TMA-DPH: A suitable fluorescence polarization probe for specific plasma membrane fluidity studies in intact living cells

Fluorescence intensity measurements and fluorescence microscopy data showed that TMA-DPH (trimethylammonium diphenylhexatriene), a cationic derivative of the fluorescence polarization probe DPH, has a considerably different behavior in L929 cultured cells than does its parent molecule. In contrast to DPH, it incorporates very rapidly in the plasma membranes of the treated cells, and remains specifically localized on the cell surface for at least 25 min. It can therefore be recommended for specific plasma membrane fluidity measurements in whole living cells. No relevant information about the localization of the probes could be obtained by other techniques used in parallel, namely: subcellular fractionation and fluorescence inhibition by trinitrobenzene sulfonate (TNBS).