Some Physiological Characteristics of the Esophagogastric Junction in the Opossum

Christensen, James; Freeman, Barry W.; Miller, J. Karen

doi:10.1016/s0016-5085(73)80066-6

Cited by 79 publications

(20 citation statements)

References 7 publications

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“…These studies demonstrated that LES muscle generates tone at rest and activation of its intrinsic innervation causes LES relaxation (6,7). Resting LES tone was felt to be myogenic, i.e., a property of LES muscle, since tetrodotoxin, a neurotoxin that blocks Na ϩ channels, did not abolish it (8,31).…”

Section: Discussionmentioning

confidence: 99%

Effect of electrical stimulation of the LES on LES pressure in a canine model

Sanmiguel¹,

Hagiike²,

Mintchev³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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Gastric electrical stimulation modulates lower esophageal sphincter pressure (LESP). High-frequency neural stimulation (NES) can induce gut smooth muscle contractions. To determine whether lower esophageal sphincter (LES) electrical stimulation (ES) can affect LESP, bipolar electrodes were implanted in the LES of four dogs. Esophageal manometry during sham or ES was performed randomly on separate days. Four stimuli were used: 1) low-frequency: 350-ms pulses at 6 cycles/min; 2) high-frequency-1: 1-ms pulses at 50 Hz; 3) high-frequency-2: 1-ms pulses at 20 Hz; and 4) NES: 20-ms bipolar pulses at 50 Hz. Recordings were obtained postprandially. Tests consisted of three 20-min periods: baseline, stimulation/sham, and poststimulation. The effect of NES was tested under anesthesia and following IV administration of l-NAME and atropine. Area under the curve (AUC) and LESP were compared among the three periods, by ANOVA and t-test, P < 0.05. Data are shown as means +/- SD. We found that low-frequency stimulation caused a sustained increase in LESP: 32.1 +/- 12.9 (prestimulation) vs. 43.2 +/- 18.0 (stimulation) vs. 50.1 +/- 23.8 (poststimulation), P < 0.05. AUC significantly increased during and after stimulation. There were no significant changes with other types of ES. With NES, LESP initially rose and then decreased below baseline (LES relaxation). During NES, N(G)-nitro-l-arginine methyl ester increased both resting LESP and the initial rise in LESP and markedly diminished the relaxation. Atropine lowered resting LESP and abolished the initial rise in LESP. In conclusion, low frequency ES of the LES increases LESP in conscious dogs. NES has dual effect on LESP: an initial stimulation, cholinergically mediated, followed by relaxation mediated by nitric oxide.

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Section: Discussionmentioning

confidence: 99%

Effect of electrical stimulation of the LES on LES pressure in a canine model

Sanmiguel¹,

Hagiike²,

Mintchev³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…The nervous system and the contractile muscle behavior of the esophagus have been studied extensively [10,15] but the mechanics of the esophagus tissues is lagging far behind. The stress-strain-velocity history of the tissues of the esophagus is unknown.…”

Section: Discussionmentioning

confidence: 99%

A two-layered mechanical model of the rat esophagus. Experiment and theory

2004

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Background: The function of esophagus is to move food by peristaltic motion which is the result of the interaction of the tissue forces in the esophageal wall and the hydrodynamic forces in the food bolus. The structure of the esophagus is layered. In this paper, the esophagus is treated as a two-layered structure consisting of an inner collagen-rich submucosa layer and an outer muscle layer. We developed a model and experimental setup for determination of elastic moduli in the two layers in circumferential direction and related the measured elastic modulus of the intact esophagus to the elastic modulus computed from the elastic moduli of the two layers.

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“…The peristaltic transport of swallowed material is a neuromuscular function affected by a number of factors. The active neuromuscular system of the gastrointestinal (GI) tract has been studied extensively (1,2) but the study of the structuremechanics relationship in GI tissues is lagging far behind. Despite the scarcity of data, it is generally believed that the collagen matrix in the submucosa layer is an important structural determinant of the mechanical properties in the esophagus and intestine due to the high collagen content in the submucosa (3).…”

mentioning

confidence: 99%

The Effect of Digestion of Collagen and Elastin on Histomorphometry and the Zero-Stress State in Rat Esophagus

et al. 2005

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To understand the physiology and pathology of the esophagus, it is necessary to know the mechanical properties and their dependence on the structural components. The aim of this study was to investigate the effect of collagenase and elastase on the morphological and biomechanical properties in the no-load and zero-stress states in the rat esophagus. Twenty tissue rings from each esophagus of seven normal rats were sectioned in an organ bath containing calcium-free Krebs solution with dextran and EGTA. After the rings were photographed in the no-load state, 8 of the 20 rings were separated into mucosa-submucosa and muscle rings and the rings were transferred to four different solutions containing collagenase, elastase, or corresponding control solutions. The rings were cut radially to obtain the zero-stress state and photographed again. The thickness, area, and opening angle were measured from the digitized images. The collagen and elastin area fractions were determined from histological slides with Van Gieson and Weigert's elastic stain. The opening angles and residual strain did not differ in the nonseparated enzyme-treated rings and control rings. However, in the separated mucosa-submucosa ring the opening angle was significantly smaller after treatment than that in control rings (P < 0.01). Collagenase and elastase reduced collagen and elastin in the mucosa-submucosa layer about 40% in the nonseparated wall and 54% in the separated mucosa-submucosa layer (P < 0.01). Collagenase and elastase increased the thickness in the separated mucosa-submucosa layer compared to the control (P < 0.05). Disconnection between the epithelia and the lamina propria was histologically observed after elastase digestion. In conclusion, collagenase and elastase caused the opening angle and the residual strain in the separated mucosa-submucosa layer to decrease. The opening angle of the separated mucosa-submucosa layer depended to some extent on the fraction of collagen and elastin.

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Some Physiological Characteristics of the Esophagogastric Junction in the Opossum

Cited by 79 publications

References 7 publications

Effect of electrical stimulation of the LES on LES pressure in a canine model

Effect of electrical stimulation of the LES on LES pressure in a canine model

A two-layered mechanical model of the rat esophagus. Experiment and theory

The Effect of Digestion of Collagen and Elastin on Histomorphometry and the Zero-Stress State in Rat Esophagus

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