Quantitative cytochemistry of enzymes in the epithelium of ageing rat lenses.

The activities of lactate dehydrogenase (LDH), glucose 6-phosphate dehydrogenase (G6PD) and glyceraldehyde 3-phosphate dehydrogenase (GAPD) in two zones of the epithelium of the lens of 6- and 27-month-old rats were measured using quantitative cytochemical methods. In both age groups, the epithelium in the equatorial zone showed the highest enzymatic activity. LDH activity was similar in young and old rats in both areas. G6PD and GAPD activities in the central area were similar in both age groups, but their activity was markedly lower in the equatorial zone in old rats compared to young ones. This decrease in G6PD and GAPD activities may play a role in cataract formation.