Motor mechanisms associated with slowing of the gastric emptying of a solid meal by an intraduodenal lipid infusion

The aim of this study was to define better the motor phenomena associated with the slowing of gastric emptying by a duodenal lipid infusion. Antral, pyloric and duodenal motility were recorded in 10 healthy subjects with a manometric assembly which incorporated multiple perfused side-holes and a sleeve sensor positioned astride the pylorus. The gastric emptying of a standard solid meal and the distribution of the ingesta between the proximal and distal stomach were monitored with a radionuclide technique. A triglyceride emulsion was infused into the duodenum for 45 min once 25% of the meal had emptied. The infusion caused significant slowing in the rate of gastric emptying (P less than 0.01). This slowing in gastric emptying was associated with the suppression of pressure waves in the distal antrum (P less than 0.01) and proximal duodenum (P less than 0.01), the induction of pressure waves isolated to a narrow pyloric segment (P less than 0.01), and a redistribution of ingesta from the distal to proximal stomach. These findings suggest that pressure waves isolated to the pylorus, changes in the intragastric distribution of ingested food, and changes in proximal duodenal motility may all act in concert with changes in antral motility to regulate the gastric emptying of solids.     

Motor function of gastric antrum and pylorus for evacuation of low and high viscosity meals in dogs.

In five conscious dogs motility of the antrum, pyloric sphincter, and duodenum was recorded with strain gauge transducers and induction coils. Gastric evacuation of low, medium, and high viscosity meals was measured via a duodenal cannula and observed simultaneously by radiography. Computer analysis of the propagation of the gastric waves revealed increased velocity in the distal antrum but no simultaneous contractions of the terminal antrum and pyloric sphincter. Radiography showed, and measurements of the antral diameter confirmed, that the indentations of the gastric waves were significantly deeper with the low viscosity liquid meal compared with the medium and high viscosity meals. Thereby, retropulsion of the medium and high viscosity ingesta was produced. Results indicated that gastric evacuation was regulated predominantly by the depth of the peristaltic indentation, which depended on the viscosity of the gastric contents. Nothing indicated that the phasic contractions of the pyloric sphincter were of importance for the regulation of gastric emptying.     

Intravenous erythromycin overcomes small intestinal feedback on antral, pyloric, and duodenal motility.

The retardation of gastric emptying caused by intraduodenal lipid is associated with suppression of antral contractions and stimulation of localized pyloric contractions. Similar patterns of motility have been described in patients with gastroparesis. The effect of erythromycin on the antropyloroduodenal motor responses to intraduodenal lipid was investigated. In 17 volunteers an intraduodenal lipid infusion (10% Intralipid) was given at 1 mL/min for 50 minutes. Either erythromycin (3 mg/kg) or saline was administered IV for 15 minutes, beginning 20 minutes after the start of the intraduodenal lipid infusion. Antral, pyloric, and duodenal motility were measured with a sleeve/sidehole manometric assembly. Intraduodenal lipid stimulated localized pyloric contractions. Erythromycin suppressed localized phasic (P less than 0.003) and tonic (P less than 0.002) pyloric pressure waves and stimulated antral (P less than 0.003) and duodenal pressure waves (P less than 0.02). After erythromycin antral pressure waves were usually of high amplitude (greater than 50 mm Hg) and often associated with duodenal pressure waves. It was concluded that erythromycin overcomes the effects of intraduodenal lipid on antral, pyloric, and duodenal motility. These effects probably contribute to the gastrokinetic properties of erythromycin.     

Relation of pyloric motility to pyloric opening and closure in healthy subjects.

