Bovine hemoglobin anaerobically reacted with divinyl sulfone: a potential source for hypothermic oxygen carriers

The bifunctional reagent divinyl sulfone was anaerobically reacted with bovine hemoglobin to give a noncrosslinked intramolecularly-modified new derivative (HbBv-DVS). By employing a high molar ratio of divinyl sulfone to HbBv-DVS, it was possible to effect anaerobic intermolecular crosslinkage. The polymerized material (Poly HbBv-DVS) was shown to consist of a mixture of modified intermolecularly-crosslinked hemoglobins characterized by molecular masses ranging from 130 to -500 kDa. Some functional properties of HbBv-DVS and Poly HbBv-DVS have been evaluated in vitro and in vivo. Viscosities of HbBv-DVS solutions at temperatures as low as 15 degrees C and concentrations up to 14.0 g/dl were proved to be much lower than that of normal human blood at 37 degrees C (-4 cp). Poly HbBv-DVS (14.0 g/dl) was iso-oncotic (COP = 23 mm Hg) with plasma, and had viscosities of 3.37 and 4.57 cp at 37 and 15 degrees C, respectively. The clearance of Poly HbBv-DVS from the circulation was significantly delayed (T1/2 = 270 min), compared with those of HbBv and HbBv-DVS (T1/2 = 80 and 100 min, respectively. The P50 values were substantially increased (P50 = 52 and 61 mm Hg at 37 degrees C, 0.15 M Cl- and pH 7.4 for HbBv-DVS and Poly HbBv-DVS, respectively). Due to their right-shifted oxygen equilibrium curves, these derivatives still yielded P50 values of about 20 mm Hg at the low temperature of 15 degrees C, as compared with only 7 mm Hg for native bovine hemoglobin. These properties make HbBv-DVS and Poly HbBv-DVS potential new candidates for low-temperature organ perfusion.