Fig. 6

a Fluorescence emission spectra of acridine orange (5 µM) in the standard salt solution before and after application of NDs (0.05–1.0 mg/ml). b Quenching of fluorescence signal of acridine orange in the presence of NDs (0.05–1.0 mg/ml) without synaptosomes; c acidification of synaptosomes in the presence of NDs (0.05–1.0 mg/ml); d an increase in the fluorescence signal of acridine orange in response to application of NDs (0.05–1.0 mg/ml). The synaptosomes were equilibrated with acridine orange (5 µM); when the steady level of the dye fluorescence had been reached, NDs at concentrations 0.05–1.0 mg/ml (arrows) were added. Trace represents four experiments performed with different preparations. Data is mean ± SEM. *p < 0.05 as compared to the steady level of the dye fluorescence