The relation between pyloric motor activity, opening, and closure was examined in eight healthy men. Manometry was performed with an assembly combining 13 side holes and a sleeve sensor positioned astride the pylorus. Simultaneous with manometry, pyloric opening and closure and antroduodenal contractions were observed fluoroscopically with the antrum filled with barium. During intraduodenal normal saline infusion, coordinated antral pressure waves swept over the pylorus and ejected barium into the duodenum. No localised pyloric motor pattern was observed under these conditions. In contrast, the intraduodenal triglyceride infusion was associated with the absence of antral pressure waves and virtual absence of antral wall movement. At the pylorus, there was a zone of luminal occlusion less than 1 cm long that persisted for the period of observation. This zone of luminal occlusion corresponded precisely with manometric recordings of a narrow zone of pyloric phasic and tonic activity. During the duodenal triglyceride infusion, the pylorus was closed for 98.5% of the measurement period when basal pyloric pressure was 4 mm Hg or more, and during this motor pattern, barium did not traverse the pylorus. Localised pyloric contractions cause sustained pyloric closure, whether these contractions are phasic or tonic. These contractions occur independently of antral or duodenal contractions and may interrupt gastric emptying.     

Antro-pyloro-duodenal motor responses to gastric and duodenal nutrient in critically ill patients

BACKGROUND: Gastric emptying is frequently delayed in critical illness which compromises the success of nasogastric nutrition. The underlying motor dysfunctions are poorly defined. AIMS: To characterise antro-pyloro-duodenal motility during fasting, and in response to gastric and duodenal nutrient, as well as to evaluate the relationship between gastric emptying and motility, in the critically ill. SUBJECTS: Fifteen mechanically ventilated patients from a mixed intensive care unit; 10 healthy volunteers. METHODS: Antro-pyloro-duodenal pressures were recorded during fasting, after intragastric administration (100 ml; 100 kcal), and during small intestinal infusion of liquid nutrient (6 hours; 1 kcal/min). Gastric emptying was measured using a (13)C octanoate breath test. RESULTS: In healthy subjects, neither gastric nor small intestinal nutrient affected antro-pyloro-duodenal pressures. In patients, duodenal nutrient infusion reduced antral activity compared with both fasting and healthy subjects (0.03 (0-2.47) waves/min v 0.14 (0-2.2) fasting (p = 0.016); and v 0.33 (0-2.57)/min in healthy subjects (p = 0.005)). Basal pyloric pressure and the frequency of phasic pyloric pressure waves were increased in patients during duodenal nutrient infusion (3.12 (1.06) mm Hg; 0.98 (0.13)/min) compared with healthy subjects (-0.44 (1.25) mm Hg; p<0.02 after 120 minutes; 0.29 (0.15)/min; p = 0.0002) and with fasting (-0.06 (1.05) mm Hg; p<0.03 after 160 minutes; 0.49 (0.13)/min; (p = 0.0001). Gastric emptying was delayed in patients (gastric emptying coefficient 2.99 (0.2) v 3.47 (0.1); p = 0.015) and inversely related to the number of pyloric pressure waves (r = -0.563, p = 0.029). CONCLUSIONS: Stimulation of pyloric and suppression of antral pressures by duodenal nutrient are enhanced in the critically ill and related to decreased gastric emptying.     

Hyperglycaemia stimulates pyloric motility in normal subjects.

The motor correlates of the delay in gastric emptying produced by hyperglycaemia were investigated in 11 healthy volunteers. Fasting gastroduodenal motility was measured during euglycaemia (blood glucose concentration 3-5 mmol/l) and during hyperglycaemia induced by intravenous dextrose (blood glucose concentration 12-16 mmol/l). Antral, pyloric, and proximal duodenal pressures were recorded by a sleeve/sidehole manometric assembly positioned across the pylorus, with the aid of measurements of transmucosal potential difference. During hyperglycaemia there was stimulation of isolated pyloric pressure waves when compared with the euglycaemia period (p less than 0.05). This was associated with inhibition of antral pressure waves (p less than 0.05). In nine of the 11 subjects an episode of duodenal 'phase III like' activity occurred within 15 minutes of the onset of hyperglycaemia. It is proposed that the stimulation of localised pyloric contractions and inhibition of antral contractions contribute to the delayed gastric emptying induced by hyperglycaemia. Abnormal gastric motility in patients with diabetes mellitus may be the result of hyperglycaemia itself, rather than irreversible autonomic neuropathy.     

Postprandial antropyloroduodenal motility and gastric emptying in gastroparesis--effects of cisapride.

