Effect of an oral beta2-adrenergic agonist on lower esophageal sphincter pressure in normals and in patients with achalasia

The effect of the beta₂-adrenergic agonist, carbuterol, was studied on the lower esophageal sphincter (LES) pressure in normals and in patients with achalasia. In normals, the mean LES pressure decreased from 23.1±6.2 mm Hg (mean±sem) to 16.0±5.0 mm Hg at a 4.0-mg dose of carbuterol (P<0.05). In patients with achalasia, the mean LES pressure decreased from 50.1±5.1 mm Hg to 22.7±2.4 mm Hg after a 4.0-mg dose of carbuterol (P<0.01). The duration of action following oral administration exceeded 90 min. These studies indicate that the LES in man has beta₂-adrenergic receptors that mediate a reduction in pressure. The magnitude of LES pressure reduction in patients with achalasia suggests that this drug may be of therapeutic benefit.     

Lower esophageal sphincter pressure in Chagas' disease

It is known that lower esophageal sphincter (LES) pressure in patients with idiopathic achalasia is higher than in normal subjects, but in patients with Chagas' disease, who have esophageal disease with similar clinical, manometric, and radiologic results, studies of LES pressure show contradictory findings. We measured the LES pressure in 118 patients with chronic Chagas' disease, 14 patients with idiopathic achalasia, and 50 control subjects using a perfused catheter and the stationary pull-through (SPT) technique. The patients with Chagas' disease had normal esophageal radiologic examination (group A, N=50), delay in esophageal clearance without dilatation (group B, N=41), or delay in esophageal clearance with dilatation (group C, N=27). The LES pressure of Chagas' disease patients of group A (18.6 ±9.1 mm Hg, mean ±SD), group B (17.8 ±9.7mm Hg), and group C (21.6 ±10.1 mm Hg) was lower (P<0.001) than the LES pressure of the controls (24.9 ±10.2 mm Hg). In patients with idiopathic achalasia, the LES pressure (40.7 ±17.8 mm Hg) was higher than in control subjects (P<0.01) and Chagas' disease patients (P<0.001). We conclude that the LES pressure of patients with Chagas' disease tended to be lower than that of control subjects and achalasia patients.Presented in part at the 8th World Congress of Gastroenterology, September 1986, São Paulo, Brazil, and published in abstract form inDig Dis Sci 31:273, 1986.     

l-Dopa inhibits metoclopramide stimulation of the lower esophageal sphincter in man

Opossum lower esophageal sphincter smooth muscle contains inhibitory dopaminergic receptors. Since metoclopramide is a dopaminergic antagonist in many experimental situations, the present study was designed to investigate whether this mechanism could explain the lower esophageal sphincter (LES) stimulating action of metoclopramide in man. The interactions of (1) orall-dopa, a dopamine precursor, and metoclopramide; and (2)l-dopa and the cholinergic agent, bethanechol, on lower esophageal sphincter pressure (LESP) in normal subjects were examined. Orall-dopa significantly inhibited LESP response to either oral metoclopramide 20 mg (P<0.05), or intravenous metoclopramide 20 mg (P<0.05). In contrast,l-dopa did not inhibit the LESP response to subcutaneous bethanechol (0.07 mg/kg). Mean basal LESP measured 50 min after ingestion of 1000 mgl-dopa, 19.3±3.1 mm Hg, was significantly less than basal LESP afterl-dopa placebo, 29.3±4 mm Hg (P<0.01). It is concluded that (1)l-dopa inhibited the metoclopramide-induced rise in LESP but not peak stimulation of LESP by bethanechol; (2) there is evidence for the possibility of LES dopaminergic inhibitory receptors in man; and (3) these data are consistent with the hypothesis that metoclopramide acts on the LES by blocking a dopaminergic pressure-lowering mechanism.     

