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  • There is no limitation for CO2 excretion across the lung in exercising American alligators ( Alligator mississippiensis )
Title: There is no limitation for CO2 excretion across the lung in exercising American alligators ( Alligator mississippiensis )
ABSTRACT Vertebrates utilize various respiratory organs such as gills, lungs and skin in combination with diverse cardiovascular structures, including single-, three- and four-chambered hearts, to enable oxygen delivery and carbon dioxide removal. They also exhibit differences in aerobic and anaerobic metabolism during exertion, but the cardiorespiratory gas transport of all vertebrates is a four-step process governed by Fick's Principle and Fick's Law of Diffusion over the entire range of metabolic rates. Hillman et al. (2013) suggested that previous exercise studies have focused too narrowly on mammals and proposed that the cardiorespiratory system's excess capacity serves an evolutionary role in enhancing CO2 excretion in non-mammalian vertebrates. In contrast, an analysis by Hicks and Wang (2021) concluded that vertebrates maintain effective gas exchange even at peak activity, finding no evidence of arterial hypercapnia at maximal oxygen consumption and thus challenging the proposal of significant limitations to pulmonary or branchial CO2 efflux. In the present study, we investigated the limits for CO2 exchange in exercising American alligators (Alligator mississippiensis) and provide evidence that the cardiorespiratory system is adequately built to sustain CO2 excretion during strenuous exercise and maintain arterial PCO2, with no evidence of diffusion limitation for pulmonary CO2 excretion.  more » « less
Award ID(s):
1755187
PAR ID:
10590602
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
The Company of Biologists
Date Published:
Journal Name:
Journal of Experimental Biology
Volume:
227
Issue:
18
ISSN:
0022-0949
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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