In which phase of the ACh life cycle is ACh rapidly hydrolyzed by AChE?

Acetylcholine (ACh) is a neurotransmitter that plays a vital role in the transmission of signals in the nervous system. The life cycle of ACh involves several phases including synthesis, uptake into storage, release, and degradation.

During the degradation phase, ACh is rapidly hydrolyzed by the enzyme acetylcholinesterase (AChE). This enzyme is located in the synaptic cleft, where it serves to break down ACh into acetate and choline shortly after ACh has been released into the synapse. This rapid hydrolysis is crucial for terminating the action of ACh and preventing continuous stimulation of the postsynaptic receptors, allowing the system to reset for the next signal.

In the synthesis phase, ACh is formed from acetyl-CoA and choline through the action of the enzyme choline acetyltransferase, which is not related to the degradation process. The uptake into storage phase involves the packaging of synthesized ACh into vesicles for later release, and the release phase is where ACh is actually expelled into the synaptic cleft to interact with receptors. None of these phases involve the hydrolysis of ACh, thus reinforcing that the correct context for rapid breakdown occurs predominantly during the