THE OXYGEN-CARRYING CAPABILITY OF HEMOGLOBIN VESICLES EVALUATED IN RAT EXCHANGE-TRANSFUSION MODELS

To evaluate the oxygen transporting capability of Hemoglobin vesicles (HbV) the physiological responses to 40% and 90% exchange transfusions with HbV in anesthetized rat were observed. Hb concentration of HbV d ispersions is 10g/dL. HbV dispersed in phosphate buffered saline and H bV dispersed in 5% albumin solution were used as samples for 40% and 9 0% exchange transfusions, respectively. HbV surface-modified with poly oxyethylene (HbV-Poe) was also used in the 90% exchange transfusion. A s controls, phosphate buffered saline, 5% albumin solution, and HbV co ntaining methemoglobin and therefore deprived of oxygen transporting c apabilities (metHbV) were administered as non-oxygen carrying fluids a nd washed rat red blood cells (ratRBC) as an oxygen carrying fluid. Me asurements included mean arterial pressure, arterial blood gas analyse s, aortic blood flow and renal cortical tissue oxygen tension. At the completion of the exchange transfusion renal cortical tissue oxygen te nsions along with oxygen delivery and consumption were sustained almos t equally well with the HbV dispersion compared to the washed rat red blood cell dispersion, but declined significantly in the phosphate buf fered saline and albumin solutions. These results indicated that the o xygen transporting capability of HbV was almost equivalent to that of rat red blood cells. in the HbV-Poe group, aortic blood flow was susta ined higher in comparison to the HbV group. As for the blood gas param eters, pH and venous oxygen tensions in the HbV-Poe group tended to be higher than those in the HbV group.