Regularities of formation of the reduced function of the heart in small laboratory animals in the process of natural growth and development

Conducted research on the dynamics of the formation of the contractile function of the heart of small laboratory animals. It was established experimentally that in white outbred laboratory rats from the first day of life and up to 70 days of age, the heart indices change heterochronically. The periods of the greatest change in the heart rate of rats alternate with stages of a significant increase in stroke volume. In the mechanisms of regulation of stroke blood volume in rats, the sympathetic regulatory effect appears much earlier than the parasympathetic one. Later, as the animals grow and develop naturally, their ratio changes somewhat: a more pronounced sympathetic regulatory effect on the CRI lasts up to the age of 70 days, whereas from 8 weeks of age the parasympathetic effect decreases significantly.