Characteristics of spontaneous and evoked motility in the isolated perfused porcine duodenum

Gregersen, Hans; Jørgensen, Claus; Dall, F.H.; Jensen, S. L.

doi:10.1152/jappl.1992.73.1.9

Cited by 21 publications

(17 citation statements)

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“…Furthermore, the pharmacological data showed that spontaneous and secondary motility was neurogenic and mediated via muscarinic receptors. The pharmacological data are consistent with previous findings in the porcine duodenum [22]. Since TTX did not further enhance motility, no neurogenic tonic inhibition of smooth muscle in the investigated segments was present.…”

Section: Discussionsupporting

confidence: 91%

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

2007

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Partial obstruction of the small intestine results in dysmotility and morphometric changes proximal to the site of obstruction. However, our understanding of the relation between the morphometric remodeling and change in the motility pattern during chronic obstruction is sparse. The aim of this study was to investigate the effect of partial chronic intestinal obstruction on motility, morphology, and collagen content proximal and distal to the site of obstruction. Twenty guinea-pigs with partial intestinal obstruction and eight sham-operated controls lived for four weeks. Spontaneous and bolus-induced motility was recorded in isolated intestinal segments proximal and distal to the site of obstruction using a perfused low-compliance pressure-measuring system in vitro. After the motility experiments, the specimens were fixed at 2 kPa luminal distension pressure and sampled for histomorphometric determination of luminal radius, layer thickness, and wall thickness. Total wall collagen was also determined. The area under the curve (AUC) of spontaneous contractions and the amplitude, frequency, and AUC for the bolus-induced motility were higher in the proximal segments of the banded animals compared to distal segments and to the intestinal segments in the control animals (P < 0.05). The radius-to-thickness ratio was lowest in the proximal segments of the obstructed animals (P < 0.01). The collagen content was three times higher proximal to the site of obstruction when compared to distal locations and to the controls (P < 0.01). The AUC at 2 ml bolus injections plotted against the radius-to-thickness ratio showed a strong association (r = 0.97 for control, and r = 0.99 for obstruction, P < 0.01). No correlation was found between the collagen content and AUC. In conclusion, partial intestinal obstruction in guinea pigs caused pronounced changes in morphology and motility. An association was found between the radius-to-thickness ratio and bolus-induced motility.

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Section: Discussionsupporting

confidence: 91%

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

2007

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“…The reduced afferent firing found in the present study in the obstructed segments may relate to the abovementioned changes. The change in nerve and ganglia morphology and function will also have an impact on smooth muscle contractile activity due to intrinsic stretch sensitive neural reflexes (18). During distension we and others found increased muscle force and hyposensitivity to stretch (36).…”

Section: Afferent Discharge In Hypertrophic Intestinementioning

confidence: 62%

Interdependency between mechanical parameters and afferent nerve discharge in hypertrophic intestine of rats

Yang

Zhao

Chen

et al. 2016

American Journal of Physiology-Gastrointestinal and Liver Physi

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Partial intestinal obstruction causes smooth muscle hypertrophy, enteric neuronal plasticity, motility disorders, and biomechanical remodeling. In this study we characterized the stimulus-response function of afferent fibers innervating the partially obstructed jejunum. A key question is whether changes in afferent firing arise from remodeled mechanical tissue properties or from adaptive afferent processes. Partial obstruction was created by placing a polyethylene ring for 2 wk in jejunum of seven rats. Sham obstruction was made in six rats and seven rats served as normal controls. Firing from mesenteric afferent nerve bundles was recorded during mechanical ramp, relaxation, and creep tests. Stress-strain, spike rate increase ratio (SRIR), and firing rate in single units were assessed for evaluation of interdependency of the mechanical stimulations, histomorphometry data, and afferent nerve discharge. Partial intestinal obstruction resulted in hypertrophy and jejunal stiffening proximal to the obstruction site. Low SRIR at low strains during fast distension and at high stresses during slow distension was found in the obstructed rats. Single unit analysis showed increased proportion of mechanosensitive units but absent high-threshold (HT) units during slow stimulation, decreased number of HT units during fast stimulation, and shift from HT sensitivity towards low threshold sensitivity in the obstructed jejunum. Biomechanical remodeling and altered afferent response to mechanical stimulations were found in the obstructed jejunum. Afferents from obstructed jejunum preserved their function in encoding ongoing mechanical stimulation but showed changes in their responsiveness. The findings support that mechanical factors rather than adaption are important for afferent remodeling.

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“…This makes it difficult to apply the acquired information to an intact segment [11]. The compliance and tension-strain relations in thin-walled plane strain models were obtained from measurements of pressure and CSA in the normal and diseased esophagus using impedance planimetry [12][13][14][15][16][17][18]. However, both compliance and the tension-strain relation neglect the wall thickness.…”

Section: Introductionmentioning

confidence: 99%

Dimensions and Circumferential Stress-Strain Relation in the Porcine Esophagus in Vitro Determined by Combined Impedance Planimetry and High-Frequency Ultrasound

Zhao

Jørgensen²,

Liao

et al. 2007

Dig Dis Sci

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The mechanical properties of the esophagus are important for its function because the esophagus is subjected to changes in wall stress and strains caused by the passage of boli and the action of peristalsis. Electrodes for impedance planimetry and an ultrasound transducer were placed on the probe inside a fluid-filled bag and used to study the circumferential stress and strain relation of the porcine esophagus in vitro. Impedance planimetry was used to determine the luminal cross-sectional area (CSA) and high-frequency ultrasound was used to determine the esophageal wall thickness during bag distension. Circumferential stress and strain were computed from steady-state values of pressure, CSA, and wall thickness. The incremental elastic modulus was obtained from the slope of the stress-strain curve and was plotted as a function of strain. The steady state pressure-CSA relation was nonlinear. At the lowest and highest luminal pressure load of 1 and 5 kPa, the steady state CSA was 159+/-20 and 338+/-25 mm(2), respectively. In the same pressure range, the wall thickness decreased from 1.93+/-0.08 to 1.44+/-0.08 mm. The slope of the stress-strain curve was 2.58+/-0.35 kPa. The circumferential stress and the incremental elastic modulus as function of the strain were exponential, that is, the tissue was soft at physiologic pressures and stiffer in the supraphysiologic pressure range. These biomechanical properties of the esophageal wall seem to prevent overstretch of the esophageal wall when luminal loading becomes supraphysiologic.

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Characteristics of spontaneous and evoked motility in the isolated perfused porcine duodenum

Cited by 21 publications

References 0 publications

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

Interdependency between mechanical parameters and afferent nerve discharge in hypertrophic intestine of rats

Dimensions and Circumferential Stress-Strain Relation in the Porcine Esophagus in Vitro Determined by Combined Impedance Planimetry and High-Frequency Ultrasound

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