ISSN:
1432-136X
Keywords:
Glomerular filtration rate
;
Fasting
;
Water conservation
;
Protein catabolism
;
Elephant seal, Mirounga
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Urine production and N output were monitored in northern elephant seal (Mirounga angustirostris) pups progressing through 10 weeks of a natural postweaning fast. Urine output declind by 84% (to 69±12 ml·day−1) at 10 weeks (P〈0.05). Glomerular filtration rate at 10 weeks was 51% of the 67±3 ml serum·min−1 observed during week 1 (P〈0.05). Urine N excretion fell by 69% to 1.2±0.17 g·day−1, while urinary concentration increased (P〈0.05). Serum urea declined from an initial 11 mmol·1−1 to 5–7 mmol·1−1 by 5 weeks. The fall in urinary N loss (and thus amino acid oxidation) was concomitant with depressed metabolic rate. Therefore, protein contributed little toward meeting energy demands (i.e., 〈4% of average metabolic rate) throughout fasting. These data indicate that fasting pups improve water conservation and minimize protein catabolism during prolonged natural fasts without an exogenous source of water.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00265640
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