Changes in serotonin concentration in a living neurone: a study by on-line intracellular voltammetry.

Intraneuronal concentration of serotonin (5-HT) and its changes were measured in live serotonergic metacerebral cells of Aplysia for several hours following neuronal stimulation, after intracellular injection of 5-HT or extracellular application of L-tryptophan, reserpine, or p-chlorophenylalanine. This was achieved by an on-line intracellular differential pulse voltammetric method using a new, needle-tipped and glass-insulated, platinum microelectrode sensitive to 5-HT.