Oxygen transport studies of normal and sickle erythrocyte suspensions in artificial capillaries

Oxygen transport from normal and sickle erythrocytes was studied under known and carefully controlled conditions simulating the microcirculation. Oxygenated erythrocyte suspensions became deoxygenated as they traversed silicone rubber capillaries of 27 microns diameter. Oxygen saturation values of the flowing erythrocyte suspensions were measured at several axial positions along the capillary by use of a microspectrophotometric technique. Oxygen saturation decreased with increasing distance from the entrance of the capillary and was strongly influenced by the flow rate. Under the same hematocrit and flow conditions, the rate of oxygen saturation decrease was significantly higher for the sickle cells than for normal cells. Sickle cells would be expected to have a higher diffusional resistance to oxygen transport than that of normal cells. However, the lower oxygen affinity of the sickle cells tends to increase the oxygen delivery rate. The difference in oxygen affinity appears to account for the difference in oxygen delivery rates between normal and sickle cells.