How to express pharmacological contractions of the inflamed rat intestine

Abstract

Inflammation leads to intestinal dysmotility which can be due to both functional and trophic alterations of the neuromuscular apparatus. To discriminate between trophic and functional changes, several normalization procedures are used in contractility studies. It is important to know how normalization procedures may influence the obtained results. In a rat model of TNBS-induced ileitis, we compared seven known normalization procedures for pharmacological contractions of longitudinal muscle strips. During acute ileitis, contractility was significantly decreased, irrespective of the normalization procedure used. During the post-inflammation phase, hypertrophy and hyperplasia of smooth muscle cells led to increased contractility on raw strip chart recordings. However, when contractions were corrected for the increase in muscle mass, the contractility was either normal or decreased, depending on the normalization procedure used. Normalization of contractions to the cross-sectional area (CSA) of the longitudinal muscle is the gold standard. Comparison of three methods to determine the CSA, showed that the commonly used equation to calculate the CSA, based on the tissue weight, length and density, might overestimate the CSA. We conclude that this equation should be adapted by a muscle thickness ratio, or alternatively the CSA can be determined on histological sections.

Ablation of connexin43 in smooth muscle cells of the mouse intestine: functional insights into physiology and morphology

“…Therefore, we postulate that the observed hypercontractility might abolish the integrated propulsive activity of the normal gut, leading to a dysfunction of peristalsis and decreased gastrointestinal transit. Our findings are also consistent with those of Moreels et al (2001) who have reported similar structural and functional changes in chronically inflamed mouse ileum.…”

“…A correlation of connexin deficiency and hypertrophy has been described previously for the mouse heart Ya et al 1998). Furthermore, since histological alterations of the intestinal wall may also result from inflammation (Moreels et al 2000(Moreels et al , 2001, the significant increase in infiltration of neutrophils shown by MPO staining in tamoxifen-treated Cx43 fl/fl :SM-CreER T2 mice may also account for the morphological changes.…”

Food allergy alters jejunal circular muscle contractility and induces local inflammatory cytokine expression in a mouse model

“…After the experiments, the tissue segments were carefully removed from the hooks, air dried for some weeks, and weighted. The results were expressed as tension in mg/mm 2 , which is the contraction divided by cross-sectional area, CSA (CSA = tissue dry weight/(tissue length × tissue density); assuming that tissue density was 1.05 mg/mm 3 [12]). The contractions were compared at each concentration levels.…”

MCP-1 targeting inhibits muscularis macrophage recruitment and intestinal smooth muscle dysfunction in colonic inflammation

“…Discriminating between changes in contractility due to functional or trophic changes is thus crucial (28). To discriminate between functional and trophic changes in the present study, we used a normalization procedure as described before (15).…”