Prevention Of Calcium-induced Cataract By E-64d-an Inhibitor Of Calpains

Objective To investigate the protective effect of E-64d on calcium-induced cataract and its possible mechanism.Methods 16 paired rabbit lense were randomly divide into two group, One lens from each match lens pair was incubated in sterile supplemented 1640 medium, containing Cacl₂ with concentrations that varied between 5 and 40mM, The remaining lens of each matched lens pair was placed in 1640 medium ,The transparency of lens were observed at 12,24,36hours. 24 paired rabbits lens were randomly divide into two group, One lens from each match lens pair was incubated in sterile supplemented 1640 medium, containing Cacl₂ with concentrations that varied between 5 and 30mM. The remaining lens of each matched lens pair was placed in a corresponding solution except that the calpain inhibitor , E-64d had been added. The opacification and relative gray level of the two group lens were observed and tested. The Ca²⁺ content of the two group lens was measured by Atomic absorption spectroscopy.Results The transparent lens which had been incubated in 1640 medium alone showed no evidence of opacification. However, when incubated in 1640 medium supplemented with increasing levels of Cacl₂(5-40mM), lens showed cleared evidence of progressive opacification. Opacity of lens was enhanced in 36 hours when incubated with 1640 mediun containing E-64d.There were significant difference of relative gray scale between calcium-induced and control group( p< 0.01),However, The calcium-induced group and control group had no significant effect on Ca²⁺ uptake by lens(p > 0.05).Conclusion The high levels of extralenticular calcium can induced cataract. E-64d, an inhibitor of calpain, can inhibit calcium-induced opacity of lens, However E-64d had no significant effect on Ca uptake by lens. Its inhibitory effect on lens opacification may be due to a direct action on the activity of calpain. Moreover, Maybe it can inhibite degeneration of crystallin or apoptosis and necrosis of epithelial cell by other approaches to prevent the occurrence of cataract.