Uptake of radiolabeled copper from portal blood containing fructose or glucose

The present investigation was designed to study the uptake of(67)Cu when administered directly, into the portal vein, along with either functose or glucose, by the liver and extrahepatic tissues. Following weaning, male Sprague-Dawley rats were fed for 3 wk either commercial laboratory ration (chow) or semipurified diets deficient in Cu (0.6 ppm) or supplemented with Cu (6.0 ppm) and containing 62% carbohydrate as either fructuse or cornstarch. After an overnight fast, a single dose of rat plasma (0.1 mL) containing fructose or glucose extrinsically labeled with(67)Cu 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(67)Cu was administered with fructose than with glucose. Regardless of Cu status, rats fed diets containing fructose retained more radioactivity in extrahepatic tissues than rats fed starch. There was an increased uptake of(67)Cu by the liver, blood, muscle, and fat pad when fructose as compared to glucose was injected in combination with the isotope. These data strongly suggest that Cu requirements or utilization are greater when fructose is the main dietary carbohydrate. The results may also in part explain the reason for the increased severity of Cu deficiency in rats fed fructose.