title: Respiration and gas exchange during recovery from exercise in the American alligator.
abstract: Low respiratory exchange ratios (R) occur in reptiles. In crocodilians they have been attributed to the loss of respiratory CO2 into the urine and to the immediate exercise-history of an animal. In this study, expired ventilation (V(E)), oxygen consumption (V(O2)), and carbon dioxide excretion (V(CO2)) were measured during recovery from treadmill-exercise in the American alligator. Both V(O2) and V(CO2) decreased exponentially during recovery, but the decrease of V(CO2) was greater than that of V(O2). By 55 min into recovery R fell to 0.3 +/- 0.02 (mean +/- S.E.M). These low values of R may be partially attributable to hyperventilation that occurred during exercise. These data suggest that both hyperventilation during exercise and a metabolic acidosis deplete blood bicarbonate stores, contributing to a low R during recovery. We propose that the right to left cardiac shunt could facilitate restoration of these alkaline reserves and blood pH.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Irvine 92697, USA. cfarmer@uci.edu
authors.forename: C G
authors.initials: CG
authors.lastname: Farmer
authors.forename: D R
authors.initials: DR
authors.lastname: Carrier
mesh_terms: D000489:Alligators and Crocodiles / Q000502:physiology*; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D005080:Exercise Test; D006985:Hyperventilation / Q000503:physiopathology; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012119:Respiration
chemical_list: D002245:Carbon Dioxide