Steady-State, Hemoglobin-Facilitated O₂ Transport in Human Erythrocytes

We measured the rate of oxygen transport through thin (165 µ) films of packed erythrocytes (Hb concentration = 30 g/100 ml). Under optimal conditions steady-state O₂ diffusion was nearly three times that found when the hemoglobin was prevented from acting as a carrier molecule by carbon monoxide binding or high oxygen back pressure. After each experiment we measured hemolysis and found that it averaged less than 1%. Hemolysis could not account for the facilitation, thus proving that facilitated transport of O₂ by hemoglobin can occur in red blood cells. The rate of facilitated transport was identical for Hb solutions of equal concentration to the cells. We interpret this to mean that under the conditions of our experiments the red cell membrane offers no detectable diffusion resistance to O₂ and that the mobility of Hb in intact red cells is the same as in concentrated Hb solution.