeny P. Anyukhovsky, Eugene A. Sosunov, Motoki Hara, Michael R. Rosen

Research output: Contribution to journalArticle

115 Citations (Scopus)

Abstract

Background - Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. Methods and Results - We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12 ± 0.18 to -0.34 ± 0.2] mV (±SEM, P<0.05), and T-wave vector, which shifted from -37 ± 12°to -143 ± 4°(P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (I(to)) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. I(to) activated on membrane depolarization to - 25 ± 1 mV in C and -7 ± 1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. I(to) density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of I(to) from inactivation was significantly prolonged: it was 531 ± 80 ms (n=10) in LTM and 27 ± 6 ms (n=9) in C (P<0.05) at -65 mV. Conclusions - I(to) changes are associated with and can provide at least a partial explanation for action-potential and T-wave changes occurring with LTM.

Original languageEnglish
Pages (from-to)1898-1905
Number of pages8
JournalCirculation
Volume99
Issue number14
DOIs
StatePublished - 13 Apr 1999

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Long-Term Memory
Cardiac Myocytes
Action Potentials
Electrocardiography
Electrophysiology
Muscle Cells
Cardiac Arrhythmias
Dogs
Calcium
Messenger RNA
Membranes

Keywords

  • Electrocardiography
  • Myocytes
  • Pacing
  • Ventricles

Cite this

Yu, H., McKinnon, D., Dixon, J. E., Gao, J., Wymore, R., Cohen, I. S., ... Rosen, M. R. (1999). Transient outward current, I(to1), is altered in cardiac memory. Circulation, 99(14), 1898-1905. https://doi.org/10.1161/01.CIR.99.14.1898
Yu, Hangang ; McKinnon, David ; Dixon, Jane E. ; Gao, Junyuan ; Wymore, Randy ; Cohen, Ira S. ; Danilo, Peter ; Shvilkin, Alexei ; Anyukhovsky, Evgeny P. ; Sosunov, Eugene A. ; Hara, Motoki ; Rosen, Michael R. / Transient outward current, I(to1), is altered in cardiac memory. In: Circulation. 1999 ; Vol. 99, No. 14. pp. 1898-1905.
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abstract = "Background - Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. Methods and Results - We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12 ± 0.18 to -0.34 ± 0.2] mV (±SEM, P<0.05), and T-wave vector, which shifted from -37 ± 12°to -143 ± 4°(P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (I(to)) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. I(to) activated on membrane depolarization to - 25 ± 1 mV in C and -7 ± 1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. I(to) density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of I(to) from inactivation was significantly prolonged: it was 531 ± 80 ms (n=10) in LTM and 27 ± 6 ms (n=9) in C (P<0.05) at -65 mV. Conclusions - I(to) changes are associated with and can provide at least a partial explanation for action-potential and T-wave changes occurring with LTM.",
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Yu, H, McKinnon, D, Dixon, JE, Gao, J, Wymore, R, Cohen, IS, Danilo, P, Shvilkin, A, Anyukhovsky, EP, Sosunov, EA, Hara, M & Rosen, MR 1999, 'Transient outward current, I(to1), is altered in cardiac memory', Circulation, vol. 99, no. 14, pp. 1898-1905. https://doi.org/10.1161/01.CIR.99.14.1898

Transient outward current, I(to1), is altered in cardiac memory. / Yu, Hangang; McKinnon, David; Dixon, Jane E.; Gao, Junyuan; Wymore, Randy; Cohen, Ira S.; Danilo, Peter; Shvilkin, Alexei; Anyukhovsky, Evgeny P.; Sosunov, Eugene A.; Hara, Motoki; Rosen, Michael R.

In: Circulation, Vol. 99, No. 14, 13.04.1999, p. 1898-1905.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Transient outward current, I(to1), is altered in cardiac memory

AU - Yu, Hangang

AU - McKinnon, David

AU - Dixon, Jane E.

AU - Gao, Junyuan

AU - Wymore, Randy

AU - Cohen, Ira S.

AU - Danilo, Peter

AU - Shvilkin, Alexei

AU - Anyukhovsky, Evgeny P.

AU - Sosunov, Eugene A.

AU - Hara, Motoki

AU - Rosen, Michael R.

PY - 1999/4/13

Y1 - 1999/4/13

N2 - Background - Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. Methods and Results - We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12 ± 0.18 to -0.34 ± 0.2] mV (±SEM, P<0.05), and T-wave vector, which shifted from -37 ± 12°to -143 ± 4°(P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (I(to)) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. I(to) activated on membrane depolarization to - 25 ± 1 mV in C and -7 ± 1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. I(to) density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of I(to) from inactivation was significantly prolonged: it was 531 ± 80 ms (n=10) in LTM and 27 ± 6 ms (n=9) in C (P<0.05) at -65 mV. Conclusions - I(to) changes are associated with and can provide at least a partial explanation for action-potential and T-wave changes occurring with LTM.

AB - Background - Cardiac memory refers to an altered T-wave morphology induced by ventricular pacing or arrhythmias that persist for variable intervals after resumption of sinus rhythm. Methods and Results - We induced long-term cardiac memory (LTM) in conscious dogs by pacing the ventricles at 120 bpm for 3 weeks. ECGs were recorded daily for 1 hour, during which time pacing was discontinued. At terminal study, the heart was removed and the electrophysiology of left ventricular epicardial myocytes was investigated. Control (C) and LTM ECG did not differ, except for T-wave amplitude, which decreased from 0.12 ± 0.18 to -0.34 ± 0.2] mV (±SEM, P<0.05), and T-wave vector, which shifted from -37 ± 12°to -143 ± 4°(P<0.05). Epicardial action potentials revealed loss of the notch and lengthening of duration at 20 days (both P<0.05). Calcium-insensitive transient outward current (I(to)) was investigated by whole-cell patch clamp. No difference in capacitance was seen in C and LTM myocytes. I(to) activated on membrane depolarization to - 25 ± 1 mV in C and -7 ± 1 mV (P<0.05) in LTM myocytes, indicating a positive voltage shift of activation. I(to) density was reduced in LTM myocytes, and a decreased mRNA level for Kv4.3 was observed. Recovery of I(to) from inactivation was significantly prolonged: it was 531 ± 80 ms (n=10) in LTM and 27 ± 6 ms (n=9) in C (P<0.05) at -65 mV. Conclusions - I(to) changes are associated with and can provide at least a partial explanation for action-potential and T-wave changes occurring with LTM.

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KW - Pacing

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Yu H, McKinnon D, Dixon JE, Gao J, Wymore R, Cohen IS et al. Transient outward current, I(to1), is altered in cardiac memory. Circulation. 1999 Apr 13;99(14):1898-1905. https://doi.org/10.1161/01.CIR.99.14.1898