Study of the effect of temperature on the rectal function with evidence of thermorectal reflex

BACKGROUND AND AIMS: Rectal sensation seems to originate from mechanoreceptors which are stimulated by passive rectal filling or active contraction. We investigated the effect of temperature on rectal function. PATIENTS AND METHODS: A balloon was introduced into the rectum of 28 healthy volunteers, filled with 50 ml saline at various temperatures, and rectal pressure was recorded. The test was repeated 30 min and 3 h after rectal anesthetization. RESULTS: Rectal pressure was significantly reduced at 45 degrees and 40 degrees C, showed no change at 37 degrees or 30 degrees C, and was increased at 20 degrees, 10 degrees, and 0 degrees C. At 45 degrees C patients felt rectal pain but no sensation of warmth; at 40 degrees, 37 degrees, and 30 degrees C neither rectal pain nor warm sensation was felt; at 20 degrees C or below rectal pain and cold sensation were perceived. Rectal balloon filling 30 min after anesthetization caused no significant rectal pressure changes or sensation of coldness or warmth; after 3 h, when the anesthetic had waned, the rectal pressure response and sensation were similar to those before anesthetization. CONCLUSIONS: Warm saline appears to cause rectal relaxation and cold saline rectal contraction. Subjects did not perceive sensation of warmth in the rectum but felt cold sensation, which may indicate the presence of cold receptors in the rectal wall. The rectal response to temperature variations is suggested to be reflex in nature as evidenced by its absence on rectal anesthetization. Such reflex, designated "thermorectal reflex," is proposed to mediate the rectal response and is speculated to have clinical significance in rectal dysfunctional and neurogenic disorders.     

The reflex effects of rectal distension on heart rate, arterial blood pressure and electrocardiogram

To investigate the effect of rectal distension on the heart rate, arterial blood pressure and electrocardiogram, 50 volunteers (25 test and 25 controls) were studied. Test volunteers comprised 15 men and 10 women who had a mean age of 38.7 years. Two catheters: balloon-tipped and manometric, were introduced into the rectum. The balloon was filled with saline in increments of 50 ml until it was spontaneously expelled. The heart rate (HR), arterial blood pressure (BP) and electrocardiogram (ECg) were monitored before, during and after rectal distension. The test was repeated while the rectum was anesthetized. For the controls, the 2 aforementioned catheters were introduced into the rectum without performance of rectal distension, and the preceding variables were recorded. The HR, BP and ECG showed no significant changes upon rectal distension with 40 and 100 ml of saline (p>0.05). At rectal distension with 150 ml, HR and ECG frequencies exhibited a significant rise (p<0.05) while the BP did not (p>0.05). Rectal distension with 200 ml effected a significant rise in all the parameters. They returned to the predistension values within 1 to 2 minutes after distension release. The rectal pressure rose with 150 ml distension and above. Rectal distension of the anesthetized rectum did not effect significant changes in the parameters. The control subjects showed no significant changes in the aforementioned parameters. In conclusion, rectal distension effected an increase of the heart rate, blood pressure and ECG rhythm. These parameters returned to normal shortly after rectal deflation. It is postulated that the hemodynamic changes are reflex. The effect of the chronic rectal distension, which occurs, in constipation, on the aforementioned parameters needs to be studied.     

Effect of painless rectal distension on gastrointestinal transit of solid meal

The effect of painless intermittent rectal distension on the rate at which a standard meal passes through the stomach and small intestine was investigated in normal volunteers using noninvasive techniques. Rectal distension significantly retarded the entry of the head of the meal into the cecum and the emptying of the meal from the stomach, although it had no significant effect on basal gastric acid secretion. After administration of the H ₂ -receptor antagonist, ranitidine, there was no significant effect of rectal distension on gastric emptying, but the delay in small bowel transit time induced by rectal distension remained. These data indicate that events occurring in the rectum may influence the function of more proximal regions of the gut.     

Motor responses of the small intestine to intraluminal distension in normal volunteers and a patient with visceral neuropathy.

