Dynamic changes in the organophosphate profile of the experimental galactose-induced cataract

Dynamic changes in lens organophosphate metabolites during 24 hr incubation in 30 mM galactose media were measured with phosphorus-31 nuclear magnetic resonance spectroscopy. The following phosphates were quantitated from the intact crystalline lens: adenosine triphosphate (ATP), adenosine diphosphate (ADP), inorganic orthophosphate, alpha-glycerophosphate, phosphorylated hexoses and trioses, nicotinamide adenine dinucleotide, uridine diphosphoglucose and uridine diphosphogalactose, glycerol-3-phosphorylethanolamine and 3-phosphorylcholine, and an unidentified phosphorus-containing molecule. The temporal sequences of metabolic events that define the dynamic rates of accumulation or depletion of lens organophosphates reveal that the first event in the decline of the tissue upon galactose incubation is a net consumption of ATP, which occurs as a sigmoidal function with time and which is typified by a characteristic half-life of 18 hr. Alpha-glycerophosphate accumulated at an increasing rate with time, whereas ADP, inorganic orthophosphate, and the other organophosphates were essentially unchanged. Cataract formation in the subcapsular and superficial cortical regions was visible after 16 hr incubation in the experimental buffer. These findings support the hypothesis that alterations in the organophosphate levels of the lens are contributing factors to the initial formation of the experimental galactose cataract.