Spontaneous migrating motor complexes occur in both the terminal ileum and colon of the C57BL/6 mouse in vitro

We have studied migrating motor complexes (MMCs) in the isolated terminal ileum or colon (IMMCs and CMMCs respectively) of the C57BL/6 mouse. Periodic contractions occurred spontaneously in both preparations in the absence of intraluminal stimulation. After an initial period, complexes became synchronized between the oral and anal ends of the tissue, and could be observed for in excess of 7 h. The propagation velocity was 3.1±1.0 and 3.9±0.6 mm s−1 in the ileum and colon respectively. IMMCs occurred every 6.01±0.39 min and had a duration of 86.3±10.4 s. The interval between CMMCs was smaller (3.52±0.31 min) and contractions were shorter in duration (30.7±3.6 s). In both preparations, these motor events were dependent on cholinergic transmission: blocked by hexamethonium (500 μM) and attenuated or blocked by atropine (1 μM). This study is the first demonstration of spontaneous migrating contractions in the isolated ileum or colon of the C57BL/6 mouse, the strain of choice for neurological transgenic and targeted mice.