Norepinephrine blocks a calcium current of adult rat sympathetic neurons via an alpha 2-adrenoceptor

Eur J Pharmacol. 1990 May 3;180(1):37-47. doi: 10.1016/0014-2999(90)90590-3.


The effects of alpha-adrenoceptor agonist and antagonist drugs on the Ca2+ current of acutely isolated adult rat superior cervical ganglion (SCG) neurons were investigated to characterize the adrenoceptor which mediates a catecholamine-induced decrease of the Ca2+ current. Ca2+ currents were recorded using the whole-cell variant of the patch-clamp technique from neurons isolated enzymatically from adult rat SCG. Norepinephrine (1 microM) produced a rapid, reversible, and concentration-dependent decrease in Ca2+ current amplitude and slowed the rising phase of the Ca2+ current. These effects could be mimicked by clonidine (1 microM), an alpha 2-agonist but not by the alpha 1-agonist phenylephrine (1 microM). The norepinephrine-induced decrease in Ca2+ current amplitude was attenuated in the presence of idazoxan (1 microM), an alpha 2-antagonist, but was unaffected in the presence of the alpha 1-antagonist prazosin (1 microM). Neither antagonist displayed any Ca2+ current blocking activity. These results suggest that the alpha-receptor which mediates the norepinephrine-induced decrease of the Ca2+ current in adult rat SCG neurons is of the alpha 2-subtype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology
  • Adrenergic alpha-Antagonists / pharmacology
  • Animals
  • Calcium Channel Blockers*
  • Calcium Channels / drug effects
  • Ganglia, Spinal / drug effects
  • In Vitro Techniques
  • Norepinephrine / pharmacology*
  • Rats
  • Receptors, Adrenergic, alpha / drug effects
  • Receptors, Adrenergic, alpha / metabolism*
  • Sympathetic Nervous System / drug effects
  • Sympathetic Nervous System / metabolism*


  • Adrenergic alpha-Agonists
  • Adrenergic alpha-Antagonists
  • Calcium Channel Blockers
  • Calcium Channels
  • Receptors, Adrenergic, alpha
  • Norepinephrine