Synergism of UV Radiation and Heat for Cell Inactivation

Organisms including human beings are constantly exposed to UV radiation. The potential hazards of UV radiation have risen due to a depletion of the protective ozone layer in the stratosphere and the formation of ozone holes. Moreover, the effect of UV radiation may greatly increase due to synergistic interaction of UV radiation with other environmental factors. Fluence rate is known to constitute a very important parameter in photobiology. While it is generally accepted that lowering the UV radiation fluence rate results in a decrease of the cell killing or mutagenesis efficiency per unit dose, the matter is still unclear with regards to the synergistic interaction of UV radiation and another environmental agent. It is of great interest to investigate whether or not the synergistic interaction can take place at low intensities of such environmental factors. Heat is known to be an important modifier of UV radiation sensitivity. Exposure of skin to UV radiation is often encountered at hot ambient temperatures. Therefore, the elucidation of new fundamental aspects of the simultaneous action of UV radiation and heat is an actual task. Thus, the purpose of the present work was to establish whether the UV fluence rate alters the synergistic interaction between heat and UV radiation for cell inactivation