Hemicholinium-3

Hemicholinium-3 is a drug which blocks the reuptake of choline by the high affinity transporter ChT at the presynapse. The reuptake of choline is the rate limiting step in the synthesis of acetylcholine; hence, hemicholinium decreases the synthesis of acetylcholine. It is therefore classified as an acetylcholine antagonist.

Acetylcholine is synthesized from choline and a donated acetyl group from acetyl-CoA, by the action of choline acetyltransferase (ChAT). Thus, decreasing the amount of choline available to a neuron will decrease the amount of acetylcholine produced. Neurons affected by hemicholinium must rely on the transport of choline from the soma (cell body), rather than relying on reuptake of choline from the synaptic cleft.

Hemicholinium is frequently used as a research tool in animal and in vitro experiments.