Contraction mediated by Ca2+ influx in esophageal muscle and by Ca2+ release in the LES

1987 ◽  
Vol 253 (6) ◽  
pp. G760-G766 ◽  
Author(s):  
P. Biancani ◽  
C. Hillemeier ◽  
K. N. Bitar ◽  
G. M. Makhlouf
Keyword(s):  
Single Cells ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Enzymatic Digestion ◽  
The Body ◽  
Tissue Specimens ◽  
Resting Tone ◽  
Esophageal Contraction ◽  
Esophageal Muscle

Single cells and whole tissue specimens were used in this study to determine sources of Ca2+ utilized for contraction of the circular muscle layer of esophagus and lower esophageal sphincter (LES) of the cat. In vitro circular muscle specimens from the cat esophagus respond to electrical stimulation with phasic contractions at the end of the stimulus, whereas the LES spontaneously maintains tonic contraction and relaxes during stimulation. In Ca2+-free buffer, esophageal contractions rapidly decline and disappear within 10 min after the removal of Ca2+, while LES tone is only partially reduced. Similarly, incubation in a solution containing the Ca2+ influx blocker, La3+, abolishes esophageal contraction but only partially decreases LES tone. Conversely, strontium and caffeine substantially reduce LES tone without affecting the amplitude of esophageal contractions. In single muscle cells isolated by enzymatic digestion from the LES and the body of the esophagus, blockade of extracellular Ca2+ influx by methoxyverapamil (D 600) or ethyleneglycol-bis-(beta-aminoethylether) N,N'-tetraacetic acid abolished esophageal contraction in response to acetylcholine without affecting LES cells, and conversely, strontium abolished LES contraction without affecting esophageal cells. These data are consistent with the view that extracellular Ca2+ is required to initiate esophageal phasic contraction, while the LES has the ability to utilize intracellular Ca2+ to maintain resting tone and to contract in response to acetylcholine.

In vitro model of acute esophagitis in the cat

2005 ◽  
Vol 289 (5) ◽  
pp. G860-G869 ◽  
Author(s):  
Ling Cheng ◽  
Weibiao Cao ◽  
Claudio Fiocchi ◽  
Jose Behar ◽  
Piero Biancani ◽  
...  
Keyword(s):  
In Vitro Model ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Normal Mucosa ◽  
Esophageal Mucosa ◽  
Acute Esophagitis ◽  
Vitro Model ◽  
Esophageal Contraction

We have shown that IL-1β and IL-6, possibly originating from the mucosa in response to injury, inhibit neurally mediated contraction of esophageal circular muscle but do not affect ACh-induced contraction, reproducing the effect of experimental esophagitis on esophageal contraction. To examine the interaction of mucosa and circular muscle in inflammation, we examined the effect of HCl on in vitro esophageal mucosa and circular muscle. Circular muscle strips, when directly exposed to HCl, contracted normally. However, when circular muscle strips were exposed to supernatants of mucosa incubated in HCl (2–3 h, pH 5.8), contraction decreased, and the inhibition was partially reversed by an IL-6 antibody. Supernatants from the mucosa of animals with in vivo-induced acute esophagitis (AE) similarly reduced contraction. IL-6 levels were higher in mucosal tissue from AE animals than in control mucosa and in AE mucosa supernatants than in normal mucosa supernatants. IL-6 levels increased significantly in normal mucosa and supernatants in response to HCl, suggesting increased production and release of IL-6 by the mucosa. IL-6 increased H2O2 levels in the circular muscle layer but not in mucosa. Exposure of the mucosa to HCl caused IL-1β to increase only in the mucosa and not in the supernatant. These data suggest that HCl-induced damage occurs first in the mucosa, leading to the production of IL-1β and IL-6 but not H2O2. IL-1β appears to remain in the mucosa. In contrast, IL-6 is produced and released by the mucosa, eventually resulting in the production of H2O2 by the circular muscle, with this affecting circular muscle contraction.