Lower esophageal sphincter function in cirrhosis

Lower esophageal sphincter (LES) function in cirrhosis was evaluated using an infused manometric system. LES pressure (LESP) in 10 subjects with cirrhosis (22+1 mm Hg) (mean±se) was not significantly (P>0.05) different from that of 10 control subjects (21±1 mm Hg) but was significantly (P<0.01) greater than the LESP recorded in 5 subjects with cirrhosis and ascites (16±2 mm Hg). There was no significant difference in LES response to intravenous pentagastrin, intravenous edrophonium, or straight-leg raising in the three groups. After loss of ascitic fluid, LESP significantly (P<0.01) increased (P9±3 mm Hg) and gastric pressure (GP) significantly (P<0.01) decreased (P8±2 mm Hg). The changes in LESP and GP revealed a significant (R=0.83,P<0.001) linear correlation. These data indicate (1) cirrhosis is associated with normal LES function, and (2) the mechanism of lowered LESP with ascites may be the inability of the LES to maintain a sustained response to chronic increases in GP.Supported by Bureau of Medicine and Surgery Clinical Invesgation Program Project No. 4-16-259.The opinions or assertions expressed herein are those of the author and are not to be construed as official or as reflecting the views of the Navy Department or the naval service at large.     

Clinical and manometric findings in benign peptic strictures of the esophagus

To determine the possible factors that may contribute to the development of peptic stricture of the esophagus, clinical and manometric features were compared in patients with symptomatic gastroesophageal reflux and those with peptic strictures of the esophagus. Patients with stricture were older and had a longer duration of heartburn than patients without a stricture. Most importantly, patients with stricture had a more marked decrease in lower esophageal sphincter (LES) pressure, 4.9±0.5 mm Hg, than patients without a stricture, 7.5±0.6 mm Hg, P<0.01. The LES pressure in all patients with stricture was below 8 mm Hg, and did not overlap with normal values. Patients with stricture had either a nonspecific motor abnormality or aperistalsis (64%), compared to patients with symptomatic reflux (32%), P<0.05. Thus, peptic stricture of the esophagus is commonly associated with a long duration of reflux symptoms in patients with a very low LES pressure and esophageal motor disorder.     

Pathological esophageal acidification and pneumatic dilatation in achalasic patients too much or not enough?

Endoscopy, esophageal manometry and pH monitoring, gastric emptying test, and heartburn quantification on a visual analog scale were performed in 22 achalasic patients in order to clarify which events are associated with pathological esophageal acidification after successful LES dilatation. Five patients presented pathological acidification. Dilatation reduced LES tone from 38.3 ± 4.2 to 14.6 ± 1.1 mm Hg (mean ±sem); there was, however, no difference between nonrefluxers and refluxers (14.8 ± 1.2 vs 13.8 ± 2.5 mm Hg). The emptying time in achalasic patients was delayed compared to controls (315.9 ± 20.9 min vs 209 ± 10.4) due to prolonged lag-phase and reduced slope of the antral section-time curve, but, again, there was no difference between refluxers and nonrefluxers. The acid clearance was delayed in refluxers compared to nonrefluxers (15.9 ± 4.5 vs 2.5 ± 1.8 min,P<0.05). Two refluxers presented grade 1 esophagitis; one of them developed an esophageal ulcer. The heartburn score was the same in refluxers and nonrefluxers. Pathological acidification after pneumatic dilatation is associated with persistent problems in esophageal emptying rather than with excessive sphincter divulsion.     

