Isolated Pyloric Pressure Waves Research Articles

Modulation of individual components of gastric motor response to duodenal glucose

To evaluate individual components of the antro-pyloro-duodenal (APD) motor response to graded small intestinal glucose infusions in healthy humans. APD manometry was performed in 15 healthy subjects (12 male; 40 ± 5 years, body mass index 26.5 ± 1.6 kg/m(2)) during four 20-min intraduodenal infusions of glucose at 0, 0.5, 1.0 and 1.5 kcal/min, in a randomised double-blinded fashion. Glucose solutions were infused at a rate of 1 mL/min and separated by 40-min "wash-out" period. Data are mean ± SE. Inferential analyses are repeated measure analysis of variance with Bonferroni post-hoc testing. At 0 kcal/min frequency of pressure waves were: antrum (7.5 ± 1.8 waves/20 min) and isolated pyloric pressure waves (IPPWs) (8.0 ± 2.3 waves/20 min) with pyloric tone (0.0 ± 0.9 mmHg). Intraduodenal glucose infusion acutely increased IPPW frequency (P < 0.001) and pyloric tone (P = 0.015), and decreased antral wave frequency (P = 0.007) in a dose-dependent fashion. A threshold for stimulation was observed at 1.0 kcal/min for pyloric phasic pressure waves (P = 0.002) and 1.5 kcal/min for pyloric tone and antral contractility. There is hierarchy for the activation of gastrointestinal motor responses to duodenal glucose infusion. An increase in IPPWs is the first response observed.

Marked differences in gustatory and gastrointestinal sensitivity to oleic acid between lean and obese men

Both orosensory stimulation and feedback from the gastrointestinal tract contribute to energy intake regulation. We evaluated the hypothesis that overweight or obese subjects would be less sensitive to both oral and intraduodenal oleic acid exposure than would lean subjects. Eleven overweight or obese and 8 lean men were studied on 2 occasions, during which antropyloroduodenal pressures, plasma cholecystokinin and peptide YY, and appetite were measured during 90-min intraduodenal infusions of saline or oleic acid (18:1 load: 0.78 kcal/min); energy intake (buffet lunch) was determined immediately afterward. Oral detection thresholds for 18:1 and recent dietary intake (2-d recall) were also quantified. In lean subjects, the number of isolated pyloric pressure waves (IPPWs) was greater during 18:1 infusion than during saline infusion (P < 0.05); no significant differences were observed between the 18:1 and saline infusions in the overweight or obese subjects. In both groups, 18:1 stimulated plasma cholecystokinin and peptide YY and suppressed energy intake compared with saline (P < 0.05), with trends for reduced cholecystokinin and energy intake responses in the overweight or obese subjects. Detection thresholds for 18:1 were greater in overweight or obese (7.9 ± 0.1 mmol/L) than in lean (4.1 ± 0.4 mmol/L) subjects (P < 0.05). Overweight or obese subjects had greater recent energy (P < 0.05) and fat (P = 0.07) intakes than did lean subjects. There was a direct relation (r = 0.669) of body mass index with 18:1 detection thresholds and inverse relations (r < -0.51) of IPPWs with body mass index and 18:1 detection thresholds (P < 0.05). The ability to detect oleic acid both orally and within the gastrointestinal tract is compromised in obese men, and oral and gastrointestinal responses to oleic acid are related. This trial was registered at www.actr.org.au (Australian New Zealand Clinical Trials Registry) as 12609000557235.

