[Effect of synaptic activation and serotonin application on the calcium current in Helix neurons]

Changes in inward calcium current observed on the background of postsynaptic currents have been studied in snail neurons under voltage clamp conditions. It is shown that when inhibitory or excitatory postsynaptic current developed, the calcium current reversibly decreased. Application of serotonin to the neuronal soma has also led to a reversible block of the calcium current. Possible cellular mechanisms involved in the changes under study and their putative physiological role are discussed.