Estimation of free dopamine in the cytoplasm of the giant dopamine cell of Planorbis corneus by voltammetry and capillary electrophoresis.

Voltammetric electrodes having a tip diameter of 2-12 microns and microscale capillary zone electrophoresis have been used for dynamic and static monitoring of dopamine in the somal cytoplasm of the giant dopamine neuron of Planorbis corneus. Intracellular dopamine levels can be altered by extracellular application of dopamine or ethanol. The latter experiment provides a means to estimate total stores of endogenous dopamine, and the evidence presented suggests that at least 98% of these stores are bound and not directly accessible to the cytoplasm.