Vol. 90, Issue 5, 1679-1684, May 2001
Oxygen binding by single red blood cells from the red-eared
turtle Trachemys scripta
Sebastian
Frische1,
Stefano
Bruno2,
Angela
Fago1,
Roy E.
Weber1, and
Andrea
Mozzarelli2
1 Danish Centre for Respiratory Adaptation, Department of
Zoophysiology, University of Aarhus, 8000 Aarhus C, Denmark; and
2 Institute of Biochemical Sciences, University of Parma,
Area Parco delle Scienze, 43100 Parma, Italy
Oxygen-binding properties of
single red blood cells from the red-eared turtle Trachemys
scripta were measured by microspectrophotometry to describe the
variation in oxygen affinity of red blood cells and to gain insight
into the distribution of functionally different hemoglobins among red
blood cells. Methodologically, this study represents the first report
on the cell-to-cell variation in oxygen-binding properties based on
oxygen-binding curves of single vertebrate red blood cells. The cells
differed significantly with respect to oxygen affinity. Mean oxygen
pressure at half saturation of the cells in a blood sample was found to
be 20.1 ± 3.3 (SD) Torr. The distribution of oxygen affinities
among red blood cells is unimodal, indicating that the two hemoglobins
found in turtle blood are not segregated in distinct cells. Therefore,
the functional interaction shown by these hemoglobins in vitro is
likely to take place in vivo. The considerable variation in oxygen
affinity between individual red blood cells calls for its incorporation
in models of tissue oxygenation.
oxygen transport; microspectrophotometry; hemoglobin