Increase of swallows before onset of phase III of migrating motor complex in normal human subjects

The aim of our study was to analyze the relation between the deglutitive activity and fasting esophageal and gastric motility in normal subjects. Fifteen healthy subjects (9 males, 6 females) with a mean age of 42 years (range 19–65) were studied. A 24-hr pH-manometric recording was performed using a probe with four solid-state recording sites 10 cm apart, placed so as to record the motor activity of esophageal body, lower esophageal sphincter (LES) or distal part of the esophagus, and gastric antrum. An additional probe with one recording site was placed in the pharynx to evaluate swallowing. A pH electrode was also placed at 5 cm above the sphincter. Data were transferred to a personal computer and analyzed using specific software. Subjects received two meals during the recording session. MMCs were almost exclusively recorded during the nighttime. A mean of 2±0.94 (sd) MMC per subject was detected with a mean (±sd) interval, between each cycle, of 86.11±34.53 min. During the 30 min preceding gastric phase III, the number of swallows showed an increase that reached statistical significance 5 min before the onset of phase III. A similar pattern was observed for the area under the curve (AUC) of the esophagus and LES. In conclusion deglutition and esophageal motility vary with the MMC, suggesting that the deglutitive activity is part of the interdigestive motility pattern.     

Sphincter of oddi manometry in healthy volunteers

In this study we describe in detail the characteristics of sphincter of Oddi motor function in a large group of healthy subjects. Studies were obtained in 50 healthy volunteers. The findings showed a sphincter of Oddi segment that had a basal pressure of 14.8±6.3 mm Hg (X±sd). Phasic contractions were superimposed on the basal pressure. They had an amplitude of 119.7±32 mm Hg, a duration of 4.7±1 sec, and a frequency of 5.7±1.2 contractions/min. In 40 subjects the propagation sequence of phasic contractions could be evaluated and were simultaneous in 53%, antegrade in 35%, and retrograde in 11% of the waves. In 20 subjects, pressure measurements done at the common bile duct sphincter were similar to those obtained at the pancreatic duct sphincter. In 10 subjects, pressure values obtained at the common bile duct sphincter within a week were similar. Our study should help to establish standards for normal manometric values of the sphincter of Oddi and emphasizes the importance of having a healthy volunteer group from which to obtain the normal values of sphincter of Oddi motor function.     

Correlation between esophageal contraction amplitude and lower esophageal sphincter pressure in patients with nutcracker esophagus

Nutcracker esophagus (NE) is a primary esophageal motility disorder characterized by high-wave amplitude at the distal esophagus. The aim of this study was to analyze patients with NE and determine the relationship between distal esophageal contraction amplitude and lower esophageal sphincter (LES) pressure. Esophageal manometry tracings of patients with NE, defined as the presence of distal contraction amplitude of more than 182 mmHg after wet swallow, were analyzed. LES pressure was measured as the mean end-expiratory value. Spearman's correlation coefficient analysis was used to compare esophageal contraction amplitude with LES pressure. This comparison was also performed in patients with isolated hypertensive LES (HLES) and in subjects with normal manometry. Forty patients (25 female, 15 male; mean age 54 years) with NE were included in the study. Mean (SD) distal esophageal contraction amplitude was 230 (35.7) mmHg and mean LES pressure was 27.3 (5.7) mmHg. Esophageal contraction amplitude showed a positive correlation with LES pressure (r = 0.49, P < 0.01). In contrast, no correlation was found in patients with HLES (r = 0.21, P > 0.05) and in those with a normal manometric study (r = 0.18, P > 0.05). It is concluded that in patients with nutcracker esophagus a positive correlation exists between distal esophageal contraction amplitude and LES pressure, suggesting a diffuse hypertensive pattern involving smooth muscle at the distal esophagus and adjacent LES.     

