Refeeding after fasting in the rat: effects of carbohydrate.

In order to find ways to modify adaptations during refeeding after fasting the amount of carbohydrate fed during refeeding was varied, or its absorption slowed by a glucosidase inhibitor. Exchanging dietary carbohydrate with fat diminished refeeding adaptations in carbohydrate pathways (glycogen contents of liver and muscle, glucose incorporation into carbondioxide, and triglyceride in adipose tissue), but instead facilitated lipid storage (weight of and lipoprotein lipase activity in adipose tissue). An early specific effect of carbohydrate refeeding was an increase in the insulin response in glucose metabolic pathways in adipose tissue. Inhibiting carbohydrate absorption by a glucosidase inhibitor (Acarbose) caused a delay in energy accumulation during refeeding both in glycogen stores, and, more markedly, in adipose tissue triglyceride stores. These data are consistent with the interpretation that the drug prevents or delays carbohydrate uptake, and causes less adaptations of adipose tissue metabolic pathways for lipid storage. The tissue adaptations during refeeding after fasting seem to depend on the energy substrate reaching these tissues.