The role of ecto-ATPases of erythrocyte plasma membrane in hemodynamics of fishes

Resumo

The review addresses varied aspects of physiological and biochemical mechanisms aimed at creating special rheological conditions for blood flow termed non-Newtonian blood properties. We conducted a comparative analysis of structural features and phospholipid repertoire of the erythrocyte plasma membranes and cytoskeleton, extracellular ATP pool, and ecto-ATPase enzymatic activity in nucleated and non-nucleated erythrocytes in vertebrates, as well as a study of thermal effects in nucleated red blood cells. Based on data from the literature and our own research, we hypothesize that the phenomenon of non-Newtonian blood properties is underlain by a decrease in the relative blood viscosity due to thermal hydrolysis of extracellular ATP that erythrocytes release onto their surface most actively under capillary deformation stress. We believe that in fishes an important role in this process may belong to erythrocyte plasma membrane ecto-ATPases. Due to a heat released during hydrolysis of extracellular ATP, the marginal blood plasma layer, adjoining the capillary wall, appears to warm up. This may modify the structure of the membrane bilayer and deform the cytoskeleton, thus providing special rheological conditions for blood flow. The heat-producing ability, that we found in fish nucleated erythrocytes, may serve an additional evidence for the existence of this mechanism.