Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes

Laguë, S. L. et al. (2020) Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes. Journal of Experimental Biology, 223(5), jeb211250. (doi: 10.1242/jeb.211250) (PMID:32041807)

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Abstract

The cardiovascular system is critical for delivering O2 to tissues. Here, we examined the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared with four related low-altitude populations in North America, tested at their native altitude. Ducks were exposed to stepwise decreases in inspired partial pressure of O2 while we monitored heart rate, O2 consumption rate, blood O2 saturation, haematocrit (Hct) and blood haemoglobin (Hb) concentration. We calculated O2 pulse (the product of stroke volume and the arterial–venous O2 content difference), blood O2 concentration and heart rate variability. Regardless of altitude, all eight populations maintained O2 consumption rate with minimal change in heart rate or O2 pulse, indicating that O2 consumption was maintained by either a constant arterial–venous O2 content difference (an increase in the relative O2 extracted from arterial blood) or by a combination of changes in stroke volume and the arterial–venous O2 content difference. Three high-altitude taxa (yellow-billed pintails, cinnamon teal and speckled teal) had higher Hct and Hb concentration, increasing the O2 content of arterial blood, and potentially providing a greater reserve for enhancing O2 delivery during hypoxia. Hct and Hb concentration between low- and high-altitude populations of ruddy duck were similar, representing a potential adaptation to diving life. Heart rate variability was generally lower in high-altitude ducks, concurrent with similar or lower heart rates than low-altitude ducks, suggesting a reduction in vagal and sympathetic tone. These unique features of the Andean ducks differ from previous observations in both Andean geese and bar-headed geese, neither of which exhibit significant elevations in Hct or Hb concentration compared with their low-altitude relatives, revealing yet another avian strategy for coping with high altitude.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Dawson, Dr Neal
Creator Roles:
Dawson, N. J.Investigation, Resources, Writing – review and editing
Authors: Laguë, S. L., Ivy, C. M., York, J. M., Chua, B. A., Alza, L., Cheek, R., Dawson, N. J., Frappell, P. B., Farrell, A. P., McCracken, K. G., Scott, G. R., and Milsom, W. K.
Subjects:Q Science > Q Science (General)
Q Science > QH Natural history
Q Science > QH Natural history > QH301 Biology
Q Science > QP Physiology
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Journal of Experimental Biology
Publisher:Company of Biologists
ISSN:0022-0949
ISSN (Online):1477-9145
Published Online:11 March 2020
Copyright Holders:Copyright © 2020 The Company of Biologists Ltd
First Published:First published in Journal of Experimental Biology 223(5): jeb211250
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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