Maturation of sympathetic neurotransmission in the rat heart. VII. Suppression of sympathetic responses by dexamethasone.

Journal Article

Effects of dexamethasone on development of sympathetic nerve function in the heart were evaluated by giving 1 mg/kg of dexamethasone s.c. daily for several days beginning the day after birth. Dexamethasone interfered with tyramine- and isoproterenol-induced tachycardia in the neonates but did not cause alterations in development of a marker for presynaptic sympathetic nerve terminals (synaptic vesicle uptake of [3H] norepinephrine) nor of postsynaptic beta adrenoceptor binding of [3H]dihydroalprenolol; the deficit was also unrelated to general cellular effects of the hormone. These data suggest that the subnormal chronotropic responses of the heart to sympathetic stimulation in dexamethasone-treated neonatal rats result from uncoupling of receptors from the organ response. The effects of dexamethasone on cardiac responses were specific to the neonate, as mature rats given dexamethasone did not show suppression of cardiac sympathetic action. Neonatal dexamethasone treatment also produced a deficit of adrenomedullary development with deficiencies in catecholamine levels and in catecholamine biosynthetic enzymes; deficits in phenylethanolamine N-methyltransferase activity persisted into young adulthood.

Full Text

Duke Authors

Cited Authors

  • Lau, C; Slotkin, TA

Published Date

  • January 1, 1981

Published In

Volume / Issue

  • 216 / 1

Start / End Page

  • 6 - 11

PubMed ID

  • 6256527

International Standard Serial Number (ISSN)

  • 0022-3565

Language

  • eng

Conference Location

  • United States