FLOW CYTOMETRIC ANALYSIS OF CELL-SUSPENSIONS EXPOSED TO SHOCK-WAVES IN THE PRESENCE OF THE RADICAL SENSITIVE DYE HYDROETHIDINE

The occurrence of intracellularly and extracellularly generated free r adicals during shock wave exposure on an experimental Siemens lithotri pter was tested with the radical sensitive dyes hydroethidine and dich lorofluorescin (DCFH). DCFH, a nonfluorescent compound, is oxidised to dichiorfluorescein (DCF) by hydrogen peroxide in the presence of pero xidase. DCF green fluorescence intensity was used for fluorescence spe ctrometric measurement of hydrogen peroxide generated during shock-wav e treatment of cell-free dye solutions. The fluorescence intensity of ethidium, the oxidised form of hydroethidine, was used for the flow-cy tometric measurement of intracellular oxidising reagents present in RT 4 tumour cells during shock-wave exposure. Changes in membrane permeab ility, which influence the intracellular content of ethidium, were con trolled by counterstaining the cells with propidium iodide, an indicat or for membrane integrity. We observed no increase in intracellular et hidium fluorescence intensity after shock-wave treatment of single cel l suspensions and therefore no indication for shock-wave-induced intra cellular free radicals.