Analysis of the fluorescence anisotropy of labelled membranes submitted to a shear stress.

Human erythrocyte membranes are elastic and undergo a deformation under shear stress. The phenomenon has been analysed by recording the fluorescence anisotropy of labelled isolated membranes. A model has been developed which assumes an orientation correlation function of a molecular probe incorporated in an elongated membrane. This model has been successfully used to analyse quantitatively data obtained with (1-trimethylamino)-(1,6-diphenyl)-1,3,5-hexatriene (TMA-DPH) and 6-(9-anthroyloxy)-stearic acid (6-AS). In agreement with the model, the effect of the membrane deformation is opposite for these two probes, which corroborates the concept that the alteration of the fluorescence anisotropy reflects mainly the deformation of the membrane and not the rotational freedom of the molecular probe.