Effect of Escherichia coli lipopolysaccharide on the microviscosity of liver plasma membranes and hepatocyte suspensions and monolayers.

The fluorescence probe 1,6-diphenylhexa-1,3,5-triene (DPH) was used for monitoring structural perturbations induced by lipopolysaccharide (LPS) of Escherichia coli (0111:B4) in plasma membranes of rat liver. Changes in microviscosity were observed in plasma membrane preparations from control rats after treatment with LPS and in plasma membrane preparations from liver perfused with LPS. In both systems fluorescence polarization was measured from which microviscosity was calculated. This parameter increases with LPS treatment. From temperature dependence studies was inferred that LPS interaction with plasma membrane preparations induces an increase of both the polarization term (r0/r-1)-1 and flow activation energy (delta E). Addition of LPS to hepatocyte suspensions also induces an increase on microviscosity and a delay in the fall of microviscosity induced by a temperature rise in hepatocyte monolayers grown on microcover slides. These data suggest that LPS interaction can be attributed to its binding to membrane hydrophobic regions in a non-specific manner.