THE INFLUENCE OF SODIUM NITRITE ON THE OSMORESISTANCE OF CHINESE HAMSTER CELLS
O. I. Bolshakova, A. G. Sverdlov, S. I. Timoshenko, N. G. Nikanorova, S. A. Grachev
St. Petersburg Nuclear Physics Institute RAS, Gatchina, Leningrad District;
We have previously demonstrated that incubation of V-79 cells in the medium containing the nitric oxide donor,
NaNO2, increases cell resistance to damaging effect of γ-rays, UV radiation and hyperthermia. In the
present study, we investigated the effects of the nitric oxide donor on the sensitivity of V-79 cells to changes in
osmomolarity of the medium by adding different amounts of sodium chloride or water. We found that pretreatment of the
cells with NaNO2 resulted in a significant increase in the number of growing cells in 48 h after the
treatment. The osmomolarity-dependent morphological changes in cultured cells were also substantially diminished
following NaNO2 treatment. This effect could be observed under both hyper- and hypoosmosis, and was
dependent on concentration of sodium chloride in hypertonic medium (being maximal under 0.17 M NaCl) and on the
amount of water in hypotonic medium (being maximal under 1.1 times the dilution with water). In the experiments with
increased osmomolarity, we found that the observed increase in the number of growing cells following NaNO2
treatment was accompanied with a significant increase of the mitotic index. These findings indicate that nitric oxide
increases cell resistance to the damaging effects of osmotic shock in the way which is similar to the protective
effect of these molecules against radiation and hyperthermia. Similarities in the effects of NaNO2 under different
conditions leading to cell damage suggest that nitric oxide might serve as the universal factor participating in
recovery of damaged cells and mediating increased cellular resistance to the damaging conditions.
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