Modulation of autonomic neuroeffector transmission by nitric oxide in guinea pig ileum.
NG-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthesis, markedly enhanced tonic ("hump") responses to transmural stimulation in guinea pig ileum longitudinal muscle. The enhancement of the hump responses was probably due to a prejunctional effect on substance P-like neurotransmission, since the action of L-NMMA was exerted also in the presence of atropine, and since responses to substance P, a mimic of nerve stimulation, were unaffected by L-NMMA as were cholinergic twitch responses and the overflow of [3H]choline. Further in support, the hump responses were blocked by the substance P antagonist Spantide. All effects of L-NMMA were stereospecifically reversed by L-arginine. Endogenous nitric oxide thus selectively modulates peptidergic neurotransmission in the gut.
Gustafsson
L E
LE
Dept of Physiology, Karolinska Institutet, Stockholm, Sweden.
Wiklund
C U
CU
Wiklund
N P
NP
Persson
M G
MG
Moncada
S
S
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D002794:Choline / Q000378:metabolism; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009197:Myenteric Plexus / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D013373:Substance P / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects; D019323:omega-N-Methylarginine
D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013373:Substance P; D001120:Arginine; D002794:Choline; D000109:Acetylcholine