Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus)

Seebacher, F. and Franklin, C. E. (2007) Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus). Journal of Comparative Physiology B-Biochemical Systemic And Environmental Physiology, 177 8: 841-848. doi:10.1007/s00360-007-0181-4


Author Seebacher, F.
Franklin, C. E.
Title Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus)
Formatted title
Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (Crocodylus porosus)
Journal name Journal of Comparative Physiology B-Biochemical Systemic And Environmental Physiology   Check publisher's open access policy
ISSN 0174-1578
Publication date 2007-01-01
Sub-type Article (original research)
DOI 10.1007/s00360-007-0181-4
Volume 177
Issue 8
Start page 841
End page 848
Total pages 8
Editor Heldmaier, G.
Place of publication Germany
Publisher Springer Heidelberg
Language eng
Subject C1
270604 Comparative Physiology
780105 Biological sciences
Abstract Changes in blood flow are a principal mechanism of thermoregulation in vertebrates. Changes in heart rate will alter blood flow, although multiple demands for limited cardiac output may compromise effective thermoregulation. We tested the hypothesis that regional differences in blood flow during heating and cooling can occur independently from changes in heart rate. We measured heart rate and blood pressure concurrently with blood flow in the crocodile, Crocodylus porosus. We measured changes in blood flow by laser Doppler flowmetry, and by injecting coloured microspheres. All measurements were made under different heat loads, with and without blocking cholinergic and beta-adrenergic receptors (autonomic blockade). Heart rates were significantly faster during heating than cooling in the control animals, but not when autonomic receptors were blocked. There were no significant differences in blood flow distribution between the control and autonomic blockade treatments. In both treatments, blood flow was directed to the dorsal skin and muscle and away from the tail and duodenum during heating. When the heat source was switched off, there was a redistribution of blood from the dorsal surface to the duodenum. Blood flow to the leg skin and muscle, and to the liver did not change significantly with thermal state. Blood pressure was significantly higher during the autonomic blockade than during the control. Thermal time constants of heating and cooling were unaffected by the blockade of autonomic receptors. We concluded that animals partially compensated for a lack of differential heart rates during heating and cooling by redistributing blood within the body, and by increasing blood pressure to increase flow. Hence, measures of heart rate alone are insufficient to assess physiological thermoregulation in reptiles.
Keyword Physiology
Zoology
blood pressure
blood flow
body temperature
autonomic receptors
cardiac output
hypertension
Turtle Trachemys-scripta
Heart-rate
Cardiovascular-responses
Physiological Thermoregulation
American Alligator
Pogona-barbata
Cardiac-output
Flow
Humans
Exchange
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Tue, 19 Feb 2008, 01:39:34 EST