title: Metabolism of xylitol and glucose in rats bearing hepatocellular.
abstract: The variation in metabolism of glucose and xylitol by diverse rat hepatocellular carcinomas and partially hepatectomized rat livers was studied. The AS-30D and FB56 tumors demonstrated a significantly different degree of utilization of glucose and xylitol in vitro. This correlated partially with the low activity of polyol dehydrogenase when xylitol was used as a substrate. The activity ofa nicotinamide adenine dinucleotide-dependent polyol dehydrogenase in various hepatomas ranged from nondetectable to 30 nmol/min/mg protein, with the lower activities in FB56 and AS-30D tumors at 0 and 0.22 nmol/min/mg, respectively; while nicotinamide adenine dinucleotide phosphate-dependent xylitol dehydrogenase activities ranged from 0 to FB56 to 3.31 nmol/min/mg protein in liver regenerated for 1 week. The activities of nicotinamide adenine dinucleotide phosphate-dependent enzyme for normal liver and AS-30D tumors measured 2.2 and 0.14 nmol/min/mg protein, respectively. Although only the 311C tumor had an activity equivalent to that of normal liver, the range of the nicotinamide adenine dinucleotide phosphate-dependent polyol dehydrogenase activities among the cell lines studies is narrow. The ratios of metabolites of [14C]glucose or [14C]xylitol were determined in rats bearing AS-30D tumors. Animals were given i.v. injections of a 10% solution of [14C]glucose or [14C]xylitol, 2 g/kg body weight. Assays of neutral sugar metabolites from each substrate in the acid-soluble fraction of liver or AS-30D tumor showed that xylitol in the liver was converted primarily into glucose while in the tumor 80 to 90% of the xylitol remained unchanged. This hepatocellular carcinoma is also markedly deficient in the ability to synthesize acid-insoluble glycogen and glycoprotein from xylitol as compared to the liver.
mesh_terms: D000449:Aldehyde Reductase; D000818:Animals; D001201:Ascites; D050260:Carbohydrate Metabolism; D005947:Glucose / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D051381:Rats; D012995:Solubility; D013401:Sugar Alcohol Dehydrogenases / Q000378:metabolism; D014993:Xylitol / Q000378:metabolism*
chemical_list: D013401:Sugar Alcohol Dehydrogenases; D000449:Aldehyde Reductase; C023142:polyol dehydrogenase (NADP); D005947:Glucose; D014993:Xylitol