[The fate of intravenously-administered sugar as energy source (author's transl)]

10 micromoles of 14C-U-labelled maltose, glucose, fructose and galactose were injected intravenously into rats and it was found that more than 10% was exhaled as CO2 within 60 minutes and about 50% within 24 hours. Anaesthesia lowers the values by one third. The main amount of 14C is found in the liver. By comparison, only 0.24% and 0.17% were metabolized to CO2 within 60 minutes from sucrose and lactose respectively, whilst within 24 hours the equivalent figures were 2% and 3%. This small turnover persists after removal of the gut, as was demonstrated by an additional series of 1-hour experiments and is judged to signify parenteral hydrolysis of sucrose and lactose molecules. For both disaccharides the 1-hour renal excretion ranges from 66% to almost 100% compared with a range of 1.2% to 4.3% for glucose, maltose, fructose and galactose. Using 3-O-methylglucose, only 0.025% of the dose was exhaled as CO2 within 60 minutes, a quantity small enough to be due to contamination of the sample. Apart from glucose and fructose, maltose is considered to be useful for parenteral nutrition.