We are pleased to announce the publication of the following paper in the current issue of Journal of Experimental Biology: Tift MS, Huckstadt LA, Ponganis PJ. 2018. Anterior vena caval oxygen profiles in a deep-diving California sea lion: arteriovenous shunts, a central venous oxygen store and oxygenation during lung collapse. *Journal of Experimental Biology* 221: jeb163428 URL: *http://jeb.biologists.org/content/221/1/jeb163428 <http://jeb.biologists.org/content/221/1/jeb163428>* 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. Please email me (mtift@ucsd.edu) if you would like a PDF copy of the paper. Best regards, *Michael S. Tift, PhD |**mtift@ucsd.edu <mtift@ucsd.edu>* Postdoctoral Fellow UC San Diego School of Medicine Division of Physiology ------------------- University of California San Diego *9500 Gilman Drive <https://maps.google.com/?q=9500+Gilman+Drive&entry=gmail&source=g>: Medical Teaching Facility* *Mail Code 0623A* La Jolla, CA 92093-0623 USA Phone: 858 534 4190 <(858)%20534-4190> Website <http://michaeltift.weebly.com/> ResearchGate Profile <https://www.researchgate.net/profile/Michael_Tift> Google Scholar Profile <https://scholar.google.com/citations?user=8iOn3l4AAAAJ&hl=en&oi=ao>