Colonic Motor Activity Research Articles

Cholinergic and nitrergic regulation of in vivo giant migrating contractions in rat colon.

The aim of this study was to characterize in vivo rat colonic motor activity in normal and inflamed states and determine its neural regulation. Circular muscle contractions were recorded by surgically implanted strain-gauge transducers. The rat colon exhibited predominantly giant migrating contractions (GMCs) whose frequency decreased distally. Only a small percentage of these GMCs propagated in the distal direction; the rest occurred randomly. Phasic contractions were present, but their amplitude was very small compared with that of GMCs. Inflammation induced by oral administration of dextran sodium sulfate suppressed the frequency of GMCs in the proximal and middle but not in the distal colon. Frequency of GMCs was suppressed by intraperitoneally administered atropine and 4-diphenylacetoxy-N-methyl-piperidine methiodide and was enhanced by N(w)-nitro-L-arginine methyl ester. Serotonin, tachykinin, and calcitonin gene-related peptide receptor or receptor subtype antagonists as well as guanethidine and suramin had no significant effect on the frequency of GMCs. Verapamil transiently suppressed the GMCs. In conclusion, unlike the canine and human colons, the rat colon exhibits frequent GMCs and their frequency is suppressed in inflammation. In vivo GMCs are stimulated by neural release of acetylcholine that acts on M3 receptors. Constitutive release of nitric oxide may partially suppress their frequency.

Rectal and colonic distension elicit viscerovisceral reflexes in humans.

Colonic transit is slowed in patients with disordered rectal evacuation, but the mechanism of this phenomenon is unclear. Our objective was to investigate rectocolonic inhibitory reflexes in humans to provide potential insight into patients with obstructed defecation. In 30 healthy subjects, a barostat-manometric assembly recorded colonic tone and phasic activity in the descending colon during rectal distension and recorded rectal tone during colonic distension. Phasic distensions were 8, 16, and 32 mmHg above balloon operating pressure, and staircase inflations were comprised of balloon inflation then deflation in 2-mmHg increments at 30-s intervals from 0 to 36 mmHg. Colonic balloon volumes increased to a similar extent during phasic rectal distensions 8, 16, and 32 mmHg above operating pressure, reflecting reduced colonic tone; balloon volumes also increased and phasic pressure activity decreased during staircase rectal distensions. In contrast, rectal balloon volume declined, reflecting increased tone during phasic and staircase colonic distensions. Thus rectal distension inhibited colonic motor activity, indicative of a viscerovisceral inhibitory reflex.

Periodic colonic motor activity identified by 24-h pancolonic ambulatory manometry in humans.

The pattern of colonic motor activity in healthy humans has not been fully elucidated to date. The aim of this study was to evaluate colorectal motor activity employing 24-h ambulant pancolonic manometry. Ten healthy volunteers (6F, 4M), aged 19-31 years were studied. Motor activity was measured using two custom-made silicone coated catheters, each with five solid-state pressure transducers. No bowel preparation or sedation was used. The study period was 24 h. A total of 232 h of recording was obtained. Sixty-three high amplitude propagated contractions were observed, median six per 24-h period. Low-amplitude colonic contractile activity showed regional and diurnal variations. Frequency of contraction was highest in the right colon [median 5.26 cpm (cycles per minute)], and transverse colon and splenic flexure (median 5.15 cpm). The interval between colonic motor complexes was shortest in the transverse colon and splenic flexure. This study introduces a new technique for the evaluation of colorectal motor activity. Subjects were studied in an ambulant setting in their own environment ensuring that this method of study is as physiological as possible. This study demonstrates that colonic motor activity has two main components: high amplitude propagated contractions and low amplitude colonic contractile activity.

The proximal colonic motor response to rectal mechanical and chemical stimulation.

