Micronucleus induction in V79 cells after direct exposure to whole cigarette smoke

Previous investigations on the effects of cigarette smoke oncultured cells have used mainly smoke condensate dissolved inculture medium. A system has been designed which allows directexposure of cells to fresh cigarette smoke, without an interveninglayer of growth medium between the cells and the smoke. Preliminaryresults have been obtained which demonstrate the viability ofthe system. V79 cells were cultured on porous membranes (Transwell;Costar). During smoke exposure only the lower surface of eachTranswell is supplied with culture medium from the bottom ofthe culture chambers. In this way the cells had direct contactwith the atmosphere at the upper surface and could be exposeddirectly to the test compound. The constructed exposure systemconsists of a smoke generator and an exposure unit containingsix Transwells, the latter contained in an incubator. Cigarettesmoke was generated using a standard 2 s, 35 ml puff once permin. The puff is diluted with conditioned air from the incubatorand injected into the exposure unit. Following exposure of thecells to air only for 3 h there was no effect upon V79 cellviability. However, after exposure to smoke containing between88 and 224 mg/m³ particulate matter, an inhibition of cell proliferationand induction of micronuclei was measured. When a Cambridgefilter pad was placed between the cigarette and the cell exposuresystem to remove particulate matter cell proliferation was alsoreduced and an increased frequency of micronuclei above thecontrol value was measured. ³To whom correspondence should be addressed. Tel: +44 1703 777155; Fax: +44 1703 779856