CHARACTERIZATION OF PROPAGATING CONTRACTIONS IN PROXIMAL COLON OF AMBULATORY MINI PIGS

The aim of this study was to characterize propagating contractions in the unprepared colon of freely ambulating mini pigs. A telemetric meth od was used to record colonic motility continuously for six consecutiv e days in a 40-cm segment of proximal colon. Propagating contractions occurred over a wide range of propagation rates (0.4-16.7 cm/sec), pea k amplitudes (10-116 mm Hg) and pressure wave durations (5.3-40.0 sec) . Propagating contractions were divided into two groups by duration an d wave-form: short-duration symmetrical and long-duration asymmetrical . Short-duration (7.8 +/- 0.9 sec) symmetrical wave-from propagating c ontractions exhibited a higher frequency (27.9 +/- 2.6 events/day), mo re rapid propagation rate (3-16.7 cm/sec; mean +/- SEM: 4.9 +/- 1.7 cm /sec), and a lower peak amplitude (31.2 +/- 0.9 mm Hg) compared to lon g-duration (19.2 +/- 5.1 sec) asymmetrical propagating contractions, w hich were less frequent (6.1 +/- 0.7 events/day), slower in propagatio n rate (0.4-2 cm/sec; mean +/- SEM: 1.5 +/- 0.7 cm/sec), and higher in peak amplitude (51.6 +/- 2.4 mm Hg), The results show that propagatin g contractions occur over a wide spectrum, from short-duration, low-am plitude, rapidly propagating contractions to long-duration, high-ampli tude, slowly propagating contractions.