Effects of sematilide, a novel class III antiarrhythmic agent, on delayed rectifier K+ current in guinea pig atrial myocytes.
Effects of sematilide, a novel class III antiarrhythmic agent, on the delayed rectifier K+ current (Ik) were examined in guinea pig atrial myocytes using a voltage clamp technique. Sematilide inhibited both time-dependent outward current upon depolarization and tail currents (Ik-tail) at -40 mV. The concentration of sematilide required for a 50% decrease in Ik-tail was approximately 50 microM. The sematilide-sensitive current obtained using a triangular voltage command exhibited marked inward rectification and had the maximum amplitude at -30 mV. These results suggest that sematilide inhibits rapidly activating Ik in guinea pig atrial myocytes, resulting in the prolongation of action potential duration and refractoriness.
Ishii
Y
Y
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Muraki
K
K
Kurihara
A
A
Imaizumi
Y
Y
Watanabe
M
M
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D016275:Atrial Function; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects; D009206:Myocardium; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology; D011342:Procainamide / Q000031:analogs & derivatives* / Q000494:pharmacology
D000889:Anti-Arrhythmia Agents; C062818:sematilide; D011342:Procainamide; D011188:Potassium