scholarly journals Motoneurones of the submucous plexus regulate electrical activity of the circular muscle of canine proximal colon.

1986 ◽  
Vol 380 (1) ◽  
pp. 293-310 ◽  
Author(s):  
K M Sanders ◽  
T K Smith
Keyword(s):  
Electrical Activity ◽  
Circular Muscle ◽  
Proximal Colon ◽  
Submucous Plexus

Electrical pacemakers of canine proximal colon are functionally innervated by inhibitory motor neurons

1989 ◽  
Vol 256 (3) ◽  
pp. C466-C477 ◽  
Author(s):  
T. K. Smith ◽  
J. B. Reed ◽  
K. M. Sanders
Keyword(s):  
Electrical Activity ◽  
Motor Neurons ◽  
Circular Muscle ◽  
Proximal Colon ◽  
Nerve Fibers ◽  
Pacemaker Activity ◽  
Intracellular Recordings ◽  
Potential Oscillations ◽  
Circular Layer ◽  
Different Populations

Pacemaker activity in the canine proximal colon occurs at the submucosal and myenteric borders of the circular layer [Am. J. Physiol. 252 (Cell Physiol. 21): C215-C224 and C290-C299, 1987]. The present study investigated the neural regulation of rhythmic electrical activity. Spontaneous inhibitory junction potentials (IJPs) were observed in intracellular recordings from circular muscle cells near the myenteric border. The amplitudes of these events decayed with distance through the circular layer. Stimulation at the myenteric plexus surface evoked IJPs that mimicked the spontaneous events. Stimulation at the submucosal surface evoked IJPs in adjacent cells that were of shorter duration and of different waveform than myenteric IJPs. Amplitudes of IJPs evoked by stimulation near either surface decayed with distance from the site of stimulation. The decay functions for IJPs were essentially identical to the decay of spontaneous slow waves or myenteric potential oscillations. Spontaneous and evoked IJPs affected the amplitudes, durations, and patterns of ongoing rhythmic electrical activity. The data suggest that myenteric and submucosal pacemaker populations may be innervated by different populations of inhibitory nerve fibers. Innervation appears to be heterogeneous with dense populations of inhibitory nerve fibers predominantly located in the pacemaker regions. Neural regulations of pacemaker activity influences rhythmic electrical activity throughout the muscularis.

Interstitial cells of Cajal and electrical activity in ganglionic and aganglionic colons of mice

2002 ◽  
Vol 283 (2) ◽  
pp. G445-G456 ◽  
Author(s):  
Sean M. Ward ◽  
Michael D. Gershon ◽  
Kathleen Keef ◽  
Yulia R. Bayguinov ◽  
Cheryl Nelson ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Interstitial Cells Of Cajal ◽  
Circular Muscle ◽  
Interstitial Cells ◽  
Proximal Colon ◽  
Neural Responses ◽  
Wild Type ◽  
Circular Layer ◽  
Excitatory Junction Potentials ◽  
Cells Of Cajal

An antibody directed against Kit protein was used to investigate the distribution of interstitial cells of Cajal (ICC) within the murine colon. The ICC density was greatest in the proximal colon and decreased along its length. The distribution of the different classes of ICC in the aganglionic colons of lethal spotted ( ls/ls) mice was found to be similar in age-matched wild-type controls. There were marked differences in the electrical activities of the colons from ls/ls mutants compared with wild-type controls. In ls/ls aganglionic colons, the circular muscle was electrically quiescent compared with the spontaneous spiking electrical activity of wild-type tissues. In ls/ls aganglionic colons, postjunctional neural responses were greatly affected. Inhibitory junction potentials were absent or excitatory junction potentials inhibited by atropine were observed. In conclusion, the distribution of ICC in the ganglionic and aganglionic regions of the colons from ls/ls mutants appeared similar to that of wild-type controls. The electrical activity and neural responses of the circular layer are significantly different in aganglionic segments of ls/ls mutants.

Colonic Electrical Activity: Concerto for Two Pacemakers

Physiology ◽  
1989 ◽  
Vol 4 (5) ◽  
pp. 176-181
Author(s):  
KM Sanders
Keyword(s):  
Electrical Activity ◽  
Circular Muscle ◽  
Proximal Colon ◽  
Slow Waves ◽  
Potential Oscillations ◽  
Contraction Coupling

In the proximal colon, two discrete pacemaker populations exist: one group of cells generates the 6-cycle/min rhythm known as slow waves;other cells generate a 17-cycle/min rhythm termed myenteric potential oscillations. Summation of these events in the circular muscle provides the signal for escitation-contraction coupling. This article describes the origin and integration of pacemaker activities in the colon.

scholarly journals Intracellular electrical activity in circular muscle of canine colon.

