Studies on the Crystalline Lens. Fate of Glutathione in Parathyroid Cataract

It is well established that in senile cataract two of the principal biochemical changes are (1) a great increase of calcium and (2) an apparent total loss of glutathione. 1 Evans and Kern 2 demonstrated that in experimentally produced parathyroid cataract (by extirpation of the parathyroid glands), the calcium content of these cataractous lenses increased to approximately 25 times the amount present in normal dog lens.

It is probable that glutathione plays a definite rôle in the internal oxidation-reduction and enzymie reactions of the lens (initially suggested by Goldschmidt 3 ). We were therefore naturally interested to learn the fate of the glutathione of the crystalline lens after removal of the parathyroids. Preliminary study indicated that the normal dog lens contains approximately 0.385% reduced glutathione, and that any figure considerably below this might be considered as indicating a loss of glutathione from the lens. The opportunity to study the fate of glutathione in parathyroid cataract was afforded by the early development of bilateral lenticular opacities in 5 young dogs (2 mos. old) that had been thyroparathyroideetomized in connection with another study. A complete description of these lenticular changes has been made elsewhere. 4

At the time the dogs were sacrificed because of severe distemper, they had been without parathyroids for 57-152 days. The earliest signs of lenticular degeneration were evident at about the 25th day. The dogs were kept on a sour milk-bread-liver diet; tetany was not observed. 5 The dogs were sacrificed by the intravenous injection of small amounts of sodium cyanide. Immediately after death the eyes were excised, the crystalline lenses removed and weighed on a watch glass.