[The effect of an increased erythrocyte count on rapid blood flow fluctuations in the microvessels of the rat brain].

Polycythemia was achieved by means of substitution of the rat own blood (2 ml) with the same volume of washed out erythrocytes, the hematocrit increasing from 44 to 54%. Excessive erythrocytes altered the structure of the erythrocyte flow, its diameter being 3-13 mu. The rate of occurrence of the plasma lumens decreased. The hematocrit increase, however, did not affect the amplitude and period of the oscillations. The character of distribution of periodic components of the fluctuations of the blood flow linear velocity did not change either in the vessels under study. The data obtained suggests that the erythrocytes do not affect the occurrence of the blood flow oscillations in the microcirculation system. The main part in their formation seems to be played by the leucocytes differing by their rheological features from erythrocytes.