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Ionic basis of the action potential prolongation in ventricular myocytes from Syrian hamsters with dilated cardiomyopathy.
Cardiovasc Res. 1996 May; 31(5):747-57.CR

Abstract

OBJECTIVE

The aim of our study was to determine the main electrophysiological alterations associated with cardiac dilation in MS200 strain Syrian hamsters, a model of genetically determined cardiomyopathy.

METHODS

Ventricular action potentials (APs) were recorded with standard microelectrodes in isolated hearts from 120-day-old cardiomyopathic (strain MS200) and age-matched control (strain CHF148) Syrian hamsters. Ionic currents were recorded from single ventricular myocytes using the whole-cell patch-clamp technique.

RESULTS

In MS200, AP was prolonged and the plateau phase was markedly increased as compared to CHF148. Differences in both AP duration and 4-aminopyridine-induced AP lengthening between epicardial and endocardial tissues were less marked in MS200 than in CHF148 ventricles. Cell size and membrane capacitance were not higher in MS200 than in CHF148 myocytes, indicating the absence of cell hypertrophy in myopathic ventricles. The L-type calcium current (ICa,L) density was significantly reduced in MS200 and the voltage-dependence of both steady-state activation and inactivation was altered. The voltage-dependent outward current was composed of both transient (Ito1) and sustained (Iss) components, respectively sensitive and insensitive to 4-aminopyridine. Ito1 density was strongly depressed in MS200 compared to CHF148, whereas Iss density was only slightly reduced. The conductance-voltage and steady-state inactivation relationships for Ito1 were shifted to more positive potentials in MS200. The Ito1 recovery process was markedly slower in MS200 than in CHF148. The steady-state current-voltage relationships, in the physiological voltage range, were superimposable in MS200 and CHF148.

CONCLUSIONS

In ventricular myocytes from dilated heart of MS200 Syrian hamsters, Ito1 is more drastically depressed than ICa,L. Such an observation might partially explain dilation-induced AP lengthening.

Authors+Show Affiliations

Laboratoire de Cardiologie Moléculaire et Cellulaire, Université de Paris XI, France.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8763404

Citation

Thuringer, D, et al. "Ionic Basis of the Action Potential Prolongation in Ventricular Myocytes From Syrian Hamsters With Dilated Cardiomyopathy." Cardiovascular Research, vol. 31, no. 5, 1996, pp. 747-57.
Thuringer D, Deroubaix E, Coulombe A, et al. Ionic basis of the action potential prolongation in ventricular myocytes from Syrian hamsters with dilated cardiomyopathy. Cardiovasc Res. 1996;31(5):747-57.
Thuringer, D., Deroubaix, E., Coulombe, A., Coraboeuf, E., & Mercadier, J. J. (1996). Ionic basis of the action potential prolongation in ventricular myocytes from Syrian hamsters with dilated cardiomyopathy. Cardiovascular Research, 31(5), 747-57.
Thuringer D, et al. Ionic Basis of the Action Potential Prolongation in Ventricular Myocytes From Syrian Hamsters With Dilated Cardiomyopathy. Cardiovasc Res. 1996;31(5):747-57. PubMed PMID: 8763404.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ionic basis of the action potential prolongation in ventricular myocytes from Syrian hamsters with dilated cardiomyopathy. AU - Thuringer,D, AU - Deroubaix,E, AU - Coulombe,A, AU - Coraboeuf,E, AU - Mercadier,J J, PY - 1996/5/1/pubmed PY - 1996/5/1/medline PY - 1996/5/1/entrez SP - 747 EP - 57 JF - Cardiovascular research JO - Cardiovasc Res VL - 31 IS - 5 N2 - OBJECTIVE: The aim of our study was to determine the main electrophysiological alterations associated with cardiac dilation in MS200 strain Syrian hamsters, a model of genetically determined cardiomyopathy. METHODS: Ventricular action potentials (APs) were recorded with standard microelectrodes in isolated hearts from 120-day-old cardiomyopathic (strain MS200) and age-matched control (strain CHF148) Syrian hamsters. Ionic currents were recorded from single ventricular myocytes using the whole-cell patch-clamp technique. RESULTS: In MS200, AP was prolonged and the plateau phase was markedly increased as compared to CHF148. Differences in both AP duration and 4-aminopyridine-induced AP lengthening between epicardial and endocardial tissues were less marked in MS200 than in CHF148 ventricles. Cell size and membrane capacitance were not higher in MS200 than in CHF148 myocytes, indicating the absence of cell hypertrophy in myopathic ventricles. The L-type calcium current (ICa,L) density was significantly reduced in MS200 and the voltage-dependence of both steady-state activation and inactivation was altered. The voltage-dependent outward current was composed of both transient (Ito1) and sustained (Iss) components, respectively sensitive and insensitive to 4-aminopyridine. Ito1 density was strongly depressed in MS200 compared to CHF148, whereas Iss density was only slightly reduced. The conductance-voltage and steady-state inactivation relationships for Ito1 were shifted to more positive potentials in MS200. The Ito1 recovery process was markedly slower in MS200 than in CHF148. The steady-state current-voltage relationships, in the physiological voltage range, were superimposable in MS200 and CHF148. CONCLUSIONS: In ventricular myocytes from dilated heart of MS200 Syrian hamsters, Ito1 is more drastically depressed than ICa,L. Such an observation might partially explain dilation-induced AP lengthening. SN - 0008-6363 UR - https://www.unboundmedicine.com/medline/citation/8763404/Ionic_basis_of_the_action_potential_prolongation_in_ventricular_myocytes_from_Syrian_hamsters_with_dilated_cardiomyopathy_ L2 - https://academic.oup.com/cardiovascres/article-lookup/doi/10.1016/0008-6363(96)00018-1 DB - PRIME DP - Unbound Medicine ER -