The motor responses of the small intestine to intraluminal distension were studied proximal and distal to an inflatable balloon in 13 normal volunteers. During fasting, distension rapidly induced a persistent localised inhibition of distal contractile activity with a small proximal increase. Proximally, phase III activity was unaffected during distension but its propagation across and appearance below the balloon was inhibited. Upon deflating the balloon a normal motor pattern rapidly returned. Similar changes were observed during distension in the fed state. The changes in the motor pattern resemble those of the intrinsically mediated 'peristaltic reflex', studied in animals, and suggest that in man the response to balloon distension may also be mediated through an intrinsic mechanism. A patient with a visceral neuropathy, studied in a similar manner, had no inhibition of distal motor activity during distension, suggesting a functional defect of the enteric nerves. Further observations of the motor responses to distension in similar patients seem indicated to determine the usefulness of this technique for evaluating enteric nervous system function when an abnormality is suspected.     

Study of the effect of jejuno-ileal distension on the motor activity of the stomach with evidence of "entero-gastric inhibitory reflex"

BACKGROUND/AIMS: In chronic constipation due to delayed colonic transit, stasis of the ileal contents with resulting ileal distension may occur. The current study investigated the effect of ileal and jejunal distension on the gastric motility, aiming at elucidating the possible existence of a relationship and its role in the flow through the gut. METHODOLOGY: The response of the gastric pressure to ileal and jejunal balloon distension in increments of 2 mL of saline was recorded in 12 mongrel dogs. The test was repeated after separate local anesthetization of the ileum, jejunum and stomach. RESULTS: 2- and 4-mL ileal balloon distension produced no significant gastric pressure response, while 6- and up to 10-mL distension effected decrease of the antral and corporeal pressures (p < 0.05, p < 0.05, respectively). Jejunal distension produced a gastric pressure decline (p < 0.05) with 4 and up to 10 mL of saline. The gastric pressure decrease did not show significant changes with the various distending volumes. It was maintained as long as ileal or jejunal distension was continued. Distension of the anesthetized ileum or jejunum caused no gastric pressure changes, nor did ileal or jejunal distension produce pressure changes in the anesthetized stomach. CONCLUSIONS: The gastric pressure decline and presumably hypotonia upon ileal or jejunal distension with big volumes postulate a reflex relationship which we call "entero-gastric inhibitory reflex". The small intestine is suggested to slow down gastric emptying through this reflex. A balance is thus created between chyme delivery from the stomach and chyme processing by the small intestine. Reflex derangement in neurogenic and myogenic diseases may result in gastrointestinal disorders, a point that needs to be investigated.     

Sensibility of the rectum to distension and the anorectal distension reflex in ulcerative colitis.

The maximum volume of air tolerated within a rectal balloon was less in colitic patients than in normal subjects (P less than 0.001). Smaller volumes were tolerated by patients with a spontaneously bleeding mucosa than by those with less severe inflammation (P less than 0.001). Severe urgency of defaecation with incontinence was experienced by about half those with spontaneous mucosal haemorrhage but was infrequent among other colitics. Those patients with inactive colitis and a reduced maximum tolerable volume tended to have a smaller rectal size than those who could tolerate a normal volume within the rectum. Reflex relaxation of the internal anal sphincter on distension of the rectum appeared normal in patients with colitis.     

Effect of metoclopramide on transport in the small intestine of the dog

A method is described for the simultaneous measurement of flow rate, mean transit time, and volume of the intestine during the transport of fluid through a segment of the small intestine of the dog.Using this method, the effect of metoclopramide on motility of the small bowel was assessed. The drug resulted in a decrease in transit time and volume in the test segment of bowel while the flow rate remained constant. This finding suggests that metoclopramide-stimulated contraction of intestinal smooth muscle.     

The effects of distension of the small intestine on myocardial blood flow in anaesthetised cats: possible relevance to coronary vasospasm

Summary The haemodynamic effects of distending the small intestine (with a balloon in the lumen) were examined in cats anaesthetised with chloralose. Particular attention was paid to blood flow changes in localised areas of the left ventricular wall (as assessed using the heated thermocouple technique). Intestinal distension led to an increase in systemic blood pressure but usually to a reduction in myocardial blood flow; no cardiac dysrhythmias were observed. When the effect of increased systemic (perfusion) pressure on blood flow was eliminated (using partial correlation coefficients) flow then bore a negative relationship to intestinal pressure, probably indicating constriction of the myocardial blood vessles. This may indicate that distension of hollow organs can lead to a visceral-cardiac reflex. The resulting coronary vasospasm might be one cause of pain in certain patients with angina pectoris.

