Oxygen Delivery and Myocardial Function in Rabbit Hearts Perfused with Cell-FreeHemoglobin

摘要

Preparations of chemically modified cell-free hemoglobin have been proposed aspotential oxygen-carrying blood substitutes. A common concern when formulating these materials is whether their oxygen-binding properties will allow sufficient oxygen off-loading to vital target tissues. Removal of hemoglobin from erythrocytes and purification of the protein markedly increased its oxygen affinity as 2,3-diphosphoglycerate (2,3-DPG) is stripped from the molecule at the PO2 at which half-saturation of hemoglobin occurs (P50) of normal human hemoglobin drops from a typical value close to 30 Torr in erythrocytes to 10 Torr in solution at physiological pH and PCO2. It has been assumed that this value is too low to adequately supply the oxygen demands of most tissues, especially those with high metabolic rates, such as the heart, brain, and kidney.