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RECORD NUMBER: 12 OF 25

OLS Field Name OLS Field Data
Main Title Effects of Prenatal Dexamethasone or Terbutaline Exposure on Development of Neural and Intrinsic Control of Heart Rate.
Author Hou, Q. C. ; Slotkin, T. A. ;
CORP Author Duke Univ. Medical Center, Durham, NC. Dept. of Pharmacology.;Health Effects Research Lab., Research Triangle Park, NC.
Publisher c1989
Year Published 1989
Report Number EPA-R-813769; EPA/600/J-89/376;
Stock Number PB90-216235
Additional Subjects Heart rate ; Parasympathetic nervous system ; Sympathetic nervous system ; Graphs(Charts) ; Body weight ; Reprints ; Prenatal exposure delayed effects ; Terbutaline ; Dexamethasone ; Adrenergic beta receptor blockaders
Holdings
Library Call Number Additional Info Location Last
Modified
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Status
NTIS  PB90-216235 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 08/27/1990
Collation 6p
Abstract
The study compares the effects of prenatal exposure to terbutaline (a beta-adrenergic agonist) and dexamethansone (a glucocorticoid) on the development of heart rate control mechanisms in the rat. Both drugs produced a persistent reduction in resting heart rate appearing during the 2nd postnatal wk, but by different mechanisms. Terbutaline 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). Dexamethasone did not alter neural input to the myocardium (its actions were not reversed by ganglionic blockade), but instead reduced the intrinsic heart rate; the prenatal glucocorticoid treatment also reduced the sensitivity of the mydocardium to beta-adrenergic stimulation, a factor that could contribute to the alterations in intrinsic rate. (Copyright (c) 1989 International Pediatric Research Foundation, Inc.)