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


  • eng