Effect of cisapride on gastric sensitivity to distension, gastric compliance and duodeno-gastric reflexes in healthy humans

BACKGROUND AND AIMS: Visceral hypersensitivity and impaired gastric relaxation after the ingestion of a meal are frequent features in patients with functional dyspepsia. Cisapride improves dyspeptic symptoms. The study aims to evaluate whether cisapride influences gastric sensitivity to distension as well as gastric compliance and duodenogastric reflexes. PATIENTS AND METHODS: Eight healthy males were studied on two different days, each after 7 days' treatment either with placebo or cisapride 10 mg qid in randomized order. A spherical bag connected to a barostat was placed in the gastric fundus and an 8-lumen manometric catheter was positioned with 4 side holes in antrum and 4 in duodenum. During a phase II of the migrating motor complex, the intragastric bag was inflated at a constant pressure 1 mm Hg above the intra-abdominal pressure and the gastric volume was measured during intraduodenal infusion of lipids and citric acid at different rates. Once the stomach returned to the basal volume, the bag was distended according to two different protocols until subjects reported discomfort. Antroduodenal motility was measured throughout the study. RESULTS: Intraduodenal infusion of lipids and citric acid caused relaxation of gastric fundus. Relaxation was similar for lipids and acid (203 +/- 30 vs 199 +/- 43 ml), and was not influenced by cisapride and infusion rate. Cisapride did not influence gastric sensitivity to distension (10 +/- 1.5 vs 9.7 +/- 1.3 mm Hg) and gastric compliance (52.7 +/- 1.2 vs 49.8 +/- 1.8 ml/mm Hg). The antral motor index significantly decreased following infusion of acid and lipids with placebo but not with cisapride. CONCLUSIONS: Cisapride inhibits the physiological duodenoantral reflexes but does not influence either the mechanical properties of the gastric fundus nor the gastric sensitivity to distension.     

Influence of sumatriptan on gastric fundus tone and on the perception of gastric distension in man

BACKGROUND: In animals, activation of 5-HT(1) like receptors causes a relaxation of the gastric fundus through the activation of intrinsic inhibitory neurones. AIMS: To investigate the effect of sumatriptan, an agonist at enteric neuronal 5-HT(1) receptors, on fasting fundus tone and sensitivity to gastric distension in man. METHODS: A gastric barostat was used to study the effect of placebo and sumatriptan, 6 mg subcutaneously, on basal fundic tone in healthy subjects. In addition, stepwise isobaric and isovolumetric gastric distensions were performed and perception was measured before and after the administration of placebo and sumatriptan. RESULTS: Placebo had no significant effects on gastric tone and on perception. Sumatriptan induced an immediate relaxation of the gastric fundus, reflected by an intragastric volume increase of 209 (39) ml (p<0.0005). After sumatriptan, intragastric pressures at the thresholds for perception or discomfort were not significantly altered. However, the intragastric volumes and the corresponding calculated wall tensions at perception and discomfort thresholds were significantly increased. CONCLUSIONS: Administration of the 5-HT(1) receptor agonist sumatriptan induces a relaxation of the gastric fundus in man, allowing larger intragastric volumes before thresholds for perception or discomfort are reached. The effects of sumatriptan on the gastric fundus may have therapeutic potential in the treatment of patients with functional dyspepsia.     

Dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification

BACKGROUND AND AIM: Duodenal acidification might increase sensitivity to gastric distension, which seems to play a role in the genesis of dyspeptic symptoms in a subset of patients with functional dyspepsia. The aim of the present study was to investigate the characteristics of dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification. METHODS: An infusion tube and a barostat bag were positioned in the duodenum and gastric fundus, respectively. Sensitivity to stepwise fundic distensions with severity scoring of the seven dyspeptic symptoms was assessed before and during duodenal acid infusion in 20 healthy subjects. RESULTS: Acid infusion significantly decreased the pressures and the corresponding wall tensions at the thresholds for discomfort. At the distending level of minimal distending pressure (MDP) + 2 mmHg, significantly higher scores of fullness and bloating were obtained during acid infusion. With distending stimuli of MDP + 4 and 6 mmHg, fullness, bloating, nausea, satiety, epigastric burning and epigastric pain were significantly more severe during acid infusion than before acid infusion. At the level of MDP + 8 mmHg, the severity of epigastric pain was significantly greater, compared with that before acid infusion. CONCLUSIONS: Duodenal acidification might aggravate dyspeptic symptoms through the induction of hypersensitivity to gastric distension in healthy individuals. Those symptoms are diverse and variable, depending on the strength of the distending stimuli.     

