Studies on presynaptic cholinergic mechanisms using analogues of choline and acetate

Experiments in which analogues of choline and acetate were used in an attempt to elucidate presynaptic cholinergic mechanisms are described. The stimulation-induced accumulation of choline analogues in a sympathetic ganglion was used as an indicator of choline transport activation and the effects of various conditions on this phenomenon were tested. Acetylcholine synthesis and release, in the presence of choline, were then measured under similar conditions in order to explore the relationship between choline uptake and acetylcholine synthesis. Finally, the synthesis, storage and release of analogues of acetylcholine with altered acetyl moieties, propionylcholine and butyrylcholine, were studied using the Torpedo electric organ. Both of these analogues were incorporated into synaptic vesicles, but while butyrylcholine was as releasable as acetylcholine, propionylcholine was less releasable.