Properties of synaptic inputs from myenteric neurons innervating submucosal S neurons in guinea pig ileum

2000 ◽  
Vol 278 (2) ◽  
pp. G273-G280 ◽  
Author(s):  
B. A. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Myenteric Plexus ◽  
Intracellular Recordings ◽  
Guinea Pig Ileum ◽  
Myenteric Neurons ◽  
Synaptic Inputs ◽  
Stimulus Train ◽  
Stimulation Of ◽  
Double Chamber

This study examined synaptic inputs from myenteric neurons innervating submucosal neurons. Intracellular recordings were obtained from submucosal S neurons in guinea pig ileal preparations in vitro, and synaptic inputs were recorded in response to electrical stimulation of exposed myenteric plexus. Most S neurons received synaptic inputs [>80% fast (f) excitatory postsynaptic potentials (EPSP), >30% slow (s) EPSPs] from the myenteric plexus. Synaptic potentials were recorded significant distances aboral (fEPSPs, 25 mm; sEPSPs, 10 mm) but not oral to the stimulating site. When preparations were studied in a double-chamber bath that chemically isolated the stimulating “myenteric chamber” from the recording side “submucosal chamber,” all fEPSPs were blocked by hexamethonium in the submucosal chamber, but not by a combination of nicotinic, purinergic, and 5-hydroxytryptamine-3 receptor antagonists in the myenteric chamber. In 15% of cells, a stimulus train elicited prolonged bursts of fEPSPs (>30 s duration) that were blocked by hexamethonium. These findings suggest that most submucosal S neurons receive synaptic inputs from predominantly anally projecting myenteric neurons. These inputs are poised to coordinate intestinal motility and secretion.

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.

Neural circuitry of capsaicin-sensitive afferents innervating submucosal arterioles in guinea pig ileum

1996 ◽  
Vol 270 (6) ◽  
pp. G948-G955 ◽  
Author(s):  
S. Vanner ◽  
M. Bolton
Keyword(s):  
Guinea Pig ◽  
Neural Circuitry ◽  
Guinea Pig Ileum ◽  
Single Vessel ◽  
Opposite Chamber ◽  
Stimulation Of ◽  
Double Chamber

The circuitry of capsaicin-sensitive nerves innervating submucosal arterioles in the guinea pig ileum was examined. The orientation of in vitro submucosal preparations in a double-chamber bath was varied so that nerves on differing segments of arterioles could be stimulated with capsaicin. Capsaicin-evoked dilation of preconstricted arterioles was recorded using videomicroscopy. Superfusion of capsaicin onto either proximal or distal segments of a parent arteriole divided between the chambers evoked a dilation in the opposite chamber (63 and 58%, respectively) but had no effect on extrinsically denervated preparations. When the divider separated the vascular arcades joining the two parent arterioles on the opposite or same side of the intestine, capsaicin evoked little or no response (8 and 11%, respectively). Capsaicin stimulation confined to one branch of a single vessel dilated the opposite branch (42%). In preparations with adjacently attached mucosa, application of capsaicin to the mucosa dilated arterioles in the opposite chamber. These findings suggest that capsaicin stimulation of the mucosa evokes dilation of arterioles through a submucosal reflex and that both afferent and efferent elements are confined to the submucosa and mucosa.

Some species differences in the intrinsic factor stimulation of B12 uptake by small intestine in vitro

1959 ◽  
Vol 197 (4) ◽  
pp. 926-928 ◽  
Author(s):  
T. Hastings Wilson ◽  
Elliott W. Strauss
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Species Differences ◽  
Intrinsic Factor ◽  
Vitamin B ◽  
Guinea Pig Ileum ◽  
Rat Intestine ◽  
Intrinsic Factors ◽  
Stimulation Of

Sacs of everted small intestine from a variety of animals were incubated in bicarbonate-saline containing vitamin B12 with and without intrinsic factor (IF). B12 uptake by rat intestine was stimulated only by its own intrinsic factor. Guinea pig ileum responded to all intrinsic factors tested (guinea pig, rat, hog, hamster, human being and rabbit). The intestines of hamster and rabbit were intermediate in specificity, responding to some, but not all, of the IF preparations. Species differences occur in both the intestine and intrinsic factor preparations. The guinea pig ileum was suggested as a possible assay for both hog and human IF.

Somatostatin modulation of peptide-induced acetylcholine release in guinea pig ileum

1984 ◽  
Vol 246 (5) ◽  
pp. G509-G514 ◽  
Author(s):  
D. H. Teitelbaum ◽  
T. M. O'Dorisio ◽  
W. E. Perkins ◽  
T. S. Gaginella
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Myenteric Plexus ◽  
Acetylcholine Release ◽  
Longitudinal Muscle ◽  
Guinea Pig Ileum ◽  
Gut Motility ◽  
Release Of Acetylcholine

