[Na+/Ca2+ exchanger current and K+ current remodeling in midmyocardial cells of hypertrophic left ventricle].
OBJECTIVE
To investigate the characteristics of Na+/Ca2+ exchanger current (INa+ /Ca2+) and K+ current remodeling in midmyocardial cells of hypertrophic left ventricle for understanding the ionic basis of arrhythmia of the hypertrophic heart.


METHODS
Twenty New Zealand rabbits were divided equally into normal control group and operation group, and in the latter, left ventricular hypertrophy was induced in the rabbits by partial ligation of the abdominal aorta. Action potentials, INa+/Ca2+, slowly activating delayed rectifier K+ current (IKs) and rapidly activating delayed rectifier K+ current (IKr) were recorded in the two groups by using whole-cell patch-clamp technique.


RESULTS
At the basic cycle length of 2 s, 90% action potential duration (APD90) in control and operation groups was 522.0+/-19.5 ms (n=6) and 664.7+/-32.7 ms (n=7) respectively; at the testing potential of +40 mV, outward INa+/Ca2+ density in the two groups was 0.94+/-0.11 pA/pF (n=9) and 1.30+/-0.11 pA/pF (n=8) respectively; the testing potential of -100 mV elicited inward INa+/Ca2+ density of 0.40+/-0.05 pA/pF (n=9) and 0.56+/-0.02 pA/pF (n=8) respectively. The testing potential of +50 mV induced IKs tail current density of 0.26+/-0.03 pA/pF (n=8) and 0.17+/-0.01 pA/pF (n=9), and IKr tail current density of 0.34+/-0.02 pA/pF (n=8) and 0.23+/-0.02 pA/pF (n=9) respectively. Statistically significant differences were identified between the control and operation groups in all the above indices measured.


CONCLUSIONS
The characteristics of electrical remodeling changes in midmyocardial cells of hypertrophic left ventricle, exhibited by prolonged action potential, up-regulated INa+/Ca2+ and down-regulated IKs and IKr.
Wang
Jun-kui
JK
Department of Cardiology, First Hospital of Xi'an Jiaotong University, Xi'an 710061, China. wangjunkui@sohu.com
Cui
Chang-cong
CC
Yao
Qing-hai
QH
Yao
Xiao-wei
XW
Lian
Jiang-fang
JF
Han
Ke
K
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004452:Echocardiography; D005260:Female; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D015221:Potassium Channels / Q000502:physiology*; D011817:Rabbits; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000502:physiology*
D015221:Potassium Channels; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D002118:Calcium