Aspects of Fructose Metabolism in Normal Man

Abstract.In normal subjects infusion of fructose (1 g/kg/hr) for 4 hrs resulted in an increase in the glycogen content of them. quadriceps femorisof 3.3 g/kg wet muscle (muscle samples obtained by needle biopsy). This was equal to the amount of glycogen formed after a glucose infusion of the same magnitude. In muscle depleted of glycogen by exercise, infusion of glucose resulted in twice as much glycogen formed, as did a fructose infusion. Formation of liver glycogen was much higher after fructose than after glucose infusion (liver samples obtained by Menghini biopsy). Studies by hepatic vein catheterization indicated that glucose formation by the liver was insufficient to account for the synthesis of muscle glycogen, which presumably occurred directly from fructose taken up by the muscle. The occurrence of high lactic acid concentrations in blood resulting from infusion of fructose could be partly abolished by simultaneous infusion of amino acids, thus lessening the risk of lactic acidosis.