Relaxatory responses of canine proximal stomach to esophageal and duodenal distension

The viscerovisceral reflex control of gastric tone remains poorly characterized. We have previously demonstrated physiological variations in gastric tone that occur during fasting and after feeding. These variations are neurally regulated. We have now compared the reflex mechanisms modulating gastric tone that are elicited by esophageal or duodenal distension in fasted, conscious dogs. To determine the pathways involved in these reflexes, we combined the technique of vagal blockade (by cooling the supradiaphragmatic vagi isolated within a surgically implanted cooling jacket) with the administration of autonomic drugs. Gastric tone was measured as the air volume within an intragastric bag maintained at a constant, low pressure by an electronic barostat. Standardized distensions were performed by means of an inflatable balloon-catheter positioned either in the mid-esophagus (in three dogs) or in the distal duodenum (in three dogs). A profound and consistent gastric relaxation was induced by distension of either the esophagus (247 ±21 ml volume, P<0.05) or the duodenum (238±29 ml, P<0.05). Supradiaphragmatic vagal cooling abolished the gastric relaxatory response to duodenal distension and significantly reduced, but did not completely suppress, the response to esophageal distension. Neither cholinergic stimulation (intravenous bethanechol) nor adrenergic blockade (combined intravenous phentolamine and propranolol) had any significant effect on either gastric relaxatory response. Combined adrenergic and cholinergic (intravenous atropine) blockade induced gastric relaxation, but failed to suppress the gastric responses. We conclude that both esophageal and duodenal distension elicit gastric relaxation by a nonadrenergic, noncholinergic vagal mechanism.This work was supported in part by grant AM-26428 from the National Institutes of Health. CLINFO Data Management System was sponsored by grant RR-00585 from the National Institutes of Health.     

Evaluation of Individual Symptoms Cannot Predict Presence of Gastric Hypersensitivity in Functional Dyspepsia

Recently, the concept of gastric hypersensitivity was introduced as an important factor in the pathophysiology of functional dyspepsia (FD), but it is unclear which symptoms can predict the presence of gastric hypersensitivity. Therefore, we evaluated the relationship between common symptoms of FD and various parameters measured by gastric barostat in FD patients. Gastric barostat tests were performed in 64 FD patients and 20 healthy control subjects without gastrointestinal symptoms. Individual symptoms such as early satiety, postprandial fullness, sense of delayed emptying, nausea, vomiting, and epigastric soreness were collected and graded as mild to severe. Basal tone, gastric compliance, and postprandial receptive relaxation were similar in controls and patients, the threshold of abdominal discomfort was lower in FD patients than in controls (8.9 ± 3.6 mm Hg and 14.5 ± 3.7 mm Hg, respectively, P < 0.05). However, there were no significant differences in the threshold of abdominal discomfort according to the severity of individual symptoms. In conclusion, a simple evaluation of individual symptoms could not predict the presence of gastric hypersensitivity.     

Pressure-induced gastric accommodation studied with a new distension paradigm. Abnormally low accommodation rate in patients with functional dyspepsia

Objective. A new distension paradigm, by which the gastric volume response to ramp-tonic distension can be analysed in detail, has been developed. The aim of this study was to investigate the applicability of this new paradigm in man, and to compare pressure-induced gastric accommodation in healthy volunteers (HV) and patients with functional dyspepsia (FD). Material and methods. Ten HV, and 11 FD patients were examined twice; once in the fasting state and once postprandially. Intragastric bag pressure was raised from 1 to 12?mmHg in 4?min (ramp phase) and then kept constant for 5?min (tonic phase). Results. Compared to HV, fasting FD patients had lower gastric accommodation rates (0.9±0.2 versus 2.5±0.4?ml/s, p=0.002), lower maximum volume (239±39 versus 428±64?ml, p=0.01) and a longer accommodation time (157±26 versus 92±15 s, p=0.03). A test meal prior to distension tended to normalize the response in FD patients. Conclusions. This new barostat paradigm allowed detailed analysis of short-term pressure-induced accommodation in man. Impaired gastric distension-induced accommodation is a novel abnormality in FD.     