Dose-dependent effects of cholecystokinin-8 on antropyloroduodenal motility, gastrointestinal hormones, appetite, and energy intake in healthy men

CCK mediates the effects of nutrients on gastrointestinal motility and appetite. Intravenously administered CCK stimulates pyloric pressures, increases plasma PYY, and suppresses ghrelin, all of which may be important in the regulation of appetite and energy intake. The dose-related effects of exogenous CCK on gastrointestinal motility and gut hormone release, and the relationships between these effects and those on energy intake, are uncertain. We hypothesized that 1) intravenous CCK-8 would have dose-dependent effects on antropyloroduodenal (APD) pressures, plasma PYY and ghrelin concentrations, appetite, and energy intake and 2) the suppression of energy intake by CCK-8 would be related to the stimulation of pyloric motility. Ten healthy men (age 26 +/- 2 yr) were studied on four separate occasions in double-blind, randomized fashion. APD pressures, plasma PYY and ghrelin, and appetite were measured during 120-min intravenous infusions of 1) saline ("control") or 2) CCK-8 at 0.33 ("CCK0.33"), 3) 0.66 ("CCK0.66"), or 4) 2.0 ("CCK2.0") ng.kg(-1).min(-1). After 90 min, energy intake at a buffet meal was quantified. CCK-8 dose-dependently stimulated phasic and tonic pyloric pressures and plasma PYY concentrations (r > 0.70, P < 0.05) and reduced desire to eat and energy intake (r > -0.60, P < 0.05) without inducing nausea. There were relationships between basal pyloric pressure and isolated pyloric pressure waves (IPPW) with plasma CCK (r > 0.50, P < 0.01) and between energy intake with IPPW (r = -0.70, P < 0.05). Therefore, our study demonstrates that exogenous CCK-8 has dose-related effects on APD motility, plasma PYY, desire to eat, and energy intake and suggests that the suppression of energy intake is related to the stimulation of IPPW.

Dose-dependent effects of cholecystokinin-8 (CCK-8) on pyloric motility, appetite and energy intake.

CCK suppresses appetite and modulates gastrointestinal motility, however, the relationship between these parameters remains unclear. Furthermore, the effects of CCK on appetite may be due to nausea caused by supraphysiological CCK concentrations. We hypothesised that CCK would have dose-dependent effects on pyloric motility and appetite, in the absence of nausea. Healthy males (23±1 years; BMI 23±0.5 kg/m 2 ) were studied on 4 occasions in double-blind, randomised fashion. Appetite and pyloric pressures were measured during 120-min intravenous infusions of (i) saline (control), or CCK-8 at (ii) 0.33 (‘CCK0.33’), (iii) 0.66 (‘CCK0.66’) or (iv) 2 (‘CCK2’) ng/kg/min. At 90 min energy intake at a buffet meal was quantified. There was an effect of treatment on scores for desire-to-eat ( P <0.05). All CCK infusions decreased desire-to-eat when compared with control ( P <0.05), and their effects were dose-related ( R =0.7, P =0.05). No infusion-induced nausea. There was a treatment-by-time interaction for the number of isolated pyloric pressure waves (IPPWs) ( P =0.001). All CCK infusions increased IPPWs when compared with control; CCK0.66 and CCK2 between 0 and 90 min ( P <0.01), and CCK0.33 between 0 and 45 min ( P <0.05). Mean energy intake was less following both CCK0.66 (3630±550 kJ) and CCK2 (3319±359 kJ) when compared with control (3974±491 kJ). There was an inverse relationship between desire-to-eat and IPPWs ( R =−0.7, P <0.05), and a trend for a positive relationship between desire-to-eat and energy intake ( R =0.53, P =0.09). In conclusion (i) intravenous CCK has dose-related effects on pyloric motility and appetite, in the absence of nausea, and (ii) the stimulation of IPPWs may be a determinant of appetite suppression.

Effects of load, and duration, of duodenal lipid on antropyloroduodenal motility, plasma CCK and PYY, and energy intake in healthy men

