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Extreme blood oxygen depletion in diving elephant seals
Author(s) -
Meir Jessica Ulrika,
Champagne Cory D.,
Costa Daniel P.,
Ponganis Paul J.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.757.7
Subject(s) - oxygen–haemoglobin dissociation curve , elephant seal , bohr effect , oxygen , hemoglobin , metabolic rate , biology , hypothermia , respiration , venous blood , zoology , medicine , anatomy , chemistry , physiology , endocrinology , biochemistry , organic chemistry
The repetitive, long dives of elephant seals, Mirounga angustirostris , have remained a physiological enigma in that oxygen (O 2 ) stores appear inadequate to maintain aerobic metabolism. To investigate blood O 2 depletion in this species we 1) measured venous O 2 partial pressure (P O2 ) continuously during dives with a backpack P O2 /temperature recorder and, 2) characterized the O 2 ‐hemoglobin (Hb) dissociation curve. Similar to other marine mammals, O 2 ‐Hb dissociation curve results were: P 50 (50% saturation) ~ 31 mmHg, Bohr effect (P 50 ) ~ −0.6. End‐of‐dive P O2 routinely reached 2–10 mmHg in the extradural vein and hepatic sinus, demonstrating remarkable hypoxemic tolerance in this species. Based on prior studies, we hypothesize that arterial P O2 also reaches similarly low levels. These data allow calculation of % Hb‐saturation, the magnitude of blood O 2 store depletion during dives, and the contribution to diving metabolic rate. Venous temperature during routine dives remained near 37°C, suggesting that hypothermia‐induced hypometabolism is an unlikely contributor to metabolic suppression while diving. We believe the elephant seal's extreme hypoxemic tolerance allows near complete depletion of its previously measured large blood O 2 store, providing sufficient O 2 to maintain metabolism during repetitive, long dives. Funding: NSF grant IOS‐0641801 & SIO Halliday Student Field Research Award