---

Die hämodynamischen Folgen einer Dünndarmdehnung mit aufblasbarem Ballon wurden an narkotisierten (Chloralose) Katzen untersucht

Zusammenfassung Die regionale Durchblutung des linken Ventrikels, welche mit geheizten Thermosonden gemessen wurde, nahm nach Darmdehnung meistens ab, während der arterielle Blutdruck zunahm. Arrhythmien wurden nicht beobachtet.Wenn der Effekt der Blutdruckerhöhung auf die Koronardurchblutung durch Anwendung partialer Korrelationskoeffizienten ausgeschaltet wurde, dann wurde eine umgekehrte Relation zwischen Myokarddurchblutung und Intestinaldruck gefunden, welches als eine koronare Vasokonstriktion gedeutet wurde. Es wird gefolgert, daß die Dehnung von Hohlorganen zu einem viscero-kardialen Reflex führe kann. Der resultierende Koronarspasmus könnte eine Ursache des Schmerzes bei Angina-pectoris-Patienten sien.

---

---

With 1 figure and 1 table     

Mitochondrial neurogastrointestinal encephalomyopathy: evidence of mitochondrial DNA depletion in the small intestine

BACKGROUND & AIMS: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease clinically defined by gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy, white-matter changes in brain magnetic resonance imaging, and mitochondrial abnormalities. Loss-of-function mutations in thymidine phosphorylase gene induce pathologic accumulations of thymidine and deoxyuridine that in turn cause mitochondrial DNA (mtDNA) defects (depletion, multiple deletions, and point mutations). Our study is aimed to define the molecular basis of gastrointestinal dysmotility in a case of MNGIE. METHODS: By using laser capture microdissection techniques, we correlated histologic features with mtDNA abnormalities in different tissue components of the gastrointestinal wall in a MNGIE patient and ten controls. RESULTS: The patient's small intestine showed marked atrophy and mitochondrial proliferation of the external layer of muscularis propria. Genetic analysis revealed selective depletion of mtDNA in the small intestine compared with esophagus, stomach, and colon, and microdissection analysis revealed that mtDNA depletion was confined to the external layer of muscularis propria. Multiple deletions were detected in the upper esophagus and skeletal muscle. Site-specific somatic point mutations were detected only at low abundance both in the muscle and nervous tissue of the gastrointestinal tract. Analysis of the gastrointestinal tract from 10 controls revealed a non-homogeneous distribution of mtDNA content; the small intestine had the lowest levels of mtDNA. CONCLUSION: Atrophy, mitochondrial proliferation, and mtDNA depletion in the external layer of muscularis propria of small intestine indicate that visceral myopathy is responsible for gastrointestinal dysmotility in this MNGIE patient.     

Inhibitory reflexive effect of rectal distension on postprandial gastric myoelectrical activity

The aim of the study was to determine the effects of low-volume rectal distension on gastric myoelectrical activity. The study was performed in 14 healthy volunteers in 2 randomized sessions. In the control session, a small balloon was inserted into the rectum 10 cm beyond the anal verge and inflated with 20 ml of air. Gastric myoelectrical activity was recorded for 30 minutes in the fasting state and 30 minutes after a meal; and then the balloon was deflated and removed, and another 30-min recording was followed. The study session was the same except that after the 30-min baseline recording the balloon was inflated to reach a volume with which the subject felt an urgency for defecation. Spectral analyses were performed to compute the dominant frequency, power, and regularity (2–4 cycles/minutes, cpm) of the gastric slow waves and the percentage of gastric dysrhythmia. Results: 1). In comparison with our previously published data, the placement of the rectal balloon with a volume of 20 ml air did not affect the regularity of the slow waves (84.2 ± 3.6% in fasting, 85.3 ± 4.3% in fed); In comparison with the control session, the rectal distension inducing an urgency for defecation (average volume of air: 72.5 ml) significantly reduced the regularity of gastric slow waves in the fed state (72.0 ± 5.7%, P < 0.03 vs baseline; P < 0.02, vs control session) but not in the fasting state (80.1 ± 4.5%, P = 0.1). This postprandial change was attributed to a significant increase in bradygastria (3.1 ± 1.0% vs 7.9 ± 2.6%, P < 0.04) and a marginal increase in tachygastria (7.4 ± 2.5% vs 15.8 ± 4.3%, P = 0.06). The normal postprandial increases in the dominant frequency and power of the gastric slow wave were abolished in both sessions. conclusions, rectal distension evoking an urgency for defecation impairs postprandial gastric slow waves with an increase in the percentage of both bradygastria and tachygastria.     