HCl-induced inflammatory mediators in cat esophageal mucosa and inflammatory mediators in esophageal circular muscle in an in vitro model of esophagitis

2006 ◽  
Vol 290 (6) ◽  
pp. G1307-G1317 ◽  
Author(s):  
Ling Cheng ◽  
Weibiao Cao ◽  
Claudio Fiocchi ◽  
Jose Behar ◽  
Piero Biancani ◽  
...  
Keyword(s):  
Inflammatory Mediators ◽  
Platelet Activating Factor ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Normal Mucosa ◽  
Esophageal Mucosa ◽  
Mrna Levels ◽  
Physiol Gastrointest Liver ◽  
Krebs Buffer

Platelet-activating factor (PAF) and interleukin-6 (IL-6) are produced in the esophagus in response to HCl and affect ACh release, causing changes in esophageal motor function similar to esophagitis (Cheng L, Cao W, Fiocchi C, Behar J, Biancani P, and Harnett KM. Am J Physiol Gastrointest Liver Physiol 289: G418–G428, 2005). We therefore examined HCl-activated mechanisms for production of PAF and IL-6 in cat esophageal mucosa and circular muscle. A segment of normal mucosa was tied at both ends, forming a mucosal sac (Cheng L, Cao W, Fiocchi C, Behar J, Biancani P, and Harnett KM. Am J Physiol Gastrointest Liver Physiol 289: G860–G869, 2005) that was filled with acidic Krebs buffer (pH 5.8) or normal Krebs buffer (pH 7.0) as control and kept in oxygenated Krebs buffer for 3 h. The supernatant of the acidic sac (MS-HCl) abolished contraction of normal muscle strips in response to electric field stimulation. The inhibition was reversed by the PAF antagonist CV3988 and by IL-6 antibodies. PAF and IL-6 levels in MS-HCl and mucosa were significantly elevated over control. IL-6 levels in mucosa and supernatant were reduced by CV3988, suggesting that formation of IL-6 depends on PAF. PAF-receptor mRNA levels were not detected by RT-PCR in normal mucosa, but were significantly elevated after exposure to HCl, indicating that HCl causes production of PAF and expression of PAF receptors in esophageal mucosa and that PAF causes production of IL-6. PAF and IL-6, produced in the mucosa, are released to affect the circular muscle layer. In the circular muscle, PAF causes production of additional IL-6 that activates NADPH oxidase to induce production of H2O2. H2O2 causes formation of IL-1β that may induce production of PAF in the muscle, possibly closing a self-sustaining cycle of production of inflammatory mediators.

Circumferential, not longitudinal, colonic stretch increases synaptic input to mouse prevertebral ganglion neurons

2003 ◽  
Vol 285 (6) ◽  
pp. G1129-G1138 ◽  
Author(s):  
Steven M. Miller ◽  
J. H. Szurszewski
Keyword(s):  
Synaptic Input ◽  
Muscle Tension ◽  
Circular Muscle ◽  
Longitudinal Axis ◽  
Muscle Layer ◽  
Intraluminal Pressure ◽  
Colon Wall ◽  
Mesenteric Ganglion ◽  
Ganglion Neurons

The relationship between longitudinal and circular muscle tension in the mouse colon and mechanosensory excitatory synaptic input to neurons in the superior mesenteric ganglion (SMG) was investigated in vitro. Electrical activity was recorded intracellularly from SMG neurons, and muscle tension was simultaneously monitored in the longitudinal, circumferential, or both axes. Colonic intraluminal pressure and volume changes were also monitored simultaneously with muscle tension changes. The results showed that the frequency of fast excitatory postsynaptic potentials (fEPSPs) in SMG neurons increased when colonic muscle tension decreased, when the colon relaxed and refilled with fluid after contraction, and during receptive relaxation preceding spontaneous colonic contractions. In contrast, fEPSP frequency decreased when colonic muscle tension increased during spontaneous colonic contraction and emptying. Manual stretch of the colon wall to 10-15% beyond resting length in the circumferential axis of flat sheet preparations increased fEPSP frequency in SMG neurons, but stretch in the longitudinal axis to 15% beyond resting length in the same preparations did not. There was no increase in synaptic input when tubular colon segments were stretched in their long axes up to 20% beyond their resting length. The circumferential stretch-sensitive increase in the frequency of synaptic input to SMG neurons persisted when the colonic muscles were relaxed pharmacologically by nifedipine (2 μM) or nicardipine (3 μM). These results suggest that colonic mechanosensory afferent nerves projecting to the SMG function as length or stretch detectors in parallel to the circular muscle layer.

