Scintigraphic measurements of canine ileocolonic transit. Direct and indirect effects of eating

Eight dogs were equipped with ileal catheters, 50 cm proximal to the ileocolonic junction, and serosal electrodes at 5, 25, 55, 100, and 150 cm. Transit was assessed by injecting a bolus of 99mTc-diethylenetriamine pentaacetic acid through the ileal catheter and following isotope movements by serial, 4-min scintiscans. Isotope was injected in separate studies: during phase I of an interdigestive myoelectrical cycle, 10 min before a meal, and or 2 or 4 h after a meal (600 ml, 385 kcal, thickened with 4 g guar). At another time, mouth-to-colon transit of the same meal was measured by labeling it with 111In-diethylenetriamine pentaacetic acid and scanning at hourly intervals for 11 h. Transit of isotope through the terminal ileum and entry into the colon was characteristically erratic; long periods of immobility were interspersed with sudden "bolus" movements. In the fasting studies, most sudden movements occurred while phase III (migrating motor complex) of the interdigestive myoelectrical cycle migrated through the last 50 cm of ileum. Passage of a single migrating motor complex through the terminal ileum propelled about one-half the dose of isotope into the colon; complete clearance of the ileum required two or more migrating motor complexes. Immediately after the meal, ileal movements increased transiently; however, these were followed by a period of quiescence. Overall, the time for 50% of the counts to enter the colon was not different when isotope was injected 10 min before the meal from when the injection was made 2 h postprandially (207 +/- 16 min and 162 +/- 25 min, respectively). However, transit of isotope injected 4 h postprandially was significantly faster (91 +/- 13 min). In the fed state, some bolus movements could be related to specific patterns of ileal motility; however, the majority occurred during apparently random "fed-type" motility. In part II, meal marker accumulated faster in the colon after 3-4 h, suggesting that the rapid ileocecal transit at 4 h postcibal was due to increased flow of chyme through the ileum at this time.     

Does the ileocolonic junction differentiate between solids and liquids?

Previous observations from our laboratory have suggested that colonic filling from the ileum is characterised by a series of bolus movements. The present experiments were designed to test the hypothesis that bolus transit of ileal contents into the colon would not distinguish between solids and liquids. After a manometric infusion assembly was positioned by mouth into the ileum of 13 healthy volunteers, a mixture of nutrients (75 kcal), incorporating a solid phase radiolabel (111In labeled resin pellets) and a liquid phase marker (99mTc-DTPA), was infused into the ileum. Transit of both labels from the ileum to colon was quantified scintigraphically and ileal motility was also recorded. When markers were infused into the proximal ileum, 100 cm proximal to the ileocolonic junction (six), there were clear cut examples of discriminant transit, when liquids moved more rapidly from the small to the large bowel than did solids. When isotopes were instilled into the distal ileum, less than 50 cm from the ileocolonic junction, no separate transit of the solid and liquid phases was observed. No specific motor pattern of the ileum was regularly associated with bolus filling of the colon. These results support the hypothesis that the distal ileum can discriminate between solids and liquids but that the ileocecal junction cannot.     

Diurnal changes in colonic motor profile in conscious dogs

Continuous strain gauge recordings of ileal and proximal colonic motility were performed in 5 dogs fitted with a cannula in the ileum. The 22-hr records obtained with a normal ileocolonic transit were repeated during external deviation of digesta and after vagotomy. In the fasted state, the motility of the proximal colon was characterized by phases of contractions occurring at 25-min mean intervals modulated by the occurrence of migrating motor complexes on the ileum. Food intake induced three consecutive changes in colonic motility: a supplementary phase of activity immediately after the meal, an inhibition during the second postprandial hour, and a period of increased frequency of the phases of activity lasting 8-10 hr. The fasted motor profile of the proximal colon reappeared at the end of the postprandial disruption of the ileal cyclic activity. External deviation of ileal content abolished the late colonic response to the meal. Vagotomy did not modify any diurnal variation.     

