[Effect of high-dose parenteral fructose, glucose and mannitol on the rat kidney].

As previously observed after infusions of glycerol, fructose infusions with rates above the average maximal turnover capacity (3.5 g X kg-1 X h-1) result in damage of the kidneys as shown by a decrease of the total activity of glycerokinase and fructokinase and excretion of glycerokinase in the urine. Beginning alterations of the kidneys are dependent on time and dose become evident by a depletion of protein per gram fresh weight. In the beginning of the changes the total activity of enzymes in the kidneys remaining constant. Interrelations between the observed kidney alterations, turnover capacity, substrate concentrations in the blood, and the rate of renal excretion are discussed with regard to the results after infusions of glucose and mannitol. For infusion therapy it can be deduced, that dosage in borderline cases should be determined by the blood level of the substrate rather than by body weight, if undesirable effects are to be avoided.