Inhibitory effects of various types of stress on gastric tone and gastric myoelectrical activity in dogs

Objective. Stress impairs gastrointestinal motility, causing, for example, delayed gastric emptying and altered intestinal transit. However, little is known about the effect of various stress factors on gastric tone and gastric myoelectrical activity (GMA). The aim of this study was to assess the effect of various kinds of stress on gastric tone and GMA in a canine model. Material andmethods. Six dogs, implanted with a gastric cannula and one pair of gastric seromuscular electrodes, were studied. Three kinds of stress (visual, thermal, or audio stimulation) were applied in separate sessions. GMA and gastric tone were recorded for 30 min at baseline and 30 min during stress. Results. Visual stress (blinding) did not alter gastric tone or GMA; cold stress (ice water) and audio stress (loud noise) significantly inhibited gastric tone: gastric volume was increased from 107.2±13.5 ml at baseline to 135.6±23.8 ml with cold stress (p=0.041), and from 106.4±5.7 ml at baseline to 159.2±15.1 ml with audio stress (p=0.007). Although the dominant frequency or power of gastric slow waves was not altered, the percentage of normal gastric slow waves was markedly reduced from 98.3±0.8 to 87.5±3.7 with cold stress and from 90.2±3.3 to 80.6±2.9 with audio stress (p<0.05). Conclusions. Cold- and audio stress inhibit gastric tone and impair gastric slow waves, whereas visual stress does not seem to have such effects. These findings will help to increase our understanding of gastrointestinal motor disorders related to stress.     

Effect of atropine on proximal gastric motor and sensory function in normal subjects

BACKGROUND AND AIMS: Distension of the proximal stomach is a major stimulus for triggering transient lower oesophageal sphincter (LOS) relaxations. We have shown recently that atropine inhibits triggering of transient LOS relaxations in both normal subjects and patients with gastro-oesophageal reflux disease. Atropine could potentially act centrally by inhibiting the central integrating mechanism in the brain stem, or act peripherally by altering the response of the stomach to distension. The aim of this study was to investigate the effect of atropine on fasting gastric compliance and postprandial gastric tone using an electronic barostat. METHODS: Fasting and postprandial proximal gastric motor and sensory functions were assessed in 10 normal healthy volunteers. Oesophageal manometry and pH were simultaneously measured. On separate days, atropine (15 microg/kg bolus, 4 microg/kg/h intravenous infusion) or saline was given and maintained for the duration of the recording period. RESULTS: In the fasting period, atropine significantly reduced minimum distending pressure (5.5 (0.4) v 4.4 (0.4) mm Hg; p<0.005) and increased proximal gastric compliance (81.3 (5.3) v 102. 1 (8.7) ml/ mm Hg; p<0.05). In response to a meal, maximal gastric relaxation was similar on both study days. However, during atropine infusion, there was no recovery of proximal gastric tone in the two hour postprandial observation period. Postprandial fullness scores were higher during atropine infusion and correlated with changes in intrabag volume. Atropine significantly reduced the rate of postprandial transient LOS relaxations: first hour, 7.0 (5.3-10.0) v 3.0 (1.0-4.0) (p<0.02); second hour, 5.0 (3.3-5.8) per hour v 1.0 (0-3.0) per hour (p<0.05). CONCLUSIONS: In humans, fasting and postprandial proximal gastric motor function is under cholinergic control. Atropine induced inhibition of transient LOS relaxations is unlikely to be caused by its effect on the proximal stomach, but rather by a central action on the integrating mechanisms in the brain stem.     

Effects of muscarinic receptor stimulation and nitric oxide synthase inhibition on gastric tone and gastric myoelectrical activity in canines

Aims:  This study was designed to assess whether the muscarinic receptor stimulation and nitric oxide synthase inhibition were equally effective on gastric fundic tone or gastric myoelectrical activity (GMA) in canines, and the correlation between gastric fundic tone and GMA.
Methods:  Gastric fundic tone and GMA were recorded on seven dogs implanted with serosal electrodes and a gastric cannula.
Results:  Bethanechol and L-nitro-N-arginine (L-NNA) significantly increased gastric fundic tone; gastric volume was decreased with bethanechol or L-NNA ( P  < 0.05). Increased spike activities were observed after both bethanechol and L-NNA. The percentage of slow waves superimposed with spikes was increased with bethanechol ( P  < 0.001) and L-NNA ( P  < 0.05). There was a significant reduction in dominant frequency (DF) ( P  < 0.05), dominant power (DP) ( P  < 0.05) and percentage of normal slow waves (%N) ( P  < 0.05) with bethanechol, while no significant change was observed with L-NNA. The variation of gastric tone was not correlated with parameters of GMA.
Conclusions:  Muscarinic receptor stimulation and nitric oxide synthase inhibition have similar effects on gastric tone and gastric spike activities, but different effects on gastric slow waves. Gastric fundic tone does not correlate with gastric slow waves.     