Measurement of gastric emptying, intestinal transit time and colonic filling by scintiscan in healthy subjects

A scintigraphic technique allowing combined measurements of gastric emptying, small intestinal transit time and colonic filling was developed and its reproducibility assessed in 8 healthy volunteers. Each subject underwent four tests: a) two were performed in the fasting state (99mTc labelled water, added to lactulose), b) two in the postprandial state (balanced meal, 1,750 kJ, included pellets labelled with 111In, the gut transit of which being nearly the same as dietary fibers). Intestinal transit was modeled using linear operators (expressed as a convolution product). In fasting state (lactulose), orocecal transit time of water was 109 +/- 60 min and 89 +/- 36 min (m +/- DS) for the first and second tests, respectively. In the postprandial state, values were 297 +/- 37 min and 293 +/- 43 min respectively for the pellets. Small bowel transit times were 135 +/- 70 and 103 +/- 40 min respectively in fasting state for water, and 209 +/- 47 and 209 +/- 29 min respectively in postprandial state for the pellets. Determination of residual variance showed that reproducibility of the test was better in the postprandial state than in the fasting state. Water orocecal transit times measured using this technique and lactulose orocecal transit time measured using hydrogen breath test were strongly correlated (r = 0.98, n = 12, P less than 0.01). This isotopic method provides a reproducible assessment of gastric emptying, small bowel transit, and colonic filling and could represent a reliable and non invasive tool for further physiological and pharmacological studies.     

Chenodeoxycholic and ursodeoxycholic acids alter motility and fluid transit in the canine ileum

We examined the effects of chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) on fasting motility patterns and transit in ileocolonic loops of 5 dogs. Animals were prepared with isolated loops (40 cm ileum and 5 cm colon) which maintained neuromuscular continuity with the intact bowel through a bridge of tunica muscularis. Myoelectrical activity was recorded from multiple serosal, monopolar electrodes and muscle contractions recorded from serosal strain gauges; fluid transit was assessed by continuous perfusion (1.4 ml min-1) of solutions containing polyethylene glycol 4000 marker, with or without bile acids. Saline perfusion did not disturb the fasting cycle of motility and mean cycle length in unperfused (106 +/- 7 min) loop was the same as during perfusion of saline (108 +/- 9 min). Bile acids abolished interdigestive cycles in 11 of 12 experiments, fasting patterns returned 64-106 min after bile acid perfusion was stopped. The fasting pattern continued to cycle normally in the proximal small bowel during bile acid perfusion. CDCA (15 mM) stimulated the occurrence of propulsive contractions of long duration. Bile acids shortened transit time through the loops and altered the pattern of flow towards a more continuous, steady stream. These effects of bile acids on ileal motility, like those described previously in the colon, could play a role in bile acid diarrhea.     

Effects of serotonin on rat ileocolonic transit and fluid transfer in vivo: possible mechanisms of action.

The aim was to investigate the action of serotonin (5HT) on function of the ileocolonic junction (ICJ) in vivo. In anaesthetised rats, models were developed to study the effects of intra-aortic (ia) serotonin on ileocolonic and colonic transit, and the effects on transit of a number of 5HT receptor antagonists. In the first series of experiments, a bolus of saline labelled with 99mTc DTPA was instilled 20 cm proximal to the ICJ and transit was assessed three hours later by the geometric centre of the spread of isotope. In the second series, similar techniques were used on the postcaecal colon and transit assessed two hours later. In the third series of experiments, the effects of ia 5HT on ileal net fluid flux was evaluated by standard perfusion experiments with 14C polyethylene glycol (PEG) 4000 as a non-absorbable marker in rat plasma-like electrolyte solution. Compared with ia saline, 5HT accelerated ICJ transit significantly (p < 0.05). This acceleration was comparable with the effect of ia bethanechol. The effects of 5HT on ICJ transit were inhibited by the intraperitoneal (ip) infusion of atropine, the 5HT receptor antagonists, methysergide, ketanserin, zacopride, and the 5HT4 agonist, SC53116. Methysergide, zacopride, and SC53116 given with ia 5HT slowed ICJ transit to rates below those of ia saline alone. When these same agents were given together with ia saline, the ICJ transit was not significantly altered. Serotonin, at the dose that accelerated ICJ transit, did not significantly alter colonic transit or ileal fluid transport. In conclusion, 5HT is a potent pharmacological stimulant of transit across the rat ICJ in vivo; the action of 5HT is mediated partly through muscarinic neurones and several 5HT receptor subtypes.     

