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

Abstract

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.

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

“…2). This is consistent with previously observed increased muscle contraction force (3,30,36) and may reflect changes in the enteric reflex function. Functionally, the increased contraction force in the hypertrophic intestinal segment may serve to overcome the resistance to flow through the partial obstruction.…”

“…Time-dependent morphological and biomechanical remodeling of small intestine following partial obstruction has been described in previous studies (2,15,29,30,35). Consistent with these studies, we found significant smooth muscle proliferation and increased circumferential intestinal wall stiffness after a 2-wk obstruction.…”

“…Pronounced morphological and biomechanical changes are induced in the hypertrophied intestine oral to the obstructed site (2,16,29,35). Furthermore, motor disturbances, perturbed expression of enteric neuropeptides, and loss of Cajal cells in the hypertrophied intestine have been reported (3,11,30). The enteric nerve system is essential for intestinal function and sensation.…”

3d Mechanical properties of the partially obstructed guinea pig small intestine

“…Compared with the normal intestine, the obstruction-induced small intestinal biomechanical properties were characterized as a higher stress level in the wall and the altered material constants in the constitutive model. This tendency is consistent with our previous study on uni-axial testing of the obstructed small intestine (Storkholm et al, 2007(Storkholm et al, , 2008. However, the model and the material constants presented in this study have limitations for prediction of obstruction caused structural remodelling such as collagen fibre orientation change.…”

“…Recent biomechanical studies on the partially obstructed small intestine have shown that the intestinal hypertrophy is associated with a stiffer wall, more collagen and impaired motility of the small intestine (Storkholm et al, 2007(Storkholm et al, , 2008. Previous biomechanical studies on the obstructed small intestine only evaluated the mechanical properties on the basis of the isotropic assumption (Storkholm et al, 2007) or a two dimensional analysis by using a thin-walled model (Zhao et al, 2010).…”