Endoscopic manometry of pancreatic and biliary sphincter zones in man

An endoscopic manometric technique was applied to the study of intraductal biliary and pancreatic pressures and sphincter activity in normal subjects. A perfused system using a modified endoscopic retrograde cholangiopancreatography catheter was tested and found to provide reliable ductal and phasic recordings. Twenty-five healthy volunteers aged 19–37, underwent endoscopic manometry under diazepam sedation. Distinct zones of high-pressure phasic activity were identified on pull-through from the pancreatic duct and common bile duct at mean distances of 4.5 and 5.0 mm, respectively, from the papillary orifice with frequencies of 7.0±1.8 (mean±sd) and 5.6±2.4 waves/min, respectively. These were considered to represent separate pancreatic duct and bile duct sphincters. Peak pancreatic duct sphincter pressure (47.6±8.2 mm Hg) and bile duct sphincter pressure (57.2±10.7 mm Hg) were similar. Pancreatic duct pressure was 11.4±3.0. mm Hg and common bile duct pressure was 3.0±2.5 mm Hg. Values were adjusted to duodenal pressure as zero reference. The ductal and sphincteric pressures reported in this study provide a basis for the assessment of physiological, pharmacological, pathophysiological, and surgical effects on this area.This work was supported by grants from the Katherine Gavriluk and Sara Jordan Funds, New England Baptist Hospital, Boston, Massachusetts, and Dr. Carr-Locke is in receipt of grants from the Wellcome Research Travel Fund, London, England, the Leicester Area Health Authority, Leicester, England, and the P and C Hickinbotham Trust, Leicester, England.     

Hypertensive lower esophageal sphincter: what does it mean?

The hypertensive lower esophageal sphincter (LES) (mean LES pressure greater than 45 mm Hg; LES relaxation greater than 75%; normal peristalsis) is a poorly characterized motility disorder associated with chest pain and dysphagia. Therefore, we carried out a multidisciplinary study to assess esophageal pressures and function in 15 symptomatic hypertensive LES patients (3 men, 12 women; mean age, 53 years). On-line computer analysis showed a significant (p less than 0.05) increase in LES pressure (55.5 versus 14.9 mm Hg) and residual pressure (6.8 versus 1.1 mm Hg) as well as a decrease in percentage of LES relaxation (87 versus 93%) in patients compared with age-matched controls. All patients had normal peristalsis but 7 of 15 had nutcracker esophagus (mean distal amplitude, 216 mm Hg). No patient had evidence of impaired liquid transport on barium esophagram. The emptying of solids as assessed by radionuclide scans was normal in 14 of 15 patients. Of the 12 patients who completed both psychological inventories, nine had elevated scores on scales assessing anxiety and somatization. The heterogenous nature of this disorder is illustrated by a patient with a changeable narrowing in the distal esophagus associated with the transient impaction of a marshmallow. Dysphagia but not chest pain improved after pneumatic dilatation. We conclude that the hypertensive LES is a heterogenous disorder. Despite abnormal LES parameters, most patients have normal esophageal function, and frequent psychological abnormalities may contribute to their report of symptoms. A minority have abnormal esophageal transit.     

Lower esophageal sphincter relaxation characteristics using a sleeve sensor in clinical manometry

Objective: We undertook this study to determine the characteristics of swallow-induced lower esophageal sphincter (LES) relaxation in the setting of clinical manometry using a standardized methodology.
Methods: We reviewed 170 manometric recordings performed using a perfused manometric assembly with a sleeve sensor and a computer polygraph. Patients were categorized as patient controls, gastroesophageal reflux disease (GERD), diffuse esophageal spasm (DES), or achalasia. Tracing were semiautomatically analyzed for basal LES pressure, LES pressure during deglutitive relaxation (relaxation LES pressure), duration of LES relaxation, timing of LES relaxation, and the success rate of primary peristalsis.
Results: Forty-six patient controls, 93 with GERD, five with DES, and 26 with achalasia were identified. GERD and achalasia patients had lower or higher basal LES pressures than patient controls, respectively. Compared with patient controls, achalasia patients had higher relaxation LES pressures, lower percent LES relaxation, and shorter durations of LES relaxation. The best single measure for distinguishing achalasia was the relaxation LES pressure; using the 95th percentile value of patient controls (12 mm Hg) as the upper limit of normal, its sensitivity and positive predictive value for the diagnosis of achalasia were 92% and 88%, respectively. Coupled with the finding of aperistalsis, a relaxation LES pressure ≥10 mm Hg achieved 100% sensitivity and positive predictive value among these patients.
Conclusion: Sleeve sensor recording is a practical method for clinical manometry that reliably records LES relaxation characteristics and is amenable to both a standardized manometry protocol and a semiautomated analysis routine. Relaxation LES pressure has a high diagnostic value for achalasia.     

