Enzymatic Changes in Beta-Irradiated Epidermis of Guinea Pigs: Extracellular and Intracellular Deoxyribonucleases I and II

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Abstract
Epidermal DNases I and II of albino guinea pigs were separated into extra- and intracellular fractions by washing excised whole tissue with 0.24 [image] sucrose, prior to homogenization. After a single skin surface dose ( in vivo) of 3000 rep of [beta]-radiation from a Sr90-Y90 sealed source, there was a progressive increase in activity of extracellular DNase I. A significant increment occurred as early as the first day, well before any detectable histologic changes; it reached a peak, about 6.5 times the control value, by the 10th day, and remained at this level to the 60th day. Intracellular DNase I.increased about twofold by the tenth day. Extracellular DNase II activity was not significantly affected by 3000 rep of [beta]-radiation, but there was significant decrease in intracellular DNase II 24 hours after irradiation; it remained at a lower level to the 60th day. The 2 mechanisms most likely to account for the increase in extracellular DNase I were considered to be an increase in dermal vascular permeability and or release of the enzyme from dead and dying epidermal cells.