Enterally administered lipid modulates antropyloroduodenal motility, gut hormone release, appetite, and energy intake. We hypothesized that these effects would be dependent on both the load, and duration, of small intestinal exposure to lipid. Eleven healthy men were studied on four occasions in a double-blind, randomized, fashion. Antropyloroduodenal motility, plasma CCK and peptide YY (PYY) concentrations, and appetite perceptions were measured during intraduodenal infusion of lipid (Intralipid) at 1) 1.33 kcal/min for 50 min, 2) 4 kcal/min for 50 min, and 3) 1.33 kcal/min for 150 min, or 4) saline for 150 min. Immediately after the infusions, energy intake was quantified. Pressure wave sequences (PWSs) were suppressed, and basal pyloric pressure, isolated pyloric pressure waves (IPPWs), plasma CCK and PYY stimulated (all P < 0.05), during the first 50 min of lipid infusion, in a load-dependent fashion. The effect of the 4 kcal/min infusion was sustained so that the suppression of antral pressure waves (PWs) and PWSs and increase in PYY remained evident after cessation of the infusion (all P < 0.05). The prolonged lipid infusion (1.33 kcal/min for 150 min) suppressed antral PWs, stimulated CCK and PYY and basal pyloric pressure (all P < 0.05), and tended to stimulate IPPWs when compared with saline throughout the entire infusion period. There was no significant effect of any of the lipid infusions on appetite or energy intake, although nausea was slightly higher (P < 0.05) with the 4 kcal/min infusion. In conclusion, both the load, and duration, of small intestinal lipid influence antropyloroduodenal motility and patterns of CCK and PYY release.

Dose-related effects of lauric acid on antropyloroduodenal motility, gastrointestinal hormone release, appetite, and energy intake in healthy men

We recently reported that intraduodenal infusion of lauric acid (C12) (0.375 kcal/min, 106 mM) stimulates isolated pyloric pressure waves (IPPWs), inhibits antral and duodenal pressure waves (PWs), stimulates release of cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1), and suppresses energy intake and that these effects are much greater than those seen in response to isocaloric decanoic acid (C10) infusion. Administration of C12 was, however, associated with nausea, confounding interpretation of the results. The aim of this study was to evaluate the effects of different intraduodenal doses of C12 on antropyloroduodenal (APD) motility, plasma CCK and GLP-1 concentrations, appetite, and energy intake. Thirteen healthy males were studied on 4 days in double-blind, randomized fashion. APD pressures, plasma CCK and GLP-1 concentrations, and appetite perceptions were measured during 90-min ID infusion of C12 at 0.1 (14 mM), 0.2 (28 mM), or 0.4 (56 mM) kcal/min or saline (control; rate 4 ml/min). Energy intake was determined at a buffet meal immediately following infusion. C12 dose-dependently stimulated IPPWs, decreased antral and duodenal motility, and stimulated secretion of CCK and GLP-1 (r > 0.4, P < 0.05 for all). C12 (0.4 kcal/min) suppressed energy intake compared with control, C12 (0.1 kcal/min), and C12 (0.2 kcal/min) (P < 0.05). These effects were observed in the absence of nausea. In conclusion, intraduodenal C12 dose-dependently modulated APD motility and gastrointestinal hormone release in healthy male subjects, whereas effects on energy intake were only apparent with the highest dose infused (0.4 kcal/min), possibly because only at this dose was modulation of APD motility and gastrointestinal hormone secretion sufficient for a suppressant effect on energy intake.

Patterns of antropyloric motility in fed healthy preterm infants

Background: Antropyloric motility is important for regulation of gastric emptying and has not been adequately characterised in premature infants. Aim: To evaluate fed patterns of antropyloric motility in premature infants....

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

BACKGROUNDGlucagon-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.AIMSTo investigate the effects of GLP-1 on...

Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans.

The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) on gastric emptying and pyloric motility. Concurrent measurements of gastric emptying and antropyloroduodenal pressures were performed in six volunteers (aged 24-26 yr) who had had pyloromyotomy performed in infancy because of IHPS, and in six normal subjects. Subjects were studied on 2 days, once sitting and once in the left lateral position. Gastric emptying of 300 ml 25% dextrose labeled with 20 MBq 99mTc sulfur colloid was measured. Antropyloroduodenal motility was evaluated with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 min, starting 30 min after ingestion of the dextrose. In both body positions, gastric emptying and intragastric distribution of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number (p<0.01) and amplitude (p<0.02) of isolated pyloric pressure waves (IPPWs) was greater in the control subjects, whereas basal pyloric pressure was greater in the pyloromyotomy subjects (p<0.02). In both groups, the rate of gastric emptying in the sitting position was related to the number of IPPWs (r> or =0.40, p<0.05), but not to basal pyloric pressure. These results indicate that, in adults who have had pyloromyotomy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressure waves are less. In contrast, the overall rate of gastric emptying of a nutrient liquid meal is normal. These observations are consistent with the concept that the stomach has the capacity to compensate for changes in pyloric motility to minimize effects on gastric emptying.

