CHOLINERGIC NEUROHUMORAL TRANSMISSION Biosynthesis and Transmission of Acetylcholine • acetylcholine is biosynthesized by the acetylation of choline catalyzed by choline acetyltransferase and acetylcoenzyme A as an acetyl donor • choline accumulates in axoplasm by uptake process from extraneuronal sites • ACh accumulates in storage vesicles • action potential ------------ influx of Ca 2+ ---------------- release of ACh from vesicles • ACh in synaptic cleft is rapidly metabolized by acetylcholinesterase Synaptic Transmission at Cholinergic Synapse 1. Synthesis of neurotransmitter - Acetylcholine (ACh) a. Choline transported into presynaptic terminal. Hemicholinium inhibits transport. b. ACh synthesis from choline and acetyl-CoA is catalyzed by choline acetyltransferase (CAT). Transport and storage of ACh into vesicles in nerve terminal. Vesamicol b