Fasting and postprandial ileal function in adapted ileostomates and normal subjects.

The output of 11 established ileostomies was compared with ileal flow measured by intestinal perfusion in five normal volunteers when fasting and during the ileal passage of test meals containing different proportions of medium chain triglyceride and long chain triglyceride. Oroileal transit of the meal was the same in the two groups, but ileostomy output was less than ileal flow of normal persons both fasting (16.3 +/- 10.9 vs 62.4 +/- 24.7 ml/h, p less than 0.001) and after the long chain triglyceride rich meal (35.4 27.0 vs 96.1 +/- 20.2 ml/h, p less than 0.001). After ingestion of the medium chain triglyceride rich meal, ideal flow failed to increase in normal subjects but in ileostomates the changes in flow after medium chain triglyceride and long chain triglyceride rich meals were not significantly different. The fasting ileostomy effluent composition differed from that of normal fasting ileal content in having a higher concentration of potassium (8.0 +/- 2.9 vs 4.7 +/- 0.6 mmol/1, p less than 0.04) and a higher osmolality (353 +/- 63 vs 287 +/- 5 mosm/kg, p less than 0.05). Sodium concentration tended to be lower in ileostomy effluent, but in contrast to previous reports, ileostomy effluent was of consistently alkaline pH (7.2 +/- 0.3). These concentrations were not significantly altered by either type of meal. The long chain triglyceride rich meal increased the ileal flow of bile acids in both normal subjects and ileostomates, whereas the medium chain triglyceride rich meal increased bile acid flow in ileostomates but not in normal subjects, possibly reflecting a different amount of the bile acids in the ileum of the ileostomate. In the adapted ileostomate, the low volume and high potassium concentration of fasting effluent suggest that sodium and water absorption are continuously stimulated by chronic salt depletion.     

Ileocolonic transit does not change after right hemicolectomy.

The role of the human ileocolonic junction in the transit of solid contents through the entire gut was evaluated. Eight patients, well compensated after right hemicolectomy for localized colon cancer, and eight age-matched healthy controls were enrolled. Scintigraphic transit was quantified after subjects ingested a mixed meal containing 111In-labeled Amberlite beads (average diameter, 1 mm; Sigma Chemical Co., St. Louis, MO). Gastric emptying was initially faster in the postoperative group, but overall emptying was not different from controls; small bowel transit also did not differ between the groups. In patients in whom the distal ileum, ileocolonic sphincter, and proximal colon were absent, isotopes moved from small to large bowel in a manner that was qualitatively and quantitatively no different from that of controls. Major episodes of coloileal reflux could not be identified in either group. After hemicolectomy, the residual transverse colon, and to a lesser degree the descending colon, were able to store solid residue, although in lesser amounts than the unoperated large bowel. The ileocolonic sphincter in humans appears to play only a minor role, at most, in ileocolonic transit, and the colon remaining after right hemicolectomy stores residue so that bowel habits are not greatly disturbed.     