Long-term effects of pyloromyotomy on pyloric motility and gastric emptying in humans

OBJECTIVE: The aim of this study was to determine the long term effects of pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) on gastric emptying and pyloric motility. METHODS: Concurrent measurements of gastric emptying and antropyloroduodenal pressures were performed in six volunteers (aged 24–26 yr) who had had pyloromyotomy performed in infancy because of IHPS, and in six normal subjects. Subjects were studied on 2 days, once sitting and once in the left lateral position. Gastric emptying of 300 ml 25% dextrose labeled with 20 MBq 99mTc sulfur colloid was measured. Antropyloroduodenal motility was evaluated with a sleeve/multiple sidehole manometric assembly, which was also used to deliver an intraduodenal triglyceride infusion at 1.1 kcal/min for 60 min, starting 30 min after ingestion of the dextrose. RESULTS: In both body positions, gastric emptying and intragastric distribution of the drink did not differ between the two groups. In both groups and postures, the amount emptied was less during intraduodenal lipid infusion. The number ( p < 0.01) and amplitude ( p < 0.02) of isolated pyloric pressure waves (IPPWs) was greater in the control subjects, whereas basal pyloric pressure was greater in the pyloromyotomy subjects ( p < 0.02). In both groups, the rate of gastric emptying in the sitting position was related to the number of IPPWs (r ≥ 0.40, p < 0.05), but not to basal pyloric pressure. CONCLUSIONS: These results indicate that, in adults who have had pyloromyotomy for IHPS in infancy, patterns of pyloric motility are abnormal; pyloric tone is higher, whereas the number and amplitude of phasic pyloric pressure waves are less. In contrast, the overall rate of gastric emptying of a nutrient liquid meal is normal. These observations are consistent with the concept that the stomach has the capacity to compensate for changes in pyloric motility to minimize effects on gastric emptying.

Physiological changes in blood glucose affect appetite and pyloric motility during intraduodenal lipid infusion.

We evaluated the effects of varying blood glucose concentration within the normal postprandial range and its interaction with small intestinal nutrients on antropyloric motility and appetite. Eight healthy males (19-40 yr) underwent paired studies, with a blood glucose level of 5 or 8 mmol/l. Manometry and visual analog scales were used to assess motility and appetite, during fasting and intraduodenal lipid infusion (1.5 kcal/min). In the fasting state, antral waves were suppressed at 8 mmol/l compared with 5 mmol/l (P = 0.018). However, pyloric motility was no different between the two blood glucose concentrations. Hunger was no different at 5 mmol/l compared with 8 mmol/l, but fullness was greater at 8 mmol/l (P = 0. 01). During intraduodenal lipid infusion, antral waves were suppressed (P < 0.035) and isolated pyloric pressure waves (IPPWs) were stimulated (P < 0.02) compared with during the fasting state, with no difference between blood glucose concentrations, although the temporal patterning of IPPWs varied between blood glucose concentrations. The amplitude of IPPWs was greater at 5 mmol/l compared with 8 mmol/l (P < 0.001), and hunger decreased at 8 mmol/l compared with 5 mmol/l (P = 0.02). We conclude that "physiological" hyperglycemia modifies gastric motor and sensory function and that synergy exists between blood glucose concentration and small intestinal nutrients in modulating gastric motility and appetite.

