Cholinergics

Abstract The transmission of impulses throughout the cholinergic nervous system is mediated by acetylcholine, and compounds that produce their pharmacologic effects by mimicking or substituting for acetylcholine are called cholinergics or parasympathomimetics. Compounds that inhibit or inactivate the body's normal hydrolysis of acetylcholine by acetylcholinesterase in nervous tissue and/or by butyrylcholinesterase (pseudocholinesterase, cholinesterase) in the plasma are called anticholinesterases. The gross observable pharmacological effects of both types of compounds are quite similar. More recently, compounds have been found that enhance the release of acetylcholine from cholinergic nerve terminals, thus (like the anticholinesterases) producing cholinergic effects by an indirect mechanism. These concepts are discussed in this chapter.