Interrelation between sympathetic and parasympathetic cardiac nerves within ontogenesis

We have studied the formation of interrelation between sympathetic and parasympathetic influenceson the heart in dogs and rats in ontogenesis during electrical stimulation of nerves. To achieve the tasks set we have carried out acute experiments on adult dogs and puppies of the first, second and third age groups using artificial respiration, as well as on intact and sympathectomized growing and adult rats with natural respiration. The basic principle of interrelation in adult animals is an intercompensatory principle against the activity of both parts of nervous system. Intercompensatory principle develops gradually as the influence of sympathetic and parasympathetic outflows on the heart grows. With increasing activity of the sympathetic nervous system, the compensatory growing of influence of the parasympathetic outflow protects the heart from overloading. After sympathectomy, we revealed age-related features in the reaction of the heart to electrical stimulation vagus nerve