Korean J Thorac Cardiovasc Surg.  1998 Feb;31(2):102-107.

Nitric Oxide/cGMP-Independent Vasorelaxation Enhanced by L-Arginine

• Moon SH
• Lee JE
• Yoo KJ
• Oh BS
• Lee DJ

Abstract

It has not been clear whether L-arginine plays solely a role contributing to vascular nitric oxide (NO) synthesis. To investigate the mechanisms by which L-arginine induces vasorelaxation, effects of L-arginine on the isometric tension, and tissue NOx and cyclic guanosine monophosphate (cGMP) contents were examined in the isolated rat thoracic aorta. L-Arginine induced a dose-dependent relaxation of aortic rings only with intact endothelium only. The vasorelaxation response to low concentrations of L-arginine was abolished by the pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 10-4 mol/L), whereas the relaxation caused by higher concentrations L-arginine (10-5-10-3 mol/L) was maintained and even more pronounced in the presence of L-NAME. L-Arginine did not affect the vascular tension precontracted with KCl. The vascular tissue contents of NOx/cGMP were not significantly affected by L-arginine, while they were decreased by L-NAME. L-Arginine could not completely recover the NOx/cGMP decreased by L-NAME. Methylene blue only partially antagonized the relaxation response to L-arginine. Indomethacin did not affect the L-arginine-induced vasorelaxation, whereas ouabain markedly attenuated the relaxation. It is suggested that L-arginine induces vasorelaxation not only through its contribution to NO synthesis, but also through enhancing another endothelium-dependent mechanism which is NO/cGMP-independent and cyclooxygenase- independent.

Keyword

Vasodilation; Nitric oxide; Vasodilator agents; Aorta

MeSH Terms

Animals
Aorta
Aorta, Thoracic
Arginine*
Endothelium
Guanosine Monophosphate
Indomethacin
Methylene Blue
NG-Nitroarginine Methyl Ester
Nitric Oxide
Ouabain
Rats
Relaxation
Vasodilation*
Vasodilator Agents
Arginine
Guanosine Monophosphate
Indomethacin
Methylene Blue
NG-Nitroarginine Methyl Ester
Nitric Oxide
Ouabain
Vasodilator Agents