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Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages.
Cardiovasc Res. 1994 Aug; 28(8):1180-7.CR

Abstract

OBJECTIVE

The aim was to determine the ionic basis of action potential lengthening associated with cardiac hypertrophy.

METHODS

Action potentials and ionic currents of left ventricular myocytes isolated from normal and hypertrophied hearts were recorded with patch pipettes. Since cardiac hypertrophy is a time dependent process, myocytes isolated from hearts of spontaneously hypertensive rats (SHR) of different ages (3 and 18 months old) were compared with those of age matched normotensive controls (Wistar Kyoto rats, WKY).

RESULTS

Membrane capacitance, an index of cell size, was significantly higher in SHR than WKY. The degree of action potential prolongation was independently correlated with hypertension and its duration, resulting in a statistically significant lengthening of action potential in 18 month old SHR compared to age matched WKY and to 3 month old SHR. ICa,L density was not significantly modified in hypertrophied myocytes compared to normal controls. Depolarising steps positive to -40 mV activated an outward current, which was composed of both transient (ItO) and maintained components (Ilate) and played a major role in controlling repolarisation in rat ventricular myocytes. Ito density was significantly reduced in SHR myocytes compared to age matched WKY and was also smaller in 18 month old compared to 3 month old SHR. Ilate was not statistically different in 3 and 18 month old SHR and WKY. Current-voltage relationships for IK1 were completely superimposable in all groups.

CONCLUSIONS

Prolongation of action potential in the hypertrophied heart of SHR is due to specific alterations in the repolarising potassium current Ito. The phenomenon is directly related to the duration of hypertension.

Authors+Show Affiliations

Institute of Pharmacology, University of Ferrara, Italy.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

7954620

Citation

Cerbai, E, et al. "Ionic Basis of Action Potential Prolongation of Hypertrophied Cardiac Myocytes Isolated From Hypertensive Rats of Different Ages." Cardiovascular Research, vol. 28, no. 8, 1994, pp. 1180-7.
Cerbai E, Barbieri M, Li Q, et al. Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages. Cardiovasc Res. 1994;28(8):1180-7.
Cerbai, E., Barbieri, M., Li, Q., & Mugelli, A. (1994). Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages. Cardiovascular Research, 28(8), 1180-7.
Cerbai E, et al. Ionic Basis of Action Potential Prolongation of Hypertrophied Cardiac Myocytes Isolated From Hypertensive Rats of Different Ages. Cardiovasc Res. 1994;28(8):1180-7. PubMed PMID: 7954620.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages. AU - Cerbai,E, AU - Barbieri,M, AU - Li,Q, AU - Mugelli,A, PY - 1994/8/1/pubmed PY - 1994/8/1/medline PY - 1994/8/1/entrez SP - 1180 EP - 7 JF - Cardiovascular research JO - Cardiovasc Res VL - 28 IS - 8 N2 - OBJECTIVE: The aim was to determine the ionic basis of action potential lengthening associated with cardiac hypertrophy. METHODS: Action potentials and ionic currents of left ventricular myocytes isolated from normal and hypertrophied hearts were recorded with patch pipettes. Since cardiac hypertrophy is a time dependent process, myocytes isolated from hearts of spontaneously hypertensive rats (SHR) of different ages (3 and 18 months old) were compared with those of age matched normotensive controls (Wistar Kyoto rats, WKY). RESULTS: Membrane capacitance, an index of cell size, was significantly higher in SHR than WKY. The degree of action potential prolongation was independently correlated with hypertension and its duration, resulting in a statistically significant lengthening of action potential in 18 month old SHR compared to age matched WKY and to 3 month old SHR. ICa,L density was not significantly modified in hypertrophied myocytes compared to normal controls. Depolarising steps positive to -40 mV activated an outward current, which was composed of both transient (ItO) and maintained components (Ilate) and played a major role in controlling repolarisation in rat ventricular myocytes. Ito density was significantly reduced in SHR myocytes compared to age matched WKY and was also smaller in 18 month old compared to 3 month old SHR. Ilate was not statistically different in 3 and 18 month old SHR and WKY. Current-voltage relationships for IK1 were completely superimposable in all groups. CONCLUSIONS: Prolongation of action potential in the hypertrophied heart of SHR is due to specific alterations in the repolarising potassium current Ito. The phenomenon is directly related to the duration of hypertension. SN - 0008-6363 UR - https://www.unboundmedicine.com/medline/citation/7954620/Ionic_basis_of_action_potential_prolongation_of_hypertrophied_cardiac_myocytes_isolated_from_hypertensive_rats_of_different_ages_ L2 - https://academic.oup.com/cardiovascres/article-lookup/doi/10.1093/cvr/28.8.1180 DB - PRIME DP - Unbound Medicine ER -