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EFFECTS OF PRENATAL DEXAMETHASONE OR TERBUTALINE EXPOSURE ON DEVELOPMENT OF NEURAL AND INTRINSIC CONTROL OF HEART RATE
Citation:
Hou, Q. AND T. Slotkin. EFFECTS OF PRENATAL DEXAMETHASONE OR TERBUTALINE EXPOSURE ON DEVELOPMENT OF NEURAL AND INTRINSIC CONTROL OF HEART RATE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-89/376.
Description:
This study compares the effects of prenatal exposure to terbutaline (a B-adrenergic agonist) and dexamethasone (a glucocorticoid) on the development of heart rate control mechanisms in the rat. oth drugs produced a persistent reduction in resting hart rate appearing during the 2nd postnatal wk, but by different mechanisms. erbutaline affected the development of autonomic input from the CNS, characterized by a premature shift from sympathetic to parasympathetic dominance; thus, heart rate differences between terbutaline exposed animals and controls resolved with acute treatment with a ganglionic blocking agent (chlorisondamine). examethasone did not alter neural input to the nycardium (its actions were not reversed by ganglionic blockate), but instead reduced the intrinisic heart rate; the prenatal glucocorticoid tretment also reduced the sensitivity of the mydocardium to B-adrenergic stimulation, a factor that could contribute to the alterations in intrinsic rate. hese results suggest the potential needf or studies of the functional cardiovascular consequences of fetal or neonatal therapeutic interventions with glucocorticoids or adrenergic agents.