There is little information about the organisation of antroduodenal contractions or pyloric motility in patients with gastroparesis. The mechanisms responsible for the acceleration of gastric emptying by cisapride in patients with gastroparesis are also poorly understood. Simultaneous manometric and scintigraphic recordings were performed in 12 patients with gastroparesis and nine healthy volunteers before and after cisapride administration. Antropyloroduodenal pressures were recorded with a sleeve/side hole manometric assembly and gastric emptying with a scintigraphic method. Thirty minutes after the solid component of the test meal had begun to empty from the stomach all subjects received 5 mg cisapride intravenously over 10 minutes and recordings continued for a further 60 minutes. In the 30 minutes before cisapride there was no significant difference in the number of antral pressure waves (median 20 v 33, NS), basal pyloric pressure, or the number of isolated pyloric pressure waves between patients and volunteers, but the number of antral waves of extent > or = 6 cm (median 1 v 5, p < 0.05) was less in the patients, as was gastric emptying (8% v 20%, p < 0.05). In the patients, there was no change in the number of antral waves after cisapride, but there was an increase in the number of antral waves > or = 6 cm in extent (median 7 v 1, p < 0.05) and in the rate of gastric emptying (26% v 8%, p < 0.01). In the healthy subjects, cisapride increased gastric emptying (31% v 20%, p < 0.05), but reduced the number of antral waves (10 v 33, p < 0.05). Cisapride had no significant effect on the number of antral waves of extent more than or equal to 6 cm (11 v 5, NS). The number of isolated pyloric pressure waves decreased after cisapride (4 v 11, p < 0.05). There was a relationship between gastric emptying and the number of antral pressure waves of extent more than or equal to 6 cm in both the patients (r=0.38, p<0.05) and healthy subjects (r=0.05, p<0.01). There was no significant relationship between gastric emptying and the number of antral waves. It is concluded that disturbance of the relationship between antral, pyloric, and duodenal pressure waves is a major abnormality of postprandial gastric motor function in patients with gastroparesis. The stimulation of antral pressure waves of extent more than or equal to 6 cm may contribute to the acceleration of gastric emptying produced by cisapride in patients with gastroparesis and in normal subjects.     

Effects of glucagon-like peptide-1(7-36)amide on antro-pyloro-duodenal motility in the interdigestive state and with duodenal lipid perfusion in humans

BACKGROUND: Glucagon-like peptide-1(7-36)amide (GLP-1) is a gut hormone released postprandially. Synthetic GLP-1 strongly inhibits gastric emptying in healthy subjects and in patients with diabetes mellitus. AIMS: To investigate the effects of GLP-1 on antro-pyloro-duodenal motility in humans. METHODS: Eleven healthy male volunteers were studied on two separate days. On the interdigestive study day, a basal period was followed by a 60 minute period of saline infusion and two further 60 minute periods of intravenous infusion of GLP-1 0.4 and 1.2 pmol/kg/min to achieve postprandial and supraphysiological plasma levels, respectively. On the postprandial study day, the same infusions were coadministered with intraduodenal lipid perfusion at 2.5 ml/min (2.5 kcal/min) followed by another 60 minutes of recording after cessation of GLP-1. Antro-pyloro-duodenal motility was measured by perfusion manometry. RESULTS: GLP-1 significantly inhibited the number and amplitudes of antral and duodenal contractions in the interdigestive state and after administration of duodenal lipid. It abolished interdigestive antral wave propagation. In the interdigestive state, GLP-1 dose dependently increased pyloric tone and significantly stimulated isolated pyloric pressure waves (IPPW). Pyloric tone increased with duodenal lipid, and this was further enhanced by GLP-1. GLP-1 transiently restored the initial IPPW response to duodenal lipid which had declined with lipid perfusion. Plasma levels of pancreatic polypeptide were dose dependently diminished by GLP-1 with and without duodenal lipid. CONCLUSIONS: GLP-1 inhibited antro-duodenal contractility and stimulated the tonic and phasic motility of the pylorus. These effects probably mediate delayed gastric emptying. Inhibition of efferent vagal activity may be an important mechanism. As postprandial plasma levels of GLP-1 are sufficient to appreciably affect motility, we believe that endogenous GLP-1 is a physiological regulator of motor activity in the antro-pyloro-duodenal region.     

