Literaturdatenbank
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Maginniss, L. A., Ekelund, S. A., & Ultsch, G. R. (2004). Blood oxygen transport in common map turtles during simulated hibernation. Physiological and Biochemical Zoology, 77(2), 232–241.
Added by: Admin (25 Aug 2010 21:58:51 UTC) |
| Resource type: Journal Article DOI: 10.1086/381473 BibTeX citation key: Maginniss2004 View all bibliographic details  |
Categories: General Keywords: Emydidae, Graptemys, Graptemys geographica, Physiologie = physiology, Schildkröten = turtles + tortoises Creators: Ekelund, Maginniss, Ultsch Collection: Physiological and Biochemical Zoology |
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| Abstract |
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We assessed the effects of cold and submergence on blood oxygen transport in common map turtles (Graptemys geographica). Winter animals were acclimated for 6–7 wk to one of three conditions at 3°C: air breathing (AB-3°C), normoxic submergence (NS-3°C), and hypoxic (PO2=49 Torr) submergence (HS-3°C). NS-3°C turtles exhibited a respiratory alkalosis (pH 8.07; PCO2=7,9 Torr; [lactate =2,2mM) relative to AB-3°C animals (pH 7.89; PCO2=13,4 Torr; [lactate=1,1mM). HS-3°C animals experienced a profound metabolic acidosis (pH 7.30; PCO2=7,9 Torr; [lactat=81mM). NS-3°C turtles exhibited an increased blood O2 capacity; however, isoelectric focusing revealed no seasonal changes in the isohemoglobin (isoHb) profile. Blood O2 affinity was significantly increased by cold acclimation; half-saturation pressures (P50's) for air-breathing turtles at 3° and 22°C were 6.5 and 18.8 Torr, respectively. P50's for winter animals submerged in normoxic and hypoxic water were 5.2 and 6.5 Torr, respectively. CO2 Bohr slopes ( ) were −0.15, −0.16, and −0.07 for AB-3°C, NS-3°C, and HS-3°C turtles, respectively; the corresponding value for AB-22°C was −0.37. The O2 equilibrium curve (O2EC) shape was similar for AB-3°C and NS-3°C turtles; Hill plot n coefficients ranged from 1.8 to 2.0. The O2EC shape for HS-3°C turtles was anomalous, exhibiting high O2 affinity below P50 and a right-shifted segment above half-saturation. We suggest that increases in Hb-O2 affinity and O2 capacity enhance extrapulmonary O2 uptake by turtles overwintering in normoxic water. The anomalous O2EC shape and reduced CO2 Bohr effect of HS-3°C turtles may also promote some aerobic metabolism in hypoxic water.
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