Background/purpose: The mechanism of fetal gastric dilation in gastroschisis is controversial. This study was designed to characterize changes in the contractile profile of strips of stomach from rats following experimental gastroschisis.
Methods: Pregnant Wistar rats were operated on day 18.5. Fetuses were divided into three groups: gastroschisis (G), sham (S), and control (C). On day 21.5, gastric fundus and antrum strips were obtained and suspended to a force transducer connected to a digital data acquisition system. They were submitted to increasing concentrations of carbachol (CCh) and weighed at the end of each procedure. Frequency and amplitude of each contraction were evaluated.
Results: Under basal conditions, spontaneous oscillatory contractions of antrum and fundus strips of G, S, and C were similar (P>0.05; ANOVA). However, cumulative concentrations of CCh (0.01-100 μM) produced different effects in all groups and were characterized by a significant increase in amplitude and frequency of spontaneous contractions in antral smooth muscle and a sustained increase in tonus in fundic strips. Upon analysis, no significant difference in frequency or amplitude was noted in antral tissues comparing C to G and to S (P>0.05). No significant contractility difference was noted in fundic smooth muscle (comparing all groups, P>0.05), with the CCh-induced curve following a typical sigmoidal format, dependent on increasing concentrations (P<0.001).
Conclusions: Gastric contractile responses to CCh are preserved in experimental gastroschisis. These results do not support the theory that gastric dilation occurs secondary to intestinal inflammation alone.
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