Lactate and glucose metabolism in the resting and diving harbor seal (Phoca vitulina)
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The rates of lactate and glucose production, removal, and oxidation were measured in harbor seals before and after 10 min restrained dives using radioisotope tracer techniques. The results show: 1. Net turnover rates were 24 μmol·min-1·kg-1 for lactate and 12 μmol·min-1·kg-1 for glucose at rest (Table 2). 2. Only 21% of lactate turnover and 3% of glucose turnover were oxidized. Their combined oxidation contributed less than 9% to resting energy production. 3. During 10 min dives, there was 9 fold increase in lactate production. 4. Less than 27% of the lactate produced during diving was oxidized during recovery. 5. The blood glucose concentration decreased 1 mM during diving, but increased and remained elevated for 2 h after the dive (Fig. 5 and 6). The postdive hyperglycemia resulted from a high glucose entry rate which lasted 10-15 min after the dive. A peak entry rate of 168 μmol·min-1·kg-1 was measured 30 sec after a dive. 6. In spite of the postdive hyperglycemia, glucose oxidation was only 11% higher than predive levels. 7. The predive concentration of plasma free fatty acids (FFA) was similar to other arctic carnivores (Fig. 9). © 1983 Springer-Verlag.
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