Aim - to investigate the effect of oxidative stress on the autonomic nervous system state in patients with liver cirrhosis. In a randomized way with the preliminary startification by the presence of LC 81 patients - 55 (67.9%) males, 26 (32.1%) females, aged 46.9±10.8 years were included to the study after the signing the informed cosent. All the patients underwent the comprehensive clinical laboratory and instrumental examination of all organs and systems in accordance with the requirements of the modern medicine.Among the indicators of redox homeostasis the content of malondialdehyde (MDA) and of catalase (CAT) were determined. The study of autonomic nervous system (ANS) status was carried out using the registration of heart rate variability (HRV) before and after the physical activity. The results were processed on a personal computer in Statistica 6.0, RStudio v. 1.1.442 and R Commander v.2.4-4 using descriptive statistics. The difference was considered statistically significant if p<0.05. The results of HRV time parameters analysis before the physical activity revealed that MDA content negatively correlated with mean duration of NN (RR) intervals (RRNN), standard deviation of NN intervals (SDNN), the square root of the mean squared differences of successive NN interval (RMSSD), percent of consecutive NN intervals with difference more then 50 mc between (pNN 50%), percent of variation coefficient (CV%) and positively - with heart rate. This is verified by the fact that the CAT content positively correlated with RRNN, SDNN, RMSSD, pNN 50% and negatively - with heart rate.The results of the study of HRV spectral analysis correlation relationships revealed that MDA content negatively and CAT - positively correlated with total power (TP), high frequency (HF), low frequency (LF), very low frequency (VLF), LF/HF index, percent of very low frequency (%VLF), percent of low frequency (%LF), percent of high frequency (%HF). The results of analysis of HRV time analysis parameters after the physical activity revealed that the MDA content negatively correlated with CV% and the content of CAT positively correlated with SDNN, CV%. The results of the study of the correlation relationships of the HRV spectral analysis parameters after the physical activity revealed that the content of CAT positively correlated with TP, LF, VLF. Oxidative stress and the antioxidant defense system activity lack, as important pathogenetic parts of vascular tone dysfunction, have a significant effect on the ANS in patients with LC, causing the predominance of the sympathetic branch activity over the parasympathetic one. Oxidative stress, triggering the relevant pathogenetic mechanisms has an effect on the autonomic nervous system in patients with liver cirrhosis. However, the realization of the dominant influence of the sympathetic branch of the autonomic nervous system is minimized due to the decrease in the sensitivity of receptors to vasoconstrictors, including to neurotransmitters.