THE EFFECT OF DUODENAL DISTENSION UPON ANTRO‐PYLORIC MOTILITY AND LIQUID GASTRIC EMPTYING IN PIGS

This study has investigated first the role of the antrum and pylorus in the retardation of gastric emptying during distension of the duodenum, and second whether ascending duodenal intramural nerves contribute to control of both antro-pyloric motility and liquid gastric emptying in response to distension of the duodenum. Studies were performed on 18 pigs. In six the duodenum was transected 1-2 cm distal to the pylorus, to interrupt intramural nerves, in six the pylorus was excised and a further six pigs without any transection or resection acted as controls. Motility of the antrum, pylorus and duodenum was recorded by a sleeve/side hole manometric catheter. Gastric emptying was measured by drainage of the duodenum through a cannula. In control animals distension of the duodenum inhibited antro-pyloric pressure waves (APPW), from 1.52 waves/min at minimum distension to 0.25/min at maximum distension (P=0.0007), stimulated isolated pyloric pressure waves (IPPW), from 0.56/min to 1.80/min (P=0.034) and slowed emptying of a 1000 mL load of 5% dextrose over 30 min from 788 mL to 251 mL (P=0.0001). Duodenum transected animals did not show the duodenal distension-induced stimulations of IPPW (maximum distension: 0.93/min), but both the distension-induced inhibition of APPW (maximum distension: 0.85/min) and slowing of emptying (maximum distension: 52 mL emptied) were unaltered. Similarly in pylorus-excised animals, duodenal distension inhibited APPW (maximum distension: 0.47/min) and slowed liquid emptying (maximum distension: 267 mL), effects which did not differ from control animals. Retardation of gastric emptying by duodenal distension may be due in part to inhibition of antral contractions. Under the conditions of this experiment, increased pyloric resistance to flow does not play a major role in the slowing of emptying by duodenal distension, but the stimulation of the pylorus by duodenal distension depends on duodenal intramural neural pathways. Duodenal distension-induced feedback control of emptying is mediated primarily via pathways other than ascending intraduodenal nerves.

Relationship between surface electrogastrography and antropyloric pressures

The cutaneous electrogastrogram (EGG) and intraluminal antropyloroduodenal pressures were recorded in 12 healthy volunteers for 30-min periods during phase II of the interdigestive motor complex, during intraduodenal infusion of 10% triglyceride, and after intravenous erythromycin (3 mg/kg). During phase II, the frequency of the EGG was relatively constant in each individual, with a median frequency of 0.046 Hz [2.8 counts per minute (cpm)]. EGG frequency was greater (P < 0.05) than the median rate of antral pressure waves (1.8 cpm). The suppression of antral pressure waves (P < 0.05) and stimulation of isolated pyloric pressure waves (IPPWs) (P < 0.05) produced by triglyceride infusion were not associated with changes in EGG frequency compared with phase II. The frequency of the EGG and the rate of IPPWs were comparable. After erythromycin, EGG frequency was 0.03 Hz (1.8 cpm), less than during both phase II and triglyceride infusion (P < 0.05) and almost identical to the rate of antral pressure waves. Pressure waves were nearly always associated with an EGG signal. In contrast, the temporal relationship between the EGG signal and pressure waves was variable. During triglyceride infusion (r = 0.83, P < 0.001) and after erythromycin (r = 0.83, P < 0.001) there was a close (approximately 1:1) relationship between the rate of pressure waves and EGG frequency. However, there was no significant relationship (r = 0.32, not significant) between the number of pressure waves and EGG frequency frequency during pase II.(ABSTRACT TRUNCATED AT 250 WORDS)

Pyloric motility and liquid gastric emptying during barostatic control of gastric pressure in pigs.

