Effects of RS-2135, a new antiarrhythmic agent, on the kinetics of use-dependent decrease in maximum upstroke velocity in guinea pig ventricular myocardium.
The use-dependent decrease in maximum upstroke velocity (Vmax) caused by RS-2135, a new antiarrhythmic compound was analyzed in isolated papillary muscles of guinea pigs. RS-2135 3 and 10 microM decreased Vmax of action potential (AP) in a concentration-related manner without affecting resting membrane potential (RMP). Vmax decay in the presence of RS-2135 was exponential at stimulation rates > 0.5 Hz. This use-dependent block of Vmax was enhanced at higher stimulation frequencies. The time constants and onset rates per action potential of the use-dependent block were 10.7-26.9 s and 0.021-0.041 AP-1, respectively. The time constants of recovery from use-dependent block were 57.9 and 63.6 s, respectively, in the presence of 3 and 10 microM RS-2135. The predicted half-time of the recovery process calculated by physicochemical parameters of RS-2135 agreed well with the observed values. These results suggest that RS-2135 is a sodium channel blocking agent with slow kinetics and that the physicochemical properties underlie these characteristics.
Yorikane
R
R
Biological Research Laboratories, Sankyo Company, Tokyo, Japan.
Sada
T
T
Koike
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002227:Carbazoles / Q000494:pharmacology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects*
D000889:Anti-Arrhythmia Agents; D002227:Carbazoles; D007546:Isoquinolines; C073517:RS 2135