Kinetic studies on oxygen releasing of HBOC and red blood cells as fluids and factors affecting the process.

Red blood cells (RBCs) possess intact cyto-architectures while haemoglobin (Hb) is a cell-free, homogeneous solution. Both RBCs and Hb are generalized oxygen carriers. In this paper, kinetic studies on oxygen-releasing of high concentration of Hb and RBCs under various conditions were carried out regarding Hb and RBCs as fluids. Among them, Hb under specific conditions was seen as the simplest Hb-based oxygen carrier (HBOC), Also, factors affecting the oxygen releasing of Hb and RBCs, including osmotic pressure, viscosity and allosteric agent, have been well studied. Analysis of the results from the measurement above showed that kinetics of oxygen releasing of either pure Hb or the simplest HBOCs was obviously different from that of RBCs. The oxygen-releasing time of Hb was shorter and the oxygen-releasing rates of Hb were quicker than those of RBCs under various conditions. Therefore, as fluids, only by changing the milieus it exists in, Hb could not achieve the expected oxygen-releasing effect on the microcirculation so well as RBCs do in the same system, irrespective of the interaction between the fluids and blood vessels. Furthermore, kinetic properties of HBOCs must be considered and matched with those of RBCs in the study of HBOCs.