Reversal of triparanol-induced cataracts in the rat. II. Exchange of 22 Na, 42 K, and 86 Rb in cataractous and clearing lenses.

The cataract which develops in the rat fed triparanol is accompanied by a marked increase in sodium and a more modest decrease in the potassium. Sodium is excreted as the lens clears and potassium returns to normal. Initially triparanol causes an increaese in permeability to cations. This appears before the lens becomes cataractous. Permeability returns to normal as the lens clears. In the cataractous lens the cation pumps are accelerated. The data are compatible with the view the there are two sodium pumps, one which is ouabain insensitive and excretes sodium plus chloride from the lens, and another which is ouabain sensitive and is involved in exchange of equivalent units of sodium and potassium. The cataract develops when the ouabain-insensitive pump is either overwhelmed by the increased permeability or ceases to function.