Ileocolonic transfer of solid chyme in small intestinal neuropathies and myopathies

The aims of this study were to assess gastric emptying, small bowel transit and colonic filling in patients with motility disorders, with particular attention to the patterns of colonic filling. Gastrointestinal transit was assessed using a previously validated radiolabeled mixed meal. Fourteen patients with clinical and manometric features of chronic intestinal pseudoobstruction & classified as intestinal neuropathy and 6 as intestinal myopathy, were studied. The results were compared with those from 10 healthy controls studied similarly. Gastric emptying and small bowel transit of solids were significantly slower in both groups of patients than in healthy controls (P less than 0.05). In health, the ileocolonic transit of solid chyme was characterized by intermittent bolus transfers. The mean size of boluses transferred to the colon (expressed as a percentage of ingested radiolabel) was significantly less (P less than 0.05) in patients with intestinal myopathy (10% +/- 4% (SEM)] than in healthy controls (25% +/- 4%) or in patients with intestinal neuropathy (25% +/- 4%). The intervals between bolus transfer of solids (plateaus in the colonic filling curve) were longer (P less than 0.05) in myopathies (212 +/- 89 minutes) than in health (45 +/- 7 minutes) or neuropathies (53 +/- 11 minutes). Thus, gastric emptying and small bowel transit were delayed in small bowel neuropathies and myopathies. Bolus filling of the colon was less frequent and less effective in patients with myopathic intestinal pseudoobstruction, whereas bolus transfer was preserved in patients with neuropathic intestinal pseudoobstruction.     

Simultaneous measurement of gastric emptying, small bowel residence and colonic filling of a solid meal by the use of the gamma camera

A method for determining the profiles of gastric emptying, small intestinal residence, and colonic filling of a solid test meal, labelled with 250 microCi 99mTechnetium sulphur colloid has been evaluated in nine healthy volunteers and six patients with a disturbance in bowel habit. Mean small bowel transit time was determined by deconvolving the rate of colonic filling with the rate of gastric emptying. In normal subjects, the stomach appeared to empty exponentially with a half time of 1.2 +/- 0.3 hours (mean +/- SD). Food reached the colon by 2.8 +/- 1.5 hours. The mean small bowel transit time was 4.0 +/- 1.4 hours. In most normal subjects, the colon appeared to fill in a linear fashion with approximately 16% food residues entering every hour, and the profile of colonic filling in normal subjects was similar to the profile of ileal emptying observed after feeding a similar radiolabelled solid meal to 14 patients equipped with terminal ileostomies. There was a highly significant correlation between the onset of breath hydrogen excretion and the appearance of radioactivity over the caecum (r = 0.88, p less than 0.01), though in one third of subjects the increase in caecal radioactivity preceded the rise in breath hydrogen concentration by more than 20 minutes. There was also a highly significant correlation between the mean transit time and values for colonic filling but not values for gastric emptying. Patients with irritable bowel syndrome who had diarrhoea tended towards short small bowel transit and early colonic filling, whereas patients who have constipation tended towards long small bowel transit and delayed colonic filling. This method offers a novel means of assessing small bowel transit time, small bowel residence and the profile of colonic filling in man.     

