Prenatal Hypoxia of Early Organogenesis Period Influence on Heart Rate Variability in Rats of Prepubescent and Pubertal Age

Risk factors associated with environmental exposure, especiallyduring critical periods of intrauterine development, affect fetaldevelopment and increase the risk of certain diseases in adulthoodincluding cardiovascular diseases (CVD). Hypoxia is considered themost common and clinically significant form of intrauterine stressthat causes systemic pathological changes, in 78% of cases associatedwith cardiovascular system disorders. The purpose of this studywas to evaluate the effects of acute hypoxia on the 10th day ofgestation on heart rate and its regulation in rats’ offspring ofprepubescent and pubertal age, as well as to analyze the dependenceof resulting disorders on gender. By the beginning of puberty theheart rate of rats survived prenatal hypoxia was significantly higherthan in control accompanied by significant decrease in heart ratevariability (dX) which naturally leads to stress index (SI) increase indicatinggrowing sympathetic activity in heart rhythm regulation. At thesame time the base heart rate in animals suffered intrauterine hypoxiaturned out to be lower than in control. The fact that matured animalsof both sexes, survived intrauterine hypoxia in early organogenesis,also show changes in dX and SI indicates long-term and irreversibledisorders in heart rhythm regulation. Thus hypoxia during early organogenesisis of a programming nature potentially increasing the risk of developingCVD in adult animals. Moreover the autonomic system balance shifttowards the activation of sympathetic tone was more pronounced infemales making them more vulnerable to the risk of developing cardiacpathology in puberty.