title: Lung collapse in the diving sea lion: hold the nitrogen and save the oxygen.
abstract: Lung collapse is considered the primary mechanism that limits nitrogen absorption and decreases the risk of decompression sickness in deep-diving marine mammals. Continuous arterial partial pressure of oxygen   profiles in a free-diving female California sea lion (Zalophus californianus) revealed that (i) depth of lung collapse was near 225 m as evidenced by abrupt changes in   during descent and ascent, (ii) depth of lung collapse was positively related to maximum dive depth, suggesting that the sea lion increased inhaled air volume in deeper dives and (iii) lung collapse at depth preserved a pulmonary oxygen reservoir that supplemented blood oxygen during ascent so that mean end-of-dive arterial   was 74 ± 17 mmHg (greater than 85% haemoglobin saturation). Such information is critical to the understanding and the modelling of both nitrogen and oxygen transport in diving marine mammals.
authors.affiliation: Center for Marine Biotechnology and Biomedicine, Scholander Hall, Scripps Institution of Oceanography, 9500 Gilman Drive no. 0204, La Jolla, CA 92093-0204, USA. bimcdonald@ucsd.edu
authors.forename: Birgitte I
authors.initials: BI
authors.lastname: McDonald
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Ponganis
mesh_terms: D000818:Animals; D002140:California; D004242:Diving / Q000502:physiology*; D005260:Female; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010313:Partial Pressure; D011312:Pressure; D001261:Pulmonary Atelectasis / Q000097:blood / Q000378:metabolism*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D046070:Sea Lions / Q000502:physiology*
chemical_list: D009584:Nitrogen; D010100:Oxygen