[The modulating action of serotonin on single calcium channels in the neurons of the snail Helix pomatia].

The influence of a neurotransmitter serotonin (5-hydroxytriptamine, 5-HT) on single Ca2+ channel activity was studied on unidentified neurons of the snail Helix pomatia. Our findings showed that 5-HT influences the channel molecule in indirect manner, as it appeared effective at its application by adding to the bath solution, that had no contact with the tested membrane fragment. This finding excludes the possibility of direct binding of 5-HT to the channel molecule and shows that the effect is really mediated through a cytoplasmic messenger, cAMP-dependent cascade of phosphorylation. Also our investigations shows, that only one type of Ca2+ channel with the unitary conductance of 5 pS was identified in this kind of neurons.