[Mechanisms regulating the macrorheologic properties of the blood]

Macro-rheological features of human blood (the limit of fluidity, seeming viscosity in low shift velocities), cohesion power among erythrocytes, and hematocrit in pregnancy (36-38 weeks), in neonatal period, in acute and chronic heart disease, and in dogs with experimental hemorrhagic shock, were studied. Reduction of the cohesion power among erythrocytes was shown to occur in increase of hematocrit value. If the cohesion power increases it is followed by physiological hemodilution. The organism tries to prevent the increase of the macro-rheological parameters up to the level entailing irreversible disorders of microcirculation.