AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 5 827-R832, Copyright © 1984 by American Physiological Society
Hepatic handling of pancreatic glucagon and glucose during meals in rats
W. Langhans, K. Pantel, W. Muller-Schell, E. Eggenberger and E. Scharrer
Prandial changes in plasma pancreatic glucagon, blood glucose, and liver
glycogen levels were studied during the first meal after 12 h of food
deprivation in rats. To determine whether pancreatic glucagon secretion is
influenced by the composition of the diet, the experiments were performed
in rats fed high-carbohydrate (HC), high-fat (HF), or high-protein (HP)
diets. Plasma glucagon levels in the hepatic portal vein increased about
100% during meals in all feeding groups, whereas glucagon levels in the
hepatic vein changed very little. Blood glucose concentration in the
hepatic portal vein increased during meals in HC diet-fed rats but
decreased in HF and in HP diet-fed rats. Blood glucose in the hepatic vein
also increased in HC and HP diet-fed rats. In addition, liver glycogen
content decreased during meals in HC and HP diet-fed rats and by 14 min
after the meal in HF diet-fed rats. These results demonstrate that a
considerable amount of the glucagon released during meals in HC, HF, and HP
diet-fed rats remains in the liver. This is consistent with the hypothesis
that the liver is important for the satiety effect of glucagon. The results
also suggest that glucagon contributes to the meal-induced changes in
hepatic carbohydrate metabolism observed in all groups.