Case Report: Botulinum Toxin in Hypertensive Lower Esophageal Sphincter: A Manometric Case Study

The hypertensive lower esophageal sphincter (HLES) is a disorder of esophageal motility associated with dysphagia and chest pain. Although well characterized manometrically, opinions differ greatly with regard to its pathophysiology and its management. Therapy is limited to a few medications, esophageal dilatation, and even surgery, although none of these options are consistently successful. In this case report we describe a 54-year-old woman with HLES and dysphagia who was successfully treated with botulinum toxin injection of the lower esophageal sphincter (LES). Esophageal manometry after botulinum toxin therapy revealed normalization of LES pressures. Three months after therapy, symptoms returned and repeat esophageal manometry demonstrated the return of elevated LES pressures. This report is the only published case of botulinum toxin injection into the LES with both pre- and post-treatment esophageal manometric data. This case report is evidence that LES dysfunction produces symptoms in patients with HLES, and that reduction in LES pressure improves symptoms. Current pathophysiologic hypotheses for HLES-associated dysphagia and its treatment are briefly reviewed in this report.     

The adverse effect of chocolate on lower esophageal sphincter pressure

Decreased lower esophageal sphincter (LES) pressure after ingestion of chocolate has been previously noted. We have further evaluated the effect of chocolate on the known ability of gastric alkalinization or bethanechol to increase LES tone. 9 normal subjects were studied using an infused open-tip recording system. Pressure was monitored for a 15-min basal period, and for 60 min after ingestion of 120 ml of chocolate syrup either alone or with the concurrent administration of commercial antacid, oral bethanechol, or subcutaneous bethanechol. After chocolate ingestion, mean basal LES pressure of 14.6±1.1 (±SEM) mm Hg decreased significantly (P<0.01) to 7.9±1.3 mm Hg. An identical LES response occurred when antacid was given with the chocolate dose. Oral bethanechol (25 mg) and chocolate together resulted in lesser decreases in LES pressure. Subcutaneous bethanechol (5 mg) and chocolate produced significant increases (P<0.05) in sphincter pressure, although of lesser magnitude than reported with bethanechol alone. These results indicate that the adverse effect of chocolate on the LES is not reversed by gastric alkalinization and suggest that bethanechol in sufficient dose may overcome chocolate-induced decreases in LES pressure.This work was supported by the Department of the Navy Clinical Investigation Program Grant #5-05-530R.     

Biliary pressure variation in coordination with migrating motor complex of duodenum in patients with cholecystectomy and effects of morphine and cerulein

Pressures in the common bile duct and duodenum were continuously measured with two pressure microtransducers placed by endoscopy in 10 postcholecystectomy patients. A complete cycle of the migrating motor complex of the duodenum was obtained in seven patients, its length ranging from 62 to 174 min with a mean of 114 min. The biliary pressure showed a transient elevation of 5.0±0.6 (mean±sem) mm Hg (P<0.001) in concert with phase II of the duodenal cycle in all 10 patients, whereas it remained stable during other phases. Intramuscular morphine (0.2 mg/kg) given to induce spasm of the sphincter of Oddi 20 min after the passage of phase II invariably produced an activity front in the duodenum and a sustained increase in the biliary pressure, the magnitude of which was 8.3±0.9 mm Hg. The biliary pressure raised by morphine dropped after an intravenous injection of cerulein (0.1 g/kg) as a sphincter relaxant. These findings indicate that the biliary pressure rises transiently at phase III of the duodenal cycle in patients after cholecystectomy, probably due to contractions of the sphincter of Oddi.     