Nitric oxide mediates mechano- and chemoreceptor-activated intestinal feedback control of gastric emptying

The effect of nitric oxide (NO) synthase inhibition on the gastric emptying of nutrient and nonnutrient meals was investigated in nine dogs. The inhibition of NO synthase delayed the gastric emptying time of both nutrient and nonnutrient meals, but the percentage delay of nutrient meals was significantly greater than that of nonnutrient meals. The inhibition of NO synthase during the emptying of nonnutrient meals enhanced mainly the amplitude of antral, pyloric, and distal duodenal contractions. However, NO synthase inhibition during the emptying of nutrient meals stimulated several spatial and temporal parameters of gastropyloroduodenal contractions. We conclude that NO is one of the neurotransmitters of intestinal feedback that regulates the gastric emptying of both nutrient and nonnutrient meals. The nature and intensity of intestinal feedback by the stimulation of both chemo- and mechanoreceptors by nutrient meals is different from that by the stimulation of mechanoreceptors only by the nonnutrient meals.Supported in part by grants from the Department of Veterans Affairs Research Service and National Institutes of Diabetes, Digestive and Kidney Diseases, DK32346.     

Integration of canine proximal gastric,antral, pyloric,and proximal duodenal motility during fasting and after a liquid meal

The aim was to investigate the integration of proximal gastric, antral, pyloric, and duodenal motility during fasting and after feeding. Using a proximal gastric barostat and a manometric assembly with an array of side holes astride the gastroduodenal junction, the gastrointestinal interdigestive migrating motor complex was detected in five of seven conscious fasting dogs. During phase III of the complex, which lasted a mean ± SEM of 13 ± 0.5 min, 9.6 ± 0.9 volume waves were present in the proximal stomach. The volume waves were coordinated with clusters of antral waves 64 ± 11% of the time and with inhibition of duodenal waves 91±3% of the time. A 300-ml calorie-dense liquid meal abolished the complex and promptly increased proximal gastric volume in five of six dogs. Volume waves were nearly completely suppressed, while antral waves decreased from 24 ±3.0 waves/10 min to 10±2.8 waves/10 min (P<0.05) and isolated pyloric pressure waves increased from 7.2±2.8 waves/10 min to 22±3.3 waves/10 min (P<0.005). In summary, proximal gastric motility was integrated with antral, pyloric, and duodenal motility under both fasting and fed conditions. The integrated patterns likely account for the efficient clearance of indigestible solids during fasting and the controlled emptying of nutrients with feeding.Supported in part by USPHS NIH Grants DK 18278, DK34988, and DK07198, the Winthrop Travelling Fellowship of the Royal Australasian College of Physicians, the S.K.F. (Australia) Travelling Fellowship, and the Mayo Foundation.This work was presented in part before the World Congress of Gastroenterology, Sydney, Australia, August 30, 1990     

Rapid gastric emptying, rather than delayed gastric emptying, might provoke functional dyspepsia

It has been suggested that there could be three possible mechanisms of gastric dysfunction in patients with FD: (i) delayed gastric emptying, (ii) impaired gastric accommodation of food intake, and (iii) hypersensitivity to gastric distention. Postprandial fullness seems to be the most severe symptom in patients who report aggravation of their symptoms after meals. Therefore, it has been assumed that delayed gastric emptying and consequent prolonged antral distension could reduce hunger, increase satiety, and even cause gastric discomfort, all of which would pose a significant barrier to adequate nutrition. We previously reported that postprandial water intake inhibits gastric antral motility along with an increase of cholecystokinin (CCK) in normal subjects. We assumed that the rapid increase of CCK after water intake was initiated by a feedback mechanism related to the inflow of fatty chyme into the duodenum that inhibits gastric antral activity. This duodeno-gastric interaction is known as the "duodenal break." We also reported that total gastric emptying was more rapid after the intake of a high-viscosity liquid meal than after a low-viscosity meal, because the low-viscosity liquid meal inhibits gastric emptying after rapid initial inflow into the duodenum. Considering these results, we hypothesized that rapid gastric emptying, rather than delayed gastric emptying, could be a cause of FD. In some patients with postprandial distress syndrome (PDS), we have found a significant correspondence between PDS-related dyspepsia and accelerated gastric emptying in the early postprandial period. It is worth emphasizing that the duodenum and the duodeno-gastric interaction (duodenal break) could have an important role in the pathophysiology of FD. We consider that rapid gastric emptying might be a more important factor than delayed gastric emptying in patients with FD.     

