Effects of imidapril on heterogeneity of action potential and calcium current of ventricular myocytes in infarcted rabbits.
OBJECTIVE
To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy.


METHODS
Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated from subendocardial, midmyocardial, and subepicardial regions of the noninfarcted left ventricular wall. Action potentials and calcium current were recorded using whole-cell patch clamp technique.


RESULTS
The action potential duration of repolarization 90 % (APD90) was more prolonged in midmyocardium rather than in subepicardium and subendocardium with healed myocardial infarction. The transmural dispersion of repolarization (TDR) was increased in the three ventricular regions. The amplitude of I(Ca-L) [was enhanced but its density was decreased in noninfarcted ventricular myocytes due to increased cell membrane capacitance. The increased differences of calcium currents among subepicardium, midmyocardium, and subendocardium were also discovered. Normalization of heterogeneous changes in repolarization after treatment with imidapril was observed and decrease of TDR in noninfarcted area was measured. Early after depolarization (EAD) events of noninfarcted midmyocardium were markedly decreased by imidapril.


CONCLUSIONS
Imidapril reduced the electrophysiologic heterogeneities in noninfarcted area in rabbits after myocardial infarction. This ability of imidapril may contribute to its antiarrhythmic efficacy.
Li
Yang
Y
Institute of Geriatric Cardiology of Chinese PLA General Hospital, Beijing, China. liyangbsh@163.com
Xue
Qiao
Q
Ma
Jie
J
Zhang
Cun-tai
CT
Qiu
Ping
P
Wang
Lin
L
Gao
Wei
W
Cheng
Rei
R
Lu
Zai-ying
ZY
Wang
Shi-wen
SW
D000200:Action Potentials / Q000187:drug effects; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D002469:Cell Separation; D006352:Heart Ventricles / Q000166:cytology; D048289:Imidazolidines / Q000494:pharmacology*; D009203:Myocardial Infarction / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000502:physiology; D011817:Rabbits
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D020746:Calcium Channels, L-Type; D048289:Imidazolidines; C065166:imidapril