Spectra of voltage-sensitive fluorescence of styryl-dye in neuron membrane

The voltage sensitivity of fluorescence of an aminobenzstyryl-pyridinium dye (di4-ANEPPS) is characterized in Retzius cells dissociated from the leech. The modulation of the complete spectra of excitation and emission is determined. The spectral changes induced by depolarization are described by a blue shift of the absorption spectrum, by a weaker blue shift and an enhanced width of the fluorescence spectrum and by a decrease of the yield of fluorescence. These changes are attributed tentatively to a superposition of electrochromism and of field-induced resolvation.