title: Oxygen transport is not compromised at high temperature in pythons.
abstract: To evaluate whether the 'oxygen and capacity limited thermal tolerance' model (OCLTT) applies to an air-breathing ectothermic vertebrate, we measured oxygen uptake (V̇(O₂)), cardiac performance and arterial blood gases during a progressive rise of temperature from 30 to 40°C in the snake Python regius. V̇(O₂) of fasting snakes increased exponentially with temperature whereas V̇(O₂) of digesting snakes at high temperatures plateaued at a level 3- to 4-fold above fasting. The high and sustained aerobic metabolism over the entire temperature range was supported by pronounced tachycardia at all temperatures, and both fasting and digesting snakes maintained a normal acid-base balance without any indication of anaerobic metabolism. All snakes also maintained high arterial PO2, even at temperatures close to the upper lethal temperature. Thus, there is no evidence of a reduced capacity for oxygen transport at high temperatures in either fasting or digesting snakes, suggesting that the upper thermal tolerance of this species is limited by other factors.
authors.affiliation: Zoophysiology, Department of Bioscience, 8000 Aarhus C, Denmark.
authors.forename: Dannie
authors.initials: D
authors.lastname: Fobian
authors.affiliation: Zoophysiology, Department of Bioscience, 8000 Aarhus C, Denmark.
authors.forename: Johannes
authors.initials: J
authors.lastname: Overgaard
authors.affiliation: Zoophysiology, Department of Bioscience, 8000 Aarhus C, Denmark tobias.wang@biology.au.dk.
authors.forename: Tobias
authors.initials: T
authors.lastname: Wang
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D017821:Boidae / Q000378:metabolism*; D004063:Digestion / Q000502:physiology; D005215:Fasting; D006339:Heart Rate; D006358:Hot Temperature; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D015657:Respiratory Transport; D013312:Stress, Physiological
chemical_list: D010100:Oxygen
keywords: Cardiovascular; Digestion; Metabolism; Reptile; Temperature