Penetration and localization of furocoumarins in single living cells studied by microspectrofluorometry

The microspectrofluorometric technique has been used to study the penetration and the localization of psoralen, 4,5',8-trimethylpsoralen and 4'-aminomethyltrioxsalen in single living L-cells. The concentration of the different compounds inside the cell reached a plateau in 2 min with psoralen and aminomethyltrioxsalen and in 20 min with trioxsalen. Washing of the cells with culture medium produced only a partial removal of the three furocoumarins, distributed apparently in equivalent amount in the nucleus and cytoplasm.