Swim training increases glucose output from liver perfused in situ with glucagon in fed and fasted rats

• Published in: Metabolism, clinical and experimental clinical and experimental, 2004-08, Vol.53 (8), p.1027-1031
• Main Authors: Drouin, Réjean, Robert, Geneviève, Milot, Martin, Massicotte, Denis, Péronnet, François, Lavoie, Carole
• Format: Article
• Language: English
• Subjects: Alanine Transaminase - metabolism; Animals; Area Under Curve; Biological and medical sciences; Eating - physiology; Fasting - physiology; Glucagon - pharmacology; Glucose - metabolism; Glycogen Phosphorylase - metabolism; Lactic Acid - metabolism; Liver - metabolism; Liver - physiology; Liver Glycogen - metabolism; Male; Medical sciences; Miscellaneous; Perfusion; Physical Conditioning, Animal - physiology; Physical Endurance - physiology; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Rats; Rats, Sprague-Dawley; Swimming - physiology
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/j.metabol.2004.03.010

The effect of endurance swim training (3 hours per day, 5 days/week, for 10 weeks) on hepatic glucose production (HGP) in liver perfused in situ for 60 minutes with glucagon and insulin was studied in Sprague-Dawley rats. The experiments were performed in fed rats and in rats fasted for 24 hours, but with lactate (8 mmol/L) added to the perfusion medium. Liver glycogen content was significantly lower in fasted than fed rats (fasted untrained and trained: 14 ± 4 and 11 ± 3 μmol glycosyl U/g of liver wet weight (WW); fed untrained and trained: 205 ± 11 and 231 ± 11 μmol glycosyl U/g of liver WW; not significantly different in trained and untrained rats). Glucagon increased HGP in the 4 experimental groups, but the increases were more rapid and pronounced in trained than in untrained rats in both fed and fasted states. HGP values (area under the curve [AUC] in μmol/g of liver WW) were significantly higher in trained fed (112.1 ± 7.1 v 85.9 ± 12.2 in untrained rats) than in trained fasted rats (50.8 ± 4.4 v 34.7 ± 3.6 in untrained rats). When compared with untrained rats, the total amount of glucose released by the liver in response to glucagon in trained rats was approximately 30% higher in the fed state and approximately 45% larger in the fasted state. These results indicate that endurance training increases the response of both glycogenolysis and gluconeogenesis to glucagon.