Nitrite and Nitrate Levels in Individual Molluscan Neurons: Single‐Cell Capillary Electrophoresis Analysis

: Cell and tissue concentrations of NO2− and NO3− are important indicators of nitric oxide synthase activity and crucial in the regulation of many metabolic functions, as well as in nonenzymatic nitric oxide release. We adapted the capillary electrophoresis technique to quantify NO2− and NO3− levels in single identified buccal neurons and ganglia in the opisthobranch mollusc Pleurobranchaea californica, a model system for the study of the chemistry of neuron function. Neurons were injected into a 75‐µm separation capillary and the NO2− and NO3− were separated electrophoretically from other anions and detected by direct ultraviolet absorbance. The limits of detection for NO2− and NO3− were