We aimed to determine whether rectal distension and/or infusion of bile acids stimulates propagating or nonpropagating activity in the unprepared proximal colon in 10 healthy volunteers using a nasocolonic manometric catheter (16 recording sites at 7.5-cm spacing). Sensory thresholds and proximal colonic motor responses were assessed following rectal distension by balloon inflation and rectal instillation of chenodeoxycholic acid. Maximum tolerated balloon volume and the volume that stimulated a desire to defecate were both significantly (P < 0.01) reduced after rectal chenodeoxycholic acid. The frequency of colonic propagating pressure wave sequences decreased significantly in response to initial balloon inflations (P < 0.05), but the frequency doubled after subsequent chenodeoxycholic acid infusion (P < 0.002). Nonpropagating activity decreased after balloon inflation, was not influenced by acid infusion, and demonstrated a further decrease in response to repeat balloon inflation. We concluded that rectal chenodeoxycholic acid in physiological concentrations is a potent stimulus for propagating pressure waves arising in the proximal colon and reduces rectal sensory thresholds. Rectal distension inhibits all colonic motor activity.

Distal colonic motor activity in four subgroups of patients with irritable bowel syndrome.

With the aim of improving end organ treatment, we describe a new system of classifying irritable bowel syndrome (IBS) according to clinical features into four groups, spastic colon syndrome (SCS), functional diarrhea (FD), diarrhea-predominant spastic colon syndrome (DPSCS), and midgut dysmotility (MGD). The aim of the study was to investigate fasting and postprandial distal colonic motility in the four groups of patients and to compare the results with normal controls. Distal colonic motility studies were performed in the unprepared colon. 2.5-hr recordings were made from four channels with a standard meal administered at 0.5 hr. The intubated colon was treated as a study segment and data analyzed for study segment activity index (SSAI) and number and mean amplitude of pressure peaks over 30-min epochs. Patients with SCS had significantly higher (P < 0.05) mean amplitude of pressure peaks (60 min, 120 min) and SSAI (120 min) than controls and patients with FD, DPSCS, and MGD. In contrast, patients with FD and DPSCS had significantly (P < 0.05) lower postprandial SSAI than controls and patients with SCS (60 min, 120 min). With the exception of raised postprandial mean amplitude of pressure peaks (120 min), MGD patients had normal distal colonic motility. Division of IBS patients into subgroups has highlighted significant differences in distal colonic motility that provide insights into etiopathogenesis and should assist targeting of current and newly developed therapies, particularly receptor active agents.

Electrophysiologic identification of the location of the colonic pacemakers. A human study.

Colonic inertia, total or segmental, is a known cause of constipation, yet its etiology is poorly understood and its treatment not satisfactory. Although the colonic electric activity has been studied by many investigators, the colonic pacemakers that are assumed to generate the electric waves, are scarcely addressed and their location, to our knowledge, has not been determined. The current communication investigates the possible sites of the colonic pacemakers, aiming at a better understanding of the mechanism of colonic motility and its disorders, notably colonic inertia. The tests were performed during the repair of huge incisional hernia in 12 subjects (mean age 37.7 +/- 10.2 years, 7 women). Monopolar silver-silver chloride electrodes were applied to the terminal ileum (TI) and cecum (C), and to the ascending (AC), transverse (TC), descending (DC) and sigmoid colon (SC); they were fixed by electrode gel to the ileal and colonic serosa. The electric activity of each of the TI, C, AC, TC, DC and SC was recorded. Electric waves in the form of slow waves or pacesetter potentials and action potentials were recorded from the TI and colon. Differences in the frequency, amplitude and conduction velocity of the waves occurred between the TI and the various segments of the colon. The change in the wave variables between the TI and C occurred at the ileocecal junction, between the C and AC at the cecocolonic junction, the AC and TC at the mid third of the TC and the DC and SC at the colosigmoid junction. The colonic electric waves are suggested to be generated by at least 4 pacemakers, which are presumably located at the ileocecal junction, the cecocolonic junction, the mid third of TC and at the colosigmoid junction. The electric waves appear to be responsible for conducting the colonic motor activity. We postulate that disordered colonic pacemakers may produce segmental or total colonic inertia, a proposition that needs further investigation.

