Modulation of oxygen‐carrying capacity of artificial red cells

The oxygen‐carrying capacity of artificial red cells (ARC), which were prepared by encapsulating hemoglobin (Hb) into polymerized lipid vesicles, has been investigated in detail. It was found that the effects of inositol hexaphosphate (IHP) on the oxygen affinity of stromafree Hb and ARC are quite different. By co‐encapsulating IHP at a IHP:Hb molar ratio of 1.0, the oxygen affinity of the encapsulated Hb in ARC was decreased to such an extent that P 50 was about 60–65 mmHg, and only about 70–80% of the encapsulated Hb could be oxygenated at an oxygen partial pressure (Po 2 ) of about 100 mmHg. As pyridoxal 5‐phosphate (PLP) and chloride ions were coencapsulated instead of IHP, P 50 and the Hill coefficient of the obtained ARC were adjusted to 25–30 mmHg and 2.5–2.8 respectively. The oxygen‐transporting efficiency of PLP‐modulated ARC was similar to or better than that of red blood cells.