[THE ROLE OF ECTO-ATPASES OF PLASMATIC MEMBRANES OF ERYTHROCYTES IN HEMODYNAMICS OF FISHES].

Abstract

This paper reviews various aspects of the physiological and biochemical mechanisms directed to create special rheological conditions for blood flow called <> blood properties. The struc- tural features of the phospholipid composition of plasmatic membranes and cytoskeleton, the state of the intra- and extracellular ATP pool, ATPase ecto-enzymatic activity of nucleated and non-nucleated red blood cells of vertebrates are compared and thermal effects in nucleated erythrocytes investigated. A hypothesis based on literature and own data is suggested according to which the phenomenon of <> blood properties relies on a decrease in the relative viscosity of blood due to the thermal hydrolysis of extracellular ATP excreted by erythrocytes on their surface particularly strong during deformation stress in capillaries. We belive that in fish an important role in this process may belong to ecto-ATPases of erythrocyte plasmatic membranes. Due to generation of heat by the hydrolysis of extra- cellular ATP, the wall layer of the plasma appears to warm up. This could change the structure of the membrane bilayer and deform the cytoskeleton, thus providing the special rheological conditions for blood flow. Among the proofs of possible existence of this mechanism is heat production ability of nucleated red cells in fish revealed in our stymies.