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NANC relaxation of the circular smooth muscle of the oesophagus of the Agama lizard involves the L-arginine-nitric oxide synthase pathway.

Knight, GE; Burnstock, G; (1999) NANC relaxation of the circular smooth muscle of the oesophagus of the Agama lizard involves the L-arginine-nitric oxide synthase pathway. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol , 122 (2) pp. 165-171.

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Abstract

On carbachol (CCh; 10-30 microM) pre-contracted circular muscle strips of the Agama lizard oesophagus, electrical field stimulation evoked frequency-dependent relaxations in the presence of guanethidine (1 microM) and indomethacin (1 microM). These non-adrenergic inhibitory responses were concentration-dependently inhibited by the nitric oxide synthase (NOS) inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) within a concentration range of 30-300 microM but not D-NAME (up to 300 microM), although a component remained at 4-16 Hz even with 300 microM L-NAME. The inhibition by L-NAME (300 microM) was completely prevented when L-arginine (L-Arg; 15 mM) but not D-Arg (up to 15 mM) was applied simultaneously with L-NAME (300 microM). Increasing the L-NAME concentration to 1 mM had no additional inhibitory effect. Sodium nitroprusside (SNP) concentration-dependently relaxed pre-contracted oesophageal strips, L-NAME (up to 300 microM) had no effect. Neither adenosine 5'-triphosphate (up to 0.1 mM) nor vasoactive intestinal polypeptide (up to 0.1 microM) caused the pre-contracted oesophagus to relax. This study has shown that the NANC inhibitory response of the Agama lizard oesophagus circular muscle largely involves the L-Arg-NOS pathway as seen by the effect of L-NAME, L-Arg and SNP. The identity of the L-NAME-resistant component(s) and the lack of effect of tetrodotoxin (up to 3 microM) and omega-conotoxin GVIA (up to 0.1 microM) in relation to the nature of the inhibitory response are discussed.

Type: Article
Title: NANC relaxation of the circular smooth muscle of the oesophagus of the Agama lizard involves the L-arginine-nitric oxide synthase pathway.
Location: United States
Keywords: Adrenergic Agents, Animals, Arginine, Electric Stimulation, Epithelium, Esophagus, Female, Guanethidine, Indomethacin, Lizards, Male, Muscle Relaxation, Muscle, Smooth, NG-Nitroarginine Methyl Ester, Nitric Oxide Synthase, Nitroprusside, Peptides, Tetrodotoxin, omega-Conotoxin GVIA
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Neuro, Physiology and Pharmacology
URI: http://discovery.ucl.ac.uk/id/eprint/22250
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