Studies of the Metabolic Effects Induced in the Rat by a High Fat Diet - II. Disposal of Orally Administered (14C)-Glucose*

Abstract

(6-¹⁴C) glucose (1.5-2 gm/kg body weight) was administered orally to fasted rats fed for five weeks from weaning a fat or a carbohydrate synthetic diet. Rats were killed by decapitation at 30, 60, 120 and 180 minutes after the load. ¹⁴C in the gut, glucose. (6-¹⁴C) glucose and insulin in the serum, glycogen and (¹⁴C) glycogen in the liver, were measured.

Fat-adapted rats exhibited impaired glucose tolerance and sensitivity to endogenous insulin which resulted in higher levels of exogenous glucose in the serum and in some slackening of disposal of the load by the tissues. An altered release of glucose by the liver does not seem to be a major factor of hyperglycemia in these conditions.

The level of liver glycogen before the load and throughout the experiment is higher in the fat group. As in the control group, hepatic glycogen synthesis after glucose administration develops linearly between 30 and 120 minutes without any evident relation to the time variation of the level and the specific radioactivity of serum glucose. In addition, the specific activity of glycogen stabilized to a value much lower than that of the load glucose. After fat diet, a significant reduction of the amount of ¹⁴carbon incorporated into liver glycogen was observed which can contribute to the decrease of tolerance to orally administered glucose.

Key words

Fat Diet - Oral Load - Glucose - ¹⁴C-Glucose - Insulin - Liver Glycogen

1 This work was supported by a grant from the Fonds National Suisse de la Recherche Scientifique (request No. 3113.69).

1 This work was supported by a grant from the Fonds National Suisse de la Recherche Scientifique (request No. 3113.69).