Right-to-left shunt has modest effects on CO 2 delivery to the gut during digestion, but compromises oxygen delivery.

Autor: Malte CL; Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark christian.malte@bios.au.dk., Malte H; Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark., Reinholdt LR; Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark., Findsen A; Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark., Hicks JW; Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA., Wang T; Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark.
Jazyk: angličtina
Zdroj: The Journal of experimental biology [J Exp Biol] 2017 Feb 15; Vol. 220 (Pt 4), pp. 531-536. Date of Electronic Publication: 2016 Dec 15.
DOI: 10.1242/jeb.149625
Abstrakt: By virtue of their cardiovascular anatomy, reptiles and amphibians can shunt blood away from the pulmonary or systemic circuits, but the functional role of this characteristic trait remains unclear. It has been suggested that right-to-left (R-L) shunt (recirculation of systemic blood within the body) fuels the gastric mucosa with acidified and CO 2 -rich blood to facilitate gastric acid secretion during digestion. However, in addition to elevating P CO 2 , R-L shunt also reduces arterial O 2 levels and would compromise O 2 delivery during the increased metabolic state of digestion. Conversely, arterial P CO 2  can also be elevated by lowering ventilation relative to metabolism (i.e. reducing the air convection requirement, ACR). Based on a mathematical analysis of the relative roles of ACR and R-L shunt on O 2 and CO 2 levels, we predict that ventilatory modifications are much more effective for gastric CO 2 supply with only modest effects on O 2 delivery. Conversely, elevating CO 2 levels by means of R-L shunt would come at a cost of significant reductions in O 2 levels. The different effects of altering ACR and R-L shunt on O 2 and CO 2 levels are explained by the differences in the effective blood capacitance coefficients.
(© 2017. Published by The Company of Biologists Ltd.)
Databáze: MEDLINE
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