Correlation of Gastric Liquid Emptying with Various Thresholds of Sensation in Healthy Controls and Patients with Functional Dyspepsia

Our objective was to investigate the correlation between gastric emptying and sensation in patients with functional dyspepsia (FD). Thirty patients with FD and 15 controls were studied. Proximal gastric compliance and sensation thresholds were measured with a barostat, and gastric emptying was assessed for 70 min after the ingestion of 500 ml of water using real-time ultrasonography. Results were as follows. (1) Patients showed a significantly longer half-time of gastric emptying than controls (30.03 +/- 8.20 vs. 23.07 +/- 4.67 min; P < 0.001). The sensation thresholds were significantly lower in patients than in controls based not only on pressure but on volume. However, there was no difference in gastric compliance between patients and controls. (2) The half-time of gastric emptying was correlated with various thresholds of sensation based on the volume (perception, r = -0.52, P < 0.005; discomfort, r = -0.54, P < 0.005; pain, r = -0.58, P < 0.005; maximal tolerance, r = -0.42, P < 0.005). But there was no significant correlation between gastric emptying and sensation thresholds based on pressure. Delayed gastric emptying and/or gastric hypersensitivity are present in more than 50% of FD patients. The coexistence of these two abnormalities is more common than the single impairment. There is a correlation between gastric emptying and visceral sensation to gastric distention in patients with FD.     

Long-pulse gastric electrical stimulation at tachygastrial frequency reduces food intake by inhibiting proximal gastric tone

Objective. To investigate the effects of long pulse gastric electrical stimulation (GES) at a tachygastrial frequency on food intake, gastric tone and gastric myoelectrical activity (GMA). Material and methods. Of twelve dogs implanted with electrodes and a gastric cannula, 6 underwent truncal vagotomy. Stimulus consisted of long pulses with a frequency of 9 cycles/min. Experiment one was performed in all dogs to test for food intake with or without GES. Experiment two on six normal dogs consisted of baseline, GES and recovery periods. Gastric volume and GMA were recorded. Results. 1) GES reduced food intake in both normal (398.5±111.7 g versus 573.0±97.9 g; p<0.02) and vagotomized dogs (170.6±100.4 g versus 401.0±97.3 g; p<0.05). 2) Gastric volume was increased with stimulation from 168.4±17.7 ml to 301.1±34.1 ml (p<0.02 ANOVA) and maintained at 271.8±27.6 ml. 3) The percentages of normal slow waves before, during and after GES were 83.3±4.6%, 38.0±3.5% and 61.0±12.5%, respectively (p=0.02 ANOVA). Conclusion. Long-pulse GES at tachygastrial frequency substantially reduces food intake, and is not mediated by the vagal pathway but attributed to relaxation of the stomach and impairment of intrinsic GMA.     

5-HT1-receptor agonist sumatriptan modifies gastric size after 500 ml of water in dyspeptic patients and normal subjects

Sumatriptan, a 5-HT₁-receptor agonist has been shown to delay gastric emptying of liquids and solids in humans. However, no data are available of the effect of sumatriptan on gastric adaptation after distension with liquids and on symptoms induced by gastric distension. In 23 normal subjects and 30 dyspeptic patients with normal upper gastrointestinal endoscopy and real-time ultrasonography, the transverse gastric proximal and distal area and sagittal axis of the proximal stomach were determined by real-time ultrasonography and computed tomography after 500 ml of water. The area was determined by real-time ultrasonography and computed tomography twice at times 48 hr apart. Thirty minutes before real-time ultrasonography, placebo or sumatriptam were give subcutaneously in a double-blind fashion. Epigastric pain, bloating, heartburn, and nausea were also monitored through an intensity score from zero to 10 performed during the test. In six dyspeptic patients, the gastric distension was performed also with real-time ultrasonography and computed tomography after placebo and hyoscine butyl-bromide, a quaternary anticholinergic agent. Real-time ultrasonography and computed tomography demonstrated that after sumatriptan there is a reduction in proximal and distal transverse area and an increase in the sagittal axis of the proximal stomach. Hyoscine butyl-bromide increased all gastric measurements. Among the symptoms evaluated, only nausea was significantly reduced by sumatriptan (P < 0.01). Sumatriptan modifies gastric size, with a reduction in the transverse section and an increase of the sagittal axis of the proximal stomach and improves the nausea induced by gastric distension in dyspeptic patients.     

