Differential Effects of Glucagon, Insulin and Epinephrine on In Vivo Glucose Oxidation and Hepatic Enzyme Activity in the Rat.
Abstract
In vivo oxidation of specifically labeled carbon 14-glucose and the activity of selected hepatic enzymes involved in glucose utilization were studied in rats after the administration of glucagon, insulin or epinephrine. Compared to the controls, glucagon doubled the oxidation of U-14C-glucose and enhanced the oxidation of 6-14C-glucose and 2-14C-glucose oxidation by about 83%, but did not affect oxidation of 1-14C-glucose. Administration of insulin enhanced oxidation of U-14C-glucose by 68%, 1-14C-glucose by 71%, and 2-14C-glucose by 73%, with no effect on 6-14C-glucose oxidation. Epinephrine enhanced oxidation of 6-14C-glucose by 38% and had no effect on 1- or 2-14C-glucose oxidation. Insulin and glucagon produced rapid reciprocal changes in the activities of certain glycolytic and gluconeogenic enzymes and in the activity of acetyl CoA carboxylase, a key lipogenic enzyme. Insulin produced a rapid increase in the activity of hepatic glucokinase, phosphofructokinase, pyruvate kinase and glucose-6-phosphate dehydrogenase, and a rapid decrease in the activity of glucose-6-phosphatase and fructose-1,6-diphosphatase. Glucagon produced a rapid but reciprocal response in the activity of these enzymes. In addition, glucagon enhanced the activity of phosphoenolpyruvate carboxykinase. The effects of epinephrine were similar to those produced by glucagon. Both glucagon and epinephrine increased the level of cyclic AMP. The results of this study suggest that glucagon and epinephrine stimulate the activity of the tricarboxylic acid cycle, whereas insulin enhances the pentose cycle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1986
- Accession Number
- ADA176796
Entities
People
- George J. Klain
- Robert H. Herman
Organizations
- Letterman Army Hospital