Perendoscopic manometry of the distal ileum and ileocecal junction in humans

Previous manometric studies of the ileocolonic junction were performed without assessing the precise spatial relationship between recording sensors and ileocolonic junction. In the present study, the motor activity of the ileocolonic junction was recorded using manometric sensors localized under direct colonoscopic control in 11 patients (4 men, 7 women; mean age, 55 years) referred for hematochezia with normal stool frequency. No medications were administered before and during endoscopy. A perfused catheter (OD 1.7 mm, with three side holes 4 mm apart and marked by evenly spaced black rings in the distal 6 cm) was passed through the biopsy channel of the endoscope and advanced through the ileocolonic junction and 6 cm into the ileum. The catheter was then withdrawn into the cecum by 1-cm steps, and motor activity was recorded for 4-6 minutes at each station. A single catheter taped to the endoscope continuously recorded cecal pressure. An ileocecal pressure gradient could not be identified in the majority of subjects; individual values ranged from -8 to +4 mm Hg, and gradients were maintained over the entire length of the ileum. In the distal ileum, tonic and phasic pressure waves were detected. Tonic variations were present for 70.1% of the recording time, either alone (44%) or together with phasic waves (56%). Phasic waves were present for 10.3% of the recording time and, according to their duration, were subdivided into those compatible with the rate of ileal slow waves and prolonged waves not compatible with the rate of ileal slow waves. Regular phasic waves could be either isolated or in clusters; prolonged waves were always isolated. A similar proportion of regular (27.9%) and prolonged (31.2%) phasic waves propagated aborally along the ileum or from ileum to cecum. Clusters presented an average of 8.7 +/- 0.6 peaks/min, and 44% of them propagated aborally. The manometric characteristics did not vary between the segments 5-3 cm and 2-0 cm proximal to the ileocecal junction. In conclusion, a powerful ileocecal sphincter was not detected at the human ileocecal junction, and motor activity of the distal ileum was characterized by tonic changes and rapid phasic contractions.     

Colonic Crohn’s Disease in Children Does Not Respond Well to Treatment with Enteral Nutrition If the Ileum Is Not Involved

Data supporting a response to treatment with exclusive enteral nutrition in pediatric colonic Crohn’s disease are few. We examined clinical and biochemical responses of ileal, colonic, and ileocolonic Crohn’s disease and assessed the endoscopic and histological colonic mucosal response in the colonic and ileocolonic groups.We prospectively enrolled 65 children (age: 8–17 years) with acute intestinal Crohn’s disease (Pediatric Crohn’s Disease Activity Index [PCDAI] > 20). After ileocolonoscopy, gastroscopy, and a barium meal and follow-through, they were distributed into three groups (ileal, n = 12, ileocolonic, n = 39; and colonic, n = 14). All patients received exclusive polymeric feed as treatment, with a repeat endoscopy at completion of treatment. At enrollment the ileal group had significantly less severe disease (P = 0.05) compared to the colonic and ileocolonic groups. However, the colonic disease group showed the least fall in PCDAI scores at completion of treatment with enteral nutrition (P = 0.03), with the lowest remission rate (50%, vs 82.1% in the ileocolonic and 91.7% in the ileal group [χ² test, P = 0.021]). Endoscopic and histologic colonic mucosal assessment showed a posttreatment improvement in the ileocolonic (P ≤ 0.01) but not in the colonic disease group (P = ns). Children with disease in the colon respond better to enteral nutrition if the ileum is also involved. This may be due to different underlying inflammatory mechanisms. Detailed pretreatment assessment in studies of Crohn’s disease according to disease distribution with appropriate individualized tailoring of treatment may be important in this regard.     

Adaptation of hydrogen analysis to measure stomach to caecum transit time in the rat

Excreted hydrogen analysis was used to measure stomach to caecum transit time of the head of a test meal in 120 rats fed by gavage. Results were compared with the distribution of a labelled test meal in the gastrointestinal tract of rats killed at different time intervals after gavage. Values for stomach to caecum transit were compatible with the distribution of labelled meals in 91% of animals, although in the remainder the hydrogen concentration had not risen even though food residues were in the caecum when the animals were killed. The technique gave reproducible results; the coefficients of variation for four studies carried out in each of six animals varied between 4 and 14%. A meal consisting of homogenised baked beans had a significantly shorter stomach to caecum transit time (88.1 +/- 4.5 min; mean +/- SE; n = 21; p less than 0.001) than an equivalent volume of Complan/lactulose (180.9 +/- 8.7 min; n = 13). This technique was used to investigate the effect of ileal infusion of a fat emulsion (20% Intralipid) via a chronically implanted intestinal cannula on the stomach to caecum transit time of a bean meal, in a series of paired studies carried out in six rats. Stomach to caecum transit time was significantly delayed during ileal infusion of 20% Intralipid compared with the control infusion of an isotonic saline solution (218.3 +/- 21 min v 106.7 +/- 33 min Intralipid v saline; n = 6; p less than 0.001).     

