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Oxygen binding by single red blood cells from the red-eared turtle Trachemys scripta.
1Danish Centre for Respiratory Adaptation, Department of Zoophysiology, University of Aarhus, 8000 Aarhus C, Denmark. frische@biology.au.dk
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 12, 2001
Summary
Red blood cells in turtles show varied oxygen affinity, with hemoglobins not segregated into distinct cells. This cellular variation is crucial for understanding tissue oxygenation models.
Area of Science:
- Comparative physiology
- Red blood cell physiology
- Hemoglobin function
Background:
- Red blood cells (RBCs) are vital for oxygen transport.
- Understanding RBC oxygen-binding properties is key to respiratory physiology.
- Vertebrate RBCs exhibit variations in oxygen affinity.
Purpose of the Study:
- To quantify cell-to-cell variation in oxygen affinity within individual turtle RBCs.
- To investigate the distribution of different hemoglobin types among RBCs.
- To inform models of tissue oxygenation.
Main Methods:
- Microspectrophotometry used to measure oxygen-binding curves of single RBCs.
- Analysis of oxygen pressure at half saturation (P50) for individual cells.
- Examination of the distribution of P50 values across the RBC population.
Main Results:
- Significant differences in oxygen affinity were observed among individual turtle RBCs.
- The mean oxygen pressure at half saturation was 20.1 ± 3.3 Torr.
- The distribution of oxygen affinities was unimodal, suggesting hemoglobins are not cell-specific.
Conclusions:
- Turtle RBCs display considerable variation in oxygen-binding properties.
- Hemoglobins are likely co-expressed within RBCs, enabling in vivo functional interaction.
- Cellular heterogeneity in oxygen affinity must be considered in physiological models.