[Comparative study, in the anesthetized dog, of the dromotropic effects of N-propyl ajmaline bitartrate, ajmaline hydrochloride and ajmaline monochloroacetate, by recording of His electrogram].

A-V and intraventricular conduction disturbances induced by 3 different salts of ajmaline: N-propyl ajmaline bitartrate (NPAB), hydrochloride (CHA) and mono chloro-acetate (MCAA), were studied by recording endocavitary His bundle activity in pentobarbital anesthetized dogs. Cumulative dose-response curves were obtained with 3 doses of each compound. The results demonstrate that: a) NPAB exerts a significant depressor effect (9 to 10 times more potent than CHA) on the following three conduction times: auriculo-Hisian, His-Pinkinje and Purkinje-ventricular; b) on His-Purkinje and intra ventricular conduction, MCAA exerts a weaker depressor effect than that of Nab. The lack of parallelism of dose-response curves prevents further comparative quantification; c) on atrio-hisian conduction, MCAA presents a delayed dose-related depressor effect suggesting the presence of an active metabolite. It is concluded that among ajmaline derivatives studied, Nab appears to be the most depressor on A-V and intraventricular conduction in the pentobarbital anesthetized dog.