Lipid peroxidation in microsomes induced by crocidolite fibres

Our plain-English summary of Lipid peroxidation in microsomes induced by crocidolite fibres, by M. Gulumian, F. Sardianos, T. Kilroe-Smith, et al (Chemico-biological Interactions, 1983).

The study

• Authors: M. Gulumian, F. Sardianos, T. Kilroe-Smith, G. Ockerse
• Journal: Chemico-biological Interactions
• Published: 1983;44(1-2):111-8
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

When rat liver and lung microsomes were incubated with crocidolite fibres, a substantial increase in lipid peroxidation was observed. Increasing concentrations of this fibre in the incubation mixture, produced a concomitant induction in microsomal lipid peroxidation. This increase was very rapid as the reaction was almost complete within 10 min. The ability of these fibres to induce this process after a short period of incubation seems to be due to their binding to the microsomes. The iron present in the structure of crocidolite is thought to be responsible for catalysing the peroxidation. The formation of free radicals by asbestos and possible pathological sequelae are discussed.

In plain English

This was a laboratory experiment, not a study of people. The authors, at the National Centre for Occupational Health in Johannesburg, South Africa, took microsomes (small membrane fragments from inside cells) from the livers and lungs of male Sprague-Dawley rats. Some rats had first been injected with the chemical 3-methylcholanthrene. The microsomes were mixed in test tubes with South African crocidolite fibres. The authors measured lipid peroxidation, a type of chemical damage to the fats in cell membranes, through a breakdown product called malonaldehyde. Adding crocidolite produced a very large increase in this damage in liver microsomes and in lung microsomes from both untreated and pretreated rats. In lung microsomes the reaction was about 80% complete within 5 minutes. When microsomes stuck to the fibres were separated from those that did not stick, only the bound microsomes showed damage, and more fibre gave more damage. The authors concluded that the experiments provide evidence of free radicals on the asbestos surface, suggested that iron in crocidolite may be involved, and saw a possible connection with asbestos-related cancers. They stated that the exact mechanism remained unclear.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: In vitro laboratory experiment using rat liver and lung microsomes
• Who was studied: Liver and lung microsomes from male Sprague-Dawley rats (150 to 250 g). The rats were either controls injected with sunflower oil or rats injected with 3-methylcholanthrene (40 mg/kg body weight) for 3 consecutive days. The number of rats is not stated. National Centre for Occupational Health, Johannesburg, South Africa.
• Exposure: South African crocidolite, prepared following UICC recommendations, incubated with microsomes at 37 degrees C. Table I used 5 mg crocidolite per ml of microsomal suspension. The binding experiment used a 10 mg/ml crocidolite suspension. A range of concentrations was tested for dose dependence.
• Main results:
  • Crocidolite produced a very large increase in malonaldehyde (a marker of lipid peroxidation) in liver microsomes and in both normal and 3-methylcholanthrene-induced lung microsomes. The authors described this as statistically conclusive in all cases.
  • Adding the antioxidant BHT before colour development reduced the measured malonaldehyde by about 5% for liver and about 20% for lung. The authors attributed 80 to 95% of the colour to the direct action of crocidolite on tissue lipids.
  • In rat lung microsomes the reaction with crocidolite was rapid, virtually complete (80%) within 5 minutes.
  • In 3-methylcholanthrene-induced lung microsomes treated with crocidolite, 45% of the microsomal protein remained unbound to the fibres, and none of the unbound microsomal phospholipids were peroxidised. Only microsomes bound to the fibres showed peroxidation.
  • The degree of lipid peroxidation in bound microsomes increased with the amount of crocidolite used.
  • Without crocidolite, lung microsomes from 3-methylcholanthrene-induced rats showed no autoxidation of their lipids, either at the start or after 1 hour at 37 degrees C.
• The authors' conclusion: The authors concluded that the experiments provide evidence of free radicals on the surface of asbestos. They suggested that the iron in crocidolite is a possible site for generating these free radicals. Because free radicals have been implicated in cancer caused by other agents, they saw a possible connection with asbestos-related cancers.
• Limitations the authors state:
  • The authors stated that the exact mechanism of action of crocidolite is still unclear.
  • The authors stated that the zero-time figures in the presence of crocidolite are too high. Time elapses while reagents are added, and the reaction is not necessarily stopped by the protein-denaturing reagent.
  • Some lipid peroxidation was already present in the microsomes before the reaction started, probably artifactual, especially in liver tissue.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Crocidolite.

Related studies

• Crocidolite-induced lipid peroxidation in rat lung microsomes. I. Role of different ions — M. Gulumian, T.A. Kilroe-Smith (1987)
• The stimulatory effects of asbestos on NADPH-dependent lipid peroxidation in rat liver microsomes — M. Fontecave, D. Mansuy, et al. (1987)
• Microsomal lipid peroxidation and oxy-radicals formation are induced by insoluble iron-containing minerals — M. Fontecave, M. Jaouen, et al. (1990)
• The role of catalytic iron in asbestos induced lipid peroxidation and DNA-strand breakage in C3H10T1/2 cells — C.J. Turver, R.C. Brown (1987)
• Chrysotile inhibits glutathione-dependent protection against the onset of lipid peroxidation in rat lung microsomes — J.M. Arif, I. Ahmad, et al. (1996)
• Interrelationship between hemolysis and lipid peroxidation of human erythrocytes induced by silicic acid and silicate dusts — S.V. Singh, Q. Rahman (1987)

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