Effects of chronic amiodarone therapy on L-type calcium current recovery and action potential duration of rabbit ventricular myocytes.
- Author:
Xiao-jing ZHAO
1
;
Dong-lin GUO
;
Ying WU
;
Teng-xian LIU
;
Gan-xin YAN
Author Information
- Publication Type:Journal Article
- MeSH: Action Potentials; Amiodarone; pharmacology; Animals; Anti-Arrhythmia Agents; pharmacology; Calcium Channels, L-Type; drug effects; physiology; Myocytes, Cardiac; drug effects; physiology; Patch-Clamp Techniques; Rabbits; Sotalol; pharmacology
- From: Chinese Journal of Cardiology 2009;37(6):528-531
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVETo investigate the effects of chronic amiodarone therapy on L-type calcium current recovery and action potential duration of rabbit ventricular myocytes.
METHODSHealthy rabbits (1.6-1.8 kg) were treated with amiodarone (80 mg x kg(-1) x d(-1)) for four weeks. Action potential duration (APD) was recorded under isolated arterially perfused left ventricular wedge preparation, then single myocytes were isolated using enzyme digestion. L-type calcium current recovery (time constant, tau) were determined by fitting data with monoexponential. Tau/APD90 were compared in cells treated with saline, amiodarone and sotalol (3 x 10(-5) mmol/L).
RESULTSIn chronic amiodarone treated myocytes, tau [(164 +/- 8) ms vs. (98 +/- 8) ms, P<0.05], APD90 [(321 +/- 12) ms vs. (220 +/- 10) ms, P<0.05] and tau/APD90 (0.51 +/- 0.03 vs. 0.44 +/- 0.03, P<0.05) were significantly increased than those in control myocytes. Sotalol significantly increased tau [(128 +/- 7) ms vs. (98 +/- 8) ms, P<0.05] and ADP90 [(405 +/- 13) ms vs. (220 +/- 10) ms, P<0.05] while reduced the tau/APD90 (0.32 +/- 0.05 vs. 0.44 +/- 0.03, P<0.05) compared to control myocytes.
CONCLUSIONThe differential effect of amiodarone and sotalol on ventricular myocytes tau/APD90 ratio might be responsible for the safety profile of these two drugs.
