Impairment of endothelial relaxations by glycosylated human oxyhemoglobin depends on the oxidative state of the heme group

While nanomolar met- or cyanomethemoglobin, either non-glycosylated or glyc osylated, did not alter endothelial function, glycosylated oxyhemoglobin in duced contractile responses and caused an impairment of endothelium-depende nt relaxations in rat aortic segments. The vascular effects induced by glyc osylated oxyhemoglobin were prevented by superoxide dismutase. Furthermore, glycosylated oxyhemoglobin produced higher amounts of superoxide anions th an other hemoglobin derivatives. These results suggest that glycosylated he moglobin requires the existence of a functional heme group containing iron in ferrous state to interfere with the endothelial function at nanomolar co ncentrations. This effect is mediated by generation of superoxide anions. ( C) 1999 Elsevier Science Inc. All rights reserved.