Effects of 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists on gastrointestinal motor activity in dogs

Figure 5 5-hydroxytryptamine 4 receptor antagonists on normal colonic motor activity. A: Typical effect of the 5-hydroxytryptamine (5-HT) 4 receptor antagonist. The 5-HT4 receptor antagonist inhibited phase III of the interdigestive motor complex at the antrum and whole colonic motor activity, CMMCs corresponding to phase III of the migrating motor complex at the ileum were sometimes observed (see arrow); B: The inhibition ratio compared with before 5-HT4 receptor antagonist administration. The inhibitory effect of the 5-HT4 receptor antagonist was dose dependent in the proximal colon (C1-C2). Values are mean ± SE. ^aP < 0.05 vs control (0 mg/kg). ICS: Ileocecal sphincter; C1-4: Colon 1-4.