Norepinephrine release is reduced by I(1)-receptors in addition to alpha(2)-adrenoceptors

Ann N Y Acad Sci. 2003 Dec;1009:270-3. doi: 10.1196/annals.1304.034.

Abstract

In pithed spontaneous hypertensive rats, noradrenaline overflow was diminished by moxonidine even when alpha(2)-adrenoceptors were blocked quantitatively using phenoxybenzamine, suggesting an I(1)-receptor-mediated mechanism of noradrenaline release. This hypothesis was confirmed, since the noradrenaline overflow was (1) increased under alpha(2)-adrenoceptors blockade by the mixed I(1)/alpha(2)-antagonists efaroxan or idazoxan, (2) still reduced by moxonidine when both alpha(2)- and I(1)-receptors were blocked, and (3) diminished by agmatine after pretreatment with phenoxybenzamine, but not with AGN192403. An indirect ganglionic I(1)-receptor-mediated mechanism of noradrenaline release is supposed.

MeSH terms

  • Adrenergic alpha-Antagonists / pharmacology
  • Agmatine / pharmacology
  • Animals
  • Benzofurans / pharmacology
  • Blood Pressure / physiology
  • Bridged Bicyclo Compounds / pharmacology
  • Electric Stimulation
  • Heptanes / pharmacology
  • Hypertension / metabolism*
  • Idazoxan / pharmacology
  • Imidazoles / metabolism
  • Imidazoles / pharmacology
  • Imidazoline Receptors
  • Male
  • Norepinephrine / metabolism*
  • Phenoxybenzamine / pharmacology
  • Rats
  • Rats, Inbred SHR
  • Receptors, Adrenergic, alpha-2 / metabolism*
  • Receptors, Drug / antagonists & inhibitors
  • Receptors, Drug / metabolism*
  • Spinal Cord / metabolism

Substances

  • AGN 192403
  • Adrenergic alpha-Antagonists
  • Benzofurans
  • Bridged Bicyclo Compounds
  • Heptanes
  • Imidazoles
  • Imidazoline Receptors
  • Receptors, Adrenergic, alpha-2
  • Receptors, Drug
  • imidazoline I1 receptors
  • Phenoxybenzamine
  • Agmatine
  • moxonidine
  • efaroxan
  • Norepinephrine
  • Idazoxan