How does morphine work on colonic motility? An electromyographic study in the human left and sigmoid colon.

The effect of morphine on colonic motility was investigated by recording the colonic myoelectric spiking activity by means of a 50 cm long silastic tube equipped with 4 bipolar AgAgCl ring electrodes fixed at 10 cm intervals that was introduced into the left colon in 8 healthy subjects by flexible sigmoidoscopy. Tracings were obtained for 1 hour in the fasting state and for another 1 hour after i.m. injection of morphine sulphate 0.15 mg/kg. The different types of spike bursts were compared before and after morphine injection. The control tracings showed that the spiking activity of the colon was made of 2 types: 1)- Rhythmic Stationary Spike Bursts (RSB), that were seen at only one electrode site; 2)- Sporadic Bursts, that were either propagating over all 4 electrodes (SPB) or non propagating (SNPB). Injection of morphine was followed by 1)- a considerable increase in the number of RSB from 107 +/- 43 bursts/hour (mean +/- SEM) to 491 +/- 23 bursts/hour; 2)- the complete disappearance of the SPB dropping from 7.3 +/- 2.0 bursts/hour to 0.3 +/- 0.2 bursts/hour; 3)- no significant change in SNPB (from 52 +/- 4 bursts/hour to 57 +/- 5 bursts/hour). These results indicate that 1)- stimulation of colonic smooth muscle activity by morphine seems to result from an increase in the number of rhythmic stationary bursts; 2)- however inhibition of colonic transit may be related to the decrease in the number of sporadic propagating bursts.

[Constipation caused by colonic inertia and distal obstruction: electromyographic study]. / Constipation par inertie colique et obstruction distale: étude électromyographique.

Colonic motility was evaluated in 15 patients with chronic constipation and 12 healthy subjects by both measuring the transit time of 20 radiopaque markers and recording the colonic myoelectric signals by means of a silastic tube equipped with 4 ring contact electrodes. The tube was introduced by flexible sigmoidoscopy so as the electrodes be located at 50, 40, 30 and 20 cm from the anal verge. Constipation resulted from colonic inertia in 7 patients, the markers being delayed over the whole length of the colon. In the 8 other patients, constipation was due to distal obstruction, the markers accumulating electively in the rectum. The myoelectric tracings showed in the control subjects, on one hand rhythmical stationary spike potentials that occurred at only one electrode site at a mean rate of 10 per minute; on the other hand sporadic (non-rhythmic) spike potentials that were either propagating over the colonic segment (sporadic propagating potentials) or not (sporadic non-propagating potentials). In the constipated patients, the following changes were observed: 1) the number of sporadic propagating potentials was significantly decreased in colonic inertia (2.5 +/- 1.3 bursts of spikes per hour) compared to the controls (8.5 +/- 1.1 bursts/h) or distal obstruction (7.9 +/- 1.3 bursts/h); 2) sporadic propagating potentials usually moved aborally; however, 19.8 +/- 0.9 p. 100 moved orally in colonic obstruction, while 4.6 +/- 0.2 p. 100 in the controls and 4.7 +/- 0.1 p. 100 in colonic inertia.(ABSTRACT TRUNCATED AT 250 WORDS)

[Vasopressin and colonic motility]. / Vasopressine et motilité colique.

Vasopressin (VS) has been reported to stimulate colonic peristalsis in different therapeutic conditions. In order to determine the mechanisms involved in this effect, colonic function was studied with three different techniques staying: a) the transit time of radioopaque markers through the colon was measured in 7 healthy subjects after VS IM (0.3 U/kg of weight). A marked propulsive effect was observed. One hour after injection, 64.7 +/- 16.2 p. 100 of the markers (m +/- sem) had left the right colon vs 9.1 +/- 4.6 p. 100 after injection of NaCl (p less than 0.01) and 70.5 +/- 10.8 p. 100 of the markers emptied from the left colon vs 4.3 +/- 4.5 p. 100 after NaCl (p less than 0.01); b) an electromyographic study was carried out in 6 other healthy subjects with an intraluminal device equipped with contact electrodes, introduced into the left colon by colonoscopy. The injection of VS was followed by an increase in the number of the propagating electrical spike bursts that are known to correlate well with the propulsion of the colonic intraluminal contents. The number of bursts was 2.7 +/- 0.6 bursts/30 min after NaCl and 5.2 +/- 1.4 bursts/30 min after VS (p less than 0.02); c) finally, the outflow of ileostomies and colostomies was measured in respectively 3 and 8 subjects over one h after IM 0.3 U/kg of VS. A considerable increase in the outflow of intestinal fluids was observed: output from the colostomies was 10 +/- 10 ml/h after NaCl and 250 +/- 39 ml/h after VS (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Myoelectrical activity and intraluminal flow in human sigmoid colon.

