Send to

Choose Destination
See comment in PubMed Commons below
Br J Pharmacol. 1993 Nov;110(3):1003-8.

Selective inhibition of basal but not agonist-stimulated activity of nitric oxide in rat aorta by NG-monomethyl-L-arginine.

Author information

  • 1Department of Pharmacology, University of Glasgow.


1. Two inhibitors of nitric oxide synthase, NG-monomethyl-L-arginine (L-NMMA, 1-100 microM) and NG-nitro-L-arginine (L-NOARG, 3-300 microM), each produced a concentration-dependent augmentation of phenylephrine-induced tone in endothelium-containing but not endothelium-denuded rings of rat aorta. Pretreatment with L-arginine (10 mM) prevented the augmentation of tone induced by L-NOARG and L-NMMA. 2. Following induction of sub-maximal tone with phenylephrine in endothelium-containing rings, acetylcholine (1 nM-3 microM) induced relaxations which were inhibited in a concentration-dependent manner by L-NOARG (10-100 microM). 3. In contrast to the action of L-NOARG, L-NMMA (100-1000 microM) had no effect on acetylcholine-induced relaxations. L-NMMA (100-300 microM) also had no effect on the endothelium-dependent relaxant actions of ATP (0.1-100 microM), whereas L-NOARG (100 microM) produced powerful blockade. 4. Unexpectedly, pretreatment with L-NMMA (30-300 microM), as with the endogenous substrate L-arginine (10 microM-10 mM), inhibited in a concentration-dependent manner the ability of L-NOARG (30 microM) to block acetylcholine-induced relaxation. 5. The ability of L-NOARG to augment phenylephrine-induced tone and inhibit relaxation by acetylcholine and ATP in endothelium-containing rings is consistent with blockade of basal and agonist-stimulated production of nitric oxide, respectively. 6. The ability of L-NMMA to augment phenylephrine-induced tone without affecting relaxation to acetylcholine or ATP in endothelium-containing rings suggests a selective ability to block basal but not agonist-stimulated production of nitric oxide in rat aorta.

[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Wiley Icon for PubMed Central
    Loading ...
    Write to the Help Desk