Deep‐diving sea lions exhibit extreme bradycardia in long‐duration dives (879.3)
Abstract
Heart rate and peripheral blood flow distribution are the primary determinants of the rate and pattern of oxygen store utilization and ultimately breath‐hold duration. We investigated dive heart rate (ƒH) in five California sea lions (Zalophus californianus) during maternal foraging trips by instrumenting them with digital electrocardiogram (ECG) loggers and time depth recorders. In all dives, dive ƒH (50 ± 9, range 28‐81 beats min‐1) decreased compared to surface rates (113 ± 5 beats min‐1), with all dives exhibiting an instantaneous ƒH below resting (‐1). Typical instantaneous ƒH profiles of deep dives consisted of 1) an initial rapid decline in ƒH resulting in the lowest instantaneous ƒH of the dive at the end of descent, often below 10 beats min‐1, 2) a slight increase in ƒH during the bottom portion of the dive, 3) a gradual increase in ƒH during ascent with a rapid increase prior to surfacing. Extreme bradycardia and the associated reductions in pulmonary and peripheral blood flow during late descent of deep dives should a) contribute to preservation of the lung O2 store, b) increase dependence of muscle on the myoglobin‐bound O2 store, c) conserve the blood O2 store, and d) help limit the absorption of N2 at depth. This ƒH profile during deep dives of sea lions may be characteristic of deep‐diving higher vertebrates that dive on inspiration.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 01, 2014
- Source ID
- 10.1096/fasebj.28.1_supplement.879.3
Entities
People
- Birgitte I McDonald
- Paul J. Ponganis
Organizations
- Aarhus University
- Office of Naval Research
- Scripps Institution of Oceanography