AUTHOR=Fahlman Andreas , Madigan Johnny 

TITLE=Respiratory Function in Voluntary Participating Patagonia Sea Lions (Otaria flavescens) in Sternal Recumbency

JOURNAL=Frontiers in Physiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00528

DOI=10.3389/fphys.2016.00528

ISSN=1664-042X

ABSTRACT=<p>We measured esophageal pressures (<italic>n</italic> = 4), respiratory flow rates (<italic>n</italic> = 5), and expired O<sub>2</sub> and CO<sub>2</sub> (<italic>n</italic> = 4) in five adult Patagonia sea lions (<italic>Otaria flavescens</italic>, body mass range 94.3–286.0 kg) during voluntary breaths while laying down out of water. The data were used to estimate the dynamic specific lung compliance (sCL), the O<sub>2</sub> consumption rate (<inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:math></inline-formula><italic>O</italic><sub>2</sub>) and CO<sub>2</sub> production rates (<inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:math></inline-formula><italic>CO</italic><sub>2</sub>) during rest. Our results indicate that the resting tidal volume in Patagonia sea lions is approximately 47–73% of the estimated total lung capacity. The esophageal pressures indicated that expiration is passive during voluntary breaths. The average sCL of sea lions was 0.41 ± 0.11 cmH<sub>2</sub>O<sup>−1</sup>, which is similar to those measured in anesthetized sea lions and awake cetaceans, and significantly higher as compared to humans (0.08 cmH<sub>2</sub>O<sup>−1</sup>). The average estimated <inline-formula><mml:math id="M3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:math></inline-formula><italic>O</italic><sub>2</sub> and <inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:math></inline-formula><italic>CO</italic><sub>2</sub> using breath-by-breath respirometry were 1.023 ± 0.327 L O<sub>2</sub> min<sup>−1</sup> (range: 0.695–1.514 L O<sub>2</sub> min<sup>−1</sup>) and 0.777 ± 0.318 L CO<sub>2</sub> min<sup>−1</sup>, (range: 0.510–1.235 L CO<sub>2</sub> min<sup>−1</sup>), respectively, which is similar to previously published metabolic measurements from California and Steller sea lions using conventional flow-through respirometry. Our data provide end-tidal gas composition and offer novel data for respiratory physiology in pinnipeds, which may be important for clinical medicine and conservation efforts.</p>