Preliminary research on possible relationship of NO with agmatine at the vascular level

Rom J Physiol. Jan-Jun 1999;36(1-2):67-79.

Abstract

The comparative study of the vascular effects of agmatine and L-arginine as physiological precursors of NO indicated the following: When administered intravenously, both vasoactive substances produced a decrease of the systemic blood pressure in rats and rabbits, diminished in the case of agmatine and suppressed in that of arginine by the previous administration of L-NAME. Myorelaxing vascular effects were obtained in isolated thoracic aorta rings, precontracted with phenylephrine and noradrenaline. Endothelium removal suppressed the myorelaxing properties of L-arginine, without affecting the effects of agmatine, both before and after administration of L-NAME or yohimbine. The persistence of the relaxing effects of agmatine after NOS and guanylate-cyclase inhibition with methylene blue excludes the participation of NO and cGMP in their occurrence. The enhancement of agmatine myorelaxation by moxonidine pleads for the stimulation of imidazoline receptors.

MeSH terms

  • Agmatine / pharmacology*
  • Animals
  • Aorta, Thoracic / drug effects*
  • Aorta, Thoracic / physiology*
  • Arginine / pharmacology
  • Blood Pressure / drug effects
  • Endothelium, Vascular / physiology
  • Enzyme Inhibitors / pharmacology*
  • Guanylate Cyclase / antagonists & inhibitors
  • In Vitro Techniques
  • Male
  • Methylene Blue / pharmacology
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase / antagonists & inhibitors
  • Rabbits
  • Rats
  • Rats, Wistar
  • Vasodilator Agents / pharmacology*

Substances

  • Enzyme Inhibitors
  • Vasodilator Agents
  • Nitric Oxide
  • Agmatine
  • Arginine
  • Nitric Oxide Synthase
  • Guanylate Cyclase
  • Methylene Blue
  • NG-Nitroarginine Methyl Ester