Correlation between electrical and morphological properties of canine pyloric circular muscle

1991 ◽  
Vol 260 (3) ◽  
pp. G390-G398 ◽  
Author(s):  
F. Vogalis ◽  
S. M. Ward ◽  
K. M. Sanders
Keyword(s):  
Single Cells ◽  
Electrical Coupling ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Morphological Properties ◽  
Morphological Examination ◽  
Isolated Cells ◽  
Time Constants ◽  
Morphological Studies ◽  
Cable Properties

Electrical slow waves decay in amplitude as they conduct from the myenteric to the submucosal regions of the circular muscle layer in the canine pyloric sphincter. We used the partitioned chamber method to study the passive and active properties of pyloric muscles, and we found that length constants of circular muscles of myenteric region were significantly longer than muscles near the submucosal surface. These data suggested differences in either membrane resistance, junctional resistance, or cytoplasmic resistance. The first parameter was evaluated by measuring time constants in intact tissues and single cells isolated from the submucosal and myenteric regions. Membrane time constants were not different in the two regions, nor were differences found in the input resistances of isolated cells. Morphological studies failed to demonstrate differences in cell diameters in the two regions suggesting that cytoplasmic resistances are similar. These findings suggest that the different cable properties in the two regions may be due to differences in electrical coupling. Morphological examination revealed similar numbers of gap junctions between cells in the two regions, but large differences were noted in the size of muscular bundles. Muscles of the myenteric region were arranged into large, tightly packed bundles, whereas muscles of the submucosal region consisted of small bundles with an extensive extracellular space filled with connective tissue. We suggest that the difference in cable properties may be due to differences in electrical coupling between bundles. These data suggest that submucosal muscles function more like a multiunit smooth muscle, whereas myenteric muscles behave as a single unit.

Origin of Motion in the Human Ureter: Mechanics, Energetics and Kinetics of the Myosin Molecular Motors

2012 ◽  
Vol 79 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Romina Vargiu ◽  
Anna Perinu ◽  
Antonello De Lisa ◽  
Frank Tintrup ◽  
Francesco Manca ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Molecular Motors ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Shortening Velocity ◽  
Smooth Muscle Layer ◽  
Circular Smooth Muscle ◽  
Longitudinal Smooth Muscle ◽  
Human Ureter

Background Ureteral peristalsis is the result of coordinated mechanical motor performance of longitudinal and circular smooth muscle layer of the ureter wall. The main aim of this study was to characterize in smooth muscle of proximal segments of human ureter, the mechanical properties at level of muscle tissue and at level of myosin molecular motors. Methods Ureteral samples were collected from 15 patients, who underwent nephrectomy for renal cancer. Smooth muscle strips longitudinally and circularly oriented from proximal segments of human ureter were used for the in vitro experiments. Mechanical indices including the maximum unloaded shortening velocity (Vmax), and the maximum isometric tension (P0) normalized per cross-sectional area, were determined in vitro determined in electrically evoked contractions of longitudinal and circular smooth muscle strips. Myosin cross-bridge (CB) number per mm2 (Ψ) the elementary force per single CB (Ψ) and kinetic parameters were calculated in muscle strips, using Huxley's equations adapted to nonsarcomeric muscles. Results Longitudinal smooth muscle strips exhibited a significantly (p<0.05) faster Vmax (63%) and a higher P0 (40%), if compared to circular strips. Moreover, longitudinal muscle strips showed a significantly higher unitary force (Ψ) per CB. However, no significant differences were observed in CB number, the attachment (f1) and the detachment (g2) rate constants between longitudinal and circular muscle strips. Conclusions The main result obtained in the present work documents that the mechanical, energetic and unitary forces per CB of longitudinal layer of proximal ureter are better compared to the circular one; these preliminary findings suggested, unlike intestinal smooth muscle, a major role of longitudinal smooth muscle layer in the ureter peristalsis.

