In the canine small intestine several simple (S) and complex (C) patterns of propulsive and nonpropulsive activities were found. The nonpropulsive activity consisted of 1) stationary individual contractions (S) and 2) stationary clusters of contractions (C). Patterns leading to aboral propulsion of luminal contents were 1) propagating contractions (S), 2) propagating power contractions (S), 3) phase III of the migrating motor complex (C), and 4) migrating clusters of contractions (C). The propagation velocities of the propulsive motor patterns differed markedly; they increased in the following order: phase III, migrating clustered contractions, propagating power contractions, propagating contractions. A retrograde transport of luminal contents was produced by two different activities: 1) retrograde propagating contractions (S) and 2) retrograde power contractions (S). They were accompanied with enterogastric reflux.

In the present study, effects of ileal infusions of nutrients on motor patterns of the proximal small intestine and on gastric emptying were investigated in dogs. An acaloric meal was administered orally, and equicaloric loads of amino acids, oleate, and glucose were infused into the ileum at different doses (0.3, 0.6, and 0.9 kJ/min). The computerized analysis of motor patterns was focused on the differentiation between stationary and propagated contractions recorded by closely spaced extraluminal strain gauges. All three nutrients exerted inhibitory effects on gastric emptying and on contraction force and frequency of the proximal small intestine. Additionally, the propulsive motor pattern induced by the acaloric meal was modulated by reducing the number of contraction waves and their length of spread. All the effects were dose dependent. Among the three nutrients, glucose significantly changed motility at lower doses compared with amino acids and oleate. We conclude that in dogs the ileal brake mechanism is induced by all three nutrients and that it influences not only contraction force and frequency but also the motor patterns of the proximal small intestine.

In the present study ileal motor patterns caused by orally administered noncaloric and nutrient meals were investigated. Effects of nutrients were additionally elucidated by an ileal infusion of nutrients. Conscious dogs equipped with closely spaced extraluminal transducers were used. Motor patterns were quantified by a computerized method. Transit rates were measured fluoroscopically. Compared with the motor pattern caused by the noncaloric meal, the nutrient meal diminished the number of contractions from 11.7 to 5.9/min, reduced the incidence of contraction waves from 70.8 to 39.4%, shortened the length of contraction spread from 4.0 to 1.4 cm, and slowed the transit rate from 18.4 to 3.2 cm/min. Ileal infusion of nutrients induced a motor pattern similar to that of the nutrient meal. The transit rate correlated with the length of contraction spread (r = 0.75), the ratio between contraction waves and stationary contractions (r = 0.77), and the number of contractions (r = 0.69). The length of contraction spread was the most characteristic feature of motor patterns and the most important factor influencing transit.

The aim of this study is to elucidate the nature of ileal interdigestive contractile patterns by the computerized analysis of the contraction spread and by videofluoroscopy. Conscious dogs equipped with closely spaced strain-gauge force transducers were used. Two patterns of repetitive, phasic contractions were recorded, migrating clusters and phase IIIs; both patterns consisted of repetitive, propagated contractions. Both patterns migrated aborad by sequential movement of contraction waves down the bowel. Consequently, the rate of migration of either of the entire patterns was slower than the propagation velocity of constituent, individual contraction waves. Both patterns differed in several parameters, especially the propagated contractions of the clusters spread over shorter distances (1.47 +/- 0.4 cm) than those of phase III (4.65 +/- 0.99 cm). Compared with these complex patterns, propagating power contractions represented single contractions that propagated aborad at the same velocity as the contraction waves of the complex patterns. All three patterns propelled luminal contents distally.

Effects of intravenous infusions of somatostatin, methionine-enkephalin, and 5-hydroxytryptophan on canine ileal motor patterns and transit of chyme were investigated postprandially. Motility was recorded by multiple closely spaced extraluminal strain gauges. By a computerized method, the length of contraction spread and other motility parameters were evaluated. Transit rates were measured fluoroscopically. Somatostatin and methionine-enkephalin initiated a mixing activity by reducing the incidence and the length of spread of contraction waves induced by a noncaloric meal. Methionine-enkephalin, but not somatostatin, decreased both the number of contractions per minute and the motility index. 5-Hydroxytryptophan converted the mixing activity induced by a nutrient meal into a propulsive pattern. The incidence and the length of spread of contraction waves as well as the number of contractions per minute, the contraction force, and the motility index were enhanced. Results suggest that somatostatin, methionine-enkephalin, and 5-hydroxytryptophan are effective modulators of ileal propulsive activity. Effects are largely similar to those observed in the proximal jejunum, although the lengths of contraction spread and the transit rates were generally less in the ileum.