Glucose Kinetics in Neonatal Elephant Seals During Postweaning Aphagia

• Main Authors: Keith, Edward O., Ortiz, Charles L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NSUWorks 1989
• Subjects: Northern elephant seal; Glucose metabolism; Fasting; Marine Biology; Oceanography and Atmospheric Sciences and Meteorology; Elephant Seal; Elephant Seals
• Online Access: https://nsuworks.nova.edu/occ_facarticles/673

Northern elephant seal (Mirounga angustirostris) pups undergo extended periods of terrestrial aphagia after weaning and exhibit a paradoxical fasting hyperglycemia. To investigate the details of glucose metabolism during this period, reversible and irreversible radiotracers were used to determine the body mass of glucose, and rates of glucose turnover, recycling, and oxidation in fasting seal pups. A typical 75 kg pup has a glucose mass of about 4.5 g (60 mg/kg), and a blood glucose concentration of about 174 mg/dl. Blood glucose removal rate was about 30 grams per day (17 mg/kg · h-1), but less than 2.5% of this glucose was oxidized, contributing less than 1% of the total metabolic rate. About 20% of the glucose pool was removed from the blood per hour, yielding a turnover time in the vascular space of about five hours. Most glucose removed from the blood was returned to the blood by recycling. Such recycling may contribute to mechanisms which prolong survival during fasting, such as high rates of triacyclglycerol turnover, synthesis of new protein pools, low ketone levels, and the Cori cycle which is important during diving.