Open AccessUptake and efflux of polycyclic aromatic hydrocarbons by Tetrahymena pyriformis : Evidence for a resistance mechanism
Author(s) -
Bamdad Mahchid,
Reader Stéphanie,
Grolière Claude A.,
Bohatier Jacques,
Denizeau Francine
Publication year - 1997
Publication title -
cytometry
Language(s) - English
Resource type - Journals
eISSN - 1097-0320
pISSN - 0196-4763
DOI - 10.1002/(sici)1097-0320(19970601)28:2<170::aid-cyto11>3.0.co;2-n
Subject(s) - efflux , mechanism (biology) , environmental chemistry , chemistry , resistance (ecology) , tetrahymena pyriformis , biophysics , biochemistry , biology , ecology , physics , tetrahymena , quantum mechanics
The action of benzo(a)pyrene (BP), 3‐methylcholanthrene (3MC), benzanthracene (BA), and 7,12‐dimethylbenzanthracene (DMBA), four polycyclic aromatic hydrocarbons (PAHs), was studied on the unicellular protozoan Tetrahymena pyriformis . This ciliatewas exposed to the PAHs at 1, 15, and 37 μM for up to 6 h. BP and BA caused a slight inhibition of cell growth, whereas 3MC and DMBA showed no detectable effect. Cell viability remained unaffected by the PAHs at all concentrations and exposure times tested. Cellular accumulation of PAHs was studied using flow cytometry. The results show immediate accumulation followed by rapid elimination of the compounds. BP uptake was also studied in the presence of verapamil and cyclosporin, compounds known as inhibitors of the multidrug resistance (MDR) pump. In the presence of verapamil, BP was accumulated in larger amounts in cells. With cyclosporin, the accumulation of the PAH was several times higher than under control conditions. The results of GC/MS analysis show that PAH elimination was not linked to biotransformation. These results suggest that the resistance of Tetrahymena against PAH cytotoxicity may be attributed to the rapid efflux of these agents from the cells via an efflux pump probably of the MDR type. Cytometry 28:170–175, 1997. © 1997 Wiley‐Liss, Inc.