Comparative effects of duodenal and ileal intubation on gastric emptying and postprandial antral, pyloric, and duodenal motility

The influence of gastric and small-intestinal intubation on fed patterns of antropyloroduodenal motility and gastric emptying of a solid meal has been investigated in normal volunteers. In 10 subjects a manometric assembly was passed as far as the fourth part of the duodenum; in 8 other subjects the terminal ileum was intubated; and a further 8 subjects were not intubated. The manometric assemblies were similar, apart from their length, and both incorporated a sleeve/side hole assembly located across the pylorus. All subjects ingested a meal of 100 g 99mTc-labelled liver/ground beef. There was no significant difference in either the lag phase or the linear emptying phase of gastric emptying between the control and duodenal intubation groups. The emptying phase of the test meal, but not the lag phase, was slower (p less than 0.01) in the ileal intubation group than in the non-intubated and duodenal intubation groups. There were fewer (p less than 0.01) antral pressure waves in the ileal than in the duodenal intubation group. We conclude that ileal but not duodenal intubation has an important inhibitory influence on gastric emptying and antral motility.     

Relationship of the motor activity of the antrum, pylorus, and duodenum to gastric emptying of a solid-liquid mixed meal

The postprandial motor activity of the antrum, pylorus, and duodenum in 15 healthy volunteers was compared with the profiles of emptying of the solid and liquid components of a meal. The liquid component of the meal emptied rapidly in an exponential manner, whereas the solid remained in the fundus of the stomach until approximately 80% of the liquid had emptied and then emptied in a linear manner. The onset of solid emptying was associated with an increase in the rate of occurrence of antral pressure waves (p less than 0.05), and the half-time for solid emptying (t1/2 - lag period) was inversely correlated (p less than 0.05) with the rate of coordinated contractions involving the antrum. The substitution of 25% dextrose in normal saline as the liquid component of the meal increased the half-time for liquid emptying from a median of 8 to 40 min (p less than 0.01), increased the lag period for solid emptying from 40 to 87 min (p less than 0.01), and increased the rate of occurrence of isolated pyloric pressure waves during the solid lag phase from 7 to 58/h (p less than 0.05), but did not affect the slope of solid emptying or the rate of coordinated contractions involving the antrum during the solid emptying period.     

Erythromycin accelerates solid emptying at the expense of gastric sieving

Erythromycin accelerates gastric emptying by inducing antral contractions similar to phase III of interdigestive MMC. These powerful contractions are capable of forcing coin-sized indigestibles out of the stomach. In contrast, fed motility is associated with submaximal contractions that fragment (trituration) and propel solids while retaining large (>0.5 mm) pieces for further size reduction (gastric sieving). In this study, using dogs with duodenal fistulas, we tested the hypothesis that erythromycin-induced acceleration of gastric emptying resulted in the passage of inadequately triturated (>0.5 mm) chunks of solids into the duodenum. We found that gastric emptying was accelerated by erythromycin (vs 0.15 M NaCl control,P<0.05). However, the percentage of chyme collected in the >0.5-mm fraction was much greater (P<0.01) in the erythromycin-treated experiments (63±9%) than the controls (7±1%). Correspondingly, while a fine gruel was passed during controls, under erythromycin infusion, most of the solids were emptied as large chunks virtually unchanged from the swallowed pieces. We conclude that erythromycin accelerates gastric emptying at the expense of gastric sieving.     