Gut ◽  
1984 ◽  
Vol 25 (11) ◽  
pp. 1268-1270 ◽  
Author(s):  
M M Chambers ◽  
Y J Kingma ◽  
K L Bowes
Keyword(s):  
Electrical Activity ◽  
Circular Muscle

GASTROINTESTINAL HYPOMOTILITY IN MAGNESIUM-DEFICIENT SHEEP

1980 ◽  
Vol 60 (2) ◽  
pp. 293-301 ◽  
Author(s):  
L. BUENO ◽  
J. FIORAMONTI ◽  
E. GEUX ◽  
Y. RAISSIGUIER
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Electrical Activity ◽  
Digestive Tract ◽  
Experimental Period ◽  
Proximal Colon ◽  
Slow Waves ◽  
Deficient Diet ◽  
Intravenous Infusions ◽  
Spiking Activity

The electrical activity of the gastrointestinal tract and gallbladder was recorded in four sheep fed a Mg-deficient diet during 10 to 15 days. The mitigating effect of intravenous infusions of MgCl2 was tested at the end of the experimental period in animals presenting hypomagnesemia. Motility of the reticulo-rumen remained unchanged in Mg-deficient sheep except that there was no postprandial increased frequency of contractions. By contrast, the contractions of gallbladder, cecum and proximal colon were reduced in both amplitude and frequency. The amplitude but not the frequency of the antro-duodenal slow-waves was reduced. The amplitude of the regular spiking activity of the small intestine was reduced as well as the number of complexes produced per day. The activity of the spiral colon was correlated to the blood magnesium concentrations but Mg infusion was unable to restore immediately the motor profile of the rest of the gut to its intitial level. This was done within 2–3 days by changes in the diet in three of the four animals. It is concluded that the motility of the whole digestive tract, including the reticulo-rumen, is modified on a Mg-deficient diet and that hypomagnesemia, involved in the atony of the spiral colon, is only one of the factors responsible for the hypomotility.

Pacemaker activity in septal structures of canine colonic circular muscle

1990 ◽  
Vol 259 (2) ◽  
pp. G264-G273 ◽  
Author(s):  
S. M. Ward ◽  
K. M. Sanders
Keyword(s):  
Slow Wave ◽  
Electrical Coupling ◽  
Circular Muscle ◽  
Proximal Colon ◽  
Slow Waves ◽  
Pacemaker Activity ◽  
Electrical Measurements ◽  
Morphological Studies ◽  
Circular Layer ◽  
And Function

Morphological and electrophysiological experiments were performed to characterize the pacemaker areas of the circular muscle in the canine proximal colon. Morphological studies showed interstitial cells of Cajal lining the submucosal surface of the circular layer and the septal structures that separate the circular layer into bundles. Electrical measurements suggested that slow waves may propagate into the thickness of the circular muscle in a regenerative manner along the surface of these septa. Removal of the submucosal pacemaker region blocked generation of slow waves in nonseptal regions of the circular muscle, but slow-wave activity continued in the circular muscle near septa. These data suggest that slow-wave pacemaker activity is not limited to a two-dimensional surface at the submucosal surface but extends into the interior of the circular layer along septal invaginations. Experiments were also performed to determine the dominance of pacemaker activity (i.e., septal vs. submucosal), and examples were found in which both areas appeared to initiate slow waves in intact muscles. Other studies showed that slow waves could propagate across septa, suggesting some form of electrical coupling between circular muscle bundles. This study provides a more complete view of the structure and function of pacemaker areas in the canine proximal colon.

Patterns of electrical activity and neural responses in canine proximal duodenum

1992 ◽  
Vol 263 (6) ◽  
pp. G887-G894 ◽  
Author(s):  
O. Bayguinov ◽  
F. Vogalis ◽  
B. Morris ◽  
K. M. Sanders
Keyword(s):  
Electrical Activity ◽  
Circular Muscle ◽  
Sphincter Of Oddi ◽  
Electrical Field Stimulation ◽  
Muscle Cells ◽  
Proximal Region ◽  
Inhibitory Neurotransmitter ◽  
Proximal Duodenum ◽  
Circular Layer ◽  
Excitatory Junction Potentials