Total colonic manometry as a guide for surgical management of functional colonic obstruction: Preliminary results

Background/Purpose: Functional colonic obstruction (pseudo-obstruction) encompasses a broad group of motility disorders. Medical management of colonic pseudo-obstruction is complex and often fails, leading to surgical referral. In most cases (excepting Hirschsprung's disease) the surgeon is unable to precisely localize the area of functional obstruction. Total colonic manometry can directly measure intraluminal pressures and contractile function along the entire length of the colon. The authors propose that total colonic manometry can be used by the pediatric surgeon to guide the timing and extent of surgical therapy in refractory functional colonic obstruction. Methods: Four patients were evaluated for functional colonic obstruction. All underwent barium enema and rectal biopsy with a diagnosis of Hirschsprung's disease in one patient. All patients underwent colonoscopy and total colonic manometry. Manometric tracings were obtained while fasting, after feeding, and after pharmacologic stimulation both preoperatively (n = 4) and postoperatively (n = 3). Results: Total colonic manometry identified an abrupt end of normal peristalsis in 2 of the non-Hirschsprung's patients (one in the proximal colon and one in the transverse colon). Medical therapy failed in both of these patients, and they underwent diverting ostomy proximal to the loss of normal peristalsis. The third non-Hirschsprung's patient essentially had normal manometry and was able to have her colon decompressed successfully on a laxative regimen. Repeat manometry after colonic decompression showed return of normal peristalsis in 2 of these patients and continued abnormal peristaltic activity in the third. Definitive surgical intervention based on the results of total colonic manometry was performed on the latter. All 3 patients achieved normal continence. A fourth patient had Hirschsprung's disease confirmed by rectal biopsy and underwent a 1-stage neonatal modified Duhamel procedure, which was complicated by postoperative functional obstruction. Manometry showed a lack of peristaltic function beginning in the right colon. An ileostomy was performed, and timing of ileostomy closure was guided by the return of normal colonic peristalsis seen on manometry. Conclusions: These initial cases show the utility of total colonic manometry in the management of colonic pseudo-obstruction syndromes. In addition to its diagnostic utility, direct measurement of colonic motor activity can be valuable in deciding the need for and timing of diversion, the extent of resection, and the suitability of the patient for restoring bowel continuity. In Hirschsprung's disease, total colonic manometry can potentially be used to determine suitability for primary neonatal pull-through versus a staged approach. J Pediatr Surg 36:1757-1763. Copyright © 2001 by W.B. Saunders Company.

Descartes and the gut: “I'm pink therefore I am”

See articles on pages 209 and 214 In 1637 Rene Descartes wrote “The soul by which I am, what I am, is entirely distinct from my body and even if...

CCK-1 and CCK-2 receptors mediate differential effects of cholecystokinin on the motor activity of distal colon

CCK-1 and CCK-2 receptors mediate differential effects of cholecystokinin on the motor activity of distal colon

CCK-1 and CCK-2 receptors mediate differential effects of cholecystokinin on the motor activity of distal colon

CCK-1 and CCK-2 receptors mediate differential effects of cholecystokinin on the motor activity of distal colon

Oxytocin stimulates colonic motor activity in healthy women

Oxytocin stimulates colonic motor activity in healthy women

Oxytocin stimulates colonic motor activity in healthy women

Oxytocin stimulates colonic motor activity in healthy women

Effects of VIP and NO on the motor activity of vascularly perfused rat proximal colon

