Certain aspects of hemorheology in a near zero gravity environment 1

Abstract

Hemorheology, viz., rheology of blood and vessel wall, is considered to be affected in a near zero gravity environment. As body water, constituting a predominant component of the body mass of living subjects, is mainly distributed among intracellular, interstitial and plasma compartments, gravity appears to be important in the regulation of their volumes. Exposure of human and other vertebrate subjects to a near zero gravity environment may bring about a number of hemorheological changes, affecting the blood and the vessel structures with which blood or its components come into direct contact. Since no hemorheological studies have been made in such an environment, experiments, employing a newly designed light-weight rheogoniometer (LWR), are proposed to be performed on ground and in the Spacelab Module. The modified Weissenberg Rheogoniometer is recommended for comparative testing the efficacy and precision of the LWR and accessories. The following studies, based on research in my laboratory, are proposed: 1. Viscosity and elasticity measurements of human blood (HB); 2. cinephotomicrographic recordings of HB in steady and oscillatory shears; 3. rheological studies of viscosity and elasticity of surface layers of purified fibrinogen and other proteins; 4. measurements of viscoelasticity and rigidity of fibrin gels. The findings to be secured promise to shed new light on recent findings in astronauts exposed to protracted stay in a near zero gravity environment. The information gained may also identify the role which gravity plays in situations on earth which thus far could not be fully appreciated. Our proposed studies may lead to corrective prophylactic measures to enable people to live and work during protracted stay in a near zero gravity environment.