Different mechanisms of contraction generation in circular muscle of canine colon

Smooth muscle cells from the circular muscle layer of the dog colon showed a mechanical threshold of -44 mV. No gradient in mechanical threshold was measured between the cells from the submucosal and myenteric plexus surface. The threshold was passed during the upstroke and the plateau phase of the spontaneous slow-wave activity from cells at the submucosal surface and by spike potentials occurring mainly in cells at the myenteric plexus …