Calorigenic effect of glucagon and catecholamines in king penguin chicks.
The calorigenic action of glucagon and catecholamine infusion was evaluated in winter-acclimatized king penguin chicks at 20 and 0 degrees C ambient temperature (Ta). At Ta = 20 degrees C the mean increase in metabolic rate was 0.73 W . kg-1 for epinephrine (80 micrograms . kg-1), 0.42 W . kg-1 for norepinephrine (150 micrograms . kg-1), and 1.16 W . kg-1 for glucagon (0.75 micrograms . kg-1); i.e., respectively 30, 17, and 47% of the control value. The maximum response to glucagon reached 89% over control. At Ta = 0 degrees C, for the same glucagon infusion, the mean increase in specific metabolic rate was 0.84 W . kg-1, 27% of control rate. In the cold, glucagon infusion inhibited shivering and substituted its calorigenic action, resulting in a less apparent effect. In contrast with the negligible effect of catecholamines, glucagon infused at low doses exerted a powerful calorigenic action in young king penguins and could be considered as a possible nonshivering thermogenesis mediator.
D000064:Acclimatization; D000818:Animals; D001481:Basal Metabolism / Q000187:drug effects*; D001717:Birds / Q000502:physiology*; D002151:Calorimetry; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D005934:Glucagon / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D013696:Temperature
D005934:Glucagon; D009638:Norepinephrine; D004837:Epinephrine