Lipid fluidity of red cell membranes assessed with different fluorescent probes.

Two fluorescent probes, DPH and its cationic derivative, TMA-DPH, have been employed to probe the lipid fluidity of red cell membranes. The results show that the informations given by DPH and TMA-DPH can present important dif ferences, suggesting that DPH and TMA-DPH are not localized in the same areas of cell membranes. In an attempt to investigate relations between lipid fluidity and rheological properties, the behavior of probes was studied in a Couette viscometer with a device for studying the emissive properties of probes when red cell membranes are under shear conditions. This report describes the system and provides preliminary results in employing the device.