Myoelectric spike bursts were recorded in the sigmoid colon by means of an intraluminal silastic tube equipped with 3 Ag-AgCl ring electrodes fixed 15 cm apart on the tube that was introduced by flexible sigmoidoscopy. In six subjects, the tube was also equipped with three catheters whose tip opened 1 cm aborad from each electrode, for pressure recordings. In six other subjects, the tube was equipped with both electrodes and a catheter opening at the tip of the probe for infusing fluids at a rate of 12 ml/min into the colonic lumen. The fluid was collected with another tube inserted in the rectum and the volume was measured at 1-min intervals. Colonic spiking activity was made of rhythmic stationary bursts (RSB) and of sporadic bursts that were either propagating (SPB) or not propagating (SNPB). All sporadic bursts were associated with intraluminal pressure waves whose amplitude was significantly higher than that associated with rhythmic bursts. In the infusion experiments, the volume of fluid collected did not change significantly whether rhythmic bursts were present or not (3.9 +/- 1.7 ml/min and 3.3 +/- 1.9 ml/min respectively) (mean +/- SD). However, the volume was significantly higher when sporadic nonpropagating bursts were present (9.4 +/- 4.1 ml/min), and even higher when the sporadic bursts were propagating (21.6 +/- 8.8 ml/min). These results indicate that the occurrence of sporadic bursts, particularly when propagating, is associated with intraluminal pressure waves that lead to significant propulsive movements; and rhythmic bursts do not seem to be involved in colonic propulsive activity.

Changes in colonic myoelectric spiking activity during stimulation by bisacodyl.

The purpose of this study was to determine some relationships between colonic myoelectric spiking activity and intraluminal propulsion when colonic peristalsis was stimulated by bisacodyl. Myoelectric recordings were obtained in 12 subjects by means of a 50 cm long Silastic tube equipped with four bipolar electrodes fixed at 10-cm intervals. The tube was introduced into the left colon by flexible sigmoidoscopy and the electrodes were located at 50, 40, 30, and 20 cm from the anal verge. A small polyethylene catheter opening at the proximal end of the Silastic tube was used for introducing the laxative into the colon. One hour recording sessions were obtained before and after bisacodyl administration (5 mL of 0.4% solution). The control tracings showed that colonic spiking activity was made of rhythmic stationary bursts that occurred at only one electrode site and of sporadic bursts that were either propagating over the whole colonic segment or nonpropagating. Administration of bisacodyl was followed by complete suppression of the rhythmic stationary activity; a considerable increase in the sporadic spiking activity, propagating as well as nonpropagating; the occurrence of abdominal cramps and urgency to defecate, both associated with the propagating sporadic spike bursts. It is concluded that colonic propulsion induced by bisacodyl may be dependent upon the production of the sporadic bursts, particularly the propagating ones, while the rhythmic stationary bursts do not seem to play a significant role in colonic transit.

Effects of rest, stress, and food on myoelectric spiking activity of left and sigmoid colon in humans.

The great variability which is known to affect colonic motility may partly be the result of changes in physiological conditions. In order to test this hypothesis, 40 subjects were sequentially put in conditions of vigilance, rest, stress, and feeding while colonic motility was monitored. The myoelectric spiking activity of the left colon was recorded with a 50-cm-long silastic tube equipped with four bipolar ring electrodes (located 10 cm apart) introduced into the left colon by flexible sigmoidoscopy. Tracings were performed while the subjects were kept awake (by conversation) for 1 hr, put at rest (quiet) for another 1 hr, submitted to a stress (by alternatively immersing and removing one hand from 2-4 degrees C cold water) for 20 min, and finally recorded for 2 hr after a 800-kcal meal. In 18 other subjects, the sequences of vigilance and rest were randomized. The results showed that colonic spiking activity was made of sporadic bursts that are known to be associated with intraluminal propulsion and of stationary bursts that probably play no role in colonic peristalsis. The duration of sporadic spiking activity was respectively 13.6 +/- 1.2 min/hr (mean +/- SEM) during the period of vigilance, 5.4 +/- 0.6 min/hr during the period of rest (P less than 0.001), 14.3 +/- 1.0 min/hr during the period of stress (NS), and 16.8 +/- 1.2 min/hr after a meal (P less than 0.05). The duration of stationary spiking activity did not change significantly throughout the four periods, respectively, 6.6 +/- 4.9, 4.4 +/- 3.7 (NS), 5.2 +/- 3.9 (NS), and 3.3 +/- 2.8 min/hr (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemic fecal incontinence and rectal angina.