1. In conscious pigs, intragastric pressure was controlled by a water barostat such that the gastroduodenal pressure gradient was always positive with the barostat set above 15 cm. In six pigs pyloric motor function was removed by prior pylorectomy. 2. In pylorus-intact animals, isolated pyloric pressure waves (IPPWs) occurred at a median of 2.9 min-1 during duodenal dextrose infusion with the barostat set at or above a threshold of 15 cm. Increases of intragastric pressure above this threshold had no additional effect upon rates of IPPWs. Below this threshold, with identical duodenal dextrose infusion, IPPWs occurred infrequently (0.5 min-1). In pylorus-excised animals virtually no IPPWs were seen. 3. In both pylorus-intact and -excised animals, the rate of antral pressure waves (APWs) was dependent upon intragastric pressure during duodenal infusion of both saline and dextrose. No threshold for stimulation was seen. Duodenal dextrose infusion inhibited APWs in pylorus-intact animals only. 4. With a positive gastroduodenal pressure gradient, gastric emptying was more rapid in pylorus-excised animals than pylorus-intact animals during duodenal dextrose infusion. In contrast, gastric emptying rates were not different between pylorus-intact and -excised animals during saline infusion. 5. These findings suggest an all-or-none-type stimulation of localized pyloric contractions by distension of the stomach beyond a threshold, in synergism with stimulation by nutrients within the upper small bowel. In contrast, stimulation of antral motility is in proportion to distension of the stomach. The pylorus, by way of localized pyloric contractions, is an effective resistor to transpyloric flow in the face of a positive gastroduodenal pressure gradient.

Duodenal intramural nerves in control of pyloric motility and gastric emptying

We have investigated the role of ascending duodenal intramural nerves in the control of isolated pyloric pressure waves (IPPW) and liquid gastric emptying. In six pigs, the proximal duodenum was transected to interrupt intramural nerves. A further six pigs had a sham operation. Four weeks after operation, motility of the antrum, pylorus, and duodenum was recorded by side holes and a sleeve sensor. Gastric emptying of a 1,000-ml test meal was significantly more rapid in duodenum-transected animals (P less than 0.0001) during intraduodenal infusion of each of isosmolar dextrose (424 ml emptied), fatty acid (335 ml), and amino acids (396 ml) than in duodenum-intact animals (dextrose: 128 ml; fatty acid: 57 ml; amino acids: 192 ml). Associated with this, in duodenum-transected animals infusion of each of isosmolar dextrose, fatty acid, amino acids, and hyperosmolar saline failed to produce the stimulation of IPPW seen in duodenum-intact animals. In both duodenum-intact and -transected animals, supramaximal stimulation by intraduodenal infusion of 25% dextrose slowed gastric emptying and stimulated IPPW. Ascending duodenal intramural nerves are a major physiological pathway for nutrient- and osmolar-stimulated feedback control of pyloric motility and gastric emptying.

Effect of Intraduodenal Infusion of Acid on the Antropyloroduodenal Motor Unit in Human Volunteers

Intraduodenal acid has been shown to delay gastric emptying. We have investigated the effect of infusing hydrochloric acid into the duodenum on the motor activity of the gastric antrum, pylorus, and duodenum in 18 healthy volunteers. Pressures in the gastric antrum, pylorus, and duodenum and the pH in the antrum and duodenum were recorded in response to alternate duodenal infusions of normal saline and 0.1 M isotonic hydrochloric acid at constant (1 or 2 ml/min) or increasing (1, 2, 3.75, and 5 ml/min) rates. Repetitive infusions of acid (1 or 2 ml/min) were associated with 1) a decrease in antral pressure waves (p &lt; 0.05), 2) a reduction in coordinated pressure waves involving the duodenum (p &lt; 0.05) and replacement by random contractile activity, and 3) an increase in isolated pyloric pressure waves (IPPWs) (p &lt; 0.05). Increasing the rate of acid infusion reduced the rate of coordinated contractions involving the antrum (r = ‐0.39; p &lt; 0.01) and increased the rate of IPPWs (r = 0.45; p &lt; 0.01). There were significant correlations between the percentage of time that the duodenal pH was less than 2, and both the rate of coordinated contractions involving the antrum (r = ‐0.28; p &lt; 0.01) and the rate of IPPWs (r = 0.34; p &lt; 0.01). These changes in antropyloroduodenal motor activity may contribute to the delay in emptying of acidic solutions from the stomach.