This program is designed to provide a multidisciplined approach to the study of the physiological significance of in vitro blood rheology studies. The experimental approach to the problem involves: 1) the development and accumulation of techniques necessary to acquire various hemorrheological data (such as low or high shear rate viscometry, cellular deformability, erythrocyte morphology-shear stress relations) on physicochemically and morphologically defined blood samples; 2) the continued development of a relevant in vitro flow replica, derived from a vascular bed, suitable for viscometry as well as flow visualization; 3) the systematic use of these instruments and techniques to define more fundamental properties of human blood, with particular emphasis directed toward detailing physical-rheological changes in stored blood. Additionally, it is proposed to utilize these techniques to provide hemorrheological data as potential supporting information for patient care. BIBLIOGRAPHIC REFERENCES: Meiselman, H. J. and Baker, R. F.: "Flow behavior of ATP-Depleted Human Erythrocytes". Biorheology, in press, 1977. Corry, W. D. and Meiselman, H. J.: "Red Cell Deformation Via Centrifugation". Fed. Proc., in press, 1977.