Uptake of radiolabeled copper by the liver as affected by fructose or glucose

The present investigation was designed to study liver uptake of 67Cu when administered directly into the portal vein with either fructose (Fr) or glucose (GL). Following weaning, male Sprague-Dawley rats, were fed either commercial laboratory ration (chow) or semipurified diets containing 62% carbohydrate as either (Fr) or cornstarch (St) deficient in copper (CuD) (0.6 ppm) or supplemented (CuS) (6.0 ppm) for 3 weeks. After an overnight fast, a single dose of rat plasma (0.1 ml) containing Fr or GL extrinsically labeled with 67Cu was injected directly into their portal vein. Although not always statistically significant, rats fed chow retained more radioactivity in the liver and several extrahepatic tissues when 67Cu was administered with Fr than with GL. Regardless of Cu status, rats fed diets containing Fr retained more radioactivity in extrahepatic tissues than rats fed St. The combination of Fr with 67Cu resulted in an additional uptake of the isotope by the liver, blood, muscle and fat pad when compared with GL. These data in conjunction with our previous studies where the isotope was administered i.p. strongly suggest that Cu requirements or utilization are greater when Fr is the main dietary carbohydrate. Also the results may in part explain the reasons for the increased severity of Cu deficiency in rats fed Fr