Control of heart rate during thermoregulation in the heliothermic lizard Pogona barbata: importance of cholinergic and adrenergic mechanisms

Seebacher, F. and Franklin, C. E. (2001) Control of heart rate during thermoregulation in the heliothermic lizard Pogona barbata: importance of cholinergic and adrenergic mechanisms. Journal of Experimental Biology, 204 24: 4361-4366.

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Author Seebacher, F.
Franklin, C. E.
Title Control of heart rate during thermoregulation in the heliothermic lizard Pogona barbata: importance of cholinergic and adrenergic mechanisms
Journal name Journal of Experimental Biology   Check publisher's open access policy
ISSN 0022-0949
1477-9145
Publication date 2001-01-01
Sub-type Article (original research)
Open Access Status File (Publisher version)
Volume 204
Issue 24
Start page 4361
End page 4366
Total pages 6
Editor R.G. Boutilier
Place of publication Cambridge
Publisher The Company of Biologists
Collection year 2001
Language eng
Subject 270603 Animal Physiology - Systems
780105 Biological sciences
Abstract During thermo regulation in the bearded dragon Pogona barbata, heart rate when heating is significantly faster than when cooling at any given body temperature (heart rate hysteresis), resulting in faster rates of heating than cooling. However, the mechanisms that control heart rate during heating and cooling are unknown. The aim of this study was to test the hypothesis that changes in cholinergic and adrenergic tone on the heart are responsible for the heart rate hysteresis during heating and cooling in P. barbata. Heating and cooling trials were conducted before and after the administration of atropine, a muscarinic antagonist, and sotalol, a beta-adrenergic antagonist. Cholinergic and beta-adrenergic blockade did not abolish the heart rate hysteresis, as the heart rate during heating was significantly faster than during cooling in all cases. Adrenergic tone was extremely high (92.3%) at the commencement of heating, and decreased to 30.7% at the end of the cooling period. Moreover, in four lizards there was an instantaneous drop in heart rate (up to 15 beats min(-1)) as the heat source was switched off, and this drop in heart rate coincided with either a drop in beta-adrenergic tone or an increase in cholinergic tone. Rates of heating were significantly faster during the cholinergic blockade, and least with a combined cholinergic and beta-adrenergic blockade. The results showed that cholinergic and beta-adrenergic systems are not the only control mechanisms acting on the heart during heating and cooling, but they do have a significant effect on heart rate and on rates of heating and cooling.
Keyword Biology
Thermoregulation
Heart Rate
Neural Control
Cholinergic
Adrenergic
Reptile
Lizard
Pogona Barbata
Exercise
Rest
Toad
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Biological Sciences Publications
Ecology Centre Publications
 
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Created: Wed, 15 Aug 2007, 02:29:29 EST