Zinc–desferrioxamine reduces damage to lenses exposed to hyperbaric oxygen and has an ameliorative effect on catalase and Na, K-ATPase activities

Abstract

Our purpose was to investigate the effects of exposure to high partial pressure of oxygen on lens optical quality and on the activities of lenticular catalase and Na, K-ATPase in culture and to examine the effect of zinc–desferrioxamine (Zn–DFO) addition to cultured lenses exposed to high oxygen partial pressure on these parameters. Bovine lenses, kept in organ culture, were exposed to different combinations of partial pressure of oxygen with and without addition of Zn–DFO complex (20 μM) and examined during a 14-day period. Lens optical quality, catalase, and Na, K-ATPase activity were compared between study and control groups. Two hundred lenses were included in the present study. Decreased lenticular optical quality and decreased catalase and Na, K-ATPase activities were observed in lenses exposed to hyperbaric oxygen. Lenses exposed to normobaric oxygen showed a reduction in these parameters to a lesser degree. The damaging optical and enzymatic effects of oxygen on lenses in culture increased in magnitude along the culture period. Addition of Zn–DFO to the culture just before the exposure to hyperbaric oxygen eliminated most of the optical and enzymatic oxygen-induced damage. Addition of Zn–DFO after the first exposure demonstrated reduction in the oxidative damage induced reduction of optical quality in a time-dependent manner – the later the addition of Zn–DFO took place the smaller the protective effect observed. High oxygen load has toxic effects on bovine lenses in organ culture conditions as determined by optical parameters as well as reduction of catalase and Na, K-ATPase activities. These toxic effects can be attenuated by introducing Zn–DFO just before lenses are exposed to oxygen. The beneficial effect of Zn–DFO, applied after lenses have been exposed to hyperbaric oxygen, on the oxidative damage was time-dependent – the earlier the application the more significant the observed protective effect. The present results may indicate a possible future role for Zn–DFO as a protective agent against oxygen-induced human cataract formation.