Identification of multiple distinct neurogenic motor patterns that can occur simultaneously in the guinea pig distal colon

Background.In the guinea pig distal colon, non-propulsive neurally-mediated motor patterns have been observed in different experimental conditions. Methods.Isolated segments of guinea pig distal colon were used to investigate these neural mechanisms by simultaneously recording wall motion, intraluminal pressure and smooth muscle electrical activity in different conditions of constant distension and in response to pharmacological agents. Results.Three distinct neurally-dependent motor patterns were identified; Transient Neural Events (TNEs), Cyclic Motor Complexes (CMC) and Distal Colon Migrating Motor Complexes (DCMMC). These could occur simultaneously and were distinguished by their electrophysiological, mechanical and pharmacological features. TNEs occurred at irregular intervals of about 3s, with bursts of action potentials at 9Hz. They propagated orally at 12 cm/s via assemblies of ascending cholinergic interneurons which activated final excitatory and inhibitory motor neurons, apparently without invo...