Abstract
Fluorescence correlation spectroscopy (FCS) has been used to analyze the plasma membrane fluidity and heterogeneity of multidrug resistant cells. At the single cell level, the effects of different membrane agents present in the extra-cellular medium have been explored. Firstly, we reveal a modification of plasma membrane heterogeneities according to the addition of a fluidity modulator, benzyl alcohol. On the other hand, revertants such as verapamil and cyclosporin-A appear to act more specifically on the slow diffusion sites, such as lipids microdomains.