[The blocking effects of six antiarrhythmic drugs on transient outward current in rat ventricular myocytes].
The effects of six antiarrhythmic drugs on transient outward current (Ito) in rat ventricular myocytes were examined by using the patch-clamp whole-cell recording technique. Quinidine, nifedipine, and imipramine resulted in a concentration-dependent inhibition of Ito with IC50s of 5.4, 10.9 and 6.0 mumol.L-1, respectively. All three agents produced a concentration-dependent increase in the rate of inactivation of Ito. Disopyramide, procainamide and E-4031 produced little inhibition of Ito even when present at 100 mumol.L-1. The results from this study show that quinidine, nifedipine and imipramine are potent inhibitors of Ito and that inhibition is mediated through preferential interaction with the open channel.
Liu
Q Y
QY
Department of Pharmacology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050.
Wang
X L
XL
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D007099:Imipramine / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000166:cytology*; D009543:Nifedipine / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects*; D011802:Quinidine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D016276:Ventricular Function
D000889:Anti-Arrhythmia Agents; D015221:Potassium Channels; D009543:Nifedipine; D011802:Quinidine; D007099:Imipramine