Effect of a feeding schedule on crypt cell proliferation in the small intestine of the rat.

Using a stathmokinetic technique, the mitotic rate in the small intestinal crypts of two groups of male Sprague-Dawley rats was studied. The first group was fed solids for 3 h daily only. The second group was fed solids ad libitum. In the first group it was found that the mean daily weight of food consumed rose quickly to normal 24-hour levels but the mean daily weight of the rats fell rapidly and did not approach the original level throughout the experiment. There was no significant difference in the mitotic rate of the small intestinal crypt cells between the two groups.     

Effect of irradiation on morphology and motility of canine small intestine

In addition to severe damage to the intestinal mucosa, there is evidence based on altered transit that irradiation affects intestinal motor function. A single dose of 938 cGy to the intestine of dogs consistently produced an acute intestinal radiation syndrome consisting of vomiting and diarrhea but was not lethal. In the fasting state, the migrating myoelectric complex was uniformly interrupted. After a meal, jejunal myoelectric activity analyzed by a computer program showed a progressive decline in the number, duration, and length of migration of spike bursts. There were occasionally bizarre motility patterns consisting of clusters of migrating spike bursts. Slow waves demonstrated irregular rhythm and nonuniform morphology. They occasionally migrated in an orad direction and at times were totally uncoupled. At 24 hr and four days after irradiation, the muscle and the neural plexus were nearly normal by light microscopy, but the mucosa exhibited severe necrosis. Therefore, irradiation produces profound functional abnormalities in intestinal muscle even though the morphology is minimally altered.This study was supported by Veterans Administration Medical Research Funds and NIH Digestive Disease Core Center grant AM 34986-01.     

Effect of chyme on mucosal enzyme levels in small intestine of the rat

Partial jejunectomies, gastrojejunostomies (with closed pylorus), and jejunal Thiry-Vella loops were made in order to elucidate the role of chyme in the control of mucosal mass and the activities of alkaline phosphatase, ATPase, and maltase in the small intestine of the rat. After partial jejunectomy, a partially reversible mucosal hyperplasia was seen in the small intestine with the exception of distal ileum. After gastrojejunostomy a similar hyperplasia took place in the jejunum and proximal ileum. In the jejunal Thiry-Vella loops a mucosal atrophy was found in 4 wk. After partial jejunectomy the activity of alkaline phosphatase decreased slowly in 4 wk in the remaining small intestine with the duodenum as an exception. ATPase activity decreased in the duodenum. Maltase activity remained unchanged during 8 postoperative wk. In gastrojejunostomized rats the activity of alkaline phosphatase and ATPase increased slowly during 12 wk in the jejunum aborally from the gastroenterostomy. A slight depression of maltase activity was observed in the operation area and a slight increase of enzyme activity was found in the middle of the small intestine. In jejunal Thiry-Vella loops the activity of alkaline phosphatase decreased, but no change of maltase activity could be observed during 4 wk. Perfusion of a loop with maltose solution did not cause any changes in the activity of alkaline phosphatase or maltase. The results indicate that after a change in chyme passage the adaptation takes place in the small intestine primarily by the change of mucosal mass, and at least some enzyme levels in the mucosal cells are remarkably stable.     

Biopsy of the small intestine with the Crosby-Kugler capsule

Experience with 3,866 peroral intestinal biopsies performed over 6-1/2 years is presented. Fifty-five infants and children had 101 biopsies performed. Initial attempts at obtaining tissue in three children were unsuccessful, but tissue was obtained in all three on the second attempt. One infant receiving heparin experienced significant bleeding, which stopped spontaneously when the heparin was discontinued. Tissue was obtained in 93–98% of all biopsies performed on 3,765 adult individuals and six had significant bleeding. Only one required transfusion and no perforations were encountered. We find that peroral intestinal biopsy is a relatively easy and safe procedure in both adults and children. It should be performed under the direction of those experienced in intestinal biopsy techniques because of occasional complications.