Measurements of reduced pyridine nucleotides in a single neuron

The microfluorimetric technique to measure the intracellular oxidation-reduction state of pyridine nucleotides was applied to the isolated neuron preparation which is provided by the stretch receptor organ of the crayfish. The method allows the simultaneous recording of impulse activity. Emission spectrum of the fluorescence and the behavior of the fluorescence with continuous ultraviolet exposure were studied. Glycolytic, Krebs-cycle and respiratory inhibitors were used to investigate the cell metabolism. It was found that the fluorescence level is not altered under several conditions known to affect in other preparations the oxidized pyridine nucleotide/reduced pyridine nucleotide ratio. While Amytal and anoxia were shown, as expected, to increase the reduced pyridine nucleotides, terminal inhibitors of the cytochrome chain were ineffective. Sustained impulse activity did not alter the fluorescence level although the O₂ uptake is increased.