Carbohydrate Metabolism in the Experimental Galactose Cataract

Abstract

ALTHOUGH the cataractogenic influence of galactose has long been appreciated^1,2,3, the mechanism whereby galactose exerts its effect on the ocular lens has not been clarified. It was recently shown that galactose-1-phosphate acts as, or gives rise to, an inhibitor of the enzyme glucose-6-phosphate dehydrogenase in the rat lens, both in vitro and in vivo ⁴. In order to investigate further the hexose monophosphate shunt in such lenses, six Holtzman strain white male rats, 27 days old and weighing approximately 55 gm. each, were placed on a high galactose diet⁵ while six similar animals were fed a control glucose diet⁵. One animal from each group was killed after 1½ days on its respective diet; their lenses were immediately removed, weighed, and placed in an incubation apparatus similar to the one employed by Kinoshita and Wachtl⁶. Each incubation tube contained 5 ml. Krebs Ringer bicarbonate buffer which had been gassed for 1 hr. with 5 per cent carbon dioxide, 95 per cent oxygen, in order to stabilize the pH at 7.5.