[Analysis of the biological effect of city smog extract. V. Comparative investigations on the effect of city smog extracts on DNA synthesis of Syrian hamster kidney and embryonic cells and of African green monkey kidney cells in vitro (author's transl)].

We analysed the effect of two samples of city smog extract from Bochum and Duisburg on DNA synthesis of mammalian cells in vitro. As a test system we used tissue cultures of kidney and embryonic cells from the Syrian golden hamster and monkey kidney cells from Cercopithecus aethiops. DNA synthesis of cells was measured by autoradiography using 3H-Thymidine. Both samples of city smog extract exerted a dose-dependent decrease of the rate of DNA synthesis in tissue culture cells. These alterations of nucleic acid metabolism were expressed by a reduction of DNA-synthesizing cells and by a delay of entrance of cells in DNA synthesis. High concentrations of city smog extracts induced a large number of cell necroses. Monkey kidney cells were more sensitive to the toxic action than hamster cells. Furthermore the city smog extract from Duisburg showed a stronger toxic effect than the extract from Bochum.