Organophosphorous insecticide fenitrothion alters the lipid dynamics in the spider Polybetes pythagoricus high density lipoproteins

CUNNINGHAM, M.L.; GARCIA, C.F.; GONZALEZ-BARO, M.R.; GARDA, H.A.; POLLERO, R.J.

PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY

Academic Press

Año: 2002 vol. 73 p. 37 - 47

0048-3575

The effect of the organophosphorous liposoluble insecticide fenitrothion (FS) on the physical properties in the lipid phase of two spider’s plasma high density lipoproteins (HDL) was investigated. HDL1 and HDL2 have similar lipid compositions, but they significantly differ in their lipid/protein ratio and apolipoprotein compositions. Lipid dynamics in the lipoproteins’ core and outer regions was determined by studying the rotational behavior of the fluorescent probes 1,6-diphenyl 1,3,5-hexatriene (DPH) and its propionic acid derivative (DPH–PA), respectively. Fluorescent steady-state anisotropy (rs), lifetime (s), rotational correlation time ðsrÞ, and the limiting anisotropy ðr1Þ of these probes were measured in the lipoproteins exposed in vitro to different concentrations of FS. The results showed the FS penetration into both plasma lipoproteins, altering the lipid dynamics in their hydrophobic cores as well as in the hydrophilic outer regions. In the two lipoproteins subjected to FS action, both the limiting and steady-state anisotropy values were increased, showing an increment of the lipid ordering. The increase of r1 produced by FS depends on the initial lipid order, and it is higher in the less-ordered samples. Fluorescence lifetimes of DPH and DPH–PA indicate that FS increases the polarity of the probe environments, suggesting an enhanced water penetration into the lipoprotein lipid phase, possibly due to the induction of failures in the lipid packing. Its action, depending on the temperature and lipid packing in each region, affects differently either the inner or the outer portions of lipoproteins, being more affected the hydrophobic core. The alteration in the lipoprotein structure causes misfunctions in their physiological behavior, reflected in a diminished capacity of oxygen binding.