胃胀舒合剂对功能性消化不良大鼠胃排空及血浆胃肠激素水平的影响

[目的]观察胃胀舒合剂对功能性消化不良（FD）大鼠胃排空和胃肠激素的影响，探讨其可能的作用机制。[方法]采用不规则进食加稀盐酸喂养以及劳倦过度的复合因素制作大鼠FD模型。随机分成胃胀舒合剂高、低剂量（高、低剂量）组、多潘立酮组、正常对照（正常）组、模型对照（模型）组共5组，连续给药14d后，放免法检测血浆胃动素（MOT）和生长抑素（SS）水平，以酚红法观察胃排空。[结果]与正常组相比，模型组胃排空和血浆MOT水平显著降低，SS显著升高（均P〈0．05），与模型组相比，高、低剂量及多潘立酮组胃排空和血浆MOT显著升高，SS显著降低（均P〈0．05）。[结论]胃胀舒合剂具有促进内源性MOT及抑制SS释放和促进胃排空作用，是其治疗FD机制之一。     

Effects of nifedipine on esophageal tone and perception of esophageal distension

The effects of nifedipine (20 mg orally) on esophageal body resting tone and perception of esophageal distension were compared with those of placebo in 10 healthy volunteers, using a double-blind crossover design. A 3-cm silicon balloon positioned 10 cm above the lower esophageal sphincter was inflated with 2–20 ml of air, in 2-ml increments. The subjects scored their chest sensations, while pressure in the balloon was continuously recorded. In each experiment three series of measurements were made, at baseline and 15 and 30 min after administration of nifedipine or placebo. Bench tests were run to determine pressure-to-volume relationships for each of the balloons used in the study. Thirty minutes after nifedipine ingestion, a significant decrease in systolic blood pressure (from 112.6±2.3 to 99.0±2.0 mm Hg) was observed. Amplitude and duration of esophageal peristaltic contractions were significantly decreased by nifedipine (from 128.1±16.7 to 98.7±10.6 mm Hg and from 3.9±0.3 to 3.3±0.2 sec, respectively). With balloon volumes of 8 ml and higher, balloon pressures were higher with the balloon in the esophagus than on the bench, the difference being determined by the compliance of the esophagus. This difference rose from 18.5±6.8 to 40.2±7.2 mm Hg (8–20 ml) with placebo and from 23.1±3.7 to 35.9±5.8 mm Hg with nifedipine. No significant differences between nifedipine and placebo were found. The esophageal sensation scores increased linearly with increasing balloon volume from 6 ml onwards. Nifedipine had no significant effect on the perception of esophageal balloon distension.     

Effect of cisapride on gastric emptying in dyspeptic patients

The effect of the new gastrokinetic agent cisapride on gastric emptying was evaluated in 17 dyspeptic patients using the dual radionuclide technique. Eight patients with idiopathic dyspepsia and nine postsurgical dyspeptic patients were studied and compared to a control group. Gastric emptying of solids and liquids was determined after ingestion of a standardized meal using^99mTc-sulfur colloid scrambled eggs as the solid phase and [¹¹¹In]DTPA-labeled water as the liquid phase. Following a basal study and on a separate occasion, each patient received an intravenous bolus of 10 mg of cisapride after ingestion of the test meal; 10 of the patients were restudied after a two-week period of chronic oral administration of the drug (10 mg four times a day). Baseline gastric emptying of solids was significantly delayed in idiopathic and postsurgical patients; liquid emptying was only delayed in the postsurgical group. Intravenous and oral administration of cisapride significantly shortened gastric emptying in both groups. In all but one patient, the clinical improvement was confirmed by the test. Cisapride appears to be a good alternative to metoclopramide and domperiodone in the treatment of dyspeptic patients. The dual radionuclide technique appears to be a useful physiologic tool for evaluating and predicting the efficacy of a gastric prokinetic therapy in man.     

