The physiology of diving in a north-temperate and three tropical turtle species |
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Authors: | C E Crocker G R Ultsch D C Jackson |
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Institution: | (1) Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI 02912, USA e-mail: carlos_crocker@brown.edu, donald_jackson@brown.edu, US;(2) Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487; USA e-mail: gultsch@biology.as.ua.edu, US |
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Abstract: | We examined changes in blood gases, plasma ions, and acid-base status during prolonged submergence (6 h) of four aquatic
turtle species in aerated water at 20 °C. Our objective was to determine whether the temperate species, Chrysemys picta bellii, exhibits greater tolerance to submergence apnea than the tropical species, Pelomedusa subrufa, Elseya novaeguineae, and Emydura subglobosa. Blood was sampled from indwelling arterial catheters for measurements of blood PO2, PCO2, pH, and hematocrit and for plasma concentrations of lactate, glucose, Na+, K+, Cl−, total Ca, and total Mg. The pattern of change was similar in all species: a combined respiratory and metabolic acidosis
associated with a marked decrease of blood PO2. The severity of the acidosis developed in the temperate species, however, was significantly less than that of the tropical
turtles. Lactate rose significantly and HCO3
− fell proportionately in all turtles; changes in other plasma ion concentrations were small but were generally in the directions
consistent with compensatory exchanges with other body compartments; i.e., cations (K+, Ca, and Mg increased) and anions (Cl− decreased). The results indicate that hypoxia tolerance is a conserved trait in turtles, even in those that do not experience
enforced winter submergence, and that the temperate species may be superior in this capacity because of reduced metabolic
rate.
Accepted: 3 March 1999 |
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Keywords: | Anoxia Turtles Acidosis Chrysemys Lactate |
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