Origin of gas retention and symptoms in patients with bloating

BACKGROUND & AIMS: Patients reporting abdominal bloating exhibit impaired tolerance to intestinal gas loads. The aim of this study was to identify the gut compartment responsible for gas retention. METHODS: In 30 patients predominantly reporting abdominal bloating (24 with irritable bowel syndrome and 6 with functional bloating) and 22 healthy subjects, gas (nitrogen, carbon dioxide, and oxygen) was infused into the intestine for 2 hours while measuring rectal gas outflow. First, in 12 patients and 10 healthy subjects, gas transit (24 mL/min jejunal infusion labeled with 74 MBq bolus of 133 Xe) was measured by scintigraphy. Second, in groups of patients and healthy subjects, the effects of gas infusion (12 mL/min) in the jejunum versus ileum, jejunum versus cecum, and jejunum versus sham infusion (n=6 each) were compared by paired tests. RESULTS: In patients, total gut transit of gas was delayed (50% clearance time, 33 +/- 4 min vs 23 +/- 4 min in healthy subjects; P <.05) owing to impaired small bowel transit (50% clearance time, 20 +/- 2 min vs 12 +/- 3 min in healthy subjects; P <.05), whereas colonic transit was normal (50% clearance time, 13 +/- 2 min vs 11 +/- 2 min in healthy subjects; not significant). Furthermore, jejunal gas infusion in patients was associated with gas retention (329 +/- 81 mL vs 88 +/- 79 mL in healthy subjects; P <.05), whereas direct ileal or colonic infusion was not (61 +/- 103 mL and -143 +/- 87 mL retention, respectively). CONCLUSIONS: In patients reporting bloating, the small bowel is the gut region responsible for ineffective gas propulsion.     

Scintigraphic demonstration of lactulose-induced accelerated proximal colon transit.

Although lactulose, a widely used cathartic, is known to increase stool frequency, details of its site of action in the colon are obscure. In the present study a noninvasive scintigraphic technique was used to closely follow the movements of proximal colonic contents. Lactulose, 10-20 mL three times daily, significantly accelerated mean transit through the ascending colon from 12.9 +/- 3.7 to 7.0 +/- 2.5 hours (n = 11; P less than 0.01). This was associated with the occurrence of mass movements, with six such events seen during lactulose treatment whereas only one was seen during the control study (P less than 0.05). Lactulose also accelerated movement through the rest of the colon so that at 24 hours after dosing the geometric center of the isotope bolus was distal to that seen during the control study (6.6 +/- 1.2 vs. 4.7 +/- 1.3; n = 11, P less than 0.001). This model of diarrhea in otherwise normal subjects was subsequently used to study the effects of viscous gels in diarrhea. The viscous and relatively poorly fermented gel ispaghula, 3.5 g three times daily, abolished mass movements and was associated with a small but significant increase in proximal colonic transit time, which increased from 6.1 +/- 2.1 to 7.7 +/- 1.5 hours (n = 8; P less than 0.05). By contrast, the viscous but readily fermentable gelling agent guar gum, 5 g three times daily, further accelerated the cathartic effect of lactulose, with the mean transit time decreasing from 6.4 +/- 2.3 to 4.7 +/- 1.7 hours (n = 8; P less than 0.05). The acceleration of proximal colonic transit by lactulose may be a useful model to study diarrhea and its modification by therapy.     

