Elucidating the responses and role of the cardiovascular system in crocodilians during diving: Fifty years on from the work of C.G. Wilber

Axelsson, Michael and Franklin, Craig E. (2011) Elucidating the responses and role of the cardiovascular system in crocodilians during diving: Fifty years on from the work of C.G. Wilber. Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology, 160 1: 1-8. doi:10.1016/j.cbpa.2011.05.015


Author Axelsson, Michael
Franklin, Craig E.
Title Elucidating the responses and role of the cardiovascular system in crocodilians during diving: Fifty years on from the work of C.G. Wilber
Journal name Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology   Check publisher's open access policy
ISSN 1095-6433
1531-4332
Publication date 2011-09
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1016/j.cbpa.2011.05.015
Volume 160
Issue 1
Start page 1
End page 8
Total pages 8
Place of publication Philadelphia, PA , United States
Publisher Elsevier
Collection year 2012
Language eng
Abstract In 1960, C.G. Wilber in a laboratory-based study described for the first time the changes in heart rate with submergence in the American alligator noting in particular the marked bradycardia that occurred during forced dives. This short review summarizes the major advances in our understanding of diving and the responses and role of the cardiovascular system of crocodilians during submergence in the 50 years since Wilber published his findings. These advances are attributable in part to the technological advances made in physiological monitoring devices and wildlife telemetry that have not only provided greater elucidation of the hemodynamics of the unique crocodilian cardiovascular system but also allowed the natural diving behaviors and heart rates in free-ranging crocodiles to be recorded. Of note, telemetric field-based studies have revealed that wild free-ranging crocodiles typically undertake only short dives, less than 20 min, yet crocodiles are also capable of dives of many hours in duration. In contrast to Wilber's study, dives recorded from free-ranging crocodiles were found to be accompanied by only a modest bradycardia, highlighting the often confounding effects associated with captive animals monitored under laboratory conditions. More recent studies have also documented the complex central flow and pressure patterns of crocodilians, including a pulmonary to systemic shunt that can be initiated by a unique intracardiac valve located in the subpulmonary conus. The role and significance of this cardiac shunt remains controversial and the focus of recent lab-based studies. We contend that elucidation of the role and significance of the cardiac shunt in crocodilians will only be achieved by monitoring telemetrically the central cardiovascular flows and pressures in non-captive animals that are undisturbed and free-ranging. This presents the challenge ahead in the next 50 years.
Keyword Diving
Heart
Cardiovascular
Haemodynamic
Foramen of Panizza
Cardiac output
Shunting
Pulmonary perfusion
Bradycardia
Telemetry
Reptile
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 25 May 2011

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Official 2012 Collection
School of Biological Sciences Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 2 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 3 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Sun, 21 Aug 2011, 01:25:41 EST by System User on behalf of School of Biological Sciences