Comparison of posttetanic changes of the acetylcholine-induced inward current (ACh-current) in command Helix lucorum neurones at different conditions (using stop flow of saline through the chamber with a ganglia preparation and using flow of saline) was made. Flow of saline reduces latency and degree of posttetanic increase of the ACh-current in neurones. Earlier and weak posttetanic potentiation of the ACh-current in command Helix lucorum neurones during flow of saline through the chamber with a ganglia preparation testifies to participation of the humoral factor in the mechanism of posttetanic potentiation of cholinosensitivity of somatic membrane in postsynaptic neurone.