INTESTINAL GLUCOSE-ABSORPTION IS LOWER IN OBESE THAN IN LEAN ZUCKER RATS

Obese Zucker (fa/fa) rats had lower intestinal glucose absorption foll owing an intragastric [U-C-14] glucose load than lean (+/?) Zucker rat s. In the fa/fa animals, the rate of oxidation of the tracer to (CO2)- C-14 was similar to that observed in their lean counterparts. Although there were no differences in the incorporation of the tracer in liver and skeletal muscle glycogen, the conversion and incorporation of [U- C-14]glucose into tissue [C-14]lipid was higher in the obese animals. Isolated enterocytes from lean and obese Zucker rats showed a similar capacity for [U-C-14]glucose utilization. Reconstituted brush border m embrane vesicles from obese Zucker rats showed a higher V(max) for glu cose transport than those from their lean counterparts. The lower gluc ose absorption found in the fa/fa rats in vivo may contribute to the m aintenance of normoglycemia in these animals.