In:
American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 276, No. 4 ( 1999-04-01), p. G862-G866
Abstract:
Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [ 3 H]citrulline during incubation with [ 3 H]arginine. Spontaneous [ 3 H]citrulline production after 30 min was 80–90 dpm/mg, which constituted ∼1% of the tissue radioactivity. Electrical stimulation (10 Hz) led to a threefold increase in [ 3 H]citrulline formation. Removal of calcium from the medium or addition of N G -nitro-l-arginine strongly inhibited both spontaneous and electrically induced production of [ 3 H]citrulline. TTX reduced the electrically induced but not spontaneous [ 3 H]citrulline formati on. The electrically induced formation of [ 3 H]citrulline was diminished by (+)-tubocurarine and mecamylamine and enhanced by scopolamine, which suggests that endogenous ACh inhibits, via muscarinic receptors, and stimulates, via nicotinic receptors, the NO synthesis in the myenteric plexus. The GABA A receptor agonist muscimol and GABA also reduced the electrically evoked formation of [ 3 H]citrulline, whereas baclofen was without effect. Bicuculline antagonized the inhibitory effect of GABA. It is concluded that nitrergic myenteric neurons are equipped with GABA A receptors, which mediate inhibition of NO synthesis.
Type of Medium:
Online Resource
ISSN:
0193-1857
,
1522-1547
DOI:
10.1152/ajpgi.1999.276.4.G862
Language:
English
Publisher:
American Physiological Society
Publication Date:
1999
detail.hit.zdb_id:
1477329-6
SSG:
12
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