Pyloric electrical stimulation reduces food intake by inhibiting gastric motility in dogs

BACKGROUND & AIMS: The pylorus plays an important role in regulating gastric emptying. The aim of this study was to investigate the therapeutic potential of pyloric electrical stimulation (PES) for obesity in dogs. METHODS: The study was composed of 3 separate experiments. The first experiment was designed to study the effects of PES with various parameters on gastric emptying and gastric slow waves in 5 sessions. The second experiment was used to test the effects of PES on antral contractions. The acute effect of PES on food intake was studied in the third experiment. RESULTS: (1) Pyloric myoelectrical recording showed dual frequencies. The lower frequency was identical to the frequency of the gastric slow waves, and the higher frequency was similar to that of the intestinal slow waves. (2) Gastric emptying was significantly delayed with PES, and the delay in gastric emptying was significantly and negatively correlated with stimulation energy ( r = -.673; P < .001). (3) PES significantly impaired the regularity and coupling of the intrinsic gastric myoelectrical activity in an energy-dependent manner. The delayed gastric emptying was significantly correlated with the impairment of the coupling of gastric myoelectrical activity ( r = .441; P < .02). (4) Antral contractions on the fed state were significantly and substantially inhibited with PES. (5) Acute PES significantly reduced food intake. CONCLUSIONS: PES reduces food intake that may be attributed to its inhibitory effects on intrinsic gastric myoelectrical activity, antral contractions, and gastric emptying.     

Cholecystokinin octapeptide stimulates phasic and tonic pyloric motility in healthy humans.

Stimulation of localised pyloric contractions may be an important mechanism in the slowing of gastric emptying by cholecystokinin infusion. The effect of cholecystokinin octapeptide on fasting pyloric motility was investigated in 14 healthy volunteers. Antral, pyloric, and duodenal pressure responses to normal saline and graded injections of cholecystokinin octapeptide (5, 10, and 20 ng/kg) were measured. Injections were given double blind and in randomised order. All doses of cholecystokinin octapeptide initially stimulated (p < 0.05 cf saline) phasic pressure waves localised to the pylorus--the median number of pyloric pressure waves in the 5 minutes after injection being 0, 3.5, 6, and 7 for the saline and the 5, 10, 20 ng/kg cholecystokinin octapeptide injections respectively. The phasic pyloric motor response to 20 ng/kg cholecystokinin octapeptide injection was greater than that to 5 ng/kg (p < 0.05). Basal pyloric pressure increased after 20 ng/kg (1.0 v 0.2 mm Hg, p < 0.05 cf saline). Antral and duodenal pressure waves were suppressed initially by all doses of cholecystokinin (p < 0.05 cf saline). Subsequently, 20 of the 42 cholecystokinin octapeptide, injections but none of the saline injections, were followed by antropyloric pressure waves. Atropine, 15 micrograms/kg iv as a bolus, and then 4 micrograms/kg/hour iv as an infusion, had no effect on the stimulation of localised phasic pyloric pressure waves by cholecystokinin octapeptide 10 ng/kg. It is concluded that stimulation of pyloric contractions and suppression of antral and proximal duodenal motility may contribute to the slowing of gastric emptying produced by cholecystokinin.     

Role of the proximal and distal stomach in mixed solid and liquid meal emptying.

The role of the proximal and distal stomach in the emptying of solids and liquids from the stomach remains unclear. We have used a dual isotope technique to quantify proximal and distal stomach emptying of a solid (100 g of 99mTc labelled liver/ground beef) liquid (either 200 ml of normal saline (eight subjects) or 25% dextrose (seven subjects) labelled with 113mIn-diethylenetriaminepenta-acetic acid) mixed meal. A manometric catheter simultaneously measured antral, pyloric, and duodenal motor activity. The liquid component dispersed rapidly throughout the stomach and emptied after a minimal lag period. The emptying of the 25% dextrose was delayed compared with the saline. This delay was associated with increased retention of the liquid in the distal stomach, a significant increase in localised phasic pyloric contractions, and a suppression of antral contractions. The solid component initially resided wholly within a proximal stomach reservoir area. Solids then redistributed from proximal to distal stomach during the emptying of liquid from the stomach. Dextrose delayed gastric emptying of solids compared with saline by increasing the solid lag period and retention in the proximal stomach. There was no significant difference between saline and dextrose meals in the distal stomach retention of solid or in the linear rate of emptying after the lag period. We conclude that, contrary to general opinion, the proximal stomach plays an important role in the control of gastric emptying of solids while the distal stomach is important in the emptying of nutrient liquids.     

