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Characteristics of single Ca(2+) channel kinetics in feline hypertrophied ventricular myocytes.
Chin Med J (Engl). 2002 Apr; 115(4):502-8.CM

Abstract

OBJECTIVE

To explore the mechanism underlying the prolongation of action potential and delayed inactivation of the L-type Ca(2+) (I(Ca, L)) current in a feline model of left ventricular system hypertension and concomitant hypertrophy.

METHODS

Single Ca(2+) channel properties in myocytes isolated from normal and pressure overloaded cat left ventricles were studied, using patch-clamp techniques. Left ventricular pressure overload was induced by partial ligation of the ascending aorta for 4 - 6 weeks.

RESULTS

The amplitude of single Ca(2+) channel current evoked by depolarizing pulses from -40 mV to 0 mV was 1.02 +/- 0.03 pA in normal cells and 1.05 +/- 0.03 pA in hypertrophied cells, and there was no difference in single channel current-voltage relationships between the groups since slope conductance was 26.2 +/- 1.0 pS in normal and hypertrophied cells, respectively. Peak amplitudes of the ensemble-averaged single Ca(2+) channel currents were not different between the two groups of cells. However, the amplitude of this averaged current at the end of the clamp pulse was significantly larger in hypertrophied cells than in normal cells. Open-time histograms revealed that open-time distribution was fitted by a single exponential function in channels of normal cells and by a two exponential function in channels of hypertrophied cells. The number of long-lasting openings was increased in channels of hypertrophied cells, and therefore the calculated mean open time of the channel was significantly longer compared to normal controls.

CONCLUSION

Kinetic changes in the Ca(2+) channel may underlie both hypertrophy-associated delayed inactivation of the Ca(2+) current and, in part, the pressure overload-induced action potential lengthening in this cat model of ventricular left systolic hypertension and hypertrophy.

Authors+Show Affiliations

Department of Cardiology, First Affiliated Hospital of Suzhou University, Suzhou 215006, China.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12133284

Citation

Yang, Xiangjun, et al. "Characteristics of Single Ca(2+) Channel Kinetics in Feline Hypertrophied Ventricular Myocytes." Chinese Medical Journal, vol. 115, no. 4, 2002, pp. 502-8.
Yang X, Hui J, Jiang T, et al. Characteristics of single Ca(2+) channel kinetics in feline hypertrophied ventricular myocytes. Chin Med J (Engl). 2002;115(4):502-8.
Yang, X., Hui, J., Jiang, T., Song, J., Liu, Z., & Jiang, W. (2002). Characteristics of single Ca(2+) channel kinetics in feline hypertrophied ventricular myocytes. Chinese Medical Journal, 115(4), 502-8.
Yang X, et al. Characteristics of Single Ca(2+) Channel Kinetics in Feline Hypertrophied Ventricular Myocytes. Chin Med J (Engl). 2002;115(4):502-8. PubMed PMID: 12133284.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characteristics of single Ca(2+) channel kinetics in feline hypertrophied ventricular myocytes. AU - Yang,Xiangjun, AU - Hui,Jie, AU - Jiang,Tingbo, AU - Song,Jianping, AU - Liu,Zhihua, AU - Jiang,Wenping, PY - 2002/7/23/pubmed PY - 2002/8/9/medline PY - 2002/7/23/entrez SP - 502 EP - 8 JF - Chinese medical journal JO - Chin Med J (Engl) VL - 115 IS - 4 N2 - OBJECTIVE: To explore the mechanism underlying the prolongation of action potential and delayed inactivation of the L-type Ca(2+) (I(Ca, L)) current in a feline model of left ventricular system hypertension and concomitant hypertrophy. METHODS: Single Ca(2+) channel properties in myocytes isolated from normal and pressure overloaded cat left ventricles were studied, using patch-clamp techniques. Left ventricular pressure overload was induced by partial ligation of the ascending aorta for 4 - 6 weeks. RESULTS: The amplitude of single Ca(2+) channel current evoked by depolarizing pulses from -40 mV to 0 mV was 1.02 +/- 0.03 pA in normal cells and 1.05 +/- 0.03 pA in hypertrophied cells, and there was no difference in single channel current-voltage relationships between the groups since slope conductance was 26.2 +/- 1.0 pS in normal and hypertrophied cells, respectively. Peak amplitudes of the ensemble-averaged single Ca(2+) channel currents were not different between the two groups of cells. However, the amplitude of this averaged current at the end of the clamp pulse was significantly larger in hypertrophied cells than in normal cells. Open-time histograms revealed that open-time distribution was fitted by a single exponential function in channels of normal cells and by a two exponential function in channels of hypertrophied cells. The number of long-lasting openings was increased in channels of hypertrophied cells, and therefore the calculated mean open time of the channel was significantly longer compared to normal controls. CONCLUSION: Kinetic changes in the Ca(2+) channel may underlie both hypertrophy-associated delayed inactivation of the Ca(2+) current and, in part, the pressure overload-induced action potential lengthening in this cat model of ventricular left systolic hypertension and hypertrophy. SN - 0366-6999 UR - https://www.unboundmedicine.com/medline/citation/12133284/Characteristics_of_single_Ca_2+__channel_kinetics_in_feline_hypertrophied_ventricular_myocytes_ DB - PRIME DP - Unbound Medicine ER -