Electrical stimulation of isolated guinea pig ileum.

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.

Download Full-text

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

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2000.278.2.g273 ◽

2000 ◽

Vol 278 (2) ◽

pp. G273-G280 ◽

Cited By ~ 16

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.

Download Full-text

Putative mechanisms involved in excitatory and inhibitory effects of somatostatin on intestinal motility

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.257.4.g532 ◽

1989 ◽

Vol 257 (4) ◽

pp. G532-G538 ◽

Cited By ~ 7

Author(s):

T. Takeda ◽

K. Taniyama ◽

S. Baba ◽

C. Tanaka

Keyword(s):

Electrical Stimulation ◽

Longitudinal Muscle ◽

Cholinergic Neuron ◽

Gamma Aminobutyric Acid ◽

Inhibitory Effects ◽

Guinea Pig Ileum ◽

Excitatory Effect ◽

Ergic Neuron ◽

Gabaa Antagonist ◽

Stimulation Of

The mechanism of action of somatostatin on the motility of intestine was examined in the entire preparation and the longitudinal muscle attached with Auerbach's plexus (LA) preparation of guinea pig ileum, in relation to the cholinergic neuron and gamma-aminobutyric acid (GABA)ergic neuron. Somatostatin produced a transient potentiation of electrical stimulation-induced twitch contractions followed by an inhibition. The excitatory effect of somatostatin was associated with an increase in the release of [3H]acetylcholine (ACh) from the preparations preloaded with [3H]choline. Bicuculline, a GABAA antagonist, inhibited the somatostatin-induced excitatory effect. Somatostatin inhibited the electrical stimulation-induced twitch contraction and release of [3H]ACh, and the inhibition was greater in the entire preparation than in the LA. Phaclofen, a GABAB antagonist, prevented the inhibitory effects of somatostatin. Somatostatin induced a Ca2+ -dependent, tetrodotoxin-sensitive release of [3H]GABA from the preparations preloaded with [3H]GABA. Therefore somatostatin exerts excitatory and inhibitory effects on the cholinergic neuron due to the stimulation of the GABAergic neuron, and the motility of the intestine is regulated.

Download Full-text

Effects of neurotransmitter release on mucosal transport in guinea pig ileum

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1983.245.6.g745 ◽

1983 ◽

Vol 245 (6) ◽

pp. G745-G750 ◽

Cited By ~ 3

Author(s):

H. J. Cooke ◽

K. Shonnard ◽

G. Highison ◽

J. D. Wood

Keyword(s):

Electrical Stimulation ◽

Guinea Pig ◽

Neurotransmitter Release ◽

Short Circuit ◽

Short Circuit Current ◽

Scorpion Venom ◽

Enteric Neurons ◽

Sodium Absorption ◽

Guinea Pig Ileum ◽

Ileal Mucosa

Scorpion venom (Leiurus quinquestriatus), a substance that evokes neurotransmitter release by depolarizing neurons, was used to activate enteric neurons in short-circuited guinea pig ileum. Scorpion venom increased transmural potential difference and short-circuit current, and this response was similar to the increase that occurred after electrical stimulation of enteric neurons. The stimulus- or venom-evoked response in short-circuit current was abolished by tetrodotoxin. Atropine reduced by 47% the increments in short-circuit current produced by either electrical stimulation or venom. Scorpion venom increased active chloride secretion in short-circuited guinea pig ileal mucosa but had no significant effect on active sodium absorption, residual flux, or total tissue conductance. No morphological changes in transmission electron micrographs of ileal mucosa treated with scorpion venom were evident compared with controls. Alanine caused an increase in short-circuit current in venom-treated tissue that was similar to control values. These results show that scorpion venom mimics the mucosal effects of electrical activation of enteric neurons. These results suggest that a significant component of both scorpion venom action and the response to electrical field stimulation is mediated by neural release of acetylcholine, which activates epithelial muscarinic receptors.

Download Full-text