Manometry and impedance characteristics of achalasia. Facts and myths

BACKGROUND: Achalasia is defined manometrically by an aperistaltic esophagus. Variations in the manometric findings occur in achalasia suggesting that all manometric features should not be required to diagnose achalasia. Combined multichannel intraluminal impedance and esophageal manometry (MII-EM) allows both a functional and a manometric evaluation of esophageal motility and identifies chronic fluid retention. AIM: To compare manometric and MII characteristics in patients with achalasia. METHODS: Retrospective review of 73 MII-EM tracings from patients with achalasia done in our laboratory between October 2001 and December 2004 (38 females; mean age=53.5 y). Patients with previous esophageal interventions were excluded. Manometric and MII characteristics were identified and compared during 10 liquid and 10 viscous swallows. Patients were also divided into 2 groups: vigorous achalasia (VA) and achalasia. RESULTS: Twenty-two of the seventy-one (31%) achalasia patients had a hypertensive lower esophageal sphincter (LES). The mean lower esophageal sphincter pressure (LESP) for the 71 patients with achalasia was 37.9+/-21.2 mm Hg compared with 27.3+/-9.3 mm Hg (P<0.05) in the 73 patients with normal motility. The mean LESP in patients with achalasia was 36+/-20.3 mm Hg compared with 47+/-23.2 mm Hg (P<0.05) in patients with VA. Elevated intraesophageal pressure (IEP) was noted in 45/73 (61.6%). The mean LESP in this group was 41.1+/-22.9 mm Hg compared with 32.5+/-17 mm Hg (P<0.05) with normal IEP. The mean baseline impedance for achalasia was 801+/-732 compared with 1265.2+/-829.5 Omega (P<0.05) for the VA patients. CONCLUSIONS: Most patients with achalasia have elevated IEP, elevated LES residual pressure, normal LES pressure, and low baseline impedance. All manometric features should not be required to diagnose achalasia. Patients with an elevated IEP are likely to have an elevated LES pressure and LES residual pressure. Low MII values identify chronic fluid retention and helps confirm the diagnosis.     

Diffuse esophageal spasm

Diffuse esophageal spasm (DES) has frequently been described as a motility disorder characterized by simultaneous, high-amplitude contractions. We reviewed the results of esophageal manometry testing on a total of 1480 patients referred to our lab over 36 months. Lower esophageal sphincter (LES) pressure was determined by a mean of four station pull-throughs. Esophageal body motility was assessed following 10 wet swallows. In our lab a diagnosis of DES is made when greater than 10% but less than 100% of contractions are simultaneous. Manometric findings of DES were rare, with an overall prevalence of 4% (56/1480). Of the 56 patients with a manometric diagnosis of DES, high-amplitude (X180 mm Hg) peristaltic contractions were found in only two (4%). No simultaneous contractions with amplitude 180 mm Hg were seen. Pressures of simultaneous contractions were consistently lower than peristaltic contractions. A hypertensive LES pressure (45 mm Hg) was present in 5/56 DES patients (9%). Poor LES relaxation was found in 7/56 DES patients (13%). We conclude that DES is a rare manometric finding, regardless of the reason for referral, and that the occurrence of high-amplitude contractions in DES is equally rare.     

Effects of exogenous secretin on pancreatic and biliary ductal and sphincteric pressures in man demonstrated by endoscopic manometry and correlation with plasma secretin levels

