Lipid composition and (Na+ + K+)-ATPase activity in rat lens during triparanol-induced cataract formation

The development of triparanol cataracts in rats is accompanied by the loss of lens (Na+ + K+)-ATPase activity and by alteration in the lens content and composition of phospholipids, sterols and phospholipid acyl groups. The lipid changes occur along the same time course as the loss of (NA+ + K+)-ATPase activity. Triparanol feeding produces a decrease in lens phospholipid content. The percentage contents of phosphatidylcholine and phosphatidyl-serine decrease while the content of sphingomyelin substantially increases. The amounts of oleic acid in lens phospholipids decrease while stearic and palmitic acids increase; however, these changes are relatively small. Sterol content is also decreased while the percentage content of desmosterol increases markedly. Feeding of the cataractogenic agents galactose and diazacholesterol also alters the lens lipid compositions and (Na+ + K+)-ATPase activity. A loss of phosphatidylserine is the only change in lipid properties which always accompanies a loss of the enzyme activity. The possible relationships between the lens content of phosphatidylserine, (Na+ + K+)-ATPase activity and the mechanism of triparanol-induced cataract formation are discussed.