Effect of Direct and Mediated through Maternal Organism Activation of the Catecholaminergic System on Heart Rate Parameters in Rat Fetuses.

We performed a comparative analysis of direct and mediated through the maternal organism effects of elevated catecholamine concentration on changes in the cardiac activity parameters in female rats and their fetuses on gestation days 18 and 20 under in vivo conditions. Administration of L-DOPA, a precursor of catecholaminergic transmitters, did not cause chronotropic effects in fetuses. Analysis of HR variability showed that in fetuses, irrespective of the administration route, there was an increase in nervous influences while the leading role of humoral-metabolic factors in the regulation of HR was preserved. In females receiving L-DOPA injection on day 18 of gestation, a decrease in humoral-metabolic and an increase in nerve effects were observed; in rats injected with L-DOPA on day 20 of gestation, an increase in sympathetic influences was found. Administration of L-DOPA to fetuses provoked a slight increase in the power of all components of the heart rhythm periodogram spectrum in females on day 18 of gestation and their decrease on day 20. Changes in the parameters of HR variability in females can confirm the hypothesis that in the "mother-fetus" system, the heart rhythm in the mother can be affected by both maternal and fetal influences presumably through the humoral-metabolic regulation.