Interactions of pyrethroids with phosphatidylcholine bilayers: comparisons in liposomal systems exhibiting large or small radii of curvature.
Pyrethroid interactions with dipalmitoyl phosphatidylcholine (DPPC) vesicles have been characterized in bilayers having large and small radii of curvature. The abilities of pyrethroids to alter the gel-fluid phase transition profiles were determined by steady state fluorescence anisotropy and phase-modulation lifetime techniques using the fluorescent probes cis- and trans-parinaric acid. Using the geometric isomers of parinaric acid as membrane probes, pyrethroids were found to lower the phase transition temperature (Tc) of DPPC large multilamellar vesicles with the same order of comparative effectiveness as previously reported using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH). Permethrin had a greater depressive effect upon the Tc of DPPC in the small unilamellar vesicle (SUV) system than in the large multilamellar system. Conversely, allethrin was less effective in reducing the Tc of DPPC SUVs. The enhanced effect of permethrin in decreasing the Tc of DPPC SUVs was greatest in regions of more rigid lipid packing, as determined by trans-parinaric acid fluorescence parameters. The results indicate that changes in lipid packing configuration caused by differing bilayer radii of curvature may alter the interactive characteristics of pyrethroids with lipid membranes.
D004161:Diphenylhexatriene; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D011663:Pulmonary Surfactants; D011722:Pyrethrins / Q000378:metabolism*
D005231:Fatty Acids, Unsaturated; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D011663:Pulmonary Surfactants; D011722:Pyrethrins; D004161:Diphenylhexatriene; C013641:parinaric acid