ABSTRACT
ACh is degraded by the enzyme acetylcholinesterase to form acetate and choline. There are high levels of acetylcholinesterase in the synaptic cleft between cholinergic neurons and their target cells. This is the major method for limiting the action of ACh action on target cells. Choline is then transported back into the cholinergic neuron by specific choline uptake transporter proteins embedded in the presynaptic membrane, and is used in the subsequent synthesis of more ACh.
