Effect of cold-acclimation on oxygen uptake and glucose production of perfused duckling liver

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2001-04, Vol.128 (4), p.851-861
• Main Authors: Bedu, E., Cohen-Adad, F., Dallevet, G., Garin, D., Barré, H., Duchamp, C.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Animals; Aves; Birds; Cold Temperature; Ducks - physiology; Fasting; Freshwater; Glucagon; Glucagon - metabolism; Gluconeogenesis; Glucose - metabolism; In Vitro Techniques; Lactic Acid - pharmacology; Liver - drug effects; Liver - metabolism; Male; Norepinephrine; Oxygen - metabolism; Oxygen consumption; Perfused liver; Perfusion; Rats; Thermogenesis
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/S1095-6433(00)00347-0

The control of hepatic metabolism by substrates and hormones was assessed in perfused liver from young Muscovy ducklings. Studies were performed in fed or 24-h fasted 5-week-old thermoneutral (25°C; TN) or cold-acclimated ducklings (4°C; CA) and results were compared with those obtained in rats. Basal oxygen uptake of perfused liver (LVO 2) was higher after cold acclimation both in fed (+65%) and 24-h fasted (+29%) ducklings and in 24-h fasted rats (+34%). Lactate (2 mM), the main gluconeogenic substrate in birds, similarly increased LVO 2 in both TN and CA ducklings and the effect was larger after fasting. Both glucagon and norepinephrine dose-dependently increased LVO 2 in ducklings and rats, but cold acclimation did not improve liver response and liver sensitivity to norepinephrine in ducklings was even reduced in CA animals. Liver contribution to glucagon-induced thermogenesis in vivo was estimated to be 22% in TN and 12% in CA ducklings. Glucagon stimulated gluconeogenesis from lactate in duckling liver and the stimulation was 2.2-fold higher in CA than in TN fasted birds. These results indicate a stimulated hepatic oxidative metabolism in CA ducklings but hepatic glucagon-induced thermogenesis (as measured by LVO 2) was not improved. A role of the liver is suggested in duckling metabolic acclimation to cold through an enhanced hepatic gluconeogenesis under glucagon control.