Assessment of orocaecal transit time in different localization of Crohn's disease and its possible influence on clinical response to therapy

BACKGROUND: A study on orocaecal transit time (OCTT) in patients with different localizations of Crohn's disease (CD) is not available. Because slow-release drug formulations are increasingly available for the treatment, there is a concrete risk that delayed OCTT may impair the efficacy of these formulations. AIMS: We investigated OCTT before and after therapy using lactulose H2-breath test and we studied whether OCTT can influence the clinical response to therapy with slow-release mesalazine formulations in adult CD patients.(2) PATIENTS AND METHODS: We studied 45 adult patients with non-obstructive CD and Crohn's Disease Activity Index (CDAI) <200 (29 men, 16 women; mean age 42 years, range 22-73 years). Twenty patients had ileocolonic, 16 colonic and 9 ileal localization of CD. The control group consisted of 20 healthy subjects (13 men, seven women; mean age 53 years, range 22-71 years). After OCTT assessment, 29 patients were treated with time-dependent mesalazine 3.6 g/day, while 16 patients were treated with pH-dependent mesalazine 3.6 g/day. If bacterial overgrowth was detected, the patients were also treated with rifaximin 800 mg/day for 7 days. RESULTS: OCTT was delayed (120 min, range 115-210 min) in 30 of the 45 CD patients (67%). Four patients (9%) showed bacterial overgrowth, while OCTT was regular (82.5 min, range 75-90 min) in 11 patients (24%). In the control group, the mean OCTT was 88.2 min (range 75-135 min); (P<0.01). OCTT was more prolonged in ileal localization (182.2 min, range 150-210 min), rather than in patients with ileocolonic (122 min, range 75-180 min) or colonic (106 min, range 75-150 min) localization of CD; (P<0.01). Thirty-nine patients showed normal OCTT after starting therapy (83 min, range 75-105 min), while OCTT remained slightly delayed in the remaining patients (110 min, range 105-115 min); (P<0.01). CDAI was <100 (mean value 83) in all patients with reduction of OCTT to normal value 4 months after starting therapy, while it was >140 (mean value 143) in patients with a slight reduction but not normalization of OCTT respectively (five patients with ileal and one with ileocolonic localization of CD) with a statistically significant correlation between OCTT and CDAI (P<0.01). CONCLUSIONS: This study shows clearly for the first time that OCTT is not only delayed in patients with active CD, but also that it is prolonged in ileal and ileocolonic rather than colonic localization of CD. Moreover we obtained these results using a simple, sensitive, non-invasive and repeatable method, namely, a lactulose hydrogen breath test.     

The gastrorectal reflex in women with obstructed defecation

This study evaluated the tonic response of the rectum to a meal in women with obstructed defecation. Fifteen control subjects and 60 women with obstructed defecation were studied. Total colonic transit time was normal in 30 patients (group I) and prolonged in the other 30 (group II). After over-night fasting an "infinitely compliant" polyethylene bag was inserted into the rectum. Rectal tone was assessed by measuring variations in bag volume with a computerized electromechanical air injection system. After an adaptation period of 30 min all subjects consumed a 450-kcal liquid meal. Postprandial recordings were continued for 3 h. In a second recording session we investigated the tonic response of the rectum to an evoked urge to defecate. In a third session rectal sensory perception was assessed. Following the meal all controls showed an increase in rectal tone (mean 74.8 +/- 17%). Patients in whom colonic transit time was normal showed a similar tonic response. In group II the increase in rectal tone was significantly lower (mean 27.8 +/- 10%; P < 0.001). Three patients of this group showed no response to a meal at all. All controls showed an increase in rectal tone during an evoked urge to defecate (mean 39.2 +/- 9%). In both groups this tonic response was absent or significantly blunted (mean 15.3 +/- 6% and 16.4 +/- 5%, respectively; P < 0.001). In both groups rectal sensory perception was significantly impaired. In conclusion, patients with obstructed defecation in whom colonic transit time is normal have an intact gastrorectal reflex. The increase in rectal tone after a meal is absent or blunted in patients with obstructed defecation in whom transit time is prolonged. The tonic response of the rectum to an evoked urge to defecate as well as rectal sensory perception are significantly impaired both in patients with a normal and in those with a prolonged transit time.     

