Aggregation of red cells and blood viscosity under near-zero gravity 1

Abstract

This paper outlines NASA experiment No. MPS77F113, proposed for Space Shuttle No. 3. The objectives of this investigation are: (a) to study aggregation of human red blood cells in order to define the maximum size and morphology of aggregates under near-zero gravity; (b) to define effects of various agents (such as fibrinogen, cholesterol, paraproteins, snake-venom derivatives, etc.) on the size of red cell aggregates and kinetics of their formation; (c) to study blood viscosity under high and low shear rates; and (d) to consider these tests with a view to possible use as, or elaboration of existing, diagnostic tests. The space environment offers the advantage of weightlessness which allows formation of cell aggregates undisturbed by sedimentation. The background to these studies is given, and the development of the automatic parallel-plate slit-capillary viscometer is described. Aggregation of red cells is recorded by a photocamera equipped with bellows or with a microscope. Pressure drop and temperature are also recorded in the memory of a microprocessor. About six blood samples are used with a single set of plates. Blood samples from healthy donors and from patients suffering from hypertension, diabetes, myocardial infarction and some types of cancer are used. Effect of ABO blood group of the donor will be studied.