Effects of the pyrethroid insecticide permethrin on membrane fluidity.
The interaction of permethrin with dimyristoyl- (DMPC), dipalmitoyl- (DPPC) and distearoyl- (DSPC) bilayers has been investigated by differential scanning calorimetry (DSC) and DPH and TMA-DPH fluorescence anisotropy. In experiments performed by DSC, we show that the addition of permethrin to liposomes, in a 5:1 phospholipid/pyrethroid ratio, decreases the phase transition temperature (Tm) of DMPC, DPPC and DSPC by 3.2, 2.3 and 1.1 degrees C, respectively. Furthermore, DSC profiles reveal that permethrin decreases the cooperativity for the phase transition of DMPC, DPPC and DSPC membranes. DPH and TMA-DPH fluorescence anisotropy experiments show that permethrin increases membrane fluidity at temperatures below the Tm. The results are discussed in terms of a preferential localization of permethrin in the hydrophobic core of the membrane, where it diminishes the lipid packing in the gel phase and has no effect in the liquid-crystalline phase.
Moya-Quiles
M R
MR
Departamento de Bioquimica y Biologia Molecular A, Facultad de Biologia, Edificio de Veterinaria, Campus de Espinardo, Universidad de Murcia, Spain.
Munoz-Delgado
E
E
Vidal
C J
CJ
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects; D005454:Fluorescence Polarization; D005782:Gels; D006801:Humans; D007306:Insecticides / Q000494:pharmacology; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008560:Membrane Fluidity / Q000187:drug effects*; D008565:Membrane Proteins / Q000378:metabolism; D008968:Molecular Conformation; D015394:Molecular Structure; D026023:Permethrin; D010713:Phosphatidylcholines / Q000378:metabolism; D011722:Pyrethrins / Q000494:pharmacology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D013696:Temperature
D005782:Gels; D007306:Insecticides; D008051:Lipid Bilayers; D008081:Liposomes; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D011722:Pyrethrins; D026023:Permethrin