The effects of vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) on the motor activity of the rat proximal colon were examined in an ex vivo model of vascularly perfused rat proximal colon. VIP reduced motor activity and this inhibitory effect was not altered by either atropine, hexamethonium, tetrodotoxin (TTX) nor TTX plus acetylcholine (ACh), but was completely antagonized by NO synthase inhibitor N G-nitro-L-arginine (L-NA) and by VIP receptor antagonist, VIP(10–28). These results suggest that VIP may exert a direct inhibitory effect on the motor activity of the rat proximal colon via a VIP receptor located on the smooth muscle and this effect is mediated by NO but not by cholinergic pathways. Atropine and hexamethonium reduced but ACh stimulated motor activity and the effect of ACh was not changed by TTX, suggesting that the cholinergic pathway may exert a direct stimulatory effect on motor activity. Single injection of TTX, VIP(10–28) or L-NA induced a marked increase in motor activity, suggesting that the motor activity of rat proximal colon is tonically suppressed by VIP and NO generating pathways, and elimination of inhibitory neurotransmission by TTX may induce an abnormal increase of the motor activity. The interaction between VIP and NO in regulation of motor activity was further examined by a measurement of NO release from vascularly perfused rat proximal colon. Results showed that NO release was significantly increased during infusion of VIP and this response was reversed by L-NA. These results suggest that VIP generating neurons may inhibit colonic motility by stimulating endogenous NO production in either smooth muscle cells or nerve terminals.

Peripheral corticotropin-releasing factor and stress-stimulated colonic motor activity involve type 1 receptor in rats

Background & Aims: Corticotropin-releasing factor (CRF) exerts its action through CRF receptors 1 and 2 (CRF-R1 and CRF-R2). CRF has preferential affinity for CRF-R1, whereas urocortin displays high affinity for both. We investigated changes in colonic motor function after intraperitoneal (IP) injection of CRF-related peptides. Methods: Colonic motility was recorded in vivo in conscious rats equipped with electrodes chronically implanted in the cecum and proximal colon or in vitro in distal colon; fecal output was monitored in naive rats. Results: Rat CRF, rat urocortin, and amphibian sauvagine (10 μg/kg, IP) induced a new pattern of cecocolonic myoelectric activity characterized by clustered spike bursts of long duration; the percentage of occurrence was highest after CRF. The rank order of potency to increase fecal pellet output after IP peptide injection (0.3–10 μg/kg, IP) was CRF > urocortin = sauvagine. The CRF-R1/R2 antagonist astressin (33 μg/kg, IP) and the CRF-R1 antagonist CP-154,526 (20 mg/kg, subcutaneously) inhibited IP CRF-induced changes in cecocolonic myoelectric activity and IP CRF- and water avoidance stress–induced fecal output. In vitro, CRF injected into the inferior mesenteric artery increased distal colonic myoelectric activity compared with saline injection. Conclusions: These results demonstrate that CRF acts peripherally to stimulate colonic motility and that CRF-R1 is primarily involved in mediating IP CRF/urocortin– and water avoidance stress–induced colonic motor response.GASTROENTEROLOGY 2000;119:1569-1579

Effects of a serotonin 5-HT4 receptor antagonist SB-207266 on gastrointestinal motor and sensory function in humans

BACKGROUNDSerotonin 5-HT4 receptors are located on enteric cholinergic neurones and may regulate peristalsis. 5-HT4 receptors on primary afferent neurones have been postulated to modulate visceral sensation. While 5-HT4 agonists are...

Effects of polyethylene glycol 4000 on twenty hours manometric recordings of colonic motor activity

Effects of polyethylene glycol 4000 on twenty hours manometric recordings of colonic motor activity

Chapter 29 Towards an integrative model of irritable bowel syndrome

It is being increasingly recognized that a significant amount of human suffering, medical costs, and general loss of productivity can be attributed to what traditionally has been labeled “functional” medical disorders or syndromes. Symptoms of functional disorders may appear in almost any organ system and take a variety of forms, but most common are symptoms of pain, discomfort, and loss of vitality. Functional disorders are characterized by the lack of a detectable organ lesion to account for these symptoms, which can vary from mild and infrequent to severe, continuous, and disabling. Biobehavioral models of chronic medical conditions have as their goal the integration of cognitive, behavioral, and neuroscience perspectives. While it is generally accepted that all chronic and uncomfortable conditions can in theory, be better understood if a multifactor approach is taken, it is much more difficult to describe specifically the mechanisms by which cognitive, affective and sensory processes produce symptoms and complex behaviors such as disability. This chapter discusses the application of such an integrative approach to one common functional disorder, irritable bowel syndrome. This chapter: (a) briefly reviews evidence that links psychological, colonic motor activity, and visceral sensory processes individually with the development and maintenance of IBS symptoms, (b) describes the use of evolving human experimental paradigms to study visceral psychophysiology in IBS, (c) based on recent findings, presents a preliminary biobehavioral model of IBS, which integrates neurophysiological, perceptual, and behavioral processes, and (d) describes how psychological and physiological treatment approaches can be integrated into this model.

