Myoelectrical activity of the gastrointestinal tract has been studied in the postoperative period of 13 patients who underwent cholecystectomy. The recordings have been performed by means of extracellular electrodes which were implanted at the levels of stomach, jejunum, ileum and colon during the surgical procedure. The records showed that fast activity is always persistent while the basic electrical rhythm is greatly disorganized during the immediate postoperative period. Such a characteristic pattern of the electrical activity suggested that the lack of peristaltic and propulsive movements, always noted during this period, is not correlated with a disappearance of gastrointestinal contractions, but only with a disturbance in their coordination.

The effects of VIP on intestinal motility were studied on isolated canine jejunal loops ex vivo perfused at normothermia, under pulsatile flow with heparinized, oxygenated and nonrecirculated canine whole blood, by means of an intraluminal balloon. VIP was administered intraarterially either by 1 min injections or by long-time infusions. The results showed that for arterial concentrations of the polypeptide ranging between 25 pg/ml and 300-500 pg/ml a fast but short-lasting relaxant effect was observed. For higher concentrations VIP usually produced a biphasic response: The relaxant effect is followed by an increase of the basal muscular tone often accompanied, for concentrations higher than about 25 ng/ml, by a marked and transient increase in amplitude of the intestinal rhythmic contractions. During long-time infusions a biphasic response was also observed but both effects were of short duration. A cholingeric origin of the secondary contracting phase was expected but could not be demonstrated because, at blood concentrations at which atropine affected the biphasic response, not only was the contractile effect abolished but also the initial relaxing phase. It is suggested that the secondary contraction may be a "rebound excitation" of myogenic nature or a result of noncholingeric excitatory fiber stimulations. The short-lasting relaxant effect observed under the present experimental conditions, even during long-time infusion of the polypeptide, fails to argue for an important physiological role of VIP as an hormonal inhibitor of intestinal motility. The biphasic response, however, might have a physiological significance in so far as the aboral propulsion of the intestinal content requires a muscular inhibition which rapidly changes to contraction.

Interdigestive intestinal myoelectric activity is characterized by repetitive aborally migrating complexes which are inhibited by feeding. The aim of the present work was to study the effects of different food components on the duration of inhibition of the myoelectric complex and on the number of spike potentials during this period. 4 dogs were prepared for chronic recordings with electrodes implanted on the jejunum and an alimentary cannula placed into the duodenum. Glucose, peptides and lipids were given into the cannula at doses of 7.5 and 15 kcal/kg. The results indicated that the inhibition of the myoelectric complex was longer for lipids than for glucose and even longer than for peptides. When the caloric load was increased, the duration of inhibition was also increased. As concerns the spike potentials, their number was increased after administration of glucose and of peptides, whereas it was decreased after lipids. Lastly, the increase of the caloric load did not change the number of spike potentials significantly. These results indicated that the duration of inhibition of the myoelectric complex depended on both the nature and the caloric load of the food components, whereas the number of spike potentials was determined only by the composition of food.

A simple device allowing a pulsatile flow to be obtained in isolated organ perfusion has been developed and applied to the vascular perfusion of isolated canine jejunal segments. The principle of the device consists of superimposing on a constant pressure produced by a roller pump, a pulsatile pressure of which the amplitude, frequency, and shape of the pulses can be adjusted separately and independently of the mean pressure value. The role of the arterial pulse in intestinal vascular perfusion has been studied by comparing the hemodynamic and metabolic behavior during alternate periods of pulsatile and nonpulsatile pumping. While no striking change in vascular resistance was observed, the O₂ consumption was significantly increased under pulsatile flow. These results testify to better metabolic conditions and enhanced organ functions under pulsatile pumping and also argue for improved intestinal microcirculation despite the constancy of the vascular resistance.