The peptides caerulein, neurotensin, somatostatin, and substance P modulate the activity of intestinal neurons and alter gut motility. We examined the effects of these peptides on acetylcholine release from the myenteric plexus and intestinal contractility in vitro. Caerulein (1 X 10(-9) M), neurotensin (1.5 X 10(-6) M), and substance P (1 X 10(-7) M) significantly enhanced the release of [3H]acetylcholine from the myenteric plexus of the guinea pig ileum. This effect was inhibited by tetrodotoxin (1.6 X 10(-6) M). Somatostatin (10(-6) M) inhibited caerulein- and neurotensin-evoked release of acetylcholine but did not inhibit release induced by substance P. Caerulein, neurotensin, and substance P caused contraction of the guinea pig ileal longitudinal muscle. Somatostatin inhibited the contractions induced by caerulein and neurotensin. In contrast, substance P-induced contraction was not inhibited significantly by somatostatin. Thus, in the guinea pig ileum, caerulein-, neurotensin-, and substance P-induced contractility is due, at least in part, to acetylcholine release from the myenteric plexus. The ability of somatostatin to inhibit peptide-induced contractility is selective, and its mechanism may be attributed to inhibition of acetylcholine release.

Differential localization of 5-HT1 receptors on myenteric and submucosal neurons

1988 ◽  
Vol 255 (5) ◽  
pp. G603-G611 ◽  
Author(s):  
J. J. Galligan ◽  
A. Surprenant ◽  
M. Tonini ◽  
R. A. North
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Myenteric Plexus ◽  
Potassium Conductance ◽  
Enteric Neurons ◽  
Nerve Terminals ◽  
Intracellular Recordings ◽  
Myenteric Neurons ◽  
Synaptic Potentials ◽  
Selective Agonists

Intracellular recordings were made from guinea pig enteric neurons, and the effects of 5-hydroxytryptamine (5-HT) and the 5-HT1 selective agonists 5-carboxyamidotryptamine (5-CT) and 8-hydroxy-2-(n-dipropylamino)tetralin (DPAT) were studied on membrane potential and synaptic potentials. Most myenteric AH neurons were hyperpolarized when these agonists were applied by superfusion; this hyperpolarization was due to an increase in potassium conductance. Membrane hyperpolarizations to 5-HT, 5-CT, or DPAT were never observed in submucous neurons. Fast nicotinic excitatory postsynaptic potentials (EPSPs) and slow EPSPs recorded from S neurons in the myenteric plexus were suppressed by 5-HT, 5-CT, and DPAT; slow EPSPs in myenteric AH neurons were also inhibited by these agonists. Fast and slow EPSPs recorded from submucous S neurons were not affected by 5-CT or DPAT. However, slow EPSPs recorded from submucous AH neurons were readily blocked by 5-CT and DPAT. The results indicate that 5-HT1 receptors are located on the cell bodies of myenteric but not submucosal neurons. The nerve terminals that release the mediator or mediators of fast and slow synaptic potentials in myenteric neurons also have 5-HT1 receptors and presumably arise from other myenteric neurons; the nerve terminals responsible for the slow EPSP to AH neurons seem to be the only elements of the submucous plexus that express 5-HT1 receptors.

Acute morphological changes in guinea-pig ileum myenteric neurons after ischemia in situ with superfusion in vitro

2008 ◽  
Vol 204 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Rosa Ventura-Martinez ◽  
Jacinto Santiago-Mejia ◽  
Claudia Gomez ◽  
Rodolfo Rodriguez ◽  
Teresa I. Fortoul
Keyword(s):  
Guinea Pig ◽  
Morphological Changes ◽  
Guinea Pig Ileum ◽  
Myenteric Neurons

Organization of intrinsic cholinergic neurons projecting within submucosal plexus of guinea pig ileum

1998 ◽  
Vol 275 (3) ◽  
pp. G490-G497 ◽  
Author(s):  
B. A. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Pressure Pulse ◽  
Cholinergic Neurons ◽  
Excitatory Postsynaptic Potentials ◽  
Submucosal Plexus ◽  
Guinea Pig Ileum ◽  
Postsynaptic Potentials ◽  
Ics 205 930 ◽  
Stimulation Of

Electrophysiological techniques were employed to examine the organization of the projections of submucosal neurons in the submucosal plexus of guinea pig ileum. These neurons were activated by focal pressure-pulse application of 5-hydroxytryptamine (5-HT) to single ganglia in submucosal preparations in vitro, and resulting fast excitatory postsynaptic potentials (EPSPs) were recorded intracellularly in S-type neurons. 5-HT-evoked fast EPSPs were blocked by TTX, hexamethonium, and ICS-205-930 (tropisetron). 5-HT was applied either directly to the ganglion containing the neuron recorded intracellularly or to adjacent ganglia positioned at increasing distances on either side of the impaled cell in circumferential or longitudinal orientations. All S-type neurons recorded in this study ( n = 103) received nicotinic fast EPSPs from cholinergic neurons when 5-HT was applied directly to the ganglion containing the impaled neuron. Stimulation of adjacent ganglia also evoked nicotinic fast EPSPs, but the number of neurons that received this input decreased as the distance between the stimulus and the impaled cell increased. Maximal projections were 3 mm in the circumferential and orad-to-aborad orientations. There were no significant projections in the aborad-to-orad direction. These findings suggest that S-type neurons in the submucosal plexus are innervated by intrinsic cholinergic neurons that project over relatively short distances and have a distinct orad-to-aborad polarity.

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