Intraluminal pressure patterns in the jejunum of conscious dogs

The motility of the upper jejunum was studied in conscious dogs at rest using a chronically implanted two channel open tip catheter for sensing intraluminal pressure. Two major patterns of periodic activity were identified, i.e. regular and irregular. Regular activity consisted of rhythmic high amplitude waves with a mean frequency of 18.4 per min. Most of the regular activity episodes did not develop simultaneously at the two sites of the catheter orifices but appeared to migrate slowly caudad. Irregular activity consisted of repetitive waves of highly variable amplitude and with a mean frequency of 16.7 per min. Occasionally, the time interval between regular or irregular activity periods was occupied by rhythmic waves of uniform low amplitude. Whichever the pattern, repetitive pressure waves not simultaneous at the 2 recording sites but occurred in caudad sequence. The pressure patterns recorded in our study likely correspond to burst, intermediate and basal contractility patterns recorded with extraluminal force transducers. Our results lead to assume that mixing and propulsion of intraluminal contents depend on the intensity of the same contractile activity. The data also suggest that the caudad sequence of the pressure waves represents actual peristalsis, though no indication is given as to how far the waves travel.