Summary. 1. The effect of parenteral administration of fructose and sorbitol on hepatic adenosine phosphates (AP) and intermediates of carbohydrate metabolism was examined in man and rat.—2. Intravenous injection of fructose rapidly decreases ATP, total adenosine phosphates (AP), and inorganic phosphate in the liver of fed male and female rats. The depletion in hepatic ATP and total AP is also observed in the regenerating rat liver following partial hepatectomy. Equimolar administration of sorbitol has the same effect on liver AP has that observed following fructose, while glucose administration produces no significant changes.—3. In man i.v. infusion of 0.6–0.8 g/kg body weight of fructose or sorbitol reduces hepatic ATP to about 50 %, and total AP to about 65 % of initial values. Glucose has no effect. Blood AP content is not affected by intravenous infusion of 500 ml of 10 % fructose in man.—‐4. Fructose distinctly increases the content of various hexose phosphates and triose phosphates in the liver of man. Fructose‐1‐phosphate accumulates 4‐to 5‐fold and α‐glycerophosphate 3‐fold during infusion of 0.6–0.8 g/kg body weight of fructose within 30 minutes.—5. RNA‐synthesis in the regenerating rat liver following partial hepatectomy as neasured by incorporation of 6‐14C‐orotic acid is distinctly inhibited by i. v. injection of 1.6 g of fructose kg. The incorporation rate of 1‐14C‐D, L‐leucine into rat liver protein drops to 35 % of initial levels within 10 minutes after the same amount of fructose, whereas glucose has no inhibitory effect.—6. Both ATP and Pi are important inhibitors of AMP degradation. Thus the drop in total AP content can be explained by the increased breakdown of the latter. This assumption is supported by the observation that injection of fructose plus equimolar amounts of Pi reduces the decrease in total AP, but not in ATP content. The concentration of the final product of AMP degradation, uric acid, increases distinctly following i. v. fructose administration in man.—7. These results indicate that in clinical medicine infusion of large doses of fructose or sorbitol have more disadvantages than advantages compared to glucose.

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Parlcsak and Bode: Gut pcrmeabiiity of K 400, M r 1500, M r 4000 and M r 10000 polyethylene glycol in man 813 Eur. J. Clin. Chcm. Clin. Biochem. Vol. 32, 1994, pp. 813-820 © 1994 Summary: Polyethylene glycol has been in use for a number of years for the assessment of gut permeability. The methods so far employed are usually limited to polyethylene glycols in the low relative molecular mass r nge (up to M T 1300). We developed a method for the simultaneous determination of gut permeability to M r 400, M r 1500, Af r 4000 and M r 10000 polyethylene glycol, by applying a single oral dose of an appropriate mixture of these polyethylene glycols. After extraction from 24 h-urine, M T 1500, A/ r 4000 and M T 10000 polyethylene glycol were quantified by size exclusion chromatography, while M r 400 polyethylene glycol was determined by reversed phase chromatography. The detection limit of polyethylene glycol in the relative molecular mass r nge between M r 1500 and Μ τ 10000 was found to be 0.2 mg/1 urine, and the detection limit of Af r 400 polyethylene glycol 5 mg/1 urine. Recovery of the polyethylene glycols (N = 6) were 86.6% (CV: 4.8%) for H 400, 94.1% (CV: 7.2%) for M r 1500, 97.1% (CV: 5.5%) for M r 4000 and 97.4% (CV: 5.6%) for M r 10000.

The influence of feeding isocaloric diets containing either 65% of fructose (F 65) on 65% of glucose (G 65) were studied on the uptake of both sugars in segments of rat proximal jejunum and distal ileum. The hexose absorption was compared to that obtained in animals receiving isocaloric amounts of a diet containing 30% of glucose (G 30). Feeding fructose (F 65) for 3 days resulted in a 2.5-fold increase of fructose uptake in the jejunum and a 40% increase in the ileum as compared to group G 30. When fructose (F 65) was administered instead of G 65 the uptake of fructose was enhanced by 75% in the jejunum and 35% in the ileum. Stimulation of glucose absorption in segments of the proximal and distal small intestine by diets F 65 and G 65 was nearly identical as compared to the values of group G 30. The stimulation of the uptake of fructose induced by fructose feeding parallels an adaptive increase in the activity of enzymes involved in fructose metabolism in the mucosa of the small intestine.

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