第4級鹽基の蛙腹直筋に對するクラレ樣作用並にワゴスチグミンの拮抗に就て

Abstract

The quaternary bases examined were magnocurarine, laurifoline chloride and dauricine dimethiodide, isolated from Magnolia obovata, Cocculus laurifolius DC. and Menisperumum dauricum DC. respectively, which were tested for the curare-like activities on the frog's rectus abdominis with referenes in evaluation to ACh-, C10- as well as KCl doseresponse curves. Vagostigmin (prostigmine methylsulfate) was used as the antagonistic agent to these alkaloids, and the relation between these alkaloids and the ChE-activity of rabbits was studied in vitro where ChE activity was determined by titration after Hall and Lucas's method. Result : Curare-like action was proved in magnocurarine and laurifoline which was about one-tenth to one-twentieth as active as tubocurarine and vagostigmin was found also a potent antagonist to both alkaloids. This mode of action of vagostigmin is mainly based on its inhibitory effect on the ChE-activity and partially on its competitive ability to the receptor of neuromuscular junction. Dauricine was almost the same as active as tubocurarine, while the mode of curarelike action was not the same, unlike the above-mentionedmagnocurarine and laurifoline ; thereby vagostigmin antagonized imperfectively the action of dauricine, probably because dauricine had itself the ChE inhibitory action and so depressed the same action of vagostigmin. C10 had the ACh-like action on the frog's rectus abdominis, -under the effect of which the stimulant effect of ACh on the neuromuscular junction of the same muscle was not abolished, even if after ACh had been washed out from the preparation. This result indicated that C10 might induce the cumulation of ACh effect on the striated muscle preparation.