The ileal brake--inhibition of jejunal motility after ileal fat perfusion in man

The possibility that malabsorbed fat passing through the human ileum exerts an inhibitory feedback control on jejunal motility has been investigated in 24 normal subjects by perfusing the ileum with a fat containing solution designed to produce ileal luminal fat concentrations similar to those in steatorrhoea (30-40 mg/ml). Mean transit times through a 30 cm saline perfused jejunal segment were measured by a dye dilution technique. Thirty minutes after ileal fat perfusion, mean transit times rose markedly to 18.9 +/- 2.5 minutes from a control value of 7.5 +/- 0.9 minutes (n = 5; p less than 0.05). This was associated with an increase in volume of the perfused segment which rose to 175.1 +/- 22.9 ml (control 97.6 +/- 10.3 ml, n = 5; p less than 0.05). Transit times and segmental volumes had returned towards basal values 90 minutes after completing the fat perfusion. Further studies showed that ileal fat perfusion produced a pronounced inhibition of jejunal pressure wave activity, percentage duration of activity falling from a control level of 40.3 +/- 5.0% to 14.9 +/- 2.8% in the hour after ileal perfusion (p less than 0.01). Ileal fat perfusion was associated with marked rises in plasma enteroglucagon and neurotensin, the peak values (218 +/- 37 and 68 +/- 13.1 pmol/l) being comparable with those observed postprandially in coeliac disease. These observations show the existence in man of an inhibitory intestinal control mechanism, whereby ileal fat perfusion inhibits jejunal motility and delays caudal transit of jejunal contents.     

Reflux from ileum to colon in the dog

In four dogs we quantified the role of external (coloileal) ligaments in preventing coloileal reflux. All animals were tested under control conditions, and then two had all external ligamentous attachments between ileum and colon divided; the other pair underwent a sham operation. Coloileal reflux was quantified scintigraphically at colonic pressures of 20, 40, and 60 mm Hg, and ileal motility was recorded concurrently. During control experiments and after sham operations, no dogs showed coloileal reflux at colonic pressures of 20 and 40 mm Hg. At a colonic pressure of 60 mm Hg, two control experiments and one in a dog after sham operation resulted in reflux of 9%, 4%, and 8% of counts, respectively. In contrast, both test dogs (after division of the ligaments) refluxed 30–70% of colonic content in all of four experiments at pressure below 20 mm Hg. In control dogs and in those with a continent ileocolonic junction, ileal motility consisted of scattered clusters of phasic contractions. In dogs with coloileal reflux, these clusters occurred with a similar frequency, but they lasted longer (P <0.005). Four weeks later, ileal motility indices in control dogs were significantly less (P <0.02) than in animals with divided coloileal ligaments. These observations establish an experimental model for coloileal reflux, support the hypothesis that external ligamentous attachments help maintain continence at the ileocolonic junction, and imply that coloileal reflux changes the motor pattern of the terminal ileum.     

Effect of ileal infusion of intralipid on gastrointestinal transit, ileal flow rate, and carbohydrate absorption in humans after ingestion of a liquid meal

The effects of ileal infusion of Intralipid on the time required for a radiolabeled liquid starch meal to empty from the stomach and reach a point in the ileum that was 230 cm from the teeth and on the ileal flow rates and the degree of carbohydrate absorption were measured in 5 normal volunteers. The subjects were intubated with a four-lumen polyvinyl tube. Studies were carried out on consecutive days in random order. Infusion of fat into the ileum (a) slowed the transit of a liquid meal through the stomach, (b) delayed the arrival of the liquid meal in the ileum and increased its residence in the upper small intestine, (c) reduced the average flow of digesta through the upper small intestine and altered the pattern of flow, (d) reduced the volume of the meal entering the ileum, and (e) reduced the degree of carbohydrate absorption in the upper small intestine. These results suggest that the presence of fat in the ileum may have a profound influence on the digestion and absorption of a meal.