In 36 patients who consulted for fecal incontinence or rectal pain, or both, there was grossly visible scarring of the rectum and biopsy revealed mucosal atrophy and fibrosis. A steal from the hemorrhoidal arteries to the iliac vessels was demonstrated in 3 subjects. Maximum tolerable volumes within a rectal balloon were smaller than in control subjects, both in men (192 vs. 273 ml) and in women (142 vs. 217 ml) (p less than 0.01). The rectoanal inhibitory reflex was abnormal in all but 1 patient. Specific abnormalities were a decreased amplitude or a prolonged duration of the reflex. It was totally absent in 2 patients. This study is compatible with the hypothesis that chronic ischemia of the rectum may cause fecal incontinence or rectal pain.

Anismus as a marker of sexual abuse. Consequences of abuse on anorectal motility.

Anorectal manometry was performed in 40 women, who consulted for functional disorders of the lower gastrointestinal tract and had been sexually abused. Anismus, defined as a rise in anal pressure during straining, was observed in 39 of 40 abused women, but in only six of 20 healthy control women (P < 0.0001). Other parameters of anorectal manometry were compared with those observed in another control group composed of 31 nonabused women but with anismus, as well as the group of healthy controls. A decreased amplitude of anal voluntary contraction and an increased threshold volume in perception of rectal distension were observed in both abused and nonabused patients. A decreased amplitude of rectoanal inhibitory reflex, little rise in rectal pressure upon straining, frequent absence of initial contraction during rectal distension, and increased resting pressure at the lower part of the anal canal were observed in abused but not in nonabused patients, suggesting that these abnormalities, in association with anismus, suggest a pattern of motor activity in the anal canal that could be indicative of sexual abuse.

Megarectum.

Evaluation of the rectum by barium enema does not correlate well with rectometrographic studies and is not predictive of bowel function. The purpose of the present study was to describe clinical and functional data in patients with chronic idiopathic constipation, where a megarectum was diagnosed by a rectometrogram. Among 355 patients who underwent rectal elasticity studies, 35 were found to have a megarectum (maximum tolerable volume above 320 ml in women and 440 in men) for which no specific etiology was recognized. They, and a group of 11 healthy controls who were not sensitive to stress, underwent studies of stool frequency, colonic transit time of radiopaque markers, rectal elasticity, and anorectal pressures and reflexes. The elasticity coefficient of the rectal wall was decreased in patients as compared to controls (P less than 0.01). Seven patients had onset of symptoms at birth, with maximum tolerable volume in the rectum between 460 and 900 ml, and all were incontinent for feces. Studies of colonic transit times demonstrated normal function in the right and left colon, but there was rectosigmoid stagnation (transit time of 122 +/- 17 hr vs 8 +/- 2 in stress-free controls; X +/- SE; P less than 0.001). In the other 28 patients (late-onset megarectum), in contrast to the congenital group, there was a marked female preponderance, and their recorded stool frequency (4 +/- 0.7/week) was greater than the recalled frequency (1.4 +/- 0.2/week; P less than 0.001). Only half suffered from fecal incontinence. They did not have a greater rectal capacity when colonic transit times were prolonged (455 +/- 27 ml) than when normal (422 +/- 27). Rectal pressure was similar at the level of conscious sensation of filling, regardless of rectal capacity, suggesting a motor, rather than a sensory, abnormality. The amplitude of the rectoanal inhibitory reflex was decreased (P less than 0.001) as compared to controls, sometimes mimicking the findings of Hirschsprung's disease, but increasing rectal distension always induced a relaxation of the internal anal sphincter. The notion of a megarectum, which tolerates large amounts of fluid without sensation, lacks elasticity, and is accompanied by an abnormal rectoanal inhibitory reflex, provides an explanation for one of the mechanisms of constipation by outlet obstruction.

Prevalence of sexual abuse among patients with functional disorders of the lower gastrointestinal tract.

To evaluate the links between gastrointestinal disorders and sexual abuse, we asked 344 patients consulting in a specialized tertiary care university hospital or a gastroenterologist in private practice, if they had been sexually abused. Forty per cent of patients suffering from lower functional digestive disorder gave a history of having been victims of sexual abuse in contrast to only 10% of patients with organic diseases (P < 0.0003). The prevalence was similar in private practice and in the university hospital. Abused patients were more likely to complain of constipation (P < 0.03) and diarrhoea (P < 0.04). Anismus was more frequent in patients who had been sexually abused (P < 0.02). The prevalence of abuse was four times greater in patients with lower than with upper functional motor disorders of the gastrointestinal tract (P < 0.002). This study confirms the large prevalence of a past history of sexual abuse among patients consulting for gastrointestinal tract functional disorder, and this whatever the kind of recruitment may be. It shows the association to be much stronger in patients who have a lower rather than an upper gastrointestinal dysfunction, the major complaint of abused patients being constipation and diarrhoea.