The occurrence of intracellularly and extracellularly generated
free radicals during
shock wave exposure on an experimental Siemens lithotripter was tested with the radical sensitive
dyes hydroethidine and
dichlorofluorescin (DCFH). DCFH, a nonfluorescent compound, is oxidised to dichlorfluorescein (DCF) by
hydrogen peroxide in the presence of
peroxidase. DCF green fluorescence intensity was used for fluorescence spectrometric measurement of
hydrogen peroxide generated during
shock-wave treatment of cell-free
dye solutions. The fluorescence intensity of
ethidium, the oxidised form of
hydroethidine, was used for the flow-cytometric measurement of intracellular oxidising
reagents present in RT4 tumour cells during
shock-wave exposure. Changes in membrane permeability, which influence the intracellular content of
ethidium, were controlled by counterstaining the cells with
propidium iodide, an
indicator for membrane integrity. We observed no increase in intracellular
ethidium fluorescence intensity after
shock-wave treatment of single cell
suspensions and therefore no indication for
shock-wave-induced intracellular
free radicals.