Elemental distribution in frozen-hydrated mouse lenses with hereditary cataract.

Abstract

Nakano mice (nct/nct) and its congenic strain (Balb/c-nct/nct) develop different types of cataract: the former develop intense nuclear cataract but the latter develop milder opacity at the cortical region of lenses more later in life. The present study was undertaken to compare the elemental compositions at the localized region of these lenses in order to examine the possible role of ions in the opacification of the hereditary cataracts. Eight lenses from Nakano mice (age: 39-40 days) and ten lenses from congenic mice (age: 73 days) were prepared for the X-ray analysis with a high energy ion microprobe at a resolution of 50 microns. The age of mice was two weeks after 50% cataract formation for the respective strain. The maps of the concentrations of S, Cl, K and Ca in the central planes of the frozen-hydrated lenses were obtained. In all of the congenic lenses analyzed, the normal elemental composition, low Cl and Ca, and high K, was retained only in the narrow anterial and equatorial peripheral region and the other region underwent a K loss with a gain of Cl and Ca. In the Nakano lenses, the altered elemental composition was localized in central and in posterial cortical regions. There was no distinct difference in the concentration levels of Cl, K and Ca in the central region of the lenses between the two strains. The level of S was lower in Nakano lenses. High calcium containing spots were detected in low K regions of some of the lenses examined.