
2284. analogs parasympathetic neuroeffectors.  ii. comparative pharmacological
studies of acetylcholine, its thio and seleno analogs, and their hydrolysis
products
acetylthiocholine and acetylselenocholine exert acetylcholine-like effects on
the guinea-pig ileum and frog rectus abdominis preparations.  with the
latter preparation, responses to acetylthiocholine and acetylselenocholine,
in contrast to that to acetylcholine, are not enhanced by the addition of an
anticholinesterase.  this is attributable to the relatively high activity of
the hydrolysis products, cholinethiol and cholineselenol; acetylthiocholine
and acetyselenocholine undergo enzymatic hydrolysis at approximately the same
rate as does acetylcholine.  the hydrolysis products of acetylthiocholine and
acetylselenocholine, which have effects on the guinea-pig ileum comparable
to those of the parent esters, are readily oxidized in air to the relatively
inactive choline disulfide and choline diselenide, respectively.  these
observations are helpful in explaining many of the apparently contradictory
statements in the literature regarding the actions of acetylthiocholine.
