AUTHOR=Fahlman A. , Mcknight J. C. , Blawas A. M. , West N. , Torrente A. G. , Aoki K. 

TITLE=Cardiorespiratory coupling in the bottlenose dolphin (Tursiops truncatus)

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1234432

DOI=10.3389/fphys.2023.1234432

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> The bottlenose dolphin (<italic>Tursiops truncatus</italic>) is an intermittent breather, where the breath begins with an exhalation followed by inhalation and an extended inter-breath interval ranging from 10 to 40 s. Breathing has been shown to alter both the instantaneous heart rate (i<italic>f</italic><sub>H</sub>) and stroke volume (iSV) in the bottlenose dolphin, with a transitory ventilatory tachycardia following the breath, and an exponential decrease to a stable i<italic>f</italic><sub>H</sub> around 40 beats • min<sup>−1</sup> during the inter-breath period. As the total breath duration in the dolphin is around 1 s, it is not possible to assess the contribution of exhalation and inhalation to these changes in cardiac function during normal breathing.</p><p><bold>Methods:</bold> In the current study, we evaluated the i<italic>f</italic><sub>H</sub> response by separating expiration and inspiration of a breath, which allowed us to distinguish their respective contribution to the changes in i<italic>f</italic><sub>H</sub>. We studied 3 individual male bottlenose dolphins trained to hold their breath between the different respiratory phases (expiration and inhalation).</p><p><bold>Results:</bold> Our data show that inspiration causes an increase in i<italic>f</italic><sub>H</sub>, while expiration appears to result in a decrease in i<italic>f</italic><sub>H</sub>.</p><p><bold>Discussion:</bold> These data provide improved understanding of the cardiorespiratory coupling in dolphins, and show how both exhalation and inhalation alters i<italic>f</italic><sub>H</sub>.</p>