An electrophysiological study of the smooth muscle of the human colon.

Electrical recordings were made in vitro from preparations of human colonic smooth muscle from surgically resected specimens. The behaviour of the taenia consisted of regular spike action potentials based on a slow wave rhythm (22 +/- 5 c.p.m.), with tetanic contractions of the muscle. The actions of cholinergic drugs were studied and experiments performed to investigate the mechanism of the action potentials. The circular muscle produced clusters of spikes with solitary contractions. The differences between the two muscle layers may be of relevance to understanding the colonic electromyogram as recorded in vivo.