Cholinergic receptors activation process

Physiology of the autonomic system The receptor activation process Cholinergic agonists... 

The precise intracellular events that lead to acid secretion are not clear, but the second messengers in this process appear to be cAMP and Ca +. The H2 receptor is coupled to the adenylate cyclase system (Chapter 30), and its activation results in the intracellular elevation of cAMP concentration. Stimulation of cholinergic receptor systems is coupled to increased Ca + permeability. 

AChE is located strategically within the synapse to exert tight control over cholinergic neurotransmission, Because AChE is one of the most active of all enzymes (each molecule can hydrolyze approximately 5000 molecules of ACh per second) (Cooper el al., 2003), ACh molecules have a very short half-life in the synapse and a consequent transient ability to activate cholinergic receptors. Upon hydrolytic cleavage of the ACh molecule, chtiliuc and acetic acid are released into the synaptic space, after which choline is transported effectively back into the presynaptic terminal by a HACU process, ACh is therefore panially recycled, increasing metabolic efficiency. 

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