Comparative Activities of Certain Quaternary Ammonium Compounds as Assayed by the Isolated Auricle Technique

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Abstract
Auricles were separated from the ventricles of guinea pigs, rats and rabbits and suspended in oxygenated Locke''s soln. at 29[degree]C. After equilibration each prepn. was tested for sensitivity to ACh (acetylcholine). Then the following betaine esters were examined (in the range of 10-8-10-4 [image]) for chrono-tropic, inotropic and refractory period effects: ethyl, propyl, butyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, cyclohexyl and cholesteryl. The following trimethylated compounds were also employed: beta alanyl choline, glycyl homo-choline, and glycyl choline. The ethyl,propyl and butyl betaine esters were effective in concns. of 10-7, 10-6 and 10-5 [image], respectively, while the 3 trimethylated compounds inhibited auricular activity in concns. of 10-7, 10-5 and 10-5 [image], respectively. None of the compounds appeared to extend the refractory period as quinidine does. In expts. with auricles which had been arrested by means of quinidine, chlorguanide or exhaustion, attempts at reactivating the spontaneous beat with ACh, betaine ethyl ester, or adenosintriphosphate did not meet with complete success but epinephrine was repeatedly effective in this regard.