[Method for measuring the orientation rate of flowing erythrocytes by spin labeling]

The electron spin resonance spectra of erythrocytes labeled by 5-nitroxide stearate, flowing through a quartz sample cell of rectangular cross-section, were studied. The main cross-sectional dimension of the quartz cell is either parallel or perpendicular to the magnetic field. Comparison between experimental spectra and numerically simulated spectra allows to determine an orientation rate of the red blood cells, as a function of the flowing velocity and of other hydrodynamic parameters.