The patterns of electrical activity and neural inputs to the proximal duodenum between the pyloric sphincter and the sphincter of Oddi were studied in muscles of the dog. Smooth muscle cells in the most proximal region were electrically quiescent, but slow waves were recorded in all regions distal to the first few millimeters. Electrical activity was recorded from circular muscle cells near the myenteric and submucosal surfaces of the circular layer, and slow wave activity was similar in both regions. The nature of neural inputs was also characterized. With electrical field stimulation, responses in cells near the submucosal surface were predominantly excitatory junction potentials (EJPs); near the myenteric border responses were either inhibitory junction potentials (IJPs) or biphasic responses (i.e., small EJPs followed by IJPs). EJPs were blocked by atropine. IJPs were nonadrenergic and noncholinergic (NANC), and several experiments suggested that nitric oxide (NO), or a NO-releasing compound, serves as the inhibitory neurotransmitter in this region. Exogenous NO caused hyperpolarization of membrane potential. IJPs and the hyperpolarization response to NO were sensitive to apamin. These data describe the myogenic mechanisms and neurogenic apparatus that appear to regulate motility in the most proximal region of the duodenum.

Electrical and mechanical interactions between the muscle layers of canine proximal colon

1990 ◽  
Vol 258 (3) ◽  
pp. G484-G491 ◽  
Author(s):  
P. J. Sabourin ◽  
Y. J. Kingma ◽  
K. L. Bowes
Keyword(s):  
Membrane Potential ◽  
Circular Muscle ◽  
Longitudinal Direction ◽  
Proximal Colon ◽  
Slow Waves ◽  
The Other ◽  
Potential Oscillations ◽  
Circular Layer ◽  
Longitudinal Layer ◽  
Membrane Potential Oscillations

Electrical and mechanical interactions between the two smooth muscle layers of canine colon have been studied using a dual sucrose gap apparatus. Muscle samples were dissected into an L-shape, with one leg cut in the circular direction and the other cut in the longitudinal direction. Longitudinal muscle was removed from the circular leg and circular muscle was removed from the longitudinal leg. The bend of the L contained both layers. The activity of the two layers was studied simultaneously under basal conditions, after stimulation by neostigmine and carbachol, and in the presence of tetrodotoxin. Interactions were more common after stimulation and were marked by modification of one layer's mechanical and electrical activity during increased activity in the other layer. Two patterns were commonly observed. First, during a burst of membrane potential oscillations and spike potentials in the longitudinal layer, slow waves in the circular layer developed spike potentials and some slow waves were also prolonged. Second, during a slow-wave cycle in the circular layer, the amplitude of membrane potential oscillations in the longitudinal layer was increased with an associated increase in the incidence of spike potentials. These interactions were associated with contractions of increased strength, which were similar in both layers. All interactions continued after nerve-conduction blockade by tetrodotoxin.

Nitrergic Prejunctional Inhibition of Purinergic Neuromuscular Transmission in the Hamster Proximal Colon

2003 ◽  
Vol 89 (5) ◽  
pp. 2346-2353 ◽  
Author(s):  
Hayato Matsuyama ◽  
AbuBakr El-Mahmoudy ◽  
Yasutake Shimizu ◽  
Tadashi Takewaki
Keyword(s):  
Nitric Oxide ◽  
Nerve Stimulation ◽  
Smooth Muscles ◽  
Circular Muscle ◽  
Single Pulse ◽  
Proximal Colon ◽  
Paired Stimulus ◽  
Physiological Control ◽  
Purinergic Transmission ◽  
Intramural Nerve

Neurogenic ATP and nitric oxide (NO) may play important roles in the physiological control of gastrointestinal motility. However, the interplay between purinergic and nitrergic neurons in mediating the inhibitory neurotransmission remains uncertain. This study investigated whether neurogenic NO modulates the purinergic transmission to circular smooth muscles of the hamster proximal colon. Electrical activity was recorded from circular muscle cells of the hamster proximal colon by using the microelectrode technique. Intramural nerve stimulation with a single pulse evoked a fast purinergic inhibitory junction potential (IJP) followed by a slow nitrergic IJP. The purinergic component of the second IJP evoked by paired stimulus pulses at pulse intervals between 1 and 3 s became smaller than that of the first IJP. This purinergic IJP depression could be observed at pulse intervals <3 s, but not at longer ones, and failed to occur in the presence of NO synthase inhibitor. Exogenous NO (0.3–1 μM), at which no hyperpolarization is produced, inhibited purinergic IJPs, without altering the nitrergic IJP and exogenously applied ATP-induced hyperpolarization. In the presence of both purinoceptor antagonist and nitric oxide synthase (NOS) inhibitor, intramural nerve stimulation with 5 pulses at 20 Hz evoked vasoactive intestinal peptide (VIP)-associated IJPs, suggesting that VIP component may be masked in the IJPs of the hamster proximal colon. Our results suggest that neurogenic NO may modulate the purinergic transmission to circular smooth muscles of the hamster proximal colon via a prejunctional mechanism. In addition, VIP may be involved in the neurotransmitter in the hamster proximal colon.

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