Scaling of heart rate with breathing frequency and body mass in cetaceans.
Journal Article (Journal Article)
Plasticity in the cardiac function of a marine mammal facilitates rapid adjustments to the contrasting metabolic demands of breathing at the surface and diving during an extended apnea. By matching their heart rate (f H ) to their immediate physiological needs, a marine mammal can improve its metabolic efficiency and maximize the proportion of time spent underwater. Respiratory sinus arrhythmia (RSA) is a known modulation of f H that is driven by respiration and has been suggested to increase cardiorespiratory efficiency. To investigate the presence of RSA in cetaceans and the relationship between f H , breathing rate (f R ) and body mass (M b ), we measured simultaneous f H and f R in five cetacean species in human care. We found that a higher f R was associated with a higher mean instantaneous f H (if H ) and minimum if H of the RSA. By contrast, f H scaled inversely with M b such that larger animals had lower mean and minimum if H s of the RSA. There was a significant allometric relationship between maximum if H of the RSA and M b , but not f R , which may indicate that this parameter is set by physical laws and not adjusted dynamically with physiological needs. RSA was significantly affected by f R and was greatly reduced with small increases in f R . Ultimately, these data show that surface f H s of cetaceans are complex and the f H patterns we observed are controlled by several factors. We suggest the importance of considering RSA when interpreting f H measurements and particularly how f R may drive f H changes that are important for efficient gas exchange. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.
Full Text
Duke Authors
Cited Authors
- Blawas, AM; Nowacek, DP; Rocho-Levine, J; Robeck, TR; Fahlman, A
Published Date
- August 2021
Published In
Volume / Issue
- 376 / 1830
Start / End Page
- 20200223 -
PubMed ID
- 34121456
Pubmed Central ID
- PMC8200651
Electronic International Standard Serial Number (EISSN)
- 1471-2970
International Standard Serial Number (ISSN)
- 0962-8436
Digital Object Identifier (DOI)
- 10.1098/rstb.2020.0223
Language
- eng