Lactate Dehydrogenase Activity in the Epidermis of Mouse Ear Exposed to Monochromatic Wavelengths of Ultraviolet Light

The lactate dehydrogenase activity in mouse ear epidermis exposed to monochromatic wavelengths of ultraviolet light was determined. The wavelengths used in this experiment were between 260 and 380nm at intervals of 20nm. The exposure energy was 50 millijoules per cm 2 for each wavelength. Ultraviolet light exposure caused an immediate increase in enzyme activity, which remained above normal for at least 3hr post exposure. The greatest increase in enzyme activity was observed at 280nm, whereas activity remained close to the normal level at 320nm. The effect of 8-methoxypsoralen injected intraperitoneally prior to ultraviolet exposure was determined. Lactate dehydrogenase activity was significantly higher in 8-methoxypsoralen-treated mice than in untreated controls. The increase in enzyme activity associated with 8-methoxypsoralen administration was found to be maximal between 320nm and 340nm.