[In vitro studies on the influence of volatile anaesthetics on cell number, cell volume, and cellular protein, DNA, and RNA content (author's transl)].

The aim of the present investigations was to see, if halothane (h), enflurane (e), isoflurane (i), and methoxyflurane (m) exert cytostatic or cytotoxic effects. The experiments were performed on suspension cultures of an established line of Ehrlich ascites tumor cells, which were gased by a mixture of N2 (78%), O2 (20%), and CO2 (2%) to which the volatile anaesthetics in 5 different concentrations were added by vaporizers. Under standardized conditions (incubation time: 24 or 48 hrs; initial cell density: 2 X 10(5) cells/ml culture medium) the following results were obtained: 1. All anaesthetics exerted dose dependent cytostatic effects, which were reversible up to concentrations of 2.0 vol% (m), 3.0 vol% (h), and 5.0 vol% (e, i). The cytostatic ID50 values (mmol/l) were found to be 0.50 (h), 1.00 (e), 0.72 (i), 1.25 (m). 2. In cell cultures, which were exposed to anaesthetics for 48 hrs cytotoxic effects were observed after doses of 2.0 vol% (m), 3.0 and 4.0 vol% (h), 4.0 and 5.0 vol% (e and i). 3. In contrast to colchicine, which was studied in comparison to the volatile anaesthetics, the mean cell volume of anaesthetic treated cultures showed only minimal deviations from control values. 4. With exception of m, which produced a significant decrease of the cellular protein content in the dose range 1.5-2.0 vol% and of the cellular DNA content in all concentrations applied the 3 other anaesthetics caused an increase of the cellular protein content and a somewhat smaller increase of the cellular nucleic acids content. The obtained results indicate that the effect of anaesthetic agents on dividing cells is not due to the same mode or site of action, but to an influence on different stage of the cell cycle, particularly the interphase. Colchicine-like c-mitosis were not obtained.