Lack of anticholinergic effect of NG-nitro-L-arginine methylester in the small intestine

The nitric oxide (NO)-synthase inhibitor, N-G-nitro-L-arginine methylester (L-NAME), has been reported to have an atropine-like action. We compared the effects of L-NAME (1 mM) and atropine on isolated small intestinal preparations of the guinea-pig, rat, rabbit and mouse. Half-maximal longitudinal contractions in response to acetylcholine (50-100 nM) were not influenced by L-NAME, but were strongly suppressed by atropine (1 nM). Cholinergic 'twitch' contractions of the guinea-pig ileum were slightly enhanced by L-NAME; this effect was prevented by pretreatment with N-G-nitro-L-arginine (L-NOARG, 100 mu M), another NO synthase inhibitor.'Twitch' contractions were concentration dependently inhibited by atropine (1-100 nM). We conclude that L-NAME is foe of atropine-like activity in isolated intestinal preparations. (C) 1999 Elsevier Science B.V. All rights reserved.