Human serum albumin incorporating synthetic heme: Red blood cell substitute without hypertension by nitric oxide scavenging

The administration of extracellular, hemoglobin‐based oxygen carriers often elicits an acute increase in blood pressure by vasoconstriction. This side effect is now recognized to be due to the depletion of nitric oxide (endothelial‐derived relaxing factor) by the extravasuated hemoglobins. We have recently found that the administration of a recombinant human serum albumin (rHSA)‐based oxygen carrier involving synthetic tetraphenyporphinatoiron(II) derivative (FeP) (rHSA‐FeP) does not induce such hypertensive action, because of its low permeability through the vascular endothelium. The heart rate responses after the rHSA‐FeP injection were also negligibly small. Visualization of the intestinal microcirculatory changes clearly revealed the widths of the venule and arteriole to be fairly constant. The entirely synthetic rHSA‐FeP becomes a promising material as a new type of red blood cell substitute.