S.A. Kedik, S.V. Vorozhtsova, E.I. Yartsev, I.V. Sakaeva, Ju.V. Kochkina (Cherta), A.V. Panov

In the framework of study of N-vinylpyrrolidone - 2-methyl-5-vinylpyridine copolymer biological effectiveness (Covidon) the influence of the various concentration solutions on the abnormalities in corneal epithelium cells of mice and rats damaged by the -irradiation was investigated. The fulfilled experiments demonstrated that -irradiation of the mice and rats in 2,5 Sv dose promotes abnormalities in physiological regeneration of corneal epithelium cells. Particularly it is exhibited in reduction of cell mitotic activity level and formation of aberrant mitoses. The mitotic index values decreased after the -irradiation in first day then increased and decreased again. After that the final recovery of mitotic activity took place. Initial reduction of mitotic index of corneal epithelium cells for radiation-exposed animals on Covidon influence promotes more active reparation of post-irradiation cytogenetic changes caused by -irradiation. Besides of abortive suppression of cell mitotic activity the ionizing radiation results in changes in cell genetic organization. The most profound alteration exhibited in the form of the chromosome aberration. The formation frequency of aberrant mitoses depends both upon the kind of animal species, Covidon concentration and time of instillation. Optimal concentration of Covidon is 10% but its instillation must be carried out just after the radiation exposure. The reduction of the formation frequency of aberrant mitoses after Covidon instillation occurs due to its ability to regulate metabolic processes considerably, particularly to promote the functional normalization of metabolic processes and cell membranes. Average time of the chromosome aberration existence in corneal epithelium cells of mice and rats caused by radiation is equal to 5.2 cell cycles. Instillations of 0.05 % Covidon solution right after the radiation exposure decrease this value up to 3.5 cell cycles. Thus, the Covidon solutions exhibits moderate bioprotective effect and it appears that the reason of its prophylactic and therapeutic effect is connected with reduction of initial changes as a result of temporal delay of mitosis.