Microsomal membrane peroxidation by an Fe/Paraquat system.

Descriptions of the effects of paraquat (P) on the peroxidation of liver microsomes are very divergent. Therefore, the presence of ferric iron in the medium and the activity of microsomal mixed-function oxidase system are two factors that we have taken into consideration to explain the discrepancies. The results showed that 100 μ M P potentializes the slight production of MDA induced by low concentrations of Fe (≤15 μ M). In these conditions, P, arising from the one-step reduction of P by NADPH-cytochrome C reductase, could reduce Fe and cause the formation of species that initiate peroxidation. However, unlike the results obtained with CBrCl, for animals induced by phenobarbital (Ph), the production of MDA in the presence of FeCl and of P was weaker than for the controls. The establishment of a new Fe/Fe equilibrium owing to increased production of P could be responsible. [ABSTRACT FROM AUTHOR]