After UV irradiation to mouse epidermis, autoradiography using H3-thymidine was performed to study the effects of UV on scheduled and unscheduled DNA syntheses. The results can be summarized as follows.
1. In case of UVB 100mJ/㎠, heavily labeled cells (HLCs) representing scheduled DNA synthesis began to decrease immediately after UVB irradiation and were significantly decreased after 24 hours, but then recovered after 48 hours. The recovery
was
maintained from 72 hours, up to 7 days. Sparsely labeled cells (SLCs) representing unscheduled DNA synthesis were significantly increased from immediately after UVB irradiation and up 6 hours later. Repair was present at 24 hours, and was
maintained at
48 hours. 72 hours. and 7 day after irradiation.
2. In case of UVA, UVA 10J/㎠ did not affect DNA synthesis significantly. But in cases of UVA 30J/㎠ and 50J/㎠, HLCs began to decrease immediately after UVA irradiation and were significantly decreased for 24 hours. Recovery occurred at 48
hours,
and
was maintained from 72 hours up to 7 days. SLCs were significantly increased immediately after and up to 6 hours after UVB irradiation. Repair generally occurred after 24 hours. and was maintained at 48 hours, 72 hours, and 7 days after
irradiation.
(Kor J Dermatol 1992:30 (2) : 186-196)
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