Effects of asbestos on membrane transport and metabolism of benzo(a)pyrene

Our plain-English summary of Effects of asbestos on membrane transport and metabolism of benzo(a)pyrene, by C. Kandaswami, P.J. O'Brien (Biochemical and Biophysical Research Communications, 1980).

The study

• Authors: C. Kandaswami, P.J. O'Brien
• Journal: Biochemical and Biophysical Research Communications
• Published: 1980;97(2):794-801
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

SUMMARY: The effect of asbestos on benzo(a)pyrene uptake by microsomal membranes and lipid micelles has been investigated. Asbestos mediates a rapid transport of the carcinogen into the membrane and also impairs benzo(a)pyrene metabolism in rabbit and rat liver microsomes by markedly inhibiting aryl hydrocarbon hydroxylase.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was a laboratory study, not a study of people. The authors tested how asbestos affects the uptake and breakdown of benzo(a)pyrene, a cancer-causing chemical found in cigarette smoke. They used liver membrane fractions (microsomes) from rabbits and rats, plus fatty-acid and lecithin preparations, with standard asbestos samples. When benzo(a)pyrene was first incubated with crocidolite and then added to microsomes, fluorescence (a measure of uptake into the membrane) was higher than with benzo(a)pyrene and microsomes alone. All four asbestos types tested (crocidolite, Canadian chrysotile, amosite and anthophyllite) lowered the activity of aryl hydrocarbon hydroxylase, the enzyme that metabolizes benzo(a)pyrene. Chrysotile gave the greatest inhibition, reducing activity to 31% of control in rabbit microsomes. More asbestos did not increase the inhibition, and the metal-binding agent EDTA did not change it, so the authors judged that trace metals were unlikely to explain it. The authors concluded that asbestos's effect on benzo(a)pyrene metabolism "could have a possible role in cocarcinogenesis."

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: Laboratory (in vitro) biochemical experiment using animal liver microsomes and lipid preparations
• Who was studied: Liver microsomes from rabbits and Sprague-Dawley rats (some rats pretreated with 3-methylcholanthrene), plus linoleate and soybean lecithin preparations; number of animals not stated
• Exposure: Standard asbestos samples (crocidolite, Canadian chrysotile, amosite, anthophyllite) from the International Union Against Cancer, combined with benzo(a)pyrene
• Main results:
  • Benzo(a)pyrene pre-incubated with crocidolite and then added to microsomes gave higher fluorescence (100%) than benzo(a)pyrene incubated with microsomes alone (60%)
  • Benzo(a)pyrene pre-incubated with asbestos and then added to lecithin gave 82% fluorescence, compared with 65% for benzo(a)pyrene with lecithin alone
  • Crocidolite reduced aryl hydrocarbon hydroxylase activity to 44% (rabbit), 49% (control rat) and 77% (3-methylcholanthrene-treated rat) of control
  • Canadian chrysotile reduced enzyme activity to 31% (rabbit), 45% (control rat) and 52% (3-methylcholanthrene-treated rat) of control; chrysotile gave the greatest inhibition in all fractions
  • Amosite reduced enzyme activity to 71% (rabbit) and 62% (control rat) of control. Anthophyllite reduced it to 74% (rabbit), 71% (control rat) and 63% (3-methylcholanthrene-treated rat)
  • Increasing the asbestos concentration did not increase the inhibition, and EDTA had no effect on it
  • Asbestos incubated with benzo(a)pyrene reversed benzo(a)pyrene's inhibition of linoleate oxidation
• The authors' conclusion: The authors concluded that asbestos's modifying effect on benzo(a)pyrene metabolism could have a possible role in cocarcinogenesis

Related studies

• Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1983)
• Effects of asbetos, iron oxide, silica, and carbon black on the microsomal availability of benzo[a]pyrene — J.R. Lakowicz, D.R. Bevan (1979)
• Effect of particulates on metabolism and mutagenicity of benzo[a]pyrene — D.R. Bevan, W.E. Manger (1985)
• Pulmonary metabolism of benzo(a) pyrene : effect of asbestos — C. Kandaswami, P.J. O'Brien (1981)
• Asbestos-mediated membrane uptake of benzo[a]pyrene observed by fluorescence spectroscopy — J.R. Lakowicz, J.L. Hylden (1978)
• Benzo[a]pyrene uptake into rat liver microsomes: effects of adsorption of benzo[a]pyrene to asbestos and non-fibrous mineral particulates — J.R. Lakowicz, D.R. Bevan (1980)

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