OSMOTIC EFFECTS OF A LIQUID DIET IN AN ETHANOL TREATMENT STUDY

Fischer 344 male rats were fed a liquid diet containing either sucrose (Sucrose group) or ethanol (Ethanol group) in equicaloric amounts or chow ad lib (Chow group). Treatment was begun at three months of age a nd continued for approximately 26 weeks. At the end of this time one r at from each group was subjected to magnetic resonance imaging (MRI). All rats were weighed weekly; and once each week 24 hour urine volumes were collected along with tail vein blood for measurement of renal fu nction. After euthanasia brains and kidneys were removed, kidneys diss ected into cortex, outer medulla and inner medulla and sorbitol and in ositol measured in these tissues. The results demonstrated that the Su crose group gained weight at a significantly greater rate than either of the other two groups. This was associated with large accumulation o f fat when visualized by MRI. The major effect on renal function was a continual osmotic diuresis resulting from the liquid diet and accordi ngly plasma osmolalities were significantly greater in the Sucrose and Ethanol groups than in the Chow group. Small but significant decrease s in sodium and potassium excretion were found for the Ethanol group w hen compared to the Sucrose Group at 25 to 26 weeks. Prolonged exposur e to high plasma osmolalities was also associated with an apparent dow n regulation of intracellular sorbitol and inositol concentrations, si nce these polyols were significantly lower (less than half the concent ration) in the brain and kidneys of the Sucrose and Ethanol groups tha n in the Chow group.