Membrane fluidity is different in intact erythrocytes and ghost membranes.

The fluorescence anisotropy of 1,6-diphenylhexatriene (DPH) and trimethylammonium-DPH in the membranes of intact human erythrocytes and ghost membranes was compared. The anisotropy of fluorophores is significantly higher in intact erythrocytes compared to that in ghost membranes. Perturbation of membranes by heating at 47 degrees C and use of a rotating stirrer affected the anisotropy of fluorophores in intact erythrocytes only. These results suggest that: (a) spectrin has a significant modulating effect on membrane fluidity, and (b) the physical properties of the cell membrane are different between intact erythrocytes and erythrocyte ghost membranes.