[The role of intracellular processes in regulating neuronal sensitivity to acetylcholine].

Intracellular regulatory mechanisms of neuronal response to acetylcholine were studied on intracellularly perfused isolated neurones of Lymnaea stagnalis using voltage-clamp technique. It was found that at the change of concentration of free intracellular Ca2+ from 0.06 to 0.7 microM the inhibitory effect of intracellularly added serotonin depends on Ca2+, and the modulation of acetylcholine responses by intracellular serotonin is unchanged. The blockers of calmoduline trifluoperazine and W-7 inhibit inward acetylcholine current at both intra- and extracellular introduction. Possible mechanisms mediating the effect of intracellularly added serotonin on the membrane cholinoreceptors of neurones are discussed.