[Effect of ultraviolet light on the hamster pupil]

This is the first study on the effects of ultraviolet light (UV) on the hamster pupil in vivo and in vitro. UV caused constriction of the pupil even after the death of the hamster. Both visible light and UV induced myosis of the enucleated hamster eyes. UV-induced miosis occurred very late and continued after the cessation of UV stimuli. The UV-induced miosis was not significantly affected by ascorbic acid, catalase, allopurinol, but it was gradually inhibited by procaine or quinacrine, phospholipase A2 inhibitors. Withdrawal of Ca2+ and Mg2+ with EGTA and/or EDTA strongly inhibited the UV-induced miosis. This study suggests that the UV-induced miosis was not related to oxidative stress, but related to a second messenger via the muscle cell membrane.