An endoscopic manometric technique was used to investigate the effects of exogenous secretin on pancreatic duct, common bile duct, pancreatic duct sphincter, and bile duct sphincter pressures in 20 healthy volunteers. Synthetic secretin was infused intravenously at rates of 8.05, 16.1, 32.2, 64.4, 129, 258, and 516 ng/kg/hr, and plasma secretin concentrations were measured by a radioimmunoassay. Secretin produced a significant fall in peak and trough pancreatic duct sphincter pressures from basal values of 48.2±7.9 mm Hg (mean±sd) and 16.9±7.7 mm Hg, respectively, to 34.4±6.8 mm Hg and 11.2 ±5.8 mm Hg (P<0.005), respectively, at a mean plasma secretin concentration of 16 pg/ml (during an infusion rate of 32.2 ng/kg/hr). Higher infusion rates had no additional effect. Pancreatic duct pressure became significantly elevated above basal (11.5±4.0 mm Hg) at the two highest secretin rates. Secretin had no effect on common bile duct or bile duct sphincter pressures. Plasma secretin concentrations were within the postprandial range during the lowest four secretin infusion rates. We conclude that secretin produces selective physiological relaxation of the pancreatic duct sphincter.This work was supported by grants from the Katherine Gavriluk and Sara Jordan Funds, New England Baptist Hospital, Boston, Massachusetts; NIH Research Grant AM 25962. Dr. Carr-Locke is also in receipt of grants from the Wellcome Research Travel Fund, London, England, the Leicester Area Health Authority, Leicester, England, and the P&C Hickinbotham Trust, Leicester, England.     

Lower esophageal sphincter pressure as an index of gastroesophageal acid reflux

The purpose of this study was to determine the relationship of lower esophageal sphincter (LES) pressure and the volume of acid placed into the stomach required to induce gastroesophageal reflux in man. LES pressure was recorded continuously and by station pull-through by three radially oriented catheters in both symptomatic and asymptomatic subjects during the graded infusions of 0.1 N HCl acid into the stomach. Sumptomatic subjects had a mean LES pressure of 7.5±0.7 mm Hg and refluxed at a volume of 140.0±21.0 ml. Fifty-five percent of asymptomatic subjects refluxed at a mean volume of 380.0±24.7 ml, and had a mean LES pressure of 13.8±0.4 mm Hg. Asymptomatic nonrefluxers at a volume of 500 ml of 0.1 HCL acid had a mean LES pressure of 18.9±1.1 mm Hg. The mean LES pressure and acid volumes showed statistical significance between the three groups (P<0.01). There was an excellent overall correlation between LES pressure and acid volume required to produce reflux in all subjects (r=0.91,P<0.001). Following reflux, asymptomatic but not symptomatic subjects showed a significant increase in LES pressure. These studies suggest that: (1) LES pressure does provide an accurate index of the gastroesophageal antireflux mechanism, provided that acid volume is considered; and (2) asymptomatic subjects showing acid reflux have higher LES pressures, reflux at higher volumes, and develop an LES contractile response after the reflux episode.This work was supported by a grant from the Smith Kline & French Laboratories, Philadelphia, Pennsylvania.     

Response of canine ileocolonic sphincter to intraluminal acetic acid and colonic distension

The aim was to determine the effect of intraluminal acetic acid and proximal colonic distension on canine ileocolonic sphincter pressure, ileal motility, and coloileal reflux. In six conscious dogs with an isolated ileocolonic loop, basal pressure of the ileocolonic sphincter was similar during ileal perfusion with 100 mM acetic acid at 1 ml/min (mean±sem=18±0.4 mm Hg) and with saline (18±0.5 mm Hg;P=0.81). Discrete clustered ileal contractions were more frequent with acetic acid, however, and when they propagated across the sphincter, sphincter pressure increased from 18±0.4 mm Hg to 36±1.3 mm Hg (P=0.002). Sphincter pressure was also greater during colonic perfusion with acetic acid (32±0.7 mm Hg) than during ileal perfusion with acetic acid or saline (P<0.017). Moreover, sphincter pressure gradually increased as the colon was distended with saline (slope=0.8 mm Hg/cm H₂O,P<0.017) or acetic acid (slope=0.5 mm Hg/cm H₂O,P<0.017), but the increase did not prevent coloileal reflux. In conclusion, ileal clustered contractions, colonic perfusion of acetic acid, and colonic distension all increased canine ileocolonic sphincter pressure.