DOSE-RESPONSE, WAVELENGTH DEPENDENCE, AND TIME COURSE OF ULTRAVIOLET RADIATION-INDUCED UNSCHEDULED DNA-SYNTHESIS IN MOUSE SKIN INVIVO

  • 1 January 1984
    • journal article
    • research article
    • Vol. 44  (5) , 2150-2154
Abstract
A new method for autoradiographic measurement of unscheduled DNA synthesis (UDS) in the skin in vivo after treatment with UV light was developed. The skin of the back of ICR mice was shaved and exposed to short-wave UV (254 nm) or UVAB (sunlamp, 270-440 nm, predominant emission at 312 nm) at various doses. Immediately after irradiation, an isotonic aqueous solution of [methyl-3H]thymidine was injected s.c. into a portion of the skin clamped off with ring-shaped forceps. By this method, dose-dependent UDS was clearly demonstrated as Ag grains on various types of cells in the skin in response to 254 nm UV or sunlamp UV. The energy values at the 2 wavelengths required to induce the same UDS level differed by 1 order of magnitude. This system should be useful for quantitative analysis of UV-induced DNA repair in individual cells of the skin in vivo. By this method, the wavelength difference in transmissibility was studied. Autoradiographic results clearly showed that sunlamp UV could reach deeper sites in the skin than did 254 nm UV. A time course study indicated that UDS was almost complete by 48 h after 254 mm UV but still persisted at 48 h after sunlamp UV. These results, together with the differences in transmissibility, support higher tumorigenic activity of sunlamp UV than of 254 nm UV to experimental animals.