Indirect cholinergic stimulants (cholinesterase inhibitors,anticholinesterases) Acetylcholinesterase(AChE) Bound to the basement membrane in the synaptic cleft at cholinergic synapses Also present as a soluble form in cholinergic nerve terminals;function unknown Binds Ach,forming a transient intermediate which then becomes acetylated AChE and choline:spontaneous and rapid deacylation follows,regenerating the enzyme Butyrylcholinesterase(BChE,pseudocholinesterase) .Widely present,including a presence in soluble form in the plasma Not particularly associated with cholinergic synapases Broader substrate specificity than AChE;hydrolyses butyrylcholine more efficiently than acetylcholine;function remains largely unknown Together with AChE,keeps acetylcholine concentration in plasma nearly undetectable Reversible cholinesterase inhibitors (compared to acetylcholine) 6c-c-0-CHg-CH2-NC Acetylcholine -CH HC一NH一C Carbaryl CHa Physostigmine Edrophonium 1010 Indirect cholinergic stimulants (cholinesterase inhibitors, anticholinesterases) Acetylcholinesterase (AChE) • Bound to the basement membrane in the synaptic cleft at cholinergic synapses • Also present as a soluble form in cholinergic nerve terminals; function unknown • Binds Ach, forming a transient intermediate which then becomes acetylated AChE and choline; spontaneous and rapid deacylation follows, regenerating the enzyme Butyrylcholinesterase (BChE, pseudocholinesterase) • Widely present, including a presence in soluble form in the plasma • Not particularly associated with cholinergic synapases • Broader substrate specificity than AChE; hydrolyses butyrylcholine more efficiently than acetylcholine; function remains largely unknown • Together with AChE, keeps acetylcholine concentration in plasma nearly undetectable Reversible cholinesterase inhibitors (compared to acetylcholine) Ester of carbamic acid Quaternary ammonium