Stopped-flow kinetics of oxygen uptake and release by embryonic red blood cells

The processes of O2 uptake and release by the three embryonic haemoglobins contained within early mouse embryonic red blood cells have been studied using dual-wavelength stopped-flow kinetic spectroscopy. The rate of O2 uptake in the pseudo-spherical, nucleated, embryonic red blood cells exhibits a greater than first-order dependence on O2 concentration. The time courses for the release from the red blood cells into dithionite-containing solutions tends towards a limiting rate at high dithionite concentrations. The rates of both the uptake and release processes observed in the embryonic cells are compared with those previously seen for adult mouse red blood cells. A new mathematical model is described which accurately simulates both uptake and release experimental data for the nucleated embryonic red blood cells.