Organophosphate metabolic changes in the rat lens during the development of galactose-induced cataract

Using phosphorous-31 nuclear magnetic resonance (31P-NMR) spectroscopy, we observed the metabolic kinetics of organophosphate compounds in the rat lens during cataract development induced by different doses of galactose (5%, 15%, 25%, and 40%) added to rat chow. The metabolic and histologic changes in the lenses were compared among the rats fed with different doses of galactose. alpha-Glycerophosphate significantly increased in response to the galactose doses, followed by a decrease to steady values of approximately 120% of the base line value, except in the 40% galactose group, which had a marked decrease to 68% of the base line value. Choline phosphate decreased rapidly during dosing in all but the 5% group, but no changes in those levels were observed after 2 weeks of galactose dosing. ATP decreased significantly when the histologic destruction progressed in the entire lens. Although inorganic phosphate increased significantly in a dose-dependent manner, it did not exceed the peak level. The histologic changes were closely related to the dynamic changes in the phosphorous compounds in the rat lens during formation of the galactose-induced cataract. Our results indicated that the development of a galactose-induced cataract was associated with the metabolic changes of the phosphate compounds.