Norepinephrine-induced down regulation of alpha 1 adrenergic receptors in cultured rabbit aorta smooth muscle cells.

Published

Journal Article

Drug-induced refractoriness of alpha-adrenergic receptor-mediated vasoconstriction may be a clinically important phenomenon. We have investigated the possible molecular mechanisms underlying this phenomenon in cultured vascular smooth muscle cells derived from the rabbit aorta. alpha 1-Adrenergic receptors were identified in membranes prepared from these cells by [125I]HEAT binding. The radioligand bound to a high affinity site (Kd = 140 pM) in a saturable fashion (202 fmol/mg protein). Adrenergic agonists and antagonists competed for binding of [125I]HEAT with the expected order of potency for an alpha 1-receptor, (-)epinephrine greater than or equal to (-) norepinephrine greater than (+)epinephrine greater than isoproterenol and prazosin greater than phentolamine greater than yohimbine. Exposure of cells for 26 hours to 10 microM norepinephrine resulted in a 70% decrease in the number of alpha 1-receptors as measured by [125I]HEAT binding without any significant change in the affinity of the receptor for the ligand. When the alpha-receptors were blocked with 10 microM phentolamine the loss of receptors induced by norepinephrine was completely prevented. Similar down-regulation of the [125I]HEAT binding sites was observed when the alpha 1-agonist phenylephrine was used instead of norepinephrine. It is concluded that alpha-agonists induce down-regulation of aortic smooth muscle alpha 1-receptors. This reduction of alpha-receptors could be important in the mechanisms by which vascular smooth muscle develops refractoriness to alpha-adrenergic stimulation.

Full Text

Duke Authors

Cited Authors

  • Wikberg, JE; Akers, M; Caron, MG; Hagen, PO

Published Date

  • October 3, 1983

Published In

Volume / Issue

  • 33 / 14

Start / End Page

  • 1409 - 1417

PubMed ID

  • 6137750

Pubmed Central ID

  • 6137750

International Standard Serial Number (ISSN)

  • 0024-3205

Digital Object Identifier (DOI)

  • 10.1016/0024-3205(83)90824-x

Language

  • eng

Conference Location

  • Netherlands