Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Babies with gastroschisis (G) have high morbidity rate and long hospital stay due to bowel hypomotility caused by chronic exposure of the bowel to the amniotic fluid. Our aim was to evaluate the reactivity of isolated ileum in fetal rats selected for experimental gastroschisis. G was surgically created at 18.5 days of gestation (term = 22 days). Concentration-dependent curve to the muscarinic agonist methacholine (1-30 mu M) and contractions induced by electrical field stimulation (EFS, 1-16 Hz, 50 V, 1 ms) were carried out in isolated ileum of groups control (C), sham (S) and gastroschisis (G) (n = 30). Protein expression for M(3) was assessed by western blot analysis. The frequency and amplitude of spontaneous contractions were decreased in G (p < 0.001). Methacholine produced concentration-dependent contractions being the maximal response values higher in G (p < 0.01). EFS-induced frequency-dependent contractions showed 1.8 times higher in G as well as an increase of M(3) expression. The frequency and the amplitude of rhythmic contractions were reduced along with an increase in the contraction induced by mucarinic agonist and by EFS in G. These results suggest the occurrence of an adaptative supersensitivity to cholinergic response via increases in the protein expression for M(3) receptor.27910151019Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [08/51487-9]