Anterior vena caval oxygen profiles in a deep-diving California sea lion: arteriovenous shunts, a central venous oxygen store and oxygenation during lung collapse

TitleAnterior vena caval oxygen profiles in a deep-diving California sea lion: arteriovenous shunts, a central venous oxygen store and oxygenation during lung collapse
Publication TypeJournal Article
Year of Publication2018
AuthorsTift M.S, Huckstadt L.A, Ponganis P.J
JournalJournal of Experimental Biology
Volume221
Date Published2018/01
Type of ArticleArticle
ISBN Number0022-0949
Accession NumberWOS:000419924000004
KeywordsBlood oxygen; blood-flow; brain structures; cardiac-output; dive; Dive response; emperor penguins; exercise; heart-rate; hemoglobin saturation; Otariid; Vena cava; volumes; weddell seals; zalophus-californianus
Abstract

Deep-diving California sea lions (Zalophus californianus) can maintain arterial hemoglobin saturation (S-O2) above 90% despite lung collapse (lack of gas exchange) and extremely low posterior vena caval S-O2 in the middle of the dive. We investigated anterior vena caval P-O2 and S-O2 during dives of an adult female sea lion to investigate two hypotheses: (1) posterior vena caval S-O2 is not representative of the entire venous oxygen store and (2) a well-oxygenated (arterialized) central venous oxygen reservoir might account for maintenance of arterial S-O2 during lung collapse. During deep dives, initial anterior vena caval S-O2 was elevated at 83.6 +/- 8.4% (n = 102), presumably owing to arteriovenous shunting. It remained high until the bottom phase of the dive and then decreased during ascent, whereas previously determined posterior vena caval S-O2 declined during descent and then often increased during ascent. These divergent patterns confirmed that posterior vena caval S-O2 was not representative of the entire venous oxygen store. Prior to and early during descent of deep dives, the high S-O2 values of both the anterior and posterior venae cavae may enhance arterialization of a central venous oxygen store. However, anterior vena caval S-O2 values at depths beyond lung collapse reached levels as low as 40%, making it unlikely that even a completely arterialized central venous oxygen store could account for maintenance of high arterial S-O2. These findings suggest that maintenance of high arterial S-O2 during deep dives is due to persistence of some gas exchange at depths beyond presumed lung collapse.

DOI10.1242/jeb.163428
Short TitleJ. Exp. Biol.
Student Publication: 
No
Research Topics: 
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