title: NMR visibility studies of N-delta proton of proximal histidine in deoxyhemoglobin in lysed and intact red cells.
abstract: Recent in vivo 1H MRS studies of muscle oxygen levels by means of myoglobin (Mb) oxygenation have necessitated an investigation of the possible contamination from deoxy-hemoglobin (Hb). To determine the contribution of Hb in these NMR measurements, we studied the NMR visibility of histidyl N-delta proton of Hb in lysed and intact RBC (red blood cell) suspensions. We found that the visibility of deoxy-Hb was significantly lower in intact RBCs (ca. 16%) than the solution form at an equivalent concentration of beta heme-iron, even though the visibility of deoxy-Hb from lysed RBC and deoxy-Mb was almost identical. Our study also shows that visibility increases with RBC swelling. Based on the difference in concentration and compartmentation, we conclude that less than 17% contribution from Hb is expected in Mb measurements in vivo. The possible mechanisms which cause the low visibility of Hb in RBCs are discussed.
authors.affiliation: Department of Radiology, School of Medicine, University of Pennsylvania, Philadelphia 19104.
authors.forename: D J
authors.initials: DJ
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Nioka
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
authors.forename: B
authors.initials: B
authors.lastname: Chance
mesh_terms: D004912:Erythrocytes / Q000737:chemistry*; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis; D006639:Histidine / Q000032:analysis*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D009211:Myoglobin / Q000097:blood
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; D006639:Histidine; C100003:deoxyhemoglobin