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A precise and rapid procedure employing gel filtration on Superose-12 to measure the tetramer-dimer dissociation constants of some natural and recombinant hemoglobins in the oxy conformation is described. Natural sickle hemoglobin was chosen to verify the validity of the results by comparing the values with those reported using an independent method not(More)
We have measured plasma volume and cardiac index in rats after 50% isovolemic exchange transfusion with human hemoglobin cross-linked between the alpha-chains with bis(3,5-dibromosalicyl)fumarate (alpha alpha Hb) and with bovine hemoglobin modified with polyethylene glycol (PEGHb). alpha alpha Hb and PEGHb differ in colloid osmotic pressure (23.4 and 118.0(More)
Altitude hypoxia is a major challenge to the blood O2 transport system, and adjustments of the blood–O2 affinity might contribute significantly to hypoxia adaptation. In principle, lowering the blood–O2 affinity is advantageous because it lowers the circulatory load required to assure adequate tissue oxygenation up to a threshold corresponding to about(More)
The kinetics of oxygen uptake and release by human, salamander (Amphiuma means), and artificially constructed red cells were measured under a variety of physiological conditions using stopped-flow, rapid mixing techniques. The results were analyzed quantitatively using the generalized, three-dimensional disc model that was developed in two previous(More)
Oxygen release by human erythrocytes in the presence of external sodium dithionite was examined by stopped-flow, rapid mixing techniques. The resultant time courses were analyzed quantitatively using a three-dimensional disc model which had been developed previously to describe oxygen uptake (Vandegriff, K. D., and Olson, J. S. (1984) Biophys. J. 45,(More)
Repeated exposure to brief periods of hypoxia leads to pathophysiological changes in experimental animals similar to those seen in sleep apnea. To determine the effects of such exposure on oxygen levels in vivo, we used an optical method to measure PO2 in microcirculatory vessels and tissue of the rat cremaster muscle during a 1-min step reduction of(More)
Oxygen equilibrium curves of human hemoglobin Ao (HbAo) and human hemoglobin cross-linked between the alpha chains (alpha alpha Hb) by bis(3,5-dibromosalicyl) fumarate were measured as a function of pH and chloride or organic phosphate concentration. Compared to HbAo, the oxygen affinity of alpha alpha Hb was lower, cooperativity was maintained, although(More)
We compared rates of oxygen transport in an in vitro capillary system using red blood cells (RBCs) and cell-free hemoglobins. The axial PO(2) drop down the capillary was calculated using finite-element analysis. RBCs, unmodified hemoglobin (HbA(0)), cross-linked hemoglobin (alpha alpha-Hb) and hemoglobin conjugated to polyethylene-glycol (PEG-Hb) were(More)
Oxygen uptake by human erythrocytes has been examined both experimentally and theoretically in terms of the influence of unstirred solvent layers that are adjacent to the cell surface. A one-dimensional plane sheet model has been compared with more complex spherical and cylindrical coordinate schemes. Although simpler and faster, the plane sheet algorithm(More)
Haemoglobin-based oxygen carriers can undergo oxidation of ferrous haemoglobin into a non-functional ferric form with enhanced rates of haem loss. A recently developed human haemoglobin conjugated to maleimide-activated poly(ethylene glycol), termed MP4, has unique physicochemical properties (increased molecular radius, high oxygen affinity and low(More)