Effect of fasting and refeeding on glucose metabolism in rat aorta

The effect of refeeding on accumulation of [14C]glucose carbon, oxidation of [14C]glucose and glycogen concentration in rat aortic intima-media was studied in rats fasted for 3 days. Accumulation of glucose carbon and glucose oxidation were determined by incubating rat aorta in vitro for 2 h with 5.6 mM 14C-labelled glucose in the medium. Refeeding with standard pellets for 2-4 h augmented [14C]glucose accumulation in rat aorta but had no significant effect on glucose oxidation. The glycogen concentration in rat aorta tended to increase. After refeeding for 16 h both [14C]glucose incorporation and [14C]glucose oxidation were increased in rat aorta. Refeeding with carbohydrate-rich pellets (92% carbohydrate) for 3 h increased blood glucose more than did protein-rich (92% protein) pellets, whereas the rise in plasma insulin was about the same. The accumulation of [14C]glucose carbon measured during the subsequent in vitro incubation for 2 h was augmented after refeeding with protein-rich pellets and slightly reduced after carbohydrate-rich pellets. Refeeding of diabetic rats for 2 h with standard pellets increased plasma insulin and markedly increased blood glucose but had no effect on aortic [14C]glucose incorporation. Intravenous infusion of glucose in normal rats for 2 h markedly raised blood glucose but did not increase the aortic glucose incorporation. Raising the ambient glucose concentration from 5 to 10 mM during incubation of normal rat aorta in vitro for 2 h slightly decreased the [14C]glucose incorporation determined during a subsequent incubation for 2 h. These results suggest that refeeding with standard pellets augments glucose incorporation and glucose oxidation in rat aorta.(ABSTRACT TRUNCATED AT 250 WORDS)