[Dynamics of the functional status of autonomic nervous system in rats under combined radiation/thermal injury in case of an open burn wound and wound covered by the polymer film].

: The peculiarities of the functional status of autonomic nervous system and physical efficiency were studied in white inbred rats under dynamics of combined radiation/thermal injury (CR/TI). The CR/TI model was obtained under total X-ray irradiation at dose level of 4.37 Gy and inflicting III degree burn injury making 12% of body surface in 24 rats. The studies were performed under conditions of both spontaneous CR/TI development and protecting the burn wound against infection. In 12 rats the wounds were covered by polymer films treated with iodine and succinic acid. On days 3, 7, 14, 21 and 28 of CR/TI, as well as prior to CR/TI (datum level), heart rate variability (HRV) indices, the level of physical efficiency (the retention time of own weight on the vertical pole), indices of body mass, survival, and average life-soan of animals were recorded. For registration of ECG in awake rats, corrections of motor artifacts and analysis of HRV the original software program was used. R-R intervalograms were analyzed in time and frequency domains. The sliding window technique was used (100 R-R intervals with the step of 10 seconds; epoch of analysis--7 minutes). The obtained data indicated that the survival level and the average life-span in rats with the film-covered burn wound were higher as compared to the "pure" CR/TI. At the same time body mass and physical efficiency in animals of both groups did not differ in practice. Data on the functional status of autonomic nervous system were more informative. In rats with film-covered burn wound the dynamics of HRV indices had a biphasic character with the tending to normalization beginning from day 7 of CR/TI, whereas in case of an open wound HRV indices were characterized by monotonous growth until the end of observations. In the overall picture of the CR/TI in both groups of animals the sympathotropic effects of burn stress prevailed. Methods of mathematical analysis of HRV under conditions of CR/TI were for the first time used in this study. The research outcomes signify to the expediency to apply these methods for obtaining data on functional state of the autonomic nervous system in CR/TI models in small laboratory animals.