Cholinergic effects on human gastric motility

BACKGROUND: Cholinergic regulation of chronotropic (frequency) and inotropic (force) aspects of antral contractility and how these impact on gastric emptying are not well delineated. AIMS: To determine the effects of cholinergic stimulation and inhibition on myoelectric, contractile, and emptying parameters of gastric motility. METHODS: Ten normal subjects underwent three studies each, using simultaneous electrogastrography (EGG), antroduodenal manometry, and gastric emptying with dynamic antral scintigraphy (DAS). After 30 minutes of baseline fasting manometry and EGG, subjects received saline intravenously, atropine (0.6 mg then 0.25 mg/hour intravenously), or bethanechol (5 mg subcutaneously). This was followed by another 30 minutes' recording and by three hours of postprandial recording after ingestion of a technetium-99m labelled solid meal. RESULTS: During fasting, atropine decreased, whereas bethanechol increased, the antral manometric motility index and EGG power. Postprandially, atropine decreased the amplitude of antral contractions by DAS, decreased the postprandial antral manometric motility index, and slowed gastric emptying. Atropine caused a slight increase in postprandial frequency of antral contractions by DAS and gastric myoelectrical activity by EGG. Bethanechol slightly increased the amplitude, but slightly decreased the frequency of antral contractions by DAS and decreased the frequency of gastric myoelectrical activity by EGG, with no significant increase in the motility index or gastric emptying. CONCLUSIONS: Cholinergic antagonism with atropine reduces antral contractility and slows gastric emptying. Cholinergic stimulation with bethanechol increases antral contractility, but decreases the frequency of antral contractions, without altering the antral motility index or gastric emptying.     

Effect of pirenzepine on oesophageal, gastric, and enteric motor function in man

The effect of pirenzepine on oesophageal, gastric, and enteric motor function was evaluated in six healthy volunteers. Each subject was studied before and after taking pirenzepine, 100 mg/day, for 3 days. Half and complete gastric emptying times of clear liquid, assessed by epigastric impedance, were significantly delayed by the drug: 6.16 +/- 1.74 min and 13.8 +/- 4.64 min versus 16.65 +/- 3.03 min and 25.1 +/- 8.2 min, respectively (p less than 0.05). Enteric motility was assessed by manometry, and variables studied were the duration of the various phases of the migratory motility complex, the frequency of contractions in phase III, and the amplitude of contractions in phases II, III, and in the postprandial period. Only phase I was affected and was significantly prolonged by the drug: 16.08 +/- 5.94 min versus 31.65 +/- 12.88 min (p less than 0.01). Oesophageal motility was assessed by manometry. Variables studied were amplitude and duration of contractions in the body of the oesophagus, and lower oesophageal sphincter pressure. Results were not significantly changed by the drug. We conclude that pirenzepine, given at a dose used for treatment of peptic ulcer disease, significantly delays the gastric emptying of liquids, has minimal effect on enteric motility, and has no effect on oesophageal motility. The effect on gastric emptying may be therapeutically useful by reducing the acid load on the duodenum in duodenal ulcer disease.     

Determinants of Occurrence and Volume of Transpyloric Flow During Gastric Emptying of Liquids in Dogs

The precise factors and their relative contributions that lead to individual flow pulses across the pylorus during liquid gastric emptying remain unclear. Our objective was to determine the factors leading to individual flow pulses, their relative contributions and the role of the vagus nerve in their modulation. Proximal gastric tone had a strong positive correlation with the volume of the corresponding transpyloric flow pulse whereas pyloric tone had an inverse correlation. Antral contractions were associated with the presence but not the volume of the pulse. Acute vagal blockade retarded emptying via loss of proximal gastric tone and increased outflow resistance and loss of propagating antral pressure waves. In conclusion, the major determinants of the volume of pulsatile transpyloric flow are proximal gastric and pyloric tone. The vagus nerve plays a key role in regulating both proximal gastric and pyloric tone as well as moderating propagating antral contractions.