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SUMMARY1. The motility of the reticulo-rumen and omasum in conscious sheep was studied by electromyography from chronically implanted nichrome wire electrodes. The sheep were subjected to vagotomy and were maintained totally by intragastric infusion of liquid nutrients before and after vagotomy. Before vagotomy the motility of the forestomach was essentially similar to that seen in roughage-fed sheep.2. Bilateral thoracic vagotomy transiently abolished all electrical activity of the reticulo-rumen and omasum, but within 1 day some activity returned. Frequent periods of rhythmic local small group discharges were seen over the reticulo-rumen, while the omasum showed prolonged (1-5 min) bursts of mainly slow wave activity.3. Within 1-2 weeks of vagotomy strong contractions of the reticulo-rumen were visible by radiography. Electromyographically, they comprised a rhythmic series of some two to five large group discharges recurring approximately once a minute. Each series of activity was separated from the next by a short period of quiescence. The discharges occurred almost simultaneously over the whole reticulo-rumen and so contrasted with the progressive forward or backward spread of activity seen in the intact animal. The bursts of activity in the omasum, lasting 05--2 min, were not co-ordinated with the activity of the reticulo-rumen as they are in the intact animal.4. The activity in the reticulo-rumen and omasum was not affected by bilateral section of the splanchnic nerves and removal of the coeliaco-mesenteric ganglia. Reticulo-rumen but not omasal activity was abolished by atropine (0-1 mg/kg) or hexamethonium (2 mg/kg), while both were stimulated by pentagastrin (3 jug/kg).5. Following vagotomy reticulo-rumen motility was no longer influenced by feeding, or by tactile stimulation of the buccal cavity or oesophagus. Severe distension of the abomasum caused a slight acceleration of the motility rhythm compared to the inhibition seen before vagotomy.6. It is concluded that the reticulo-rumen motility observed after vagotomy is an intrinsic cholinergic motility which is dependent upon the activity of the myenteric plexus. The motility ofthe omasum after vagotomy is similar to that seen in the intact animal and differs from that of the rumen in that it appears not to depend wholly upon cholinergic control.

1. The relation between the level of food intake and gastrointestinal motility and digesta flow in the abomasum and small intestine was studied in sheep fitted with nichrome-wire electrodes in the gut wall, an abomasal and a duodenal catheter and a terminal ileal cannula.2. Abomasal volume and outflow were calculated from CrEDTA dilution in six sheep and small intestinal transit time by the passage of Phenol Red in ten sheep.3. The frequency of the migrating myoelectric complex of the small intestine was not altered by the level of food intake but the duration of the periods of irregular spiking activity, the amplitude of abomasal activity and the frequency of duodenal rushes were decreased as the level of food intake was decreased.4. There was a linear relation between the level of food intake (FI) and abomasal outflow (mean with SEM:327 (69) ml/h for each kg FI/d; P < 0.01), and abomasal volume (mean with SEM: 344 (50) ml/kg FI per d ; P < 0.001), without any significant change in the half-time of marker dilution in the abomasum. Small intestinal transit time decreased with an increase in food intake (mean with SEM: -54.9 (5.6) min/kg FI per d ; P < 0.001). 5.It is concluded that abomasal volume and the rate of digesta flow from the abomasum and along the small intestine are linearly related to the level of food intake.

I reviewed the literature (1966-1994) concerning gastrointestinal (GI) pH, motility/transit, and permeability in cystic fibrosis (CF). Most studies reported were performed with very small numbers of patients, but even when considered together the published data do not confirm some generally expressed views on these topics. The only clear findings were a high incidence of gastroesophageal reflux in CF; pre- and postprandial duodenal pH is 1-2 U lower in patients with CF than in healthy controls; and small intestinal paracellular permeability is 4-10 times greater than normal in CF. Some patients showed abnormalities of lower esophageal sphincter pressure and of esophageal motility, but apart from one case study other disturbances of GI motility have not been reported. The results of hydrogen breath tests strongly suggest that oro-cecal transit is slowed in CF, but these results must be confirmed by an alternative test. Measurements of colonic transit and colonic permeability have not been reported. The few studies of gastric emptying reported are controversial. Whether GI pH, apart from duodenal pH, is normal in CF or whether a subset of patients has exceptionally acid intestinal contents requiring specialized pancreatic enzyme supplementation to normalize digestion is not clear. Finally, I briefly discuss the findings in relation to their possible impact on the pathogenesis of fibrosing colonopathy.