The effects of UVB and UVA on the scheduled and unscheduled DNA synthesis of mouse epidermal cells

Kim, Kyu Han; Kim, Bang Soon; Moon, Sang Eun; Youn, Jai Il

Abstract

After UV irradiation to mouse epidermis, autoradiography using H-thymidine was performed to study the effects of UV on scheduled and unschcdu ed DNA syntheses. The results can be summarized as follows. l. In case of UVB 100mJ/cm, heavily labeled cells (HLCs) representing scheduled DNA synthesis began to decrease immediately after UVB irradiai,ior and were significantly decreased after 24 hours, but then recovered after 48 hours. The ecovery was maintained from 72 hours, up to 7 days. Sparsely labeled cells (SLCs) repres inting unscheduled DNA synthesis were significantly increased from immediately after UV 3 irradiation and up to 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/cm did not affect DNA synthesis sign ficantly. But in cases of UVA 30J/cm and 50J/cm, HLCs began to decrease immediately after UVA irradiation and were significantly decreased for 24 hours. Recovery occured at 48 hours, and was maintained from 72 hours up to 7 days. SLCs were significently 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 ir rad ation.