Acetylcholine
Neurotransmitter of the interneuronal and neuroeffective signal transmission to acetylcholine receptors. Essential transmitter in the vegetative nervous system, especially in the parasympathetic nervous system.
Acetylcholine is not only a neurotransmitter of the vegetative ganglia but also a neurotransmitter for the transmission of the nerve impulse from the efferent motor neuron to the muscle. In principle, it stimulates the acetylcholine receptors of the downstream structures.
Clinically, descendants of the arrow poison of the Indians, the curare, are used for muscle relaxation during anaesthesia. They competitively block the acetylcholine receptors at the motor endplates. This will force all muscles to relax.
Some insecticides irreversibly inhibit the enzyme that breaks down acetylcholine. The acetylcholine can then no longer be broken down at the motor end plates, which results in an increase in the neurotransmitter concentration. This can lead to a fatal muscle spasm.