Distribution of 6-6(n)-3\[H\]sucrose and its radiolabeled degradation products from isolated, perfused rat small intestine loops following prolonged ingestion of chrysotile asbestos

Our plain-English summary of Distribution of 6-6(n)-3[H]sucrose and its radiolabeled degradation products from isolated, perfused rat small intestine loops following prolonged ingestion of chrysotile asbestos, by R. Jacobs, R.J. Richards (Environmental Research, 1980).

The study

• Authors: R. Jacobs, R.J. Richards
• Journal: Environmental Research
• Published: 1980;21(2):423-31
• Read it: PubMed · Publisher

In plain English

This was an animal experiment. The authors fed MRC hooded rats either ordinary rat pellets (animals 1 to 6) or pellets mixed with chrysotile asbestos at 50 mg/day (animals 7 to 11) for 10 weeks. After a 24-hour fast, a loop of each anesthetized rat's small intestine was isolated and filled with a solution containing radiolabeled sucrose. Five minutes later the authors measured how much label was present as sucrose, glucose and fructose in four places: blood from the hepatic portal vein (which carries blood from the gut to the liver), the gut wall, the liver, and the fluid left in the gut. Results varied considerably between individual rats. Only two differences were statistically significant. Chrysotile-fed rats had a lower mean level of labeled glucose in portal blood plasma (P = 0.03). They also had a lower ratio of labeled glucose to fructose in the gut wall (P = 0.002). The authors argued that the lower glucose may reflect chrysotile damage to gut-lining cells that impairs glucose transport. They also offered other explanations, and said the changes need further investigation.

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: Animal experiment comparing chrysotile-fed and normally fed rats using isolated, perfused small intestine loops and radiolabeled sucrose
• Who was studied: MRC hooded rats of equivalent age and size: normal-diet animals numbered 1 to 6 and chrysotile-fed test animals numbered 7 to 11. Location and dates are not stated.
• Exposure: Chrysotile asbestos mixed into rat pellets at 50 mg/day for 10 weeks before the experiment; control rats ate rat pellets alone
• Main results:
  • In chrysotile-fed rats, the mean level of radiolabeled glucose in hepatic portal venous plasma was significantly lower than in normal rats (P = 0.03)
  • In chrysotile-fed rats, plasma levels of radiolabeled sucrose and fructose were higher than in normal rats, but these differences were not statistically significant at the 5% level
  • In the gut wall of chrysotile-fed rats, the ratio of labeled glucose to fructose was significantly lower than in pellet-fed rats (P = 0.002); this was the only statistically significant gut-wall change
  • In both portal blood plasma and gut wall, chrysotile-fed rats had a higher percentage of label as sucrose and fructose and a lower percentage as glucose than normal rats
  • In the liver, levels of all labeled sugars were lower in chrysotile-fed rats; in the gut lumen they were higher. The authors reported that none of the liver or lumen differences were statistically significant, and that only two significant changes were found overall.
  • Mean total recovery of the administered radioactivity was higher in chrysotile-fed rats than in normal rats, by both counting methods; no significance test is reported for this
• The authors' conclusion: The authors concluded that some changes in sugar metabolism, perhaps particularly related to glucose absorption, were found in rats after prolonged chrysotile ingestion. They argued that the lower glucose may be related to chrysotile's cytotoxic action on mucosal cells impairing the energized glucose carrier. They also suggested alternatives: changes in how sugars are converted inside cells, or altered liver function.
• Limitations the authors state:
  • Results varied considerably between individual animals
  • Sucrase activity varies along the small intestine, so enzyme levels in the loop may have differed between animals even though the same segment was used
  • The precise nature of the defect and the relevance of the changes to overall body metabolism were not established

Topics

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

Related studies

• A preliminary study of biochemical changes in the rat small intestine following long-term ingestion of chrysotile asbestos — R. Jacobs, K.S. Dodgson, et al. (1977)
• Light and electron microscope studies of the rat digestive tract following prolonged and short-term ingestion of chrysotile asbestos — R. Jacobs, J. Humphrys, et al. (1978)
• Nucleic acid metabolism in the rat following short-term and prolonged ingestion of chrysotile asbestos or cigarette-smoke condensate — R. Jacobs, M. Weinzweig, et al. (1978)
• Toxic effect on the rat small intestine of chronic administration of asbestos in drinking water — T.J. Delahunty, D. Hollander (1987)
• The mesotheliomas of the small intestine — M. Paul, G. Panabokke, et al. (1965)
• Effect of asbestos on the metabolism of vasoactive substances in isolated perfused guinea pig lungs — A. Cadieux, S. Massé, et al. (1983)

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