Asbestos-elicited catecholamine secretion from isolated bovine adrenal chromaffin cells

Our plain-English summary of Asbestos-elicited catecholamine secretion from isolated bovine adrenal chromaffin cells, by S. Lemaire, I. Lemaire (Life Sciences, 1981).

The study

• Authors: S. Lemaire, I. Lemaire
• Journal: Life Sciences
• Published: 1981;29(11):1117-24
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This laboratory study used isolated cow adrenal chromaffin cells, which release adrenaline and noradrenaline (catecholamines). The authors tested UICC reference samples of Canadian chrysotile (B), Rhodesian chrysotile (A), crocidolite and amosite, plus silica and latex. Chrysotile B increased catecholamine release at concentrations as low as 1 microgram per ml, with half-maximal stimulation at 7 micrograms per ml. Maximal release was about 18% of the cells' total catecholamine content. After 30 minutes at up to 100 micrograms per ml, viability measured by trypan blue dye exclusion stayed at 95%-97%. Other asbestos types needed higher half-maximal doses: 73 micrograms per ml for chrysotile A, 160 for crocidolite and 250 for amosite. Silica's half-maximal dose was more than 500 micrograms per ml, and latex had no effect. Cobalt, nickel and magnesium ions reduced the chrysotile B effect. Removing outside calcium did not, but pre-incubating cells in calcium-free fluid with the chemicals EGTA or EDTA did. The authors concluded calcium entry into the cells is not required. They said the effect's physiological significance is unknown and any role in asbestos-related disease needs 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: Laboratory (in vitro) experiment on isolated animal cells
• Who was studied: Highly purified chromaffin cells from bovine (cow) adrenal medulla, incubated in batches of 2.5 x 10^5 cells. Experiments were repeated three times in duplicate. The study was done at the University of Sherbrooke, Quebec, Canada.
• Exposure: International (UICC) reference samples of Canadian chrysotile (B), Rhodesian chrysotile (A), amosite and crocidolite, plus silica and latex for comparison. Cells were incubated at 37°C, usually for 30 minutes, at concentrations from about 1 microgram per ml upward. Some incubations added acetylcholine, receptor blockers, calcium channel blockers or calcium-binding chemicals.
• Main results:
  • In the chrysotile B experiments, catecholamine release increased at concentrations as low as 1 microgram per ml. The increase was directly proportional to concentration up to 20 micrograms per ml, and half-maximal stimulation occurred at 7 micrograms per ml.
  • The maximal release caused by chrysotile B was 5.98 plus or minus 0.20 nmole per 10^6 cells. This was about 18% of the cells' total catecholamine content of 34.0 plus or minus 3 nmole per 10^6 cells.
  • After 30 minutes of incubation at 37°C, chrysotile B concentrations up to 100 micrograms per ml did not affect cell viability as measured by trypan blue exclusion, which stayed at 95%-97%.
  • UICC chrysotile A, crocidolite and amosite also caused significant release, with a maximum of 3 to 5 nmole per 10^6 cells above basal secretion. Their half-maximal doses were higher: 73, 160 and 250 micrograms per ml, respectively.
  • Silica's half-maximal dose was larger than 500 micrograms per ml. Latex had no effect on catecholamine secretion.
  • The effect of chrysotile B added to that of acetylcholine (50 micromolar). The combination released up to 7.8 nmole per 10^6 cells, about 23% of total cell content.
  • With chrysotile B at 20 micrograms per ml, half-maximal stimulation was reached at about 12 minutes.
  • Blockers of nicotinic, muscarinic, alpha-adrenergic and beta-adrenergic receptors did not affect the response to chrysotile B.
  • The divalent ions Co2+ (0.5 mM), Ni2+ (0.5 mM) and Mg2+ (10 mM) reduced chrysotile B-induced secretion by 81%, 59% and 31%, respectively.
  • Removing calcium from the fluid outside the cells did not by itself change the response to chrysotile B (20 micrograms per ml).
  • When cells were pre-incubated in calcium-free fluid with EGTA or EDTA, the chrysotile B response was reduced by 67% and 64%, respectively. Adding calcium back (7 mM) restored the response.
• The authors' conclusion: The authors concluded that calcium entering the cells is not required for chrysotile-stimulated catecholamine secretion. They suggested that calcium at membrane or intracellular sites plays a role.
• Limitations the authors state:
  • The authors stated that the physiological significance of the stimulation of catecholamine secretion by asbestos is still unknown.
  • The authors stated that two questions require further investigation: whether asbestos releases noradrenaline from nerve endings in the lung, and whether such an action contributes to asbestos-related disease.

Topics

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

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