多潘立酮对功能性消化不良患者阻抗式胃动力的影响

目的观察多潘立酮对功能性消化不良(FD)餐后不适综合征(PDS组)和上腹疼痛综合征(EPS组)临床症状和胃动力的影响。方法对2008年10月至2009年4月重庆医科大学附属第一医院消化内科门诊57例FD患者行症状分型和评分、检测餐后胃电和胃阻抗,多潘立酮10mg每日3次治疗2周和4周后,再次评分并复查胃动力。结果治疗2周后,PDS组和EPS组餐后饱胀不适、早饱感、上腹痛、上腹烧灼感症状较治疗前显著改善(P0.05);4周后除PDS组上腹烧灼感和EPS组早饱感、上腹痛外余症状均进一步改善(P0.05)。治疗前和治疗后2周及4周PDS组和EPS组的胃电中频百分比差异均有统计学意义(P0.05)。PDS组治疗2周后胃阻抗中频百分比较治疗前显著提高,4周后进一步提高(P0.05);治疗4周后,EPS组胃阻抗中频百分比显著高于治疗前和治疗后2周(P0.05)。结论多潘立酮治疗4周后FD患者的临床症状、胃电和胃阻抗显著改善,明显优于治疗后2周。     

Rectal Distension Modulates Canine Gastric Tone and Accommodation

Rectal distension affects upper GI myoelectrical activity and motility. The aim of this experiment was to investigate the effect of rectal distension on gastric tone, accommodation, and the underlying mechanism. Seven healthy dogs were surgically prepared and studied. Gastric tone and accommodation were assessed with a barostat. In Experiment 1, the effect of rectal distension on gastric tone and accommodation was evaluated; in Experiment 2, rectal distensions with various volumes were randomly applied and its effects on gastric tone were evaluated; and in Experiment 3, the role of the cholinergic pathway in distension-induced gastric relaxation was assessed. The results showed the following. (1) Rectal distension exerted an inhibitory effect on gastric tone, and this response was distension volume-dependent. (2) Postprandial gastric volume was similar in the control (468.6 ± 24.7 ml) and the distension study (463.2 ± 17.5 ml). However, rectal distension increased the preprandial gastric volume, and subsequently decreased the extent of gastric accommodation (139.3 ± 34.7 ml), which was significantly lower than that of the control (383.2 ± 26.3 ml; P < 0.001). (3) An intravenous bolus of atropine increased the astric volume from the baseline of 89.4 ± 12.6 ml to 161.5 ± 9.8 ml (P < 0.01), and subsequent rectal distension further increased this volume, but the overall change was comparable between the control (297.6 ± 18.7 ml) and the atropine study (312.1 ± 21.9 ml; P > 0.05). In conclusion, rectal distension inhibits gastric tone in a volume-dependent manner and impairs gastric accommodation. Atropine dose not block the effect of rectal distension on proximal gastric tone, suggesting that the observed effect may not be mediated by cholinergic pathway.     

Sensations induced by medium and long chain triglycerides: role of gastric tone and hormones

BACKGROUND: The relative roles of gastric relaxation and the neuroendocrine signals released by the small intestine in the perception of nutrient induced sensations are controversial. The different effects of long chain (LCT) and medium chain (MCT) triglyceride ingestion on perception, gastric relaxation, and hormonal release may help to elucidate the mechanisms underlying nutrient induced sensations. AIMS: To compare the effects of intraduodenal LCT and MCT infusions on perception, gastric tone, and plasma gut hormone levels in healthy subjects. SUBJECTS: Nine fasting healthy volunteers. METHODS: The subjects received duodenal infusions of saline followed by LCTs and MCTs in a randomised order on two different days. The sensations were rated on a visual analogue scale. Gastric tone was measured using a barostat, and plasma gut hormone levels by radioimmunoassay. RESULTS: LCT infusion increased satiation scores, reduced gastric tone, and increased the levels of plasma cholecystokinin, gastric inhibitory polypeptide, neurotensin, and pancreatic polypeptide. MCT infusion reduced gastric tone but did not significantly affect perception or plasma gut hormone levels. LCTs produced greater gastric relaxation than MCTs. CONCLUSIONS: The satiation induced by intraduodenal LCT infusion seems to involve changes in gastric tone and plasma gut hormone levels. The gastric relaxation induced by MCT infusion, together with the absence of any significant change in satiation scores and plasma hormone levels, suggests that, at least up to a certain level, gastric relaxation is not sufficient to induce satiation and that nutrient induced gastric relaxation may occur through cholecystokinin independent mechanisms.