Effects of Neural Blocking Agents on Motor Activity and Secretion in the Proximal and Distal Rat Colon: Evidence of Marked Segmental Differences in Nicotinic Receptor Activity

Background: Neuromodulation may be a new therapeutic approach in inflammatory bowel disease, but very little is known about neural control of colonic secretion in vivo. We therefore determined the effects of neural blockade on colonic motor activity and mucosal secretion in anaesthetized rats. Methods: A proximal and a distal colonic segment were isolated in four groups of chloralose-anaesthetized rats (n = 8 in each group), and we measured luminal pressure and transmural potential difference (PD) as a marker of electrogenic chloride secretion. Recordings were made from proximal and distal segments simultaneously, which made it possible to directly compare response patterns. Results: Under control conditions luminal pressure waves were associated with phasic, lumen-negative increases in PD which had a significantly greater magnitude and longer duration in the distal colon. Atropine blocked both pressure waves and PD waves in the proximal colon, but some PD waves, although of lower magnitude, remained in the distal colon. Hexamethonium abolished pressure waves in both segments and induced a marked reduction in PD in the distal but not in the proximal colon. Lidocaine also reduced PD, more so in the distal colon, and dissociated the pressure-PD linkage. Conclusion: In the distal but not in the proximal colon, there is a strong nicotinic, neurogenic `tone' that maintains a high basal secretory activity. The results encourage the search for neuromodulatory agents in the treatment of colonic secretory disease.

Role of anger in antral motor activity in irritable bowel syndrome.

There is considerable evidence indicating that patients with irritable bowel syndrome respond to emotional and environmental stimulation with increased colon motor activity. It has been suggested also that increased colon motor activity is not confined to the colon and may be representative of a broader disorder affecting the rest of the gastrointestinal tract in this population. The results of our current study suggest that anger may have a significant, although differential effect on antral motor activity in IBS patients compared to normal controls. We found that while antral motor activity did not differ significantly in our groups during rest, anger decreased antral motor activity in IBS patients and increased antral motor activity in normal controls. The difference was not attributable to a difference in anger levels since the groups did not differ in their response to the standardized anger stressor. Rather, the difference in the antral motor response appears to be qualitative and a possible marker for irritable bowel syndrome. Our data further suggest that increased colon motor activity in IBS patients during emotional stress is not a result of a rise in motor activity throughout the gastrointestinal tract, but a phenomenon that may be unique to the colon in this patient population.

Endoluminal Instillation of Bisacodyl inPatients with Severe (Slow Transit Type)Constipation Is Useful to Test Residual ColonicPropulsive Activity

Background: Chronic constipation is a frequent symptom among the general population, and a minority of cases do not respond to any therapeutic measures, except surgery. The purpose of this study was to test the residual colonic motor propulsive activity with a pharmacologic stimulus in a series of patients referred for severe constipation. Patients: Twenty-five chronically constipated patients, slow transit type, age range 16–71 years, unresponsive to conventional medical treatment and referred for functional evaluation, entered the study. Methods: Colonic manometry by means of an endoscopically positioned probe was carried out in all patients. Following a basal recording period, a placebo solution followed by 10 mg bisacodyl solution was infused into the colon through the more proximal recording port. Results: After bisacodyl infusion, about 90% of patients showed a motor response characterized by the appearance (within on average 13 ± 3 min) of one or more high-amplitude propagated contractions, the manometric equivalent of mass movements, and about 75% of these were followed (mean 18.5 ± 4 min) by defecation. Conclusions: Physiological and pharmacological testing of colonic motor activity may be important in severely constipated patients, especially in those labeled as ‘intractable’, in whom more in depth investigation planning may encourage further therapeutic efforts.