Flow Properties of Suspensions of Red Blood Cells in Stabilized Hemoglobin Solution(Issue Commemorating the Directorship of Prof. Yoko HASHIMOTO, at the Department of Physiology)

A solution of a pyridoxalated hemoglobin polyoxyethylene conjugate (stabilized hemoglobin; SHb) is regarded as a promising blood substitute because of its characteristics as an oxygen carrier. In the present experiments, viscometry of SHb solutions was performed and the effects of SHb on the flow properties of RBC suspensions were tested. The viscosity of SHb solution showed shear rate dependence, and increased slightly with rising SHb concentration. The RBC suspensions containing SHb showed shear rate thinning flow behavior similar to that of RBC suspensions in the absence of SHb. However, the presence of SHb caused a remarkable elevation of viscosity at a range of shear rate 19.2～384 sec^. The increase in viscosity was greater at higher SHb concentrations. Microscopic observations on RBCs in SHb solution indicated that the molecules of SHb interact with RBCs to induce rouleaux formation. This rouleaux formation depended on the SHb concentration in the medium. The relative viscosity (suspension viscosity/medium viscosity) decreased as the shear rate was reduced. These results indicate that SHb affects the flow properties of RBC suspensions, especially in the lower shear rate region