scholarly journals Clinical impact of peroral endoscopic myotomy for esophageal motility disorders on esophageal muscle layer thickness

2019 ◽  
Vol 07 (04) ◽  
pp. E525-E532
Author(s):  
Daisuke Watanabe ◽  
Shinwa Tanaka ◽  
Fumiaki Kawara ◽  
Hirohumi Abe ◽  
Ryusuke Ariyoshi ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Esophageal Motility ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Peroral Endoscopic Myotomy ◽  
Esophageal Motility Disorders ◽  
Pathological Features ◽  
Motility Disorders ◽  
Endoscopic Myotomy ◽  
Esophageal Muscle

Abstract Background and study aims Previously, we reported that esophageal muscle layer thickness was associated with technical complexity of peroral endoscopic myotomy (POEM). However, there are no data regarding the mid-term effects of POEM procedures on esophageal muscle layer thickness. Therefore, we conducted this study to elucidate mid-term effects of POEM procedures, and to examine whether postoperative changes in esophageal muscle layer thickness were related to particular clinico-pathological features in patients with esophageal motility disorders. Patients and methods Seventy-four consecutive patients with esophageal motility disorders who underwent POEM at Kobe University Hospital from April 2015 to December 2016 were prospectively recruited into this study. First, we investigated the esophageal muscle layer thickness values obtained at 1 year after POEM. Second, we evaluated the effects of a reduction in muscle layer thickness on various clinico-pathological features. Results At 1 year after POEM, mean thickness of the inner circular muscle at 0 cm, 5 cm, and 10 cm from the esophagogastric junction was 1.06 ± 0.45 mm, 0.99 ± 0.36 mm, and 0.97 ± 0.44 mm, respectively. Among all sites, muscle layer thickness had significantly decreased after POEM. However, univariate logistic regression analysis demonstrated that no clinical factors were associated with esophageal muscle layer thickness after POEM procedure. Conclusions We demonstrated for the first time that thickness of the esophageal muscle layer was significantly decreased after POEM. This result reveals that changes in esophageal muscle layer thickness caused by esophageal motility disorders are reversible.

Longitudinal contractions in the duodenum: their fluid-mechanical function

1975 ◽  
Vol 228 (6) ◽  
pp. 1887-1892 ◽  
Author(s):  
J Melville ◽  
E Macagno ◽  
J Christensen
Keyword(s):  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Slow Waves ◽  
Longitudinal Muscle Layer ◽  
Circular Muscle Layer ◽  
Model Flow ◽  
Displacement Wave ◽  
Marked Points

The hypothesis examined was that contractions of the longitudinal muscle layer occurin the duodenum which are independent of those of the circular muscle layer and that they induce flow of duodenal contents. A segment of opossum duodenum isolated in vitro was marked and photographed during periods of longitudinal muscle contraction, when the circular muscle layer appeared inactive. The prequency of longitudinal oscillation of the marked points was 20.5 cycles/min. The longitudinal displacement wave spread caudad with an average velocity of 3.27 cm/s. Frequency and velocity of electrical slow waves were determined in similiar duodenal segments. Slow-wave frquencywas 18.9 cycles/min. In a two-dimensional mechanical model, flow induced by simulatedlongitudinal muscle layer appear to be driven by the electrical slow waves of the duodenum. They are capable of inducing a pattern of flow in which ocntents flow betweenthe core and the periphery of the intestinal conduit.

Enteric locus of action of prokinetics: ABT-229, motilin, and erythromycin

2000 ◽  
Vol 278 (5) ◽  
pp. G744-G752 ◽  
Author(s):  
Sushil K. Sarna ◽  
Asensio Gonzalez ◽  
Robert P. Ryan
Keyword(s):  
Single Cells ◽  
Circular Muscle ◽  
Electrical Field Stimulation ◽  
Conscious State ◽  
Presynaptic Neuron ◽  
Electrical Field ◽  
Neuroeffector Junction ◽  
Presynaptic Neurons

We investigated the in vivo and in vitro locus of actions of prokinetics: motilin, erythromycin, and ABT-229. The test substances were infused close intra-arterially in short segments of the jejunum in the intact conscious state. Each prokinetic acted on a presynaptic neuron and utilized at least one nicotinic synapse to stimulate circular muscle contractions. The final neurotransmitter at the neuroeffector junction was ACh. Motilin and erythromycin, but not ABT-229, also released nitric oxide. Each prokinetic utilized somewhat different subtypes of muscarinic, serotonergic, tachykininergic, and histaminergic receptors, except for the M3 receptor, which was common to all of them. In contrast, none of the prokinetics stimulated contractions in mucosa-free or mucosa-attached muscle strips, or rings, even though methacholine or electrical field stimulation induced phasic contractions in all of them. The prokinetics also did not release ACh in longitudinal muscle-myenteric plexus preparations. Each prokinetic, however, decreased the length of enzymatically dispersed single cells. In conclusion, each prokinetic may act on a different subset of presynaptic neurons that converge on the postsynaptic cholinergic and nonadrenergic noncholinergic motoneurons. The presynaptic neurons may be impaired in the muscle bath environment.

Pylorectomy reduces the satiety action of cholecystokinin

1988 ◽  
Vol 255 (6) ◽  
pp. R1059-R1063 ◽  
Author(s):  
T. H. Moran ◽  
L. Shnayder ◽  
A. M. Hostetler ◽  
P. R. McHugh
Keyword(s):  
Binding Sites ◽  
Contractile Response ◽  
Behavioral Responses ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Pyloric Sphincter ◽  
Cck Receptors ◽  
Physiological Assessment ◽  
Significant Attenuation

Rat gastric cholecystokinin (CCK) receptors are localized to the circular muscle layer of the pyloric sphincter, and a role for these receptors in the mediation of CCK satiety has been proposed. To directly assess the contribution of this receptor population in CCK satiety, the area of the pyloric sphincter containing these receptors was surgically removed, and the behavioral responses to CCK were compared pre- and postpylorectomy. The presence of CCK receptors in the gastroduodenal junction was assessed by either in vitro CCK receptor autoradiography or in vitro contractile response to CCK. The results depended on the time after pylorectomy during which testing occurred. Two to 3 wk after pylorectomy rats demonstrated a significant attenuation of CCK satiety such that while the response to 1 and 2 micrograms/kg was intact, any additional inhibition by 4 and 8 micrograms/kg was eliminated. At this time, no evidence of CCK receptors around the gastroduodenal junction was found. In contrast, 2-3 mo after pylorectomy, the normal dose-response inhibition to CCK was intact. Evidence for the presence of CCK binding sites at the gastroduodenal junction was found by both autoradiography and physiological assessment. These results indicate a role for pyloric CCK receptors in the mediation of CCK satiety.

The Hydraulic System of Urechis Caupo Fisher & Macginitie

1968 ◽  
Vol 49 (3) ◽  
pp. 657-667
Author(s):  
G. CHAPMAN
Keyword(s):  
Hydraulic System ◽  
Body Wall ◽  
High Pressures ◽  
Circular Muscle ◽  
Muscle Layer ◽  
The Body ◽  
Muscle System ◽  
Urechis Caupo ◽  
Hind Gut ◽  
Whole Muscle

1. The hydrostatic pressures recorded in the coelom of Urechis during peristalsis, irrigation, burrowing and hind-gut ventilation have been recorded continuously. The main muscular activities except burrowing take place at pressures of a few centimetres of water and, it is suggested, are mainly carried out by the outer circular muscle layer. The high pressures involved in burrowing demand the recruitment of the whole muscle system. 2. The hind-gut ventilation stops when internal pressure is raised, although changes in the contained volume of the body wall do not appear to provide information leading to the maintenance of a fixed volume. Instead this control is probably excercised by the hind gut. 3. An attempt is made to calculate the energy requirements of irrigation and ventilation and it is shown that these are small compared with the respiratory rate, indicating that the movement of large volumes of water for feeding purposes is not an extravagant way of obtaining food in terms of energy expenditure.

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