Antagonism by theophylline of the adenosine receptor agonist 5′-N-ethykarboxamidoadenosine at the guinea pig ileum

1985 ◽  
Vol 63 (9) ◽  
pp. 1195-1197 ◽  
Author(s):  
F. L. Christofi ◽  
M. A. Cook
Keyword(s):  
Guinea Pig ◽  
Receptor Agonist ◽  
Acetylcholine Release ◽  
Receptor Site ◽  
Inhibitory Effect ◽  
Guinea Pig Ileum ◽  
Competitive Antagonism ◽  
Adenosine Receptor Agonist ◽  
Dose Dependent Fashion ◽  
Dose Dependent

The inhibitory effect of the putative adenosine A2 receptor agonist 5′-N-ethylcarboxamidoadenosine (NECA) on acetylcholine release from the stimulated guinea pig ileum preparation and the nature of its antagonism by theophylline were investigated. NECA was shown to inhibit the response of the ileum preparation in a dose-dependent fashion, and an EC50 value of 1.62 × 10−8 M was determined. This value was comparable with that determined for the A1 receptor agonist N6-R-phenylisopropyladenosine (R-PIA) (2.57 × 10−8 M) using the same preparation. Competitive antagonism of the inhibitory effect of NECA by theophylline was quantitated and a pA2 value of 5.04 for the methylxanthine was obtained. This value was similar to those obtained previously for R-PIA and adenosine itself and suggests that these nucleosides may be interacting with the same receptor site on myenteric nerve endings. These findings do not permit the designation of the receptor as an A1 or A2 subtype according to current criteria.

scholarly journals Relationship Between Muscarinic Autoinhibition and the Inhibitory Effect of Morphine on Acetylcholine Release From Myenteric Plexus of Guinea Pig Ileum

1998 ◽  
Vol 77 (4) ◽  
pp. 271-278 ◽  
Author(s):  
Hideyuki Nishiwaki ◽  
Noriko Saitoh ◽  
Hideaki Nishio ◽  
Tadayoshi Takeuchi ◽  
Fumiaki Hata
Keyword(s):  
Guinea Pig ◽  
Myenteric Plexus ◽  
Acetylcholine Release ◽  
Inhibitory Effect ◽  
Guinea Pig Ileum

Cholinergic and GABAergic regulation of nitric oxide synthesis in the guinea pig ileum

1999 ◽  
Vol 276 (4) ◽  
pp. G862-G866 ◽  
Author(s):  
Katalina Hebeiss ◽  
Heinz Kilbinger
Keyword(s):  
Nitric Oxide ◽  
Guinea Pig ◽  
Myenteric Plexus ◽  
Nicotinic Receptors ◽  
Receptor Agonist ◽  
Longitudinal Muscle ◽  
Inhibitory Effect ◽  
Nitric Oxide Synthesis ◽  
Guinea Pig Ileum ◽  
Threefold Increase

Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [3H]citrulline during incubation with [3H]arginine. Spontaneous [3H]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 [3H]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 [3H]citrulline. TTX reduced the electrically induced but not spontaneous [3H]citrulline formation. The electrically induced formation of [3H]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 GABAA receptor agonist muscimol and GABA also reduced the electrically evoked formation of [3H]citrulline, whereas baclofen was without effect. Bicuculline antagonized the inhibitory effect of GABA. It is concluded that nitrergic myenteric neurons are equipped with GABAAreceptors, which mediate inhibition of NO synthesis.

scholarly journals Inhibitory Effect of Endomorphin-1 and -2 on Acetylcholine Release From Myenteric Plexus of Guinea Pig Ileum

1998 ◽  
Vol 78 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Nishiwaki Hideyuki ◽  
Saitoh Noriko ◽  
Nishio Hideaki ◽  
Takeuchi Tadayoshi ◽  
Hata Fumiaki
Keyword(s):  
Guinea Pig ◽  
Myenteric Plexus ◽  
Acetylcholine Release ◽  
Inhibitory Effect ◽  
Guinea Pig Ileum

Cellular pathways mediating tachykinin-evoked secretomotor responses in guinea pig ileum

1997 ◽  
Vol 273 (5) ◽  
pp. G1127-G1134 ◽  
Author(s):  
W. MacNaughton ◽  
B. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Receptor Agonist ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Neurokinin A ◽  
Guinea Pig Ileum ◽  
Cellular Pathways ◽  
20 Nm

This study characterized tachykinin-evoked secretomotor responses in in vitro submucosal and mucosal-submucosal preparations of the guinea pig ileum using combined intracellular and Ussing chamber recording techniques. Superfusion of endogenous tachykinins substance P (SP), neurokinin A (NKA), and neurokinin B depolarized single submucosal neurons and evoked increased short-circuit current ( I sc) responses in Ussing chamber preparations. The NK1-receptor agonist [Sar9,Met(O2)11]SP [50% effective concentration (EC50) = 2 nM] depolarized all submucosal neurons examined. The NK3-receptor agonist senktide (EC50 = 20 nM) depolarized ∼50% of neurons examined, whereas the NK2-receptor agonist [Ala5,β-Ala8]NKA-(4—10) had no effect on membrane potential. [Sar9,Met(O2)11]SP and senktide evoked similar increases in I sc that were tetrodotoxin sensitive (91 and 100%, respectively) and were selectively blocked by the NK1antagonist CP-99,994 and the NK3antagonist SR-142801, respectively. Capsaicin-evoked increases in I sc were significantly inhibited (54%, P < 0.05) by CP-99,994 but not by SR-142801. Neither antagonist inhibited slow excitatory postsynaptic potentials. These findings suggest that tachykinin-evoked secretion in guinea pig ileum is mediated by NK1 and NK3 receptors on submucosal secretomotor neurons and that capsaicin-sensitive nerves release tachykinin(s) that activate the NK1 receptors.

Functional evidence that acetylcholine release from Auerbach's plexus of guinea-pig ileum is modulated by α2A-adrenoceptor subtype

1991 ◽  
Vol 205 (3) ◽  
pp. 311-313 ◽  
Author(s):  
Corrado Blandizzi ◽  
Margit Doda ◽  
Gabor Tarkovács ◽  
Mario Del Tacca ◽  
E.Sylvester Vizi
Keyword(s):  
Guinea Pig ◽  
Acetylcholine Release ◽  
Guinea Pig Ileum ◽  
Auerbach’S Plexus ◽  
Auerbach's Plexus
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