Adenosine A2 receptor-mediated excitation of a subset of AH/Type 2 neurons and elevation of cAMP levels in myenteric ganglia of guinea-pig ileum

2008 ◽  
Vol 6 (2) ◽  
pp. 67-78 ◽  
Author(s):  
F. L. CHRISTOFI ◽  
L. V. BAIDAN ◽  
R. H. FERTEL ◽  
J. D. WOOD
Keyword(s):  
Guinea Pig ◽  
Guinea Pig Ileum ◽  
Adenosine A2 Receptor ◽  
Camp Levels ◽  
Myenteric Ganglia

Elevation of cAMP facilitates noradrenergic transmission in submucous neurons of guinea pig ileum

1993 ◽  
Vol 264 (3) ◽  
pp. G442-G446 ◽  
Author(s):  
D. H. Zafirov ◽  
H. J. Cooke ◽  
J. D. Wood
Keyword(s):  
Guinea Pig ◽  
Ganglion Cells ◽  
Phosphodiesterase Inhibitor ◽  
Input Resistance ◽  
Guinea Pig Ileum ◽  
Synaptic Excitation ◽  
Before And After ◽  
Intracellular Microelectrodes

Slow synaptic excitation and inhibition were studied with intracellular microelectrodes in submucous ganglion cells of the guinea pig ileum. Elevation of adenosine 3',5'-cyclic monophosphate (cAMP) after application of forskolin or the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) resulted in slowly activating depolarization of the membrane potential. The depolarization was associated with increased input resistance, enhanced excitability, and suppression of hyperpolarizing afterpotentials. This occurred in AH/type 2 but not S/type 1 neurons. The action of forskolin or IBMX mimicked slow synaptic excitation in the same neurons. Focal electrical stimulation also evoked slow inhibitory postsynaptic potentials (IPSPs). The amplitude and duration of the IPSPs were increased by forskolin or a membrane-permeant analogue of cAMP. Treatment with phentolamine, yohimbine or idazoxan suppressed the IPSPs before and after potentiation by forskolin, suggesting that the IPSPs were mediated by release of norepinephrine acting at alpha 2-adrenoceptors. Application of adenosine or selective adenosinergic A1 agonists suppressed or abolished the IPSPs. The results suggest that elevation of cAMP facilitates the release of norepinephrine at alpha 2-synapses on submucous neurons of guinea pig small bowel.

Effect of morphine and acetylcholine on contractile activity and cyclic AMP in guinea-pig ileum

1990 ◽  
Vol 10 (1) ◽  
pp. 113-119 ◽  
Author(s):  
L. F. Alguacil ◽  
M. P. Lopez-Ruiz ◽  
J. C. Prieto ◽  
C. Alamo ◽  
E. Cuenca
Keyword(s):  
Electrical Stimulation ◽  
Guinea Pig ◽  
Prolonged Exposure ◽  
Contractile Activity ◽  
Inhibitory Effect ◽  
Guinea Pig Ileum ◽  
Camp Content ◽  
Twitch Response ◽  
Spontaneous Movements ◽  
Camp Levels

Neither acute nor prolonged exposure to morphine altered cAMP content or spontaneous movements of longitudinal muscle-myenteric plexus strips of the guinea-pig ileum. By contrast, exogenous acetylcholine or electrical stimulation of the strips elicited both a decrease of cAMP concentration and a twitch response. Atropine blocked the effects of stimulation on these parameters. Addition of morphine to electrically stimulated strips inhibited the twitch response but did not affect cAMP levels. Incubation with morphine led to the development of tolerance to the inhibitory effect on twitch activity and prevented the fall in cAMP normally elicited by electrical stimulation. These results suggest that muscarinic activation is associated with a reduction of cAMP content, an effect which would be impaired in opiate-tolerant tissues.

Myenteric neurons activate submucosal vasodilator neurons in guinea pig ileum

2000 ◽  
Vol 279 (2) ◽  
pp. G380-G387 ◽  
Author(s):  
S. Vanner
Keyword(s):  
Blood Flow ◽  
Guinea Pig ◽  
Myenteric Plexus ◽  
Guinea Pig Ileum ◽  
Recording Site ◽  
Myenteric Neurons ◽  
Outside Diameter ◽  
Myenteric Ganglia ◽  
Double Chamber

This study examined whether myenteric neurons activate submucosal vasodilator pathways in in vitro combined submucosal-myenteric plexus preparations from guinea pig ileum. Exposed myenteric ganglia were electrically stimulated, and changes in the outside diameter of submucosal arterioles were monitored in adjoining tissue by videomicroscopy. Stimulation up to 18 mm from the recording site evoked large TTX-sensitive vasodilations in both orad and aborad directions. In double-chamber baths, which isolated the stimulating myenteric chamber from the recording submucosal chamber, hexamethonium or the muscarinic antagonist 4-diphenylacetoxy- N-(2-chloroethyl)-piperdine hydrochloride (4-DAMP) almost completely blocked dilations when superfused in the submucosal chamber. When hexamethonium was placed in the myenteric chamber ∼50% of responses were hexamethonium sensitive in both orad and aborad orientations. The addition of 4-DAMP or substitution of Ca2+-free, 12 mM Mg2+ solution did not cause further inhibition. These results demonstrate that polysynaptic pathways in the myenteric plexus projecting orad and aborad can activate submucosal vasodilator neurons. These pathways could coordinate intestinal blood flow and motility.

Anti-inflammatory effect of Mitragyna speciosa crude methanol extract on the guinea pig ileum

Planta Medica ◽  
2009 ◽  
Vol 75 (09) ◽  
Author(s):  
WM Shaik Mossadeq ◽  
K Syamimi ◽  
MP Azyyati ◽  
ZA Zakaria ◽  
AK Arifah ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Methanol Extract ◽  
Guinea Pig Ileum ◽  
Mitragyna Speciosa ◽  
Anti Inflammatory ◽  
Crude Methanol Extract ◽  
Inflammatory Effect

Preparation and properties of three analogues of [5-leucine]enkephalin, substrates for enzyme conversion studies

1985 ◽  
Vol 50 (6) ◽  
pp. 1329-1334
Author(s):  
Jaroslav Vičar ◽  
Linda Servítová ◽  
Martin Flegel ◽  
Karel Hauzer ◽  
Tomislav Barth
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Guinea Pig ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Guinea Pig Ileum ◽  
Opioid Activity ◽  
C Terminus ◽  
N Terminus ◽  
Fragment Condensation

Analogues of [5-Leu]enkephalin, prolonged by methionine on the N-terminus or, by lysine or methionine on the C-terminus were prepared by fragment condensation, purified by ion exchange chromatography or high-pressure liquid chromatography. The substances were characterised by their opioid activity in a test on guinea-pig ileum in comparison with the activity of [5-Leu]enkephalin.

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