Conditioned Variation in Heart Rate During Static Breath-Holds in the Bottlenose Dolphin (Tursiops truncatus ).

Journal Article (Journal Article)

Previous reports suggested the existence of direct somatic motor control over heart rate (f H ) responses during diving in some marine mammals, as the result of a cognitive and/or learning process rather than being a reflexive response. This would be beneficial for O2 storage management, but would also allow ventilation-perfusion matching for selective gas exchange, where O2 and CO2 can be exchanged with minimal exchange of N2 . Such a mechanism explains how air breathing marine vertebrates avoid diving related gas bubble formation during repeated dives, and how stress could interrupt this mechanism and cause excessive N2 exchange. To investigate the conditioned response, we measured the f H -response before and during static breath-holds in three bottlenose dolphins (Tursiops truncatus ) when shown a visual symbol to perform either a long (LONG) or short (SHORT) breath-hold, or during a spontaneous breath-hold without a symbol (NS). The average f H (if Hstart ), and the rate of change in f H (dif H /dt) during the first 20 s of the breath-hold differed between breath-hold types. In addition, the minimum instantaneous f H (if Hmin ), and the average instantaneous f H during the last 10 s (if Hend ) also differed between breath-hold types. The dif H /dt was greater, and the if Hstart , if Hmin , and if Hend were lower during a LONG as compared with either a SHORT, or an NS breath-hold (P < 0.05). Even though the NS breath-hold dives were longer in duration as compared with SHORT breath-hold dives, the dif H /dt was greater and the if Hstart , if Hmin , and if Hend were lower during the latter (P < 0.05). In addition, when the dolphin determined the breath-hold duration (NS), the f H was more variable within and between individuals and trials, suggesting a conditioned capacity to adjust the f H -response. These results suggest that dolphins have the capacity to selectively alter the f H -response during diving and provide evidence for significant cardiovascular plasticity in dolphins.

Full Text

Duke Authors

Cited Authors

  • Fahlman, A; Cozzi, B; Manley, M; Jabas, S; Malik, M; Blawas, A; Janik, VM

Published Date

  • January 2020

Published In

Volume / Issue

  • 11 /

Start / End Page

  • 604018 -

PubMed ID

  • 33329056

Pubmed Central ID

  • 33329056

Electronic International Standard Serial Number (EISSN)

  • 1664-042X

International Standard Serial Number (ISSN)

  • 1664-042X

Digital Object Identifier (DOI)

  • 10.3389/fphys.2020.604018

Language

  • eng