Interactions of insecticides with erythrocyte membranes

Abstract

Insecticides exert antilytic effects on pig erythrocytes by preventing osmotic disruption of membranes in critical hypotonic saline media. The order of effectiveness is the following: lindane > aldrin ≈ azinphos > parathion ≈ DDT > malathion; empirical protective indexes estimated for K + leakage, at 0.09 M NaCl, were 5.6, 3.9, 2.9, 2.8, and 2.0, respectively. Erythrocytes swell and hemolyze in solutions containing glycerol below 0.6 M. At higher concentrations and temperatures below 20°C, the extent of cell lysis is very limited and virtually nil in 1 M glycerol. In hypertonic glycerol solutions, cells swell until the initial equilibrium volume is reached and, then, the swelling process ceases. Swelling in 1 M glycerol is related to its permeation through hydrophobic membrane domains. The activation energies of permeation are similar to the dehydration energies of glycerol molecules. As the temperature is increased above 20°C, erythrocytes undergo lysis. The organophosphorus insecticides, parathion and azinphos (10 −4 M), significantly increase the swelling rates and the extent of cell lysis. Malathion and chlorinated insecticides do not exert apparent effects. However, these compounds are effective in liposomes reconstituted with lipids extracted from erythrocyte membranes.