Preliminary research on possible relationship of NO with agmatine at the vascular level.
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.
Haulică
I
I
Laboratory of Experimental and Applied Physiology, Romanian Academy.
Bild
W
W
Iliescu
R
R
Georgescu
R
R
Frunză
F
F
D000376:Agmatine / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology*; D001120:Arginine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D014665:Vasodilator Agents / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009569:Nitric Oxide; D000376:Agmatine; D001120:Arginine; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D008751:Methylene Blue; D019331:NG-Nitroarginine Methyl Ester