VMR to graded pressure CRDs in control rats, CCK-8 infusion and 5% peptone infusion rats. (A) Representative abdominal muscle electromyograms of the VMR to graded-pressure CRD (20, 40 and 60 mmHg) recorded from the external oblique pelvic muscle in normal rats and rats with CCK-8 and peptone infusion. No obvious difference was found among the three groups. (B) Histograph showed the effects of CCK infusion and 5% peptone infusion on the VMR to graded-pressure CRD in rats. Mean amplitude of the abdominal muscle contraction expressed as AUC after baseline subtraction was presented. No significant difference was found among the three groups. Results were expressed as means ± SE. Statistical comparisons of the VMR in various groups were made by two-way repeated-measures ANOVA, followed by multiple comparisons adjusted by the Bonferroni test, n=5 for each groups.