Influence of Рrenatal Hypoxia of the Period of Early Organogenesis on Heart Rate Variability in Rat Pups during the First Month of Life

Recently, there has been increasing evidence in favor of prenatal programming influence on the development of many diseases in adults, including cardiovascular pathologies. However, the mechanisms underlying the programming effect of developing cardiovascular dysfunction remain unclear, which prevents timely diagnosis and identification of potential clinical therapy. The aim of this study was to evaluate the effects of acute hypoxia during early organogenesis on heart rhythm formation and its regulation in early postnatal development in rats. It was shown that acute hypoxia suffered by rat pups on day 10 of intrauterine development did not change the overall dynamics of heart rhythm formation in the first month of the postnatal period. However, the experimental animals showed lower heart rate compared to control in the first weeks of life in addition to higher values of rhythm variability and the RMSSD index (root mean square of successive differences in RR intervals) indicating an expressed tone of parasympathetic department of the ANS. Moreover, in the first week of life, the basic heart rate following pharmacological blockade of sympathetic and parasympathetic cardiotropic nervous influences in rats suffering from prenatal hypoxia turned out to be 15% higher than in control animals, supposing prenatal hypoxia influence on heart rhythm formation due to intracardiac mechanisms.