In vivo gastric and intestinal slow waves in W/WV mice.

The aim was to investigate whether there are regular gastric and intestinal slow waves in conscious W/WV mice. Eleven W/WV mice and 11 wild-type mice were implanted with two pairs of electrodes in the stomach and small intestine. Gastrointestinal slow waves were recorded both under anesthesia and in the conscious state. Atropine and verapamil were given separately to an additional 10 W/WV mice. Results were as follows. (1) The conscious W/WV mice showed lower rhythmic slow waves in the small intestine (77.1 vs 93.5%; P < 0.001). However, the frequency (10.7 vs 18.8 cpm; P < 0.0001) and the antregrade propagation of intestinal slow waves in W/Wv mice were significantly lower than in the controls. In the stomach, regular slow waves were recorded in both groups, with no difference between the two groups. (2) Anesthesia significantly impaired both gastric and intestinal slow waves in both groups. (3) Atropine and verapamil had no effects on the rhythmicity of intestinal slow waves. We conclude that ICC-MY may not be the sole pacemaker cells for slow waves in the small intestine. There may be some abnormality of smooth muscle cells in W/WV mice that causes a reduction in the frequency, rhythmicity, and antegrade propagation of slow waves.