MICRONUCLEUS INDUCTION IN V79 CELLS AFTER DIRECT EXPOSURE TO WHOLE CIGARETTE-SMOKE

Previous investigations on the effects of cigarette smoke on cultured cells have used mainly smoke condensate dissolved in culture medium. A system has been designed which allows direct exposure of cells to fre sh cigarette smoke, without an intervening layer of growth medium betw een the cells and the smoke. Preliminary results have been obtained wh ich demonstrate the viability of the system, V79 cells were cultured o n porous membranes (Transwell; Costar). During smoke exposure only the lower surface of each Transwell is supplied with culture medium from the bottom of the culture chambers. In this may the cells had direct c ontact with the atmosphere at the upper surface and could be exposed d irectly to the test compound, The constructed exposure system consists of a smoke generator and an exposure unit containing six Transwells, the latter contained in an incubator. Cigarette smoke was generated us ing a standard 2 s, 35 ml puff once per min. The puff is diluted with conditioned air from the incubator and injected into the exposure unit . Following exposure of the cells to air only for 3 h there was no eff ect upon V79 cell viability. However, after exposure to smoke containi ng between 88 and 224 mg/m(3) particulate matter, an inhibition of cel l proliferation and induction of micronuclei was measured. When a Camb ridge filter pad was placed between the cigarette and the cell exposur e system to remove particulate matter cell proliferation was also redu ced and an increased frequency of micronuclei above the control value was measured.