EFFECTS OF SOME NATURALLY-OCCURRING QUATERNARY AMMONIUM BASES ON SNAIL NERVE-CELLS ACTIVITY

1. 1. Changes induced by some naturally occuring quaternary ammonium bases on individual firing patterns of identified nerve cells of the snail Heobania Vermiculata have been examined. 2. 2. The iontophoretic injection of candicine and leptodactiline, phenolic bases, evoked both excitory and inhibitory effects which were very similar to those of acetylcholine, but less potent. 3. 3. Murexine, another quaternary ammonium base iontophoresed on snail somata, showed cholinomimetic actions often more effective than those produced by acetylcholine. 4. 4. Dopamine induced effects, usually of inhibitory type, were not closely correlated with those evoked by the two phenolic bases. There was absolutely no correlation between dopamine and murexine effects. 5. 5. Resistance of neuronal membrane decreased during the iontophoretic application of the tested quaternary bases. 6. 6. Our resulting data support the view that the trymethylammonium group, which is present in the chemical structures of acetylcholine as well as in the tested quaternar bases, plays an important role in the drug cholinomimetic action on molluscan nerve cells. © 1979.