Change in membrane organization induced by heat shock.

In vivo change in membrane organization in adult rat liver cells induced by heat shock was studied by incorporating the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) in these cells. DPH was essentially localized in the plasma membrane, as indicated by quenching of its fluorescence (over 90%) by 2,4,6-trinitrobenzenesulfonate (TNBS). Measurements of both fluorescence polarization and intensity indicate that there is an immediate change in membrane organization (order) following heat shock. The polarization changes of DPH and TMA-DPH incorporated into liver cell plasma membranes upon heat shock are in opposite directions. This result is attributed to the different locations of these probes in the membrane. This change in membrane organization could be a part of a general stress response which is then transmitted to other cellular organelles.