Interaction of insecticides with lipid membranes

Area of Science:

• Biochemistry
• Toxicology
• Membrane Biophysics

Background:

• Liposome membranes serve as models for biological membranes.
• Insecticides, including organophosphorus and organochlorinated compounds, are widely used and can pose risks to non-target organisms.
• Understanding the interaction of insecticides with cell membranes is crucial for assessing their toxicity.

Purpose of the Study:

• To investigate the effect of organophosphorus and organochlorinated insecticides on liposome membrane permeability.
• To compare the effectiveness of different insecticides in altering membrane permeability to various substances.
• To explore potential mechanisms by which insecticides might exert toxic effects on cell membranes.

Main Methods:

• Liposomes were used as a model system to study membrane permeability.
• The effect of insecticides at concentrations of 10(-5)--10(-4) M on the permeation of non-electrolytes, K+ (valinomycin-induced), and Ca2+ (X-537A-induced) was measured.
• The relative effectiveness of parathion, DDT, aldrin, malathion, lindane, and ethyl azinphos was determined.

Main Results:

• Organophosphorus and organochlorinated insecticides significantly increased liposome membrane permeability.
• The order of effectiveness for most permeation assays was parathion > DDT ≈ aldrin > malathion > lindane.
• Ethyl azinphos showed a dramatic increase in permeability, likely due to surfactant effects.
• Some organochlorinated insecticides modulated cation ionophore-mediated ion transport.

Conclusions:

• Insecticides can disrupt the integrity and function of lipid membranes.
• The observed effects on membrane permeability correlate with known mammalian toxicity of these compounds.
• Insecticides may exert toxic actions by interfering with essential cell membrane processes.