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  • Title: Effects of hyperthermia and membrane-active compounds or low pH on the membrane fluidity of Chinese hamster ovary cells.
    Author: Dynlacht JR, Fox MH.
    Journal: Int J Hyperthermia; 1992; 8(3):351-62. PubMed ID: 1607740.
    Abstract:
    Chinese hamster ovary (CHO) cells heated in the presence of the membrane-active agents procaine, ethanol, butylated hydroxytoluene (BHT) and glycerol were analysed for changes in fluorescence polarization of the lipid probe (1-[4(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene, an indicator of plasma membrane fluidity). Cells were heated in normal and acid (pH 6.6) medium. Procaine, ethanol, BHT and low pH sensitized cells to heat-killing. Procaine, ethanol and BHT decreased fluorescence polarization (increased plasma membrane fluidity) significantly. Polarization distributions for cells heated with these sensitizers were broadened substantially and were skewed toward lower polarization values. Glycerol, a heat-protector, inhibited changes in fluorescence polarization due to heating at temperatures up to 45.0 degrees C. Heating cells at either 42 or 45 degrees C in pH 6.6 medium had no significant effect on the fluorescence polarization compared with controls, while survival was reduced substantially. Thus, heat-sensitization of low pH cannot be ascribed to changes in membrane fluidity. The changes in membrane fluidity caused by other sensitizers and protector indicate that membrane fluidity changes may be a contributing cause of cell killing by hyperthermia.
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