Abstract
To investigate the mechanism of senile cataract formation in human, detailed knowledge of biochemical changes occuring during opacification is first required. In the present paper, this subject is discussed in regards to opacity-related changes of cations, adenosine-5'-triphosphate (ATP) and glutathione, reduced form (GSH) in various types of human senile cataracts. Early cataract lenses had normal cation levels. However, when lenses were separated into nucleus and cortex, cation levels of the nucleus were higher than those of cortex in all stages of cataract. GSH level in lenses of the early cataract stage had already decreased, and its level in the anterior cortex region more decreased clearly compared with other regions of the mature cataract. ATP level in the lens decreased suddenly in the mature cataract. These results suggest that ATP levels are the same in all regions of the lens. In the nucleus during all stages of cataract, both GSH and ATP levels were always of a constant value. These levels were lower compared with other regions. Mg-ATPase maintained the same activity in the early cataract lens during all stages of cataract. However, Na, K-ATPase activity decreased remarkably in the immature cataract lens. These phenomena agreed with changes in the levels of Na+ and K+ during the cataract process. These results, when compared with those reported in our previous papers, illustrate the great difference in biochemical parameters of the human senile cataract by comparing it with the experimental cataract of animals. Taken together, these results, therefore, suggest the presence of many factors that may play a role during cataract formation in the human lens.
