Retinal polyol and myo-inositol in galactosemic dogs given an aldose-reductase inhibitor.

Galactitol and myo-inositol concentrations were measured in retinas, erythrocytes, and skeletal muscle of experimentally galactosemic dogs receiving a placebo or the aldose reductase inhibitor, sorbinil, for 5 yr. The concentration of galactitol was increased more than 30-fold in the retina and other tissues by galactosemia, and the increase was inhibited 90-96% in all tissues by sorbinil. The concentration of free myo-inositol was greater than normal in retinas of galactosemic dogs, and its concentration was not altered by the aldose-reductase inhibitor. The myo-inositol concentration likewise was greater than normal in the retinas of dogs that were diabetic for 2-4 months. The marked inhibition of polyol production and accumulation in the retina of sorbinil-treated galactosemic dogs was not associated with a comparable inhibition of retinopathy.