Distribution of total and non-freezable water contents of galactosemic rat lenses.

Abstract

Galactosemic cataracts were induced in Sprague-Dawley rats by keeping them on a 50% galactose diet for 36 days. The galactosemic rat lenses as well as normal rat lenses were sliced into 0.50 mm sections and differential scanning calorimetric (DSC) and thermogravimetric (TGA) measurements were performed. The TGA measurements gave the total water content. This was much higher in cataractous lenses than in normal lenses. The total water content also showed different gradients in normal and cataractous lenses. In normal lenses the percentage of water decreases as one proceeds from cortex to nucleus. In galactosemic cataractous lenses the trend is the opposite. The non-freezable (bound) water content was obtained as the difference between the total and freezable (DSC measurements) water content. In both cataractous and normal lenses the non-freezable water content increases when one proceeds from cortex to nucleus. It seems that most of the water influx generated by